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Comparison of methods of measuring the brachial systolic pressure in determining the ankle/brachial index O'Flynn, Ellen Ivy 1991

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COMPARISON OF METHODS OF MEASURING THE BRACHIAL SYSTOLIC PRESSURE IN DETERMINING THE ANKLE/BRACHIAL INDEX by ELLEN IVY 0'FLYNN B.S.N., The U n i v e r s i t y of B r i t i s h C o l u m b i a , 1973 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE IN NURSING i n THE FACULTY OF GRADUATE STUDIES S c h o o l of N u r s i n g We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH A p r i l 1991 © E l l e n i v y o ' F l y n n , COLUMBIA 1991 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University of British Columbia Vancouver, Canada DE-6 (2/88) i i ABSTRACT T h i s s t u d y was d e s i g n e d t o dete r m i n e which method of measuring the s y s t o l i c b l o o d p r e s s u r e Is more a c c u r a t e when d e t e r m i n i n g the a n k l e / b r a c h l a l i n d e x ( A B I ) , which i s an i m p o r t a n t t o o l i n a s s e s s i n g g r a f t p a t e n c y f o r p a t i e n t s who have had p e r i p h e r a l v a s c u l a r s u r g e r y . The a c c u r a c y of the s t e t h o s c o p e diaphragm was compared w i t h the s t e t h o s c o p e b e l l and Doppler methods used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e . These p r e s s u r e s were then used i n the c a l c u l a t i o n of the ABI and then the ABI was compared by method and time s i n c e s u r g e r y . The t h e o r e t i c a l framework f o r t h i s s t u d y was drawn from t h e o r i e s on sound g e n e r a t i o n , t r a n s m i s s i o n and measurement. T h i s s t u d y used a two-repeated measures d e s i g n i n which the s u b j e c t s s e r v e d as t h e i r own c o n t r o l . The r e s u l t s were t h e n a n a l y z e d u s i n g an ANOVA s p e c i f i c t o a two-repeated measures d e s i g n . The sample c o n s i s t e d of 31 s u b j e c t s which comprised 80% of a l l p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s a d m i t t e d over a two month p e r i o d t o a l a r g e t e r t i a r y c a r e h o s p i t a l i n Western Canada. The s u b j e c t s ranged i n age from 47 t o 82 y e a r s , the m a j o r i t y had at l e a s t one o t h e r m e d i c a l c o n d i t i o n i n a d d i t i o n t o p e r i p h e r a l v a s c u l a r d i s e a s e , were on a v a r i e t y of m e d i c a t i o n s , and 35% had had p r e v i o u s v a s c u l a r s u r g e r y . The s u b j e c t s had t h e i r b r a c h i a l s y s t o l i c b l o o d p r e s s u r e measured by the t h r e e methods on the t h i r d , f o u r t h and f i f t h p o s t o p e r a t i v e day. At t h e same time t h e y a l s o had t h e i r d o r s a l l s p e d i s and p o s t e r i o r t i b i a l p r e s s u r e s measured by the Doppler method. H i There was no s i g n i f i c a n t d i f f e r e n c e i n the b r a c h i a l s y s t o l i c b l o o d p r e s s u r e r e l a t e d t o the methods used t o t a k e t h e b l o o d p r e s s u r e , the p o s t o p e r a t i v e day t h a t the b l o o d p r e s s u r e was measured, nor was t h e r e any i n t e r a c t i o n between method and o c c a s i o n . A l s o , t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n e i t h e r the d o r s a l i s p e d i s or p o s t e r i o r t i b i a l a n k l e / b r a c h l a l i n d i c e s r e l a t e d t o method used t o measure the b r a c h i a l s y s t o l i c b l o o d p r e s s u r e , t h e p o s t o p e r a t i v e day the measurement was t a k e n , nor any i n t e r a c t i o n between method and o c c a s i o n . The f i n d i n g s suggest t h a t p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s o f t e n have s y s t o l i c p r e s s u r e s t h a t d i f f e r between the r i g h t and l e f t arm which would make a major d i f f e r e n c e i n t h e c a l c u l a t i o n of the ABI. T h e r e f o r e , the p r e s s u r e s s h o u l d be measured i n bo t h arms, f o l l o w e d by do c u m e n t a t i o n and c o n s i s t e n t use of the arm w i t h t h e h i g h e s t p r e s s u r e when d e t e r m i n i n g the ABI. The f i n d i n g s a l s o suggest t h a t l n s e r v i c e e d u c a t i o n and p e r i o d i c s k i l l c h e c k i n g be implemented when the nurse i s r e q u i r e d t o employ the Doppler method owing t o the number of v a r i a b l e s t o c o n s i d e r when o p e r a t i n g t h i s i n s t r u m e n t . Table of contents Page ABSTRACT. 11 LIST OF TABLES , v i i LIST OF FIGURES. . . . . . ix ACKNOWLEDGEMENTS . . . . . , .X CHAPTER ONE: INTRODUCTION . 1 Introduction. 1 Background to the Problem.. . . 1 Problem Statement . 3 Purpose . . 4 Theoretical Framework...... . . . . . . . . 4 Research Questions. . 9 D e f i n i t i o n of Terms. . . 9 Brachial S y s t o l i c Blood Pressure.. 10 Ankle S y s t o l i c Blood P r e s s u r e . . . . . . . . . . 1 0 Peripheral Vascular Bypass S u r g e r y — . . 10 Ankle/Brachlal Index.. . 11 Continuous Wave U l t r a s o n i c Doppler 11 Assumptions . 11 Limitations 12 Significance 12 S c i e n t i f i c Significance 12 Significance to Patient Care . . . . 1 3 Overview of Thesis Content 14 CHAPTER TWO: REVIEW OF THE LITERATURE . . . 1 6 Introduction 16 Factors Affecting the Generation, Transmission and Measurement of Sound.. . . .16 Research Studies Comparing Methods of Measuring the S y s t o l i c Blood Pressure 23 Summary 26 CHAPTER THREE: METHODS 29 Introduction. . 2 9 Research D e s i g n . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . 2 9 Sample Selection and Sample C r i t e r i a . . . 3 0 Data C o l l e c t ion Instruments 32 Stethoscope 32 Sphygmomanometer . 32 Portable Continuous Wave Ultrasonic Doppler . 3 3 Data C o l l e c t i o n Sheet 34 Data Collection-Procedure 34 P i l o t Study 35 Data Analysis. 35 Procedures for Protection of Human R i g h t s — 3 6 Summary . 37 CHAPTER FOUR: PRESENTATION AND DISCUSSION OF RESULTS 39 Introduction. 39 Charact e r i s t i c s of the Sample 39 Demographic c h a r a c t e r i s t i c s of Sample..39 Surgical and Medical Status............40 Findings 42 Question 1. Differences In Brachial S y s t o l i c Blood Pressure By • • Method of Measurement .42 Question 2. Difference In The Ankle/Brachial Index By Method of Measuring the Brachial S y s t o l i c Pressure • .47 Discussion of Sample .61 Comparison of Sample With Target Population 61 Age. .62 Gender .. 62 Arteries Bypassed and Type of Surgery 64 Previous Vascular Surgery... 64 Medical Status .65 Medications 66 Discussion of Findings .67 Level of Brachial S y s t o l i c Pressure....67 Ankle/Brachial Index .71 Level of Ankle S y s t o l i c Pressure..71 Changes in the Ankle S y s t o l i c Pressure Over the Three Days 73 Level of ABI 74 Summary of Findings. 76 CHAPTER FIVE: SUMMARY, CONCLUSIONS AND RECOMMENDATIONS. . .80 Introduction.. .80 Summary. .80 Cone 1 us ions 85 Implications 86 Nursing Practice and Education 86 Theory... .. .88 Recommendations for Further Research. 89 REFERENCES . . . .91 APPENDICES A. Mercury Desk Model: 300 mm.. 95 B. Portable Ultrasonic Doppler: Model 812.. .96 C. Data C o l l e c t i o n Sheet .97 D. Patient Informed Consent. ... .98 E. Procedures for Determining the Brachial S y s t o l i c Pressure. *. .100 F. Procedures for Determining the Ankle S y s t o l i c Pressure ..103 Procedure for Determining the ABI L i s t of Tables Page Table 1. Age D i s t r i b u t i o n of the Sample....... 40 Table 2 . Frequency of Arteries Bypassed i n t h i s Sample.. . . . . . . . . . 4 1 Table 3 . Frequency of Surgical Procedures Performed on t h i s Sample ... . 41 Table 4 . Brachial S y s t o l i c Pressure Recordings by Method. . . 44 Table 5 . Means and Standard Deviations for Brachial S y s t o l i c Pressures by Day • and Method 45 Table 6 . Difference in Brachial S y s t o l i c Pressures by Method of Measurement. . . i . . . . . . 4 6 Table 7. Analysis of Variance Summary Table for Measurement, Time-Period and Brachial S y s t o l i c Pressure 47 Table 8 . DorsalIs Pedis Pressures on Each Day. . . 4 8 Table 9 . Means and Standard Deviations of Dorsalis Pedis and Posterior T i b i a l Pressures 49 Table 1 0 . Posterior T i b i a l Pressures on Each Day. . . . . . . . 4 9 Table 1 1 . Dorsalis Pedis Ankle/Brachial Index on Each Day by a 11 Methods............... . . 51 Table 1 2 . Dorsalis Pedis Ankle/Brachial Index by Method of Measur ing the Brachia1 S y s t o l i c Pressure 52 Table 1 3 . Dorsalis Pedis Ankle/Brachial Index Means and Standard Deviations by Day and Method 53 Table 1 4 . Difference i n Dorsalis Pedis Ankle/ Brachial Index by Method of Measurement .54 Table 15. Analysis of variance summary Table for Measurement Method, Time Per iod and Dorsal i s Ped is Ankle/Brachial Index 55 Table 16. Poster tor T i b i a l Ankle/Brachial Index Each Day by a l l Methods. .56 Table 17. Posterior T i b i a l Ankle/Brachial Index by Method of Measuring the Brachial S y s t o l i c Pressure .. 57 Table 18. Posterior T i b i a l Ankle/Brachial index Means and standard Deviations by Day and Method 59 Table 19. Difference in Posterior T i b i a l Ankle/ Brachial Index by Method of Measurement. .. .60 Table 20. Analysis of Variance Summary Table for Measurement Method, Time Period and- Posterior T i b i a l Ankle/Brachlal Index .61 Table 21. Comparison of sample with Target Population .. .. .63 ix L i s t of Figures Page Figure 1 .-/Theoretical Framework Reflecting Factors That Influence A r t e r i a l Sound Generation, Transmission, > and Measurement. . . . . ..-.-•. -i 5 Figure 2. Design for Measuring Differences Related to Occasion and Method for Brachial S y s t o l i c Pressures.. .30 X ACKNOWLEDGEMENTS I would l i k e to thank the members of my thesis committee, Dr. Ann Hilton (chairperson) and Ethel Warbinekfor sharing t h e i r expertise and providing guidance. I would l i k e to thank my friends for their support and -encouragement throughout t h i s endeavour. My appreciation i s extended to the nursing s t a f f and surgeons of the vascular unit and the biomedical technicians of -the hospita 1 -where the study was conducted. I would l i k e to thank Lynn Maxwell who d i l i g e n t l y collected the data and provided support •during the course of t h i s study. I am gratef u l to the Vancouver Medical Foundation for th e i r f1nancial support and Dr. W.B. Boldt for-his assistance 1n analyzing the data. F i n a l l y , I would l i k e to thank the patients who participated in t h i s study. 1 CHAPTER ONE I n t r o d u c t i o n Background t o the Problem The i n c i d e n c e of p a t i e n t m o r b i d i t y i n v o l v i n g a t h e r o s c l e r o s i s and a l l o t h e r d i s e a s e s of the a r t e r i e s , a r t e r i o l e s and c a p i l l a r i e s c o n t r i b u t e d t o 3 2 , 4 1 0 h o s p i t a l a d m i s s i o n s i n Canada i n the y e a r s 1 9 8 7 - 1 9 8 8 . One of the c o m p l i c a t i o n s of such a d i a g n o s i s i s the bl o c k a g e of an a r t e r y r e s u l t i n g In the need f o r a p e r i p h e r a l v a s c u l a r bypass. Over 350 p e r i p h e r a l v a s c u l a r bypass o p e r a t i o n s a r e performed each year i n one of Vancouver's l a r g e t e r t i a r y c a r e h o s p i t a l s . These s u r g e r i e s I n v o l v e b y p a s s i n g b l o c k a g e s i n a r t e r i e s by means of a v e i n or a s y n t h e t i c g r a f t . A f t e r s u r g e r y , t h e s e p a t i e n t s a r e a t r i s k f o r g r a f t o c c l u s i o n . Acute g r a f t o c c l u s i o n due t o t h r o m b o s i s o c c u r s i n a p p r o x i m a t e l y 5 t o 15% of f e m o r a l - p o p l i t e a l g r a f t s and i n 15 t o 30% of more d i s t a l bypasses t o the t i b i a l or p e r o n e a l v e s s e l s i n the c a l f ( B r e w s t e r , 1 9 8 5 ) . Dean and Yao (1976) s t a t e t h a t r e t u r n of a p e d a l p u l s e u s u a l l y i n d i c a t e s a p a t e n t bypass, but the v a r i a b i l i t y i n p a l p a t i o n of p u l s e s by d i f f e r e n t o b s e r v e r s , e s p e c i a l l y i n b o r d e r l i n e c a s e s and i n the presence of p o s t o p e r a t i v e edema, o f t e n makes t h i s method of assessment u n r e l i a b l e . I n c o n t r a s t , c a l c u l a t i o n of the a n k l e / b r a c h i a l Index (ABI) o f f e r s a s i m p l e , o b j e c t i v e and r e l i a b l e method of a s s e s s i n g the p a t e n c y of a r t e r i a l r e c o n s t r u c t i o n . The a n k l e / b r a c h i a l i n d e x i s d e t e r m i n e d by d i v i d i n g the a n k l e s y s t o l i c p r e s s u r e ( a n k l e SP) by the b r a c h i a l s y s t o l i c p r e s s u r e ( b r a c h i a l S P ) . A normal i n d e x , 2 i n d i c a t i n g good f l o w t o the e x t r e m i t y , Is c l o s e t o one. However, i n a p a t i e n t w i t h compromised c i r c u l a t i o n t o the lower l i m b the index i s much l e s s than t h i s (Dean & Yao, 1976; Nurse Review, 1988). P a t i e n t s , who have had p e r i p h e r a l v a s c u l a r bypass g r a f t s , r e q u i r e a c c u r a t e assessment of g r a f t p a t e n c y . The nur s e s on the v a s c u l a r u n i t i n a l a r g e m e t r o p o l i t a n h o s p i t a l i n Vancouver were d e l e g a t e d the procedure of d e t e r m i n i n g the a n k l e / b r a c h l a l i n d e x by the m e d i c a l s t a f f . As t h e n u r s i n g i n s t r u c t o r a s s i g n e d t o t h a t u n i t , t h i s i n v e s t i g a t o r was charged w i t h d r a f t i n g the procedure f o r d e t e r m i n i n g t h e ABI. I n a s e a r c h of t h e n u r s i n g l i t e r a t u r e l i t t l e i n f o r m a t i o n was found r e g a r d i n g the d e t e r m i n a t i o n of ABI i n a s s e s s i n g the pa t e n c y of p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass g r a f t s . The l i t e r a t u r e t h a t d i d d e s c r i b e how t o dete r m i n e the ABI su g g e s t e d the use of t h e u l t r a s o n i c Doppler i n d e t e r m i n i n g the a n k l e SP, but d i d not i n d i c a t e whether t o use a Doppler or a s t e t h o s c o p e i n the assessment of t h e b r a c h i a l SP ( B a s t a r a c h e , G l u c a , H o r o w i t z , & S h e l l e y , 1983; Fahey, 1988; Nurse  Review, 1988). F u r t h e r s e a r c h of m e d i c a l l i t e r a t u r e and d i s c u s s i o n w i t h some of the l o c a l v a s c u l a r surgeons r e v e a l e d t h a t o p i n i o n was d i v i d e d whether the Doppler or the a u s c u l t a t o r y ( s t e t h o s c o p e ) method s h o u l d be used In a s s e s s i n g the b r a c h i a l SP ( C a r t e r , 1968; Yao, Hobbs, & I r v i n e , 1969; D. T a y l o r , p e r s o n a l communication, March, 1990; J. S l a d e n , p e r s o n a l communication, March, 1990). I n a d d i t i o n , a n o t h e r l a r g e h o s p i t a l In Vancouver w i t h a v a s c u l a r u n i t was c o n t a c t e d and t h e i r ABI procedure was r e v i e w e d . 3 I n t h e i r d e t e r m i n a t i o n o£ the ABI the Doppler was used f o r both b r a c h i a l SP and a n k l e SP measurements (Kocher, Buden and Howard, 1989). O b s e r v a t i o n of nu r s e s and r e v i e w of the l i t e r a t u r e on t a k i n g s y s t o l i c p r e s s u r e s i l l u s t r a t e d a n o t h e r v a r i a t i o n between the use of the s t e t h o s c o p e diaphragm and s t e t h o s c o p e b e l l i n d e t e r m i n i n g the s y s t o l i c b l o o d p r e s s u r e . On the one hand, the nu r s e s were observ e d u s i n g the s t e t h o s c o p e diaphragm, on the o t h e r , the l i t e r a t u r e s u p p o r t s the use of the s t e t h o s c o p e b e l l i n d e t e r m i n i n g the b r a c h i a l SP ( C o n s t a n t , 1987; F r o h l i c h , Grim, L a b a r t h e , M a x w e l l , P e r l o f f , & Weidman, 1988; Rudy, 1986). Problem Statement A f t e r a p a t i e n t has had a p e r i p h e r a l v a s c u l a r bypass g r a f t , 5-15% of f e m o r a l - p o p l i t e a l and 15-30% of more d i s t a l bypass g r a f t s a r e a t r i s k f o r a c u t e g r a f t o c c l u s i o n t h a t can r e s u l t i n g r a f t f a i l u r e . I f g r a f t f a i l u r e i s not d e t e c t e d e a r l y t h e n the p a t i e n t w i l l have t o r e t u r n t o the o p e r a t i n g room t o have the g r a f t r e p l a c e d . Nurses a r e r e s p o n s i b l e f o r a s s e s s i n g f o r g r a f t f a i l u r e by d e t e r m i n i n g the ABI; t h e r e a r e two methods by which t h i s may be d e t e r m i n e d . One method uses a u s c u l t a t i o n ( s t e t h o s c o p e ) t o measure the b r a c h i a l SP and an u l t r a s o n i c Doppler t o measure t h e a n k l e SP and the o t h e r method uses the u l t r a s o n i c Doppler f o r both the b r a c h i a l SP and a n k l e SP. I t i s not c l e a r from the l i t e r a t u r e and from d i s c u s s i o n w i t h v a s c u l a r surgeons which of the two methods i s the more a c c u r a t e when d e t e r m i n i n g ABI. I f one method i s not as a c c u r a t e as the o t h e r , the assessment of the b r a c h i a l SP can l e a d t o a f a l s e h i g h ABI 4 and f a l s e r e a s s u r a n c e t h a t the g r a f t Is p a t e n t . Purpose The purpose of t h i s s t u d y was t o d e t e r m i n e the d i f f e r e n c e In the b r a c h i a l s y s t o l i c BP when the pressure was measured w i t h the s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and u l t r a s o n i c Doppler and t o d e t e r m i n e which method was most a c c u r a t e i n measuring the ABI. T h e o r e t i c a l Framework S i n c e b l o o d p r e s s u r e i s d e t e r m i n e d t h r o u g h the d e t e c t i o n of sound waves, the t h e o r e t i c a l framework used i n t h i s s t u d y i n c l u d e d f a c t o r s a f f e c t i n g (1) the g e n e r a t i o n of sound waves, (2) t h e t r a n s m i s s i o n of sound waves and (3) the measurement of sound waves (see F i g u r e 1). Sound waves r e s u l t from m o l e c u l a r c o m p r e s s i o n and decompression of matter i n the a i r , l i q u i d s or s o l i d s t h a t produce a v i b r a t i n g m o t i o n . The s i z e of the wave ( a m p l i t u d e ) , t h e d i s t a n c e i t t r a v e l s and the f r e q u e n c y (number of waves per second) a r e d e t e r m i n e d by the i n i t i a l magnitude of the energy f o r c e c a u s i n g the v i b r a t i o n s . The f r e q u e n c y and a m p l i t u d e of the sound wave d e t e r m i n e s i f the sound wave i s l n f r a s o n i c (below a u d i b l e r a n g e ) , s o n i c ( w i t h i n a u d i b l e range) or u l t r a s o n i c (above a u d i b l e r a n g e ) , when the sound waves a r e p r o p e l l e d outward t h e y may s t r i k e o b j e c t s of d i f f e r e n t m a t e r i a l . Upon s t r i k i n g t h e s e o b j e c t s sound waves may do one of t h r e e t h i n g s : t h e y may be r e f l e c t e d , absorbed or t r a n s m i t t e d by a d i f f e r e n t m a t e r i a l , i n which c a s e , t h e i r d i r e c t i o n or p r o p a g a t i o n and speed of t r a n s m i s s i o n a r e changed. To measure sound waves, one uses I n s t r u m e n t s t o c o n v e r t some of the energy c o n t a i n e d i n the Figure 1 Theoretical Framework Reflecting Factors that Influence A r t e r i a l  Sound Generation Transmission and Measurement A r t e r i a l Vibration Waves T R A N S M I S S I N Blood volume Factors a f f e c t i n g generation Cardiac contraction WAVES DEFINED BY: Frequency: number of waves/vibrations per second determines-pitch Amplitude: height of wave determines strength or loudness of sound TYPE OF SOUND WAVE: Infrasonic: low frequency & amplitude not detectable by human ear Sonic: detectable by human ear Ultra soni c: h i gh £requency not detectable by the human ear Factors a f f e c t i n g transmission Within patient Transmitted Absorbed Reflected Observer 4h -Factors a f f e c t i n g measurement 7 Within observer Within patient Procedure/ Equipment Environment 6 v i b r a t i o n a l motion of the medium I n t o a s i g n a l t h a t can be measured ( H u l s l z e r , & L a z a r u s , 1972; Kuhn, 1979; W i n t e r , 1967) F a c t o r s A f f e c t i n g the G e n e r a t i o n of Sound waves Two f a c t o r s t h a t a f f e c t the g e n e r a t i o n of sound waves i n the a r t e r y I n c l u d e the s t r e n g t h of the c a r d i a c c o n t r a c t i o n and the volume of b l o o d i n the v a s c u l a r system. The a m p l i t u d e and f r e q u e n c y of sound t h a t i s g e n e r a t e d i n an a r t e r y a r e d e t e r m i n e d by the volume of b l o o d t h a t the h e a r t e j e c t s w i t h each beat and by the s t r e n g t h of c a r d i a c c o n t r a c t i o n , when the volume of b l o o d e j e c t e d from the h e a r t t r a v e l s a l o n g a normal a r t e r y i t changes the s i z e of the a r t e r y from a narrow t o a w i d e r c a l i b r e and c r e a t e s e d d i e s which make the b l o o d and v e s s e l w a l l v i b r a t e ( E m s l i e - S m i t h , P a t e r s o n , S c r a t c h e r d , & Read, 1988; Thompson, 1981). F a c t o r s A f f e c t i n g the T r a n s m i s s i o n of Sound Waves The f a c t o r s t h a t f a c i l i t a t e the t r a n s m i s s i o n of sound l i e w i t h i n the p a t i e n t and i n c l u d e the d i a m e t e r of the v e s s e l and any r e s i s t a n c e t h e sound wave must pass t h r o u g h i n i t s t r a n s m i s s i o n ( E m s l i e - S m i t h e t a l . , 1988). V e s s e l d i a m e t e r When a v e s s e l I s p a r t i a l l y o c c l u d e d or of s m a l l d i a m e t e r the sound wave t h a t i s g e n e r a t e d by c a r d i a c c o n t r a c t i o n i s dampened. In an a r t e r y of s m a l l d i a m e t e r the volume of b l o o d causes o n l y s m a l l v i b r a t i o n s In the v e s s e l w a l l . When the v e s s e l i s o c c l u d e d th e wave i s dampened by the o c c l u s i o n ( E m s l i e - S m i t h e t a l . , 1988). 7 R e s i s t a n c e The gap t h a t the sound wave must c r o s s over b e f o r e i t can be t r a n s f o r m e d i n t o an a u d i b l e o u t p u t a f f e c t s the q u a l i t y and q u a n t i t y of sound d e t e c t e d . As the gap the sound wave must c r o s s i n c r e a s e s t h e r e i s a d e c r e a s e i n t h e q u a l i t y and q u a n t i t y of the sound t r a n s m i t t e d s i n c e the energy i n the sound wave i s d i s s i p a t e d w i t h d i s t a n c e ( W i n t e r , 1967). F a c t o r s A f f e c t i n g t h e Measurement of Sound Four f a c t o r s a f f e c t the a c c u r a t e measurement of sound. They a r e f a c t o r s : (1) i n h e r e n t i n the o b s e r v e r measuring the sound, (2) i n h e r e n t w i t h i n the p a t i e n t , (3) w i t h i n t h e equipment or proced u r e and (4) i n the environment In which the measurement i s t a k e n . F a c t o r s w i t h i n the Observer The o b s e r v e r must be a b l e t o r e c e i v e , u n d e r s t a n d and i n t e r p r e t the d a t a t r a n s m i t t e d from the i n s t r u m e n t s employed and be a b l e t o use the i n s t r u m e n t c o r r e c t l y . C o n s t a n t (1987) s t a t e s t h a t both v i s u a l and h e a r i n g a c u i t y a r e n e c e s s a r y f o r t h e o b s e r v e r t o r e c e i v e the t r a n s m i t t e d sound when t a k i n g a b l o o d p r e s s u r e . F a c t o r s W i t h i n the P a t i e n t F a c t o r s t h a t i n h i b i t t h e measurement of the sound t r a n s m i t t e d from the a r t e r y i n c l u d e c a l c i f i c a t i o n of the a r t e r i a l w a l l and a r t e r i a l d i s e a s e . Both of the s e c o n d i t i o n s i n h i b i t c o m p r e s s i o n of the v e s s e l which i n t u r n can l e a d t o a f a l s e h i g h measurement of the s y s t o l i c p r e s s u r e ( C a r t e r , 1985; Yao, 1985). 8 Factors within the Equipment or Procedure The accurate measurement o£ sound Is affected by the type of equipment selected and the procedure used to determine t h i s measurement. sele c t i o n of Equipment. In order to accurately measure the sound transmitted from the artery the observer must employ equipment that is properly maintained. The blood pressure cuff must be of the appropriate size for the patient to avoid overestimating or underestimating the s y s t o l i c BP (Frohlich et a l . , 1988). Procedure. The observer must know how to use the equipment properly in order to obtain an accurate measurement of the sound. In order to use the equipment e f f e c t i v e l y the nurse must have coordination of eye, hand and ear s k i l l s for proper manipulation of equipment and detection of a r t e r i a l sounds (Constant, 1987). Factors In The Environment Factors in the environment w i l l also Interfere with the measurement of the sound emitted from the artery. Measurement of sound transmitted from the artery by a stethoscope or Doppler w i l l be compromised In a noisy environment since loud sounds In the environment w i l l override the sound detected from the artery. This t h e o r e t i c a l framework outlines the factors which may influence the generation, transmission and measurement of a r t e r i a l sound. It is based on the theory of sound transmission and i d e n t i f i e s three d i f f e r e n t types of sound waves: infrasonic, sonic and ultrasonic, in t h i s study infrasonic sound waves w i l l be converted to sonic sound by the stethoscope b e l l and 9 s t e t h o s c o p e diaphragm. The u l t r a s o n i c sound waves w i l l be c o n v e r t e d t o s o n i c sound by the D o p p l e r . When c o n v e r t e d the measurements o b t a i n e d by the s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and Doppler w i l l be compared. The t h e o r y of sound t r a n s m i s s i o n p r o v i d e d a framework f o r t h i s i n v e s t i g a t o r t o i d e n t i f y , u n d e r s t a n d and o r g a n i z e t h e v a r i a b l e s t o be c o n s i d e r e d i n comparing the d i f f e r e n t methods of measuring the s y s t o l i c b l o o d p r e s s u r e . I t a l s o p r o v i d e d d i r e c t i o n f o r d a t a c o l l e c t i o n p r o c e d u r e s and i n s t r u m e n t s i n o r d e r t h a t t h e s e methods may be compared. Rese a r c h Q u e s t i o n s The f o l l o w i n g r e s e a r c h q u e s t i o n s were a d d r e s s e d i n t h i s s t u d y . 1. What i s t h e d i f f e r e n c e i n the b r a c h i a l s y s t o l i c b l o o d p r e s s u r e of p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s when t h i s p r e s s u r e i s measured by s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and u l t r a s o n i c D o p p l e r ? 2. What i s the d i f f e r e n c e i n the a n k l e / b r a c h i a l i n d e x when the b r a c h i a l s y s t o l i c p r e s s u r e of p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s i s measured by s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and u l t r a s o n i c D o p p l e r ? D e f i n i t i o n of Terms The t h e o r e t i c a l and o p e r a t i o n a l d e f i n i t i o n s of the terms a d d r e s s e d i n t h e r e s e a r c h q u e s t i o n s a r e d e s c r i b e d below. The terms t o be a d d r e s s e d I n c l u d e : b r a c h i a l s y s t o l i c b l o o d p r e s s u r e , a n k l e s y s t o l i c b l o o d p r e s s u r e , p e r i p h e r a l v a s c u l a r s u r g e r y , a n k l e / b r a c h i a l Index and c o n t i n u o u s wave u l t r a s o n i c D o p p l e r . 10 B r a c h i a l S y s t o l i c B l o o d P r e s s u r e The b r a c h i a l s y s t o l i c p r e s s u r e i s d e f i n e d as the peak p r e s s u r e w i t h i n t h e b r a c h i a l a r t e r y g e n e r a t e d by the c o n t r a c t i o n of the l e f t v e n t r i c l e ( F r o h l l c h e t a l . , 1988). The b r a c h i a l SP i s det e r m i n e d by the f i r s t f a i n t , c l e a r t a p p i n g sounds t h a t g r a d u a l l y i n c r e a s e i n i n t e n s i t y when the p r e s s u r e e x e r t e d by the o c c l u d i n g c u f f i s l e s s t h a n t h e i n t r a - a r t e r i a l p r e s s u r e . To make s u r e the sound i s not e x t r a n e o u s , one s h o u l d hear a t l e a s t two c o n n e c t i v e b e a t s as the p r e s s u r e f a l l s ( F r o h l i c h e t a l . , 1988). The b r a c h i a l SP w i l l be measured by the s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and t h e u l t r a s o n i c D o p p l e r . A n k l e S y s t o l i c B l o o d P r e s s u r e The a n k l e s y s t o l i c p r e s s u r e i s d e f i n e d as the peak p r e s s u r e w i t h i n t h e d o r s a l i s p e d i s and p o s t e r i o r t i b i a l a r t e r i e s which i s ge n e r a t e d by c o n t r a c t i o n of the l e f t v e n t r i c l e . The a n k l e SP i s de t e r m i n e d by t h e f i r s t f a i n t c l e a r t a p p i n g sounds e m i t t e d t h r o u g h the speaker of the u l t r a s o n i c Doppler (O'Mara & Yao, 1982). P e r i p h e r a l V a s c u l a r Bypass S u r g e r y T h i s o p e r a t i o n i n v o l v e s r e s t o r i n g b l o o d f l o w by p r o v i d i n g an a l t e r n a t e r o u t e around a b l o c k a g e i n an a r t e r y of a l i m b of a p a t i e n t by means of a v e i n or s y n t h e t i c g r a f t (Fahey, 1988; B r e w s t e r , 1985). The s u r g e r i e s done t o bypass a r t e r i a l b l o c k a g e s of a p a t i e n t i n c l u d e f e m o r a l - p o p l i t e a l , f e m o r a l - f e m o r a l c r o s s -o v e r , f e m o r a l - t i b l a l , p o p l i t e a l - t i b i a l , p o p l i t e a l - p e r o n e a l and a o r t i c - f e m o r a l bypasses and abdominal a o r t i c r e s e c t i o n s . A n k l e / B r a c h l a l Index The i n d e x i s a r a t i o of a n k l e s y s t o l i c p r e s s u r e compared t o the b r a c h i a l s y s t o l i c p r e s s u r e . The p r e s s u r e i n an a r t e r y w i t h compromised b l o o d f l o w i s compared t o the p r e s s u r e i n an a r t e r y w i t h normal b l o o d f l o w . T h i s r e f l e c t s t he q u a n t i t y of b l o o d f l o w t h r o u g h the compromised a r t e r y . The a n k l e / b r a c h i a l index i s de t e r m i n e d by d i v i d i n g the a n k l e s y s t o l i c p r e s s u r e by the b r a c h i a l s y s t o l i c p r e s s u r e (Dean & Yao, 1976; Nurse Review, 1988; Yao, 1985). C o n t i n u o u s Wave U l t r a s o n i c Doppler T h i s machine has a probe t h a t i s used t o d e t e c t t h e movement of r e d b l o o d c e l l s w i t h i n a v e s s e l . I n the probe of the c o n t i n u o u s wave u l t r a s o n i c Doppler t h e r e a r e two c r y s t a l s . One c r y s t a l t r a n s m i t s u l t r a s o n i c sound waves and the o t h e r c r y s t a l r e c e i v e s sound r e f l e c t e d back from a moving r e d b l o o d c e l l . The p i t c h of the a u d i b l e o u t p u t w i l l be i n d i r e c t p r o p o r t i o n t o the re d b l o o d c e l l f l o w v e l o c i t y . I f t h e r e i s no f l o w i n the b l o o d v e s s e l t h e r e i s no a u d i b l e o u t p u t ( S t r a n d n e s s e t a l . , 1967). Assumptions The assumptions made r e g a r d i n g t h i s r e s e a r c h s t u d y were the f o l l o w i n g . 1. The p r o c e d u r e s w i l l be c a r r i e d out by t h e d a t a c o l l e c t o r as p r e s c r i b e d . 2. When c a l i b r a t e d the i n s t r u m e n t s w i l l produce a c c u r a t e measurements. L i m i t a t i o n s T h i s s t u d y had l i m i t a t i o n s r e l a t e d t o t h e d a t a c o l l e c t o r , the sample s e l e c t e d and the i n s t r u m e n t s used i n d e t e r m i n i n g the measurement of the s y s t o l i c BP and ABI. L i m i t a t i o n s t h a t c o u l d have a f f e c t e d the r e s u l t s of t h i s s t u d y i n c l u d e the f o l l o w i n g . 1. There was a p o t e n t i a l f o r b i a s on t h e p a r t of the d a t a c o l l e c t o r as o n l y one d a t a c o l l e c t o r was used t o c o l l e c t a l l the d a t a . 2. A l t h o u g h the type of bypass g r a f t s u r g e r y was l i m i t e d , t h e r e may be d i f f e r e n c e s w i t h i n t h e s e p r o c e d u r e s t h a t i n f l u e n c e d t h e a n k l e s y s t o l i c b l o o d p r e s s u r e . 3. The c h o i c e of a co n v e n i e n c e sample of p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass s u r g e r y p a t i e n t s r e s t r i c t s the g e n e r a l i z a b i l i t y of the r e s u l t s beyond the scope of these p a t i e n t s . These l i m i t a t i o n s were c o n s i d e r e d when c o l l e c t i n g and a n a l y z i n g the d a t a as t h e y may have a f f e c t e d the g e n e r a l i z a b i l i t y of t h e r e s u l t s . A p p r o p r i a t e p r e c a u t i o n s were t a k e n t o reduce the impact of t h e s e v a r i a b l e s t h r o u g h the t r a i n i n g , t e s t i n g and p e r i o d i c c h e c k i n g of the d a t a c o l l e c t o r and p e r i o d i c c h e c k i n g of the i n s t r u m e n t s . S i g n i f i c a n c e S c i e n t i f i c S i g n i f i c a n c e The I n f o r m a t i o n p r o v i d e d when the two methods of sound measurement a r e compared w i l l add t o the body of knowledge about sound t r a n s m i s s i o n and measurement and w i l l p r o v i d e a knowledge base f o r d e t e r m i n i n g the most a c c u r a t e method of measuring the 13 b l o o d f l o w t o the lower l i m b . S i g n i f i c a n c e t o P a t i e n t Care S i n c e the i d e n t i f i c a t i o n of b l o c k a g e a t as e a r l y a s t a g e as p o s s i b l e I s e s s e n t i a l t o a t h e r a p e u t i c outcome, use of the most a c c u r a t e method i n the b e d s i d e measurement of the s y s t o l i c p r e s s u r e needs t o be d e t e r m i n e d . A c c u r a t e assessment of the ABI can r e s u l t i n l i m b s a l v a g e f o r some p a t i e n t s . I f g r a f t f a i l u r e i s d e t e c t e d e a r l y the p a t i e n t can be r e t u r n e d t o the o p e r a t i n g room as soon as p o s s i b l e . The e a r l i e r the i n t e r v e n t i o n , t h e g r e a t e r the l i k e l i h o o d t h a t the g r a f t can be s a l v a g e d , p a r t i c u l a r l y f o r v e i n g r a f t s where o c c l u s i o n f o r o n l y a few hours can r e s u l t In s e v e r e damage t o the e n d o t h e l i u m and i n c r e a s e d r i s k of f u r t h e r t h r o m b o s i s . When the p a t i e n t i s r e t u r n e d t o t h e o p e r a t i n g room the a n a s t o m o s i s s i t e s a r e exposed and t h e g r a f t f l u s h e d c l e a r of a l l t h r o m b i and r e v i s e d or r e p l a c e d as i n d i c a t e d . I f no cause i s found In the o p e r a t i n g room th e n the g r a f t can be s a l v a g e d w i t h the h e l p of h e p a r i n and/or d e x t r a n (Lye, 1989). A r e t u r n t o the o p e r a t i n g room of v a s c u l a r p a t i e n t s can be r i s k y s i n c e many of t h e s e p a t i e n t s s u f f e r from m u l t i p l e h e a l t h p roblems, such as l u n g impairment, c a r d i o v a s c u l a r problems and d i a b e t e s . For such p a t i e n t s e a r l y d e t e c t i o n of g r a f t f a i l u r e Is Important i n o r d e r t h a t t h e y do not have t o undergo the more e x t e n s i v e s u r g e r y i n v o l v e d when the g r a f t i s t o t a l l y o c c l u d e d and has t o be r e p l a c e d . The i n f o r m a t i o n p r o v i d e d by t h i s s t u d y w i l l a l s o have an impact on the use of n u r s i n g manpower. Owing t o the f r e q u e n c y of the assessment of the bypass g r a f t the nurse may de t e r m i n e the ABI a p p r o x i m a t e l y 28 t i m e s per p a t i e n t . There a r e c u r r e n t l y two methods used t o d e t e r m i n e the b r a c h i a l SP i n c a l c u l a t i n g the ABI: the s t e t h o s c o p e and the u l t r a s o n i c Doppler methods. Assessment of the ABI i s done a t the same time o t h e r v i t a l s i g n s , such as the b l o o d p r e s s u r e , a r e t a k e n . Use of the Doppler t o d e t e r m i n e the b r a c h i a l SP i n c a l c u l a t i n g t h e ABI r e q u i r e s more n u r s i n g time t h a n the use of the s t e t h o s c o p e s i n c e the nurse needs two b r a c h i a l SP's, one by Doppler f o r c a l c u l a t i o n of t h e ABI and one by s t e t h o s c o p e f o r a s s e s s i n g the p a t i e n t ' s b l o o d p r e s s u r e . Use of the s t e t h o s c o p e t o d e t e r m i n e the b r a c h i a l SP i n c a l c u l a t i n g the ABI does not i n v o l v e t h i s a d d i t i o n a l s t e p . J u s t i f i c a t i o n f o r the use of t h e Doppler or the s t e t h o s c o p e i n d e t e r m i n i n g the s y s t o l i c p r e s s u r e i n t h i s assessment procedure i s needed i n o r d e r t o p r o v i d e h i g h q u a l i t y c a r e and t o make the b e s t use of n u r s i n g manpower ( H i l t o n , 1984). Overview of T h e s i s Content T h i s t h e s i s i s c o mprised of f i v e c h a p t e r s . In c h a p t e r One, t h e background t o the problem, problem s t a t e m e n t , purpose, c o n c e p t u a l framework, r e s e a r c h q u e s t i o n s , d e f i n i t i o n s and s i g n i f i c a n c e of the s t u d y were g i v e n . In Chapter Two, a r e v i e w of s e l e c t e d l i t e r a t u r e i s found which p r e s e n t s the f a c t o r s t h a t a f f e c t the g e n e r a t i o n , t r a n s m i s s i o n and measurement of sound f o l l o w e d by r e s e a r c h s t u d i e s t h a t compared the methods of measuring t h e s y s t o l i c b l o o d p r e s s u r e . I n Chapter Three the r e s e a r c h methods i n c l u d i n g a d e s c r i p t i o n of the r e s e a r c h d e s i g n , s a m p l i n g p r o c e d u r e s , d a t a c o l l e c t i o n i n s t r u m e n t s and p r o c e d u r e s , e t h i c a l c o n s i d e r a t i o n s and s t a t i s t i c a l p r o c e d u r e s used i n d a t a a n a l y s i s i s p r e s e n t e d , i n Chapter F o u r , the d e s c r i p t i o n of the sample, a r e p o r t of the f i n d i n g s and a d i s c u s s i o n of the r e s u l t s a r e p r e s e n t e d . The summary, c o n c l u s i o n s , i m p l i c a t i o n s , and recommendations f o r f u t u r e r e s e a r c h are p r e s e n t e d i n Chapter F i v e . CHAPTER TWO Review of the L i t e r a t u r e I n t r o d u c t i o n In t he l i t e r a t u r e r e v i e w the f a c t o r s a f f e c t i n g the g e n e r a t i o n , t r a n s m i s s i o n and measurement of sound as t h e y a f f e c t the measurement of the s y s t o l i c b l o o d p r e s s u r e w i l l be p r e s e n t e d . The knowledge a v a i l a b l e r e g a r d i n g the comparison of the t h r e e methods of d e t e r m i n i n g the s y s t o l i c b l o o d p r e s s u r e : s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and u l t r a s o n i c Doppler w i l l be examined. The r e s e a r c h by which t h i s knowledge has been a c q u i r e d as w e l l as l i m i t a t i o n s of the s t u d i e s w i l l a l s o be d e s c r i b e d . F a c t o r s A f f e c t i n g the G e n e r a t i o n , T r a n s m i s s i o n and Measurement of  Sound G e n e r a t i o n of Sound The sound g e n e r a t e d In t h e h e a r t can be heard when one p l a c e s the s t e t h o s c o p e over the apex of the h e a r t , but the i n t e n s i t y of the sound f a l l s o f f as the wave t r a v e l s t h r o u g h the a r t e r i e s because w i t h d i s t a n c e the wave d i s s i p a t e s and l o s e s i t s energy ( W i n t e r , 1967). The sound g e n e r a t e d i n an a r t e r y i s of low f r e q u e n c y and a m p l i t u d e and t h e r e f o r e not w i t h i n the s o n i c range of the human ear u n l e s s the a r t e r y i s f i r s t compressed w i t h an o c c l u d i n g c u f f . A r t e r i a l c o m p r e s s i o n causes a b u i l d u p of sound wave energy p r o x i m a l t o the o c c l u s i o n t h a t i s r e l e a s e d when the c u f f i s d e f l a t e d . A f t e r d e f l a t i o n of the c u f f the sound waves a r e of h i g h enough a m p l i t u d e and f r e q u e n c y t o come w i t h i n the s o n i c range t h a t can then be d e t e c t e d by the human ear th r o u g h a s t e t h o s c o p e . The low f r e q u e n c y sound t h a t i s g e n e r a t e d i n an a r t e r y ( F r o h l i c h e t a l , , 1988) can be d e t e c t e d by a Doppler s i n c e t h i s i n s t r u m e n t , t h r o u g h the use of u l t r a s o n i c sound waves, can d e t e c t the movement of the r e d b l o o d c e l l ( s t r a n d n e s s , S c h u l t z , Sumner & Rushner, 1967). T r a n s m i s s i o n of sound V e s s e l d i a m e t e r i s one of the f a c t o r s t o c o n s i d e r when a s s e s s i n g the t r a n s m i s s i o n of sound from an a r t e r y . When the v e s s e l d i a m e t e r i s d e c r e a s e d due t o an o c c l u s i o n , t h e r e i s d i m i n i s h e d p r e s s u r e and f l o w d i s t a l t o the o c c l u s i o n ( C a r t e r , 1985). The sound d i s t a l t o the o c c l u s i o n i s of low f r e q u e n c y and a m p l i t u d e . With i n c r e a s i n g o c c l u s i o n In the a r t e r y the sounds become f a i n t e r u n t i l , i n t o t a l o c c l u s i o n , t h e y d i s a p p e a r (Yao e t a l . , 1969). Changes i n vasomotor t o n e , such as an i n c r e a s e i n s t i f f n e s s of the a r t e r y , a l s o produce changes i n the v e s s e l d i a m e t e r a f f e c t i n g the t r a n s m i s s i o n of the sound wave ( C a r t e r , 1985; Hugue, S a f a r , A k u e f u e r a j u s , Asmar & London, 1988). The d i s t a n c e a sound wave must c r o s s over a l s o a f f e c t s the t r a n s m i s s i o n of sound from the a r t e r y . F r o h l i c h e t a l . (1988) s t a t e d t h a t o b e s i t y and edema g r e a t l y I n c r e a s e t h i s d i s t a n c e and t h e r e f o r e d i m i n i s h the sound t h a t i s t r a n s m i t t e d . D e p o s i t s of c a l c i u m i n the a r t e r i a l w a l l and dense s c a r t i s s u e have a l s o been i d e n t i f i e d as f a c t o r s t h a t d i m i n i s h the t r a n s m i s s i o n of u l t r a s o u n d waves (Rebenson-Piano, Holm, & Powers, 1987; Dean, & Yao, 1976; C a r t e r , 1985). Measurement of Sound Human e r r o r can a f f e c t t h e measurement of sound t r a n s m i t t e d from an a r t e r y . Rebenson-Piano e t a l . (1987) and Thompson (1981) 18 noted t h a t n u r s e s , when r e c e i v i n g d a t a , o f t e n a r e u n c o n s c i o u s l y b i a s e d towards a c e r t a i n d i g i t p r e f e r e n c e . The r e s u l t i s t h a t t h e y r a i s e or lower the p a t i e n t ' s b l o o d p r e s s u r e by r o u n d i n g o f f the measurement t o the n e a r e s t z e r o or even number. Other r e s e a r c h e r s note t h a t p h y s i c i a n s and nurses a r e sometimes b i a s e d toward c e r t a i n c o n v e n t i o n a l v a l u e s , such as 120/80 mm Hg, t h a t t h e r e b y a l t e r the assessment of b l o o d p r e s s u r e s ( L a n c o u r , 1976; N e u f i e l d , & Johnson, 1986). I n o r d e r t o a v o i d t h e s e p i t f a l l s , t he measurement s h o u l d be r e c o r d e d t o the n e a r e s t 2-3 mm Hg ( F r o h l i c h e t a l . , 1988). i n a d d i t i o n , when u s i n g a Doppler t h e nurse must a l s o be a b l e t o d i s t i n g u i s h between a r t e r i a l and venous Doppler sounds ( P e a r c e , Yao & Bergan, 1983). Venous sounds have a low w h i s t l i n g c h a r a c t e r i s t i c and a r e I n f l u e n c e d by r e s p i r a t i o n s whereas a r t e r i a l sounds a r e c l e a r t a p p i n g sounds. As w e l l as human e r r o r t h e r e a r e f a c t o r s w i t h i n the p a t i e n t t h a t need t o be c o n s i d e r e d when measuring a r t e r i a l sounds. C a r t e r (1968) and Yao (1985) found t h a t c a l c i f i c a t i o n of the a r t e r i a l w a l l p r e v e n t s c o m p r e s s i o n of the v e s s e l which i n t u r n l e a d s t o a f a l s e h i g h measurement of the s y s t o l i c p r e s s u r e . They a l s o s t a t e t h a t i t may t a k e up t o 300 mm Hg t o compress t h e c a l c i f i e d v e s s e l . C a l c i f i c a t i o n of the a r t e r i a l w a l l o c c u r s i n a p p r o x i m a t e l y 1 t o 10% of t h e p o p u l a t i o n , most p a r t i c u l a r l y i n p a t i e n t s w i t h d i a b e t e s and r e n a l d i s e a s e . A r t e r i a l d i s e a s e can a l s o cause a d e c r e a s e i n t h e f l o w d i s t a l t o an a t h e r o s c l e r o t i c a r t e r y and can r e s u l t i n an u n d e r e s t i m a t i o n of the p a t i e n t ' s t r u e s y s t o l i c p r e s s u r e . K r i s t e n s e n (1982) conducted a s t u d y i n v o l v i n g 197 s u b j e c t s and noted t h a t 49% of the s u b j e c t s e x h i b i t e d 19 s y s t o l i c pressure differences of 10 mm Hg or more between the two arms. Carter (1985) attributed t h i s difference in s y s t o l i c pressure to a r t e r i a l disease In the vessels supplying the upper limb. He said i t i s important that the pressure be measured in both arms and recommended using the arm with the higher s y s t o l i c pressure on subsequent occasions since erroneous conclusions can be drawn regarding the ABI i f the ankle SP is compared with an abnormally low brachial SP. When measuring sounds transmitted from the patient's artery the methods by which t h i s sound i s measured and the equipment employed must be considered. The three pieces of equipment used to measure the s y s t o l i c pressure include the sphygmomanometer, stethoscope and ultrasonic Doppler. Sphygmomanometer. This consists of a blood pressure cuff, an In f l a t i n g bulb, a pump by which the pressure i s increased, a manometer from which the applied pressure Is read and a control exhaust to deflate the system. Frohlich et al.(1988) recommended that the width of the bladder of the blood pressure cuff selected be 40 to 50% of the width of the upper arm since too small a bladder w i l l overestimate and too large a bladder w i l l underestimate the s y s t o l i c pressure. Frohlich et a l . (1988) also recommended that the cuff bladder should be long enough to enci r c l e 80% of the arm to exert an even pressure over the artery. Manometer. Before employing the manometer the observer should check that the mercury tube i s patent and that the meniscus of the mercury manometer is at zero because i f i t Is 20 below z e r o the s y s t o l i c p r e s s u r e can be u n d e r e s t i m a t e d ( F r o h l l c h e t a l . , 1988; Lancour, 1976; Rudy, 1986). The manometer must be used a p p r o p r i a t e l y t o o b t a i n a c c u r a t e sound measurement. The manometer must be s i t u a t e d a t eye l e v e l and w i t h i n one meter of the n u r s e ' s v i s i o n t o f a c i l i t a t e a c c u r a t e r e a d i n g of t h e p r e s s u r e ( F r o h l i c h e t a l . , 1988; L a n c o u r , 1976; Rudy, 1986). C o n t r o l V a l v e s . Yao (1985) has p o i n t e d out t h a t the c o n t r o l v a l v e s must be e a s i l y m a n i p u l a t e d and when r e l e a s e d , s h o u l d a l l o w a c o n t r o l l e d f a l l of t h e mercury column. The pump s h o u l d have a competent n o n r e t u r n v a l v e and be f r e e of l e a k s . The t u b i n g and a i r v e n t s of the sphygmomanometer must be p a t e n t or a f a l s e measurement r e s u l t s owing t o leak a g e of p r e s s u r e from the system. S t e t h o s c o p e . B e f o r e u s i n g the s t e t h o s c o p e the o b s e r v e r s h o u l d check the t u b i n g f o r c r a c k s or k i n k s . Cracked or bent t u b i n g w i l l l e a d t o a d i s t o r t i o n of the sound. S i m i l a r l y a c r a c k e d diaphragm w i l l l e a d t o a d i s t o r t i o n of t h e sound e m i t t e d from the a r t e r y (Yao, 1985). The e a r p i e c e s s h o u l d be checked f o r c l e a n l i n e s s s i n c e b l o c k e d e a r p i e c e s w i l l l e a d t o an u n d e r e s t i m a t i o n of the s y s t o l i c p r e s s u r e . The s t e t h o s c o p e must be used a p p r o p r i a t e l y In o r d e r t o de t e r m i n e an a c c u r a t e measurement of the sound t r a n s m i t t e d from th e a r t e r y . C o n s t a n t (1987) s t a t e d t h a t the b e l l of the s t e t h o s c o p e i s t h e o r e t i c a l l y b e t t e r t h a n the diaphragm f o r d e t e c t i n g t h e low f r e q u e n c y K o r o t k o f f sounds, but the diaphragm i s u s u a l l y p r e f e r r e d s i n c e I t i s hard t o a t t a i n a good a i r s e a l w i t h a l a r g e d i a m e t e r b e l l on a rounded arm. The b e l l of the 21 s t e t h o s c o p e , when a p p l i e d w i t h l i g h t p r e s s u r e d i r e c t l y over the a r t e r y and w i t h no space between the s k i n and the s t e t h o s c o p e b e l l , f a c i l i t a t e s the t r a n s m i s s i o n of sound s i n c e i t a m p l i f i e s the low f r e q u e n c y sounds b e t t e r than the diaphragm ( C o n s t a n t , 1987; F r o h l i c h e t a l , 1988; Nurse Review, 1988; Thompson, 1981). F r o h l i c h e t a l . (1988) recommended t h a t when u s i n g the s t e t h o s c o p e , o b s e r v e r s s h o u l d p l a c e the ear p i e c e s i n a fo r w a r d p o s i t i o n i n the e a r s t o a v o i d an u n d e r e s t i m a t i o n of the s y s t o l i c p r e s s u r e . D o p p l e r . B e f o r e u s i n g the Doppler the o b s e r v e r s h o u l d check t h a t i t i s a d e q u a t e l y c h a r g e d . Otherwise t h e probe of the Doppler may not d e t e c t the movement of the r e d b l o o d c e l l l e a d i n g t o an u n d e r e s t i m a t i o n of the s y s t o l i c p r e s s u r e . The probe of the Doppler s h o u l d be checked f o r c l e a n l i n e s s as a probe t h a t i s c r u s t e d w i t h g e l w i l l i n t e r f e r e w i t h the t r a n s m i s s i o n and r e c e p t i o n of the u l t r a s o n i c waves and r e s u l t i n an u n d e r e s t i m a t i o n of the s y s t o l i c p r e s s u r e (O'Mara & Yao, 1982). When u s i n g a D o p p l e r , O'Mara and Yao (1982) recommended t h a t the f o l l o w i n g c o n d i t i o n s c o n t r i b u t e t o e f f e c t i v e sound t r a n s m i s s i o n . A water s o l u b l e g e l s h o u l d be used as a c o u p l i n g agent t o a i d i n the o p t i m a l p e n e t r a t i o n of t h e u l t r a s o u n d waves th r o u g h the s k i n . In a d d i t i o n , the probe s h o u l d be h e l d a t a 45-60 degree a n g l e t o the a r t e r y and p o i n t e d toward t h e d i r e c t i o n of b l o o d f l o w t o a i d i n the d e t e c t i o n of the movement of the r e d b l o o d c e l l . When measuring a p a t i e n t s ' b r a c h i a l b l o o d p r e s s u r e F r o h l i c h e t al.(1988) and Rudy (1986) made the f o l l o w i n g recommendations: (1) The limb must be at the l e v e l of the heart. i t s h o u l d not be above the heart or there w i l l be an overestimating the s y s t o l i c pressure. (2) The limb must be supported in a comfortable position. If the limb i s not supported isometric muscle contractions-will r e s u l t in.an overestimation of the s y s t o l i c pressure. (3) The bladder of the cuff must be centred over the artery i n order to provide even compression of the artery. (4) The cuff must be applied snugly to the arm since loose a p p l i c a t i o n of the cuff overestimates the s y s t o l i c pressure. (5) The cuff must be i n f l a t e d to a maximum of 30 mm Hg above the palpable range to accommodate the auscultatory gap. Excessive and unnecessary high pressure i s not only painful for the patient but can cause vasospasm and high s y s t o l i c readings. (6) when the cuff i s deflated the pressure should be released at 2-3 mm Hg per second-since rapid d e f l a t i o n leads to an»underestimation of the s y s t o l i c pressure. Constant (1987) also added that with too rapid d e f l a t i o n the f i r s t Korotkoff sounds may-be missed and that a r t e r i a l spasm may occur on i n i t i a l compression and give a false high s y s t o l i c pressure, whereas. slow d e f l a t i o n allows the spasm to disappear. A l l of the above would also apply- when taking the ankle SP except for recommendation number three as i t i s d i f f i c u l t to centre the bladder of the cuff over the artery owing to the location of the pedal a r t e r l e s . When repeated blood pressure readings are required within a short span of time Frohlich et a l . (1988) recommended that the observer wait 1-2 minutes before r e i n f l a t i n g the cuff between measurements.Reinflating the cuff prior to t h i s time period w i l l r e s u l t In an o v e r e s t i m a t l o n of the s y s t o l i c p r e s s u r e owing t o i n c r e a s e d h y d r o s t a t i c p r e s s u r e from the t r a p p e d venous b l o o d i n the forearm (Rudy, 1986). R e s e a r c h S t u d i e s Comparing Methods of M e a s u r i n g the S y s t o l i c  B l o o d P r e s s u r e Four s t u d i e s t h a t examined th e methods f o r measuring s y s t o l i c b l o o d p r e s s u r e w i l l now be p r e s e n t e d and compared. C a r t e r (1968) compared 146 p a t i e n t s whose l i m b s had v a r y i n g degrees of a r t e r i a l o c c l u s i o n w i t h 85 p a t i e n t s whose l i m b s had no a r t e r i a l o c c l u s i o n . The purpose of the s t u d y was t o compare Doppler p r e s s u r e s of p a t i e n t s who had v a r y i n g degrees of o c c l u s i o n w i t h p a t i e n t s who had no a r t e r i a l o c c l u s i o n . The v a r y i n g degrees of o c c l u s i o n were d e t e r m i n e d by a n g i o g r a p h y . T h i s s t u d y was conducted i n a v a s c u l a r l a b . For the a n k l e p r e s s u r e C a r t e r used a b l o o d p r e s s u r e c u f f connected t o a p r e s s u r e s o u r c e , mercury manometer, Stratham p r e s s u r e t r a n s d u c e r , c a p a c i t a n c e p u l s e p i c k u p s f o r the p e d a l p u l s e s and an o p t i c a l o s c i l l o g r a p h r e c o r d e r . For the b r a c h i a l p r e s s u r e no s p e c i f i c method was s t a t e d . H i s c o n c l u s i o n r e g a r d i n g the comparison of the s y s t o l i c p r e s s u r e s of the a n k l e w i t h t h a t of the b r a c h i a l a r t e r y was t h a t e s t i m a t i o n of the l o c a l s y s t o l i c p r e s s u r e [by D o p p l e r ] was easy t o p e r f o r m and i t s r e p r o d u c i b i l i t y was comparable t o t h a t of the a u s c u l t a t o r y e s t i m a t i o n of the b r a c h i a l p r e s s u r e (p. 632). In 1969, Yao e t a l . p u b l i s h e d a s t u d y comparing the s y s t o l i c p r e s s u r e s of 183 l i m b s of p a t i e n t s w i t h o c c l u s i v e a r t e r i a l d i s e a s e w i t h the s y s t o l i c p r e s s u r e s of 31 l i m b s of p o s t - o p e r a t i v e bypass s u r g e r y p a t i e n t s . The purposes of t h i s s t u d y were t o 24 evaluate the method of measuring s y s t o l i c pressure in the lover extremity by the ultrasound technique,, to compare t h i s method with the piethysmographic technique, and to determine the signi f i c a n c e of the ultrasonic technique in diagnosing and managing a r t e r i a l i n s u f f i c i e n c y of the lower extremity. As part of the procedure, s y s t o l i c measurements in the arm were made by both the Doppler and conventional auscultatory technlque. The instrument used to measure the s y s t o l i c pressures was the mercury-ln-rubber s t r a i n gauge plethysmograph. -When reportlng the resul t s of the comparison of the Doppler and auscultatory methods of determining the brachial s y s t o l i c pressure the author stated that the [Doppler) method caused no discomfort to the patient and Its r e p r o d u c i b i l i t y was comparable to that of the auscultatory estimation of the brachial s y s t o l i c pressure (p. 677). In 1973, Tahir and Adrian1 evaluated two models of Dopplers by comparing th e i r accuracy with both the d i r e c t a r t e r i a l cannulatlon and the standard Korotkoff technique. The study was conducted in a lab set t i n g and consisted of 262 adults. The transducers of both the Doppler machines were mounted on a thin p l a s t i c s t r i p moulded to f i t the arm over the brachial artery and placed under the blood pressure cuff.When the transducer was in place a stethoscope was placed over the brachial artery, d i s t a l to the cuf f , and simultaneous comparisons between Doppler and Korotkoff technique were made. The same cuff and artery were used for a l l subjects. The results of the study were that in the majority of adults, the ultras o n i c determinations did not vary s i g n i f i c a n t l y from that achieved by the Korotkoff method. When 25 compared, the two s e t s o£ measurements o£ s y s t o l i c r e a d i n g s were w i t h i n 5 mm Hg i n 90% of the c a s e s . A two-sample T - t e s t showed no s i g n i f i c a n t d i f f e r e n c e between each s e t of measurements a t p<0.01. In 1990, T h e l o o s e n - K e r s t e n s , van A s t e n , R u t t e r and S k o t n i c k i p u b l i s h e d a s t u d y i n which t h e y compared t h r e e n o n i n v a s i v e methods w i t h the i n t r a - a r t e r i a l method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e . The sample c o n s i s t e d of 49 u n v e n t i l a t e d p a t i e n t s i n the I n t e n s i v e c a r e u n i t who were hemodynamically u n s t a b l e and some of whom were on v a s o a c t i v e m e d i c a t i o n s t o r e g u l a t e t h e i r b l o o d p r e s s u r e . The purpose of t h i s s t u d y was t o det e r m i n e which n o n i n v a s i v e method of b l o o d p r e s s u r e measurement was the most a p p r o p r i a t e f o r measuring the p r e s s u r e i n the b r a c h i a l a r t e r y . D i r e c t p r e s s u r e measurement by i n t r a l u m i n a l c a n n u l a t l o n of the b r a c h i a l or r a d i a l a r t e r y was used as the " g o l d s t a n d a r d " and was compared w i t h the t h r e e o t h e r methods: s t e t h o s c o p e diaphragm, n o n d i r e c t i o n a l pocket Doppler and Dinamap a u t o m a t i c b l o o d p r e s s u r e m o n i t o r . The p r e s s u r e was measured w i t h a mercury manometer and the o c c l u d i n g c u f f was a n y l o n manchet w i t h a rubber b l a d d e r ( r e g u l a r BP c u f f ) . The p r e s s u r e s were always t a k e n on the l e f t arm and i n the same sequence. The i n t r a -a r t e r i a l p r e s s u r e was r e g i s t e r e d i m m e d i a t e l y b e f o r e and 15-30 seconds a f t e r each measurement. A f t e r each measurement a two-minute p e r i o d of e q u i l i b r i u m was a l l o w e d . i n t h e a n a l y s i s the mean v a l u e s of the t h r e e s e p a r a t e n o n i n v a s i v e measurements were p l o t t e d a g a i n s t the mean v a l u e s o b t a i n e d by l n t r a - a r t e r l a l measurements f o r e v e r y method. The 26 best c o r r e l a t i o n c o e f f i c i e n t s were found for the Doppler method (0.908) and the auscultation method (0.907). The Dinamap method showed a poorer c o r r e l a t i o n c o e f f i e l e n t (0. 859). The mean proportional differences of the--noninvasively measured s y s t o l i c blood pressures were s i g n i f i c a n t l y lower, from 5-25 mm Hg lower, (p< 0.001) when compared with the values obtained by the i n t r a -a r t e r i a l method. The. proportional percentage differences between Doppler, auscultation and Dinamap compared to the i n t r a - a r t e r i a l was -3.9%, -5.3% and -6.5% respectively. In patlents with higher blood pressure values (above 150 mm Hg), the difference became greater. These mean proportional dInferences Indicate that the Doppler method was more accurate than the other two noninvasive methods» when compared to the in t r a - a r t e r i a 1 method. From th i s data the authors concluded that the Doppler method provided the best c o r r e l a t i o n with the I n t r a - a r t e r i a l method and therefore can be used as the alternative to i n t r a - a r t e r i a l s y s t o l i c blood pressure measurements. Summary The f i r s t part of t h i s chapter reviewed the factors a f f e c t i n g the generation, transmission and measurement of sound. The factors a f f e c t i n g the generation of sound within an artery included the magnitude of the force creating the sound wave and the distance from the I n i t i a l source of generation. As the sound wave tr a v e l s further from the I n i t i a l source i t dissipates and loses i t s energy. The factors a f f e c t i n g the transmission of sound in the artery include the vessel diameter which i s affected by occlusion and vasomotor tone. Transmission i s also affected by the d i s t a n c e the wave must t r a v e l . The measurement of sound can be a f f e c t e d by human e r r o r , a r t e r i a l d i s e a s e , s t a t e of r e p a i r of the I n s t r u m e n t s , c h o i c e of i n s t r u m e n t s and how the I n s t r u m e n t s a r e used. The second p a r t of t h i s c h a p t e r f o c u s e d on the c u r r e n t knowledge a v a i l a b l e r e g a r d i n g the measurement of the s y s t o l i c BP. T h i s knowledge p r o v i d e d d i r e c t i o n f o r the d e t e r m i n a t i o n of the s y s t o l i c BP by the t h r e e d i f f e r e n t methods: s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and u l t r a s o n i c D o p p l e r . Four s t u d i e s were d e s c r i b e d t h a t f o c u s e d on p r e s s u r e measurement. The s t u d y by T h e l o o s e n - K e r s t e n s e t a l . (1990) su g g e s t e d t h a t the Doppler p r o v i d e d a more a c c u r a t e measurement of t h e p a t i e n t s ' s y s t o l i c b l o o d p r e s s u r e t h a n t h e s t e t h o s c o p e diaphragm when compared t o i n t r a - a r t e r i a l measurements. However, when n o n i n v a s i v e methods were compared the s t e t h o s c o p e diaphragm and Doppler p r o v i d e d s i m i l a r r e s u l t s f o r i n t e n s i v e c a r e p a t i e n t s who were hemodynamically u n s t a b l e and r e c e i v e d v a s o a c t i v e m e d i c a t i o n s t o r e g u l a t e b l o o d p r e s s u r e . These r e s u l t s may not be g e n e r a l i z a b l e t o p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s i n a ward s e t t i n g . The s t u d i e s by c a r t e r (1968), Yao e t a l . (1969) and T a h i r and A d r l a n i (1973) found the methods of d e t e r m i n i n g the b r a c h i a l SP comparable. However, t h e s e s t u d i e s f a i l e d t o p r o v i d e a s u b s t a n t i a l f o u n d a t i o n upon which t o base the b e d s i d e n u r s i n g m o n i t o r i n g p r o c e d u r e of t h e ABI because the s t u d i e s were conducted i n a l a b o r a t o r y s e t t i n g where many of the e n v i r o n m e n t a l and hemodynamic v a r i a b l e s were c o n t r o l l e d and the equipment used 28 in these studies would not be the type of equipment used by nurses for bedside monitoring of the ABI. The l i t e r a t u r e on determining the s y s t o l i c blood pressure suggested that the stethoscope b e l l i s more accurate than the stethoscope diaphragm however, no published research studies could be found to support t h i s claim. There i s a dearth of l i t e r a t u r e on the topic of ABI and there are no published nursing research studies describing the most accurate method to determine the ABI. Because of the lack of knowledge about the accuracy of determining the ABI and the l i m i t a t i o n s of the above studies, t h i s study has been designed to provide a d i r e c t comparison among the methods used to determine the brachial SP using the stethoscope b e l l , stethoscope diaphragm and ultrasonic Doppler and to compare the pressures r e s u l t i n g from these methods with the ankle SP, as measured by the ultrasonic Doppler. CHAPTER THREE Methods I n t r o d u c t i o n T h i s c h a p t e r I n c l u d e s an o u t l i n e of the methods used t o compare t h e t h r e e methods of b r a c h i a l SP assessment i n d e t e r m i n i n g the ABI. Content w i l l i n c l u d e a d i s c u s s i o n on the r e s e a r c h d e s i g n , sample s e l e c t i o n and c r i t e r i a , d a t a c o l l e c t i o n i n s t r u m e n t s , d a t a c o l l e c t i o n p r o c e d u r e s , d a t a a n a l y s i s and pr o c e d u r e s f o r p r o t e c t i o n of human r i g h t s . R e s e a r c h Design A " W i t h i n - S u b j e c t Two Repeated-Measures" d e s i g n was used t o ad d r e s s t h e r e s e a r c h q u e s t i o n s , i n t h i s d e s i g n each s u b j e c t s e r v e d as h i s / h e r own c o n t r o l . Each s u b j e c t had h i s / h e r b r a c h i a l SP measured by s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and u l t r a s o n i c Doppler methods and a n k l e SP measured by the u l t r a s o n i c Doppler on t h r e e c o n s e c u t i v e o c c a s i o n s ( t h i r d , f o u r t h , and f i f t h p o s t o p e r a t i v e d a y ) . The o r d e r of the b r a c h i a l SP methods was p r e d e t e r m i n e d t o e l i m i n a t e any o r d e r e f f e c t . T h i s d e s i g n a l l o w e d the i n v e s t i g a t o r t o dete r m i n e whether the d i f f e r e n c e i n method of measuring the b r a c h i a l SP was g r e a t e r t h a n the d i f f e r e n c e a t t r i b u t a b l e t o the o r d e r of the methods ( C o l l y e r and Enns, 1987). F i g u r e 2 p o r t r a y s t h e d e s i g n used t o compare the b r a c h i a l s y s t o l i c p r e s s u r e . The same d e s i g n was used t o compare the ABI of both t h e d o r s a l i s p e d i s and p o s t e r i o r t i b i a l a r t e r i e s when the b r a c h i a l SP was t a k e n by d i f f e r e n t methods. T h i s d e s i g n was used t o dete r m i n e i f : 30 1. there was a d i f f e r e n c e i n the b r a c h i a l s y s t o l i c pressure due to e i t h e r method or o c c a s i o n 2. there was a d i f f e r e n c e i n the a n k l e / b r a c h i a l index using the p o s t e r i o r t i b i a l a r t e r y s i t e due to e i t h e r method or oc c a s i o n , and 3. there was a d i f f e r e n c e i n the a n k l e / b r a c h i a l index u s i n g the d o r s a l i s pedis a r t e r y s i t e due to e i t h e r method or o c c a s i o n (see f i g u r e 2). F i g u r e 2 Design f o r Measuring D i f f e r e n c e s Related t o o c c a s i o n and Method  f o r B r a c h i a l S y s t o l i c P r e s s u r e . S A: A l A2 A3 B: B l B2 B3 B2 B3 B l B3 B l B2 A1B1 A1B2 A1B3 A2B2 A2B3 A2B1 A3B3 A3B1 A3B2 Fa c t o r A: Occasion Al=Third P o s t o p e r a t i v e Day A2=Fourth P o s t o p e r a t i v e Day A3=Fifth P o s t o p e r a t i v e Day Fa c t o r B: Method Bl=stethoscope Diaphragm B2=Stethoscope B e l l B3=Ultrasonic Doppler Sample S e l e c t i o n and Sample C r i t e r i a A convenience sample s i z e of 31 was chosen f o r t h i s repeated measures d e s i g n because with a sample s i z e of 30, an alpha l e v e l of .05, and a medium e f f e c t s i z e of .5, the power w i l l be .90 (W.B. B o l d t , p e r s o n a l communication, March, 1990) S u b j e c t s were s e l e c t e d from the v a s c u l a r u n i t i n a l a r g e t e r t i a r y c a r e h o s p i t a l l o c a t e d i n the Lower M a i n l a n d of B r i t i s h C o lumbia, Canada. I n c l u s i o n c r i t e r i a were t h a t s u b j e c t s : 1. had one of the f o l l o w i n g v a s c u l a r bypass s u r g e r i e s p erformed: a o r t i c - f e m o r a l , f e m o r a l - p o p l i t e a l , f e m o r a l - t i b i a l , f e m o r a l - f e m o r a l c r o s s o v e r , p o p l i t e a l - t i b i a l , p o p l i t e a l - p e r o n e a l or abdominal a o r t i c r e s e c t i o n . 2. were 3 days p o s t o p e r a t i v e . 3. were over 18 y e a r s of age. 4. had no p o s t o p e r a t i v e c o m p l i c a t i o n s . 5. had p a t e n t b r a c h i a l a r t e r i e s i n b oth arms. 6. were a b l e t o speak and w r i t e E n g l i s h . 7. had no edema of the arms. 8. were not o b e s e — t h e i r arm c i r c u m f e r e n c e was w i t h i n range t o use a normal a d u l t c u f f so t h a t the BP b l a d d e r w i d t h was 40-50% th e w i d t h of t h e upper arm. 9. had no wounds or p a i n f u l c o n d i t i o n s i n e i t h e r arm. P o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s were chosen f o r t h i s s t u d y s i n c e the procedure f o r t a k i n g the ABI I S d i r e c t l y r e l a t e d t o t h e s e p a t i e n t s . The t h i r d p o s t o p e r a t i v e day was chosen as the i n i t i a l measurement time because w i t h i n the f i r s t 24-48 hours t h e r e i s some f l u c t u a t i o n of b l o o d p r e s s u r e owing t o the e f f e c t s of a n a e s t h e s i a , and because a c u t e g r a f t f a i l u r e u s u a l l y o c c u r s w i t h i n t h e f i r s t 24 hours (Yao, 1 9 8 5 ) . P a t i e n t s w i t h o u t p o s t o p e r a t i v e c o m p l i c a t i o n s were chosen because 32 thos e w i t h c o m p l i c a t i o n s would not be a b l e t o p a r t i c i p a t e f u l l y i n t h e s t u d y owing t o f l u c t u a t i o n s i n h e a l t h s t a t u s . For the purpose of t h i s s t u d y p a t i e n t s w i t h edema of the arms and o b e s i t y were e l i m i n a t e d because, as was c i t e d e a r l i e r , edema and o b e s i t y p o s s i b l y i n t e r f e r e w i t h the a c c u r a t e measurement of s y s t o l i c b l o o d p r e s s u r e . P a t i e n t s w i t h p a i n or wounds i n e i t h e r arm were e x c l u d e d s i n c e the s y s t o l i c BP of bo t h arms was r e q u i r e d t o deter m i n e t h e arm w i t h the h i g h e s t s y s t o l i c BP b e f o r e d e t e r m i n i n g the ABI. Data C o l l e c t i o n I n s t r u m e n t s The f o u r i n s t r u m e n t s t h a t were used t o c o l l e c t t h e d a t a i n t h i s s t u d y i n c l u d e d a s t e t h o s c o p e , sphygmomanometer, p o r t a b l e u l t r a s o n i c Doppler and d a t a c o l l e c t i o n s h e e t . S t e t h o s c o p e The s t e t h o s c o p e used was a g e n e r a l purpose s t e t h o s c o p e w i t h a b e l l and a diaphragm of the type c u r r e n t l y b e i n g used by the nur s e s on t h a t u n i t t o d e t e r m i n e b l o o d p r e s s u r e r e a d i n g s . The s t e t h o s c o p e was checked by the b i o m e d i c a l department f o r maintenance and was used o n l y by the d a t a c o l l e c t o r f o r the d u r a t i o n of the s t u d y . sphygmomanometer The sphygmomanometer c o n s i s t e d of a com p r e s s i o n b l a d d e r e n c l o s e d i n an u n y i e l d i n g c u f f , an i n f l a t i n g b u l b , a pump by which the p r e s s u r e i s i n c r e a s e d , a manometer from which the a p p l i e d p r e s s u r e i s read and a c o n t r o l l e d e x h a u s t t o d e f l a t e the system. The sphygmomanometer used t o dete r m i n e the s y s t o l i c BP was a "Mercury Desk Model: 300mm", by W.A. Braum Co. (see 33 Appendix A ) . The c u f f used was a s t a n d a r d c o n t a c t c l o s u r e a d u l t c u f f t h a t c o n t a i n s a b l a d d e r t h a t was 12-14 cm. wide and 35-40 cm l o n g . For an average a d u l t arm t h i s w i d t h and l e n g t h have been found t o be s a t i s f a c t o r y and t o cause no more t h a n a mean e r r o r of 5% i n the i n d i r e c t b l o o d p r e s s u r e measurement ( K i r k l a n d , F e i n l e i b , F r e i s and Mark, 1980). when the column of mercury i n t h i s system a l i g n s w i t h z e r o a t no p r e s s u r e , the p r e s s u r e r e a d i n g i s r e l i a b l e and a c c u r a t e (Moskowitz, 1982). The mercury sphygmomanometer r e q u i r e s c a l i b r a t i o n y e a r l y ( K i r k l a n d , e t a l . , 1980: B. M i l t o n , B i o m e d i c a l T e c h n i c i a n , p e r s o n a l communication, May, 1990; Thompson, 1981). The sphygmomanometer was checked and c a l i b r a t e d and was used o n l y by the d a t a c o l l e c t o r f o r the d u r a t i o n of the r e s e a r c h s t u d y . P o r t a b l e C o n t i n u o u s Wave U l t r a s o n i c Doppler The model of u l t r a s o n i c Doppler used f o r t h i s s t u d y was model 812, s u p p l i e d by P a r k s M e d - E l e c t r o n i c s (see Appendix B ) . The m a n u f a c t u r e r i n f o r m a t i o n s t a t e s t h a t 90% of t h e problems w i t h the D o p p l e r , o u t s i d e d i s c h a r g e d b a t t e r i e s , a r e due t o f a i l u r e of t h e probe or t h e probe c o n n e c t o r s . Under normal c o n d i t i o n s t h i s I n strument r e q u i r e s maintenance y e a r l y (G. McKeen, B i o m e d i c a l T e c h n i c i a n , p e r s o n a l communication, May, 1990). P r i o r t o the s t u d y t h i s i n s t r u m e n t was checked and a new probe i n s t a l l e d by t h e B i o m e d i c a l Department. T h i s i n s t r u m e n t was used o n l y by the d a t a c o l l e c t o r . A l l of t h e s e i n s t r u m e n t s were checked by t h e b i o m e d i c a l department upon c o m p l e t i o n of the s t u d y and were found t o have m a i n t a i n e d t h e i r c a l i b r a t i o n . T h i s was done t o ensure t h a t the ca11bratIon and per £ormanee had been ma1ntained throughout the study. Data Go1lec tIonSheet The data c o l l e c t o r recorded relevant Information pertaining to the patient's current medical and s u r g i c a l health status, ankle SP obtained by the Doppler method, brachial SP obtained by the three methods and the c a l c u l a t i o n of the ABI (see Appendix C). Data C o l l e c t i o n Procedure Prior to data c o l l e c t i o n a nurse, who was not part of the nursing s t a f f of the unit where the data was c o l l e c t e d , was trained by the investigator. The data c o l l e c t o r received t r a i n i n g and in s t r u c t i o n regarding the purpose of the study, operation of equipment, procedures and recording on the data c o l l e c t i o n sheet. The data c o l l e c t o r provided a return demonstration of the procedures to the investigator's s a t i s f a c t i o n that the data would be c o l l e c t e d and recorded in a consistent fashion. The investigator v i s i t e d the vascular unit of the agency where the study was conducted to explain the study to the nurslng s t a f f and to answer questions regarding the study. The investigator requested that the head nurse on the vascular unit of the selected agency i d e n t i f y p atients that met the c r i t e r i a and ask those patients i f they were w i l l i n g to be approached by the investigator. The investigator then talked to potential participants about the study, reviewed-the "Patlent Informed Consent" (Appendix D) and requested the patient to sign the consent form. 35 When the s u b j e c t c o n s e n t e d , the f o l l o w i n g procedure took p l a c e . On the t h i r d , f o u r t h and f i f t h p o s t - o p e r a t i v e day the t r a i n e d d a t a c o l l e c t o r d e t e r m i n e d the b r a c h i a l SP by t h r e e d i f f e r e n t methods and t h e n d e t e r m i n e d the s y s t o l i c p r e s s u r e s of both the d o r s a l I s p e d i s and p o s t e r i o r t i b i a l a r t e r i e s . The t h r e e methods used t o d e t e r m i n e t h e b r a c h i a l SP, s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and D o p p l e r , were a s s i g n e d a p r e d e t e r m i n e d o r d e r (see F i g u r e 2 ) . The t h r e e p r o c e d u r e s used t o d e t e r m i n e the b r a c h i a l s y s t o l i c p r e s s u r e a r e d e s c r i b e d i n Appendix E. The method f o r d e t e r m i n i n g the a n k l e s y s t o l i c p r e s s u r e i s d e s c r i b e d i n Appendix F and the p r o c e d u r e f o r d e t e r m i n i n g the a n k l e / b r a c h i a l i n d e x i s d e s c r i b e d i n Appendix G. The p r e s s u r e s were then r e c o r d e d on the "Data C o l l e c t i o n Sheet". P i l o t s t u d y A p i l o t s t u d y , i n v o l v i n g t h r e e s u b j e c t s t h a t met the c r i t e r i a , was c o n d u c t e d . The purpose of t h i s p i l o t s t u d y was t o i d e n t i f y any problems a s s o c i a t e d w i t h the p r o c e d u r e s , i n s t r u m e n t s t o be used f o r d a t a c o l l e c t i o n and the d a t a c o l l e c t i o n s h e e t . No problems were i d e n t i f i e d , t h e r e f o r e , the p i l o t s t u d y d a t a became p a r t of the r e s e a r c h d a t a . Data A n a l y s i s The demographic d a t a of the sample and t h e d a t a c o l l e c t e d t o answer the r e s e a r c h q u e s t i o n s was a n a l y z e d u s i n g the f o l l o w i n g d e s c r i p t i v e s t a t i s t i c s : f r e q u e n c y , range, mean, s t a n d a r d d e v i a t i o n and v a r i a n c e . R e s e a r c h q u e s t i o n number one, "What i s the d i f f e r e n c e i n the b r a c h i a l s y s t o l i c b l o o d p r e s s u r e of p o s t o p e r a t i v e p e r i p h e r a l 36 v a s c u l a r p a t i e n t s when t h i s p r e s s u r e i s measured by: s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and u l t r a s o n i c D o p p l e r ? " and r e s e a r c h q u e s t i o n two, "What i s the d i f f e r e n c e i n the a n k l e / b r a c h i a l index when the b r a c h i a l s y s t o l i c p r e s s u r e of p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s i s measured by the t h r e e d i f f e r e n t methods?" were a n a l y z e d by u s i n g an a n a l y s i s of v a r i a n c e s p e c i f i c t o a two repeated-measures d e s i g n . The l e v e l of s i g n i f i c a n c e was s e t a t p=.05. The d a t a were a s s e s s e d t o dete r m i n e i f t h e y met the c r i t e r i a t o use a r e p e a t e d measures p a r a m e t r i c t e s t . The d a t a met the c r i t e r i a because t h e dependent v a r i a b l e was on an i n t e r v a l s c a l e , c o n t i n u o u s and n o r m a l l y d i s t r i b u t e d w i t h the independent v a r i a b l e s c a t e g o r i z e d as o c c a s i o n and method, with r e p e a t e d -measures the assu m p t i o n of compound symmetry was met because the v a r i a n c e s and c o r r e l a t i o n s a c r o s s the measurements were the same. T h i s i s an i m p o r t a n t c r i t e r i o n f o r a repeated-measures d e s i g n because t h e measures a r e from t h e same people p r o d u c i n g a c o r r e l a t i o n between the measures (Munro, V i s l n t a i n e r , & Page, 1986). P r o c e d u r e s f o r P r o t e c t i o n of Human R i g h t s The p r o p o s a l was s u b m i t t e d t o the U.B.C. B e h a v i o u r i a l S c i e n c e s S c r e e n i n g Committee f o r Research and Other S t u d i e s I n v o l v i n g Human S u b j e c t s and b o t h the E t h i c a l S c r e e n i n g Committee f o r Human E x p e r i m e n t a t i o n and the N u r s i n g Research Committee where t h e s t u d y was con d u c t e d . The names of t h e p a r t i c i p a n t s , h o s p i t a l s and a t t e n d i n g surgeons were not i d e n t i f i e d . P a r t i c i p a n t names or i d e n t i f y i n g d e t a i l s d i d not appear on any documents 37 o t h e r than the t h r e e s i g n e d c o n s e n t forms. One copy of the consent was p l a c e d on the p a t i e n t ' s c h a r t , one g i v e n t o the p a t i e n t and the t h i r d copy was r e t a i n e d by the i n v e s t i g a t o r . The i n v e s t i g a t o r ' s copy of the conse n t form was f i l e d i n a s e a l e d envelope u n t i l the c o m p l e t i o n of the s t u d y and th e n shredded. P a r t i c i p a t i o n i n the r e s e a r c h s t u d y was v o l u n t a r y . P a r t i c i p a t i o n , n o n - p a r t i c i p a t i o n or w i t h d r a w a l had no e f f e c t on a c c e s s t o n u r s i n g c a r e or m e d i c a l t r e a t m e n t and s e r v i c e s (see Appendix D). The s u b j e c t ' s p r i v a c y was r e s p e c t e d by l i m i t i n g d a t a c o l l e c t i o n t o t h e i n f o r m a t i o n deemed e s s e n t i a l t o the s t u d y . The p r o c e d u r e s used i n t h i s s t u d y t o d e t e r m i n e the b r a c h i a l SP and a n k l e SP were n o n - i n v a s i v e and d i d not d e v i a t e from the u s u a l p o s t o p e r a t i v e c a r e w i t h the e x c e p t i o n t h a t a l l t h r e e methods were used on each p a t i e n t . Summary T h i s c h a p t e r o u t l i n e d t h e methods used t o compare t h r e e methods of measuring the b r a c h i a l SP i n d e t e r m i n i n g the ABI. The r e s e a r c h d e s i g n used t o s t u d y t h e proposed r e s e a r c h q u e s t i o n s was a " W i t h i n - S u b j e c t Two Repeated-Measures". The sample c o n s i s t e d of 31 s u b j e c t s who had p e r i p h e r a l v a s c u l a r s u r g e r y and who met the i n c l u s i o n c r i t e r i a . The b r a c h i a l SP was t a k e n by 3 d i f f e r e n t methods on 3 c o n s e c u t i v e o c c a s i o n s s t a r t i n g on the t h i r d p o s t o p e r a t i v e day. The d o r s a l i s p e d i s and p o s t e r i o r t i b i a l p r e s s u r e s were t a k e n by u l t r a s o n i c Doppler on t h e same o c c a s i o n s . The In s t r u m e n t s used t o c o l l e c t the d a t a i n c l u d e d a s t e t h o s c o p e w i t h a b e l l and diaphragm, sphygmomanometer and p o r t a b l e u l t r a s o n i c D o p p l e r . One n u r s e , who was t r a i n e d by the 38 i n v e s t i g a t o r , c o l l e c t e d the d a t a . A p i l o t s t u d y was conducted and no problems were i d e n t i f i e d r e g a r d i n g p r o c e d u r e s , i n s t r u m e n t s and d a t a c o l l e c t i o n s h e e t . The r e s e a r c h q u e s t i o n s were a n a l y z e d u s i n g d e s c r i p t i v e s t a t i s t i c s and an a n a l y s i s of v a r i a n c e s p e c i f i c t o a two repeated-measures d e s i g n . The s i g n i f i c a n c e l e v e l was s e t a t p=.05. The p r o p o s a l was approved by the UBC B e h a v i o u r i a l S c i e n c e S c r e e n i n g Committee f o r R e s e a r c h and Other S t u d i e s I n v o l v i n g Human S u b j e c t s and both the E t h i c s S c r e e n i n g Committee f o r Human E x p e r i m e n t a t i o n and the N u r s i n g Research Committee where the s t u d y was con d u c t e d . P r o c e d u r e s f o r p r o t e c t i o n of s u b j e c t p r i v a c y were Implemented. CHAPTER FOUR P r e s e n t a t i o n and D i s c u s s i o n of R e s u l t s I n t r o d u c t i o n T h i s c h a p t e r i s d i v i d e d i n t o t h r e e s e c t i o n s . The f i r s t s e c t i o n d e s c r i b e s the demographic c h a r a c t e r i s t i c s and the m e d i c a l and s u r g i c a l d a t a of the s u b j e c t s i n the sample. The second s e c t i o n p r e s e n t s the r e s u l t s f o r each of the two r e s e a r c h q u e s t i o n s . The t h i r d s e c t i o n d i s c u s s e s the f i n d i n g s . C h a r a c t e r i s t i c s of the Sample D u r i n g the p e r i o d from October t o November, 1990, 40 p a t i e n t s had p e r i p h e r a l a r t e r i a l bypass s u r g e r y a t one h o s p i t a l i n Vancouver B.C. Of the 34 p a t i e n t s who met the c r i t e r i a f o r the s t u d y , two p a t i e n t s knew t h a t t h e y would be d i s c h a r g e d b e f o r e a l l the d a t a would be c o l l e c t e d and t h e y were t h e r e f o r e e x c l u d e d . One p a t i e n t was d i s c h a r g e d e a r l y which r e s u l t e d i n i n c o m p l e t e d a t a c o l l e c t i o n and was t h e r e f o r e not i n c l u d e d i n the a n a l y s i s . T h e r e f o r e , the sample c o n s i s t e d of 31 s u b j e c t s . No s u b j e c t s withdrew from the s t u d y . The sample w i l l be d e s c r i b e d i n terms of demographic c h a r a c t e r i s t i c s , and the m e d i c a l and s u r g i c a l s t a t u s of the s u b j e c t s . Demographic c h a r a c t e r i s t i c s of the Sample Demographic d a t a c o l l e c t e d from the s u b j e c t s concerned gender and age. The sample c o n s i s t e d of 18 males and 13 f e m a l e s . The age d i s t r i b u t i o n ranged from 47 t o 82 y e a r s (M =67.6, SD=8.4), w i t h Ql% of the s u b j e c t s between 61 and 80 y e a r s of age (see Table 1 ) . 40 T a b l e 1 Age D i s t r i b u t i o n of the Sample Age Frequency P e r c e n t 41-50 2 67b~ 51-60 3 10.0 61-70 13 42.0 71-80 12 39.0 81-90 1 3.0 T o t a l 31 100.0 S u r g i c a l and M e d i c a l s t a t u s S u r g i c a l S t a t u s . The sample w i l l be d e s c r i b e d i n terms of the a r t e r y bypassed, the s u r g i c a l procedure performed and h i s t o r y of p e r i p h e r a l v a s c u l a r s u r g e r y . A l l the s u b j e c t s were a d m i t t e d f o r e l e c t i v e s u r g e r y . The a r t e r y most f r e q u e n t l y bypassed was the f e m o r a l a r t e r y ( 6 6 % ) , f o l l o w e d by the i l i a c a r t e r y ( 1 6 % ) , the p o p l i t e a l a r t e r y (12%) and the a o r t i c a r t e r y (6%) (see Table 2 ) . The most f r e q u e n t s u r g i c a l procedure performed was the f e m o r a l -p o p l i t e a l bypass g r a f t p r o c e d u r e ( 6 6 % ) . Other s u r g i c a l p r o c e d u r e s i n c l u d e d : a o r t i c b i - f e m o r a l bypass, abdominal a o r t i c r e s e c t i o n , f e m o r a l - f e m o r a l c r o s s o v e r , p o p l i t e a l - t i b l a l bypass and p o p l l t e a l -p e r o n e a l bypass (see Table 3 ) . Of the 31 s u b j e c t s i n the s t u d y , 11 had had p r e v i o u s p e r i p h e r a l v a s c u l a r s u r g e r y and 6 of the s e o p e r a t i o n s were f o r r e v i s i o n s of p r e v i o u s v a s c u l a r bypass g r a f t s . Three had had a o r t i c b i - f e m o r a l bypass s u r g e r y ; one each had had a o r t i c - s u p e r i o r m e s e n t e r i c bypass, a c a r o t i d e n d a r t e r e c t o m y and an a n g i o p l a s t y . 41 Table 2 Frequency of A r t e r i e s Bypassed i n T h i s Sample A r t e r y Bypassed Frequency P e r c e n t Femoral 22 66.0 I l i a c 3 16.0 P o p l i t e a l 4 12.0 A o r t i c 2 6.0 T o t a l 31 100.0 Ta b l e 3 Frequency of s u r g i c a l P r o c e d u r e s Performed on T h i s Sample Type of S u r g e r y Frequency P e r c e n t F e r a o r a l - P o p l i t e a l ( I n S i t u ) 10 33.0 F e m o r a l - P o p l i t e a l ( S y n t h e t i c ) 10 33.0 A o r t i c B i - F e m o r a l 3 10.0 F e m o r a l - T i b i a l 2 6.0 Abdominal A o r t i c R e s e c t i o n 2 6.0 Femoral-Femoral C r o s s o v e r 2 6.0 P o p l i t e a l - T i b l a l 1 3.0 P o p l i t e a l - P e r o n e a l 1 3.0 T o t a l 31 100.0 M e d i c a l S t a t u s . R e l e v a n t i n f o r m a t i o n c o n c e r n i n g the m e d i c a l s t a t u s of each s u b j e c t i n c l u d e d h i s / h e r m e d i c a l h i s t o r y and m e d i c a t i o n s r e c e i v e d d u r i n g the t h i r d , f o u r t h and f i f t h p o s t o p e r a t i v e day. of the 31 s u b j e c t s i n the sample, 30 had h e a l t h problems o t h e r than p e r i p h e r a l v a s c u l a r d i s e a s e . These o t h e r h e a l t h problems i n c l u d e d : d i a b e t e s (n=9) c a r d i o v a s c u l a r r e l a t e d problems (n=25) i n c l u d i n g a n g i n a ( n = l l ) , h y p e r t e n s i o n (n=9), p r e v i o u s m y o c a r d i a l i n f a r c t i o n s (n=5), c e r e b r a l v a s c u l a r a c c i d e n t s (n=3) and p r e v i o u s open h e a r t s u r g e r y (n=3). Other h e a l t h problems a l s o i n c l u d e d t h y r o i d d i s o r d e r s (n=4), and 42 a r t h r i t i s (n=3). Of the 31 s u b j e c t s i n the sample, 24 were on more th a n one c a r d i o v a s c u l a r m e d i c a t i o n . The most f r e q u e n t l y p r e s c r i b e d m e d i c a t i o n s I n c l u d e d : a n t i p l a t e l e t m e d i c a t i o n s (n=17) i n c l u d i n g e n t e r i c c o a t e d A s p i r i n (n=13) and P e r s a n t i n (n=4); a n t i a r r h y t h m i c s (n=9); a n t i h y p e r t e n s i v e s (n=9); c o r o n a r y v a s o d i l a t o r s (n=9); d i u r e t i c s (n=7); p o t a s s i u m c h l o r i d e (n=5); a n t i c o a g u l a n t m e d i c a t i o n s (n=5) i n c l u d i n g W a r f a r i n (n=2) and H e p a r i n (n=3); and a n t l h y p e r l l p l d e m l c m e d i c a t i o n s (n=4). These m e d i c a t i o n s were p r e s c r i b e d i n a v a r i e t y of c o m b i n a t i o n s , the most f r e q u e n t b e i n g a n t i a r r h y t h m i c and a n t i p l a t e l e t m e d i c a t i o n s (n=10), f o l l o w e d by the c o m b i n a t i o n of a n t i h y p e r t e n s i v e s and d i u r e t i c s (n=6). M e d i c a t i o n s p r e s c r i b e d t o manage a d d i t i o n a l h e a l t h c o n d i t i o n s i n c l u d e d : n o n s t e r o i d a l a n t i - i n f l a m m a t o r y m e d i c a t i o n s (n=4); d i a b e t i c agents (n=6); t h y r o i d m e d i c a t i o n s (n=6); m e d i c a t i o n s t o d e c r e a s e g a s t r i c a c i d s e c r e t i o n s (n=6); a n t i -a n x i e t y m e d i c a t i o n s (n=4); and m e d i c a t i o n s f o r glaucoma ( n = l ) . F i n d i n g s The f i n d i n g s of the s t u d y w i l l be p r e s e n t e d i n r e l a t i o n t o each of t h e two r e s e a r c h q u e s t i o n s . A d e s c r i p t i o n of the d a t a on the dependent v a r i a b l e , i . e . the s y s t o l i c b l o o d p r e s s u r e of the b r a c h i a l a r t e r y , w i l l be p r e s e n t e d f i r s t . Q u e s t i o n 1. D i f f e r e n c e s i n B r a c h i a l S y s t o l i c B l o o d P r e s s u r e by  Method of Measurement. P r i o r t o comparing the b r a c h i a l s y s t o l i c p r e s s u r e s , d e s c r i p t i v e d a t a w i l l be p r e s e n t e d on the arm w i t h the h i g h e s t 43 p r e s s u r e f o l l o w e d by the l e v e l of the s y s t o l i c p r e s s u r e f o r each method of measurement and f o r each of the o c c a s i o n s . Because i t i s a d v i s a b l e t o use the arm w i t h the h i g h e s t b r a c h i a l s y s t o l i c p r e s s u r e , p r e s s u r e s f o r both arms were measured. S i x t y - o n e p e r c e n t of the s u b j e c t s had a h i g h e r s y s t o l i c p r e s s u r e i n the r i g h t arm, 26% had a h i g h e r s y s t o l i c p r e s s u r e i n the l e f t arm and the r e m a i n i n g 13% had e q u a l s y s t o l i c p r e s s u r e s i n both arms. T h e r e f o r e , the r i g h t arm was used more f r e q u e n t l y than the l e f t arm. The b r a c h i a l s y s t o l i c p r e s s u r e , r e g a r d l e s s of method, ranged from 92 t o 192 mm Hg on p o s t o p e r a t i v e day 3 (M=135.9 SD=4.1), 94 t o 180 on p o s t o p e r a t i v e day 4 (M=133.1 SD=3.6) and 84 t o 200 on the f i f t h p o s t o p e r a t i v e day (M=136.4 SD=4.4). The means and s t a n d a r d d e v i a t i o n s f o r method a r e the f o l l o w i n g and p r e s e n t e d i n t a b l e 4. The b r a c h i a l s y s t o l i c p r e s s u r e measured by the s t e t h o s c o p e diaphragm ranged from 98 t o 192 mm Hg on p o s t o p e r a t i v e day 3 (M=136.6 SD=4.2), 96 t o 180 on p o s t o p e r a t i v e day 4 (M=134.0 SD=3.5) and 90 t o 200 on the f i f t h p o s t o p e r a t i v e day (M=136.5 SD=4.2). The b r a c h i a l s y s t o l i c p r e s s u r e measured by the s t e t h o s c o p e b e l l method ranged from 92 to 192 mm Hg on p o s t o p e r a t i v e day 3 (M=135.0 SD=4.3), 96 t o 182 on p o s t o p e r a t i v e day 4 (M=132.3 SD=3.6), and 84 t o 200 on the f i f t h p o s t o p e r a t i v e day (M=136.4 SD=4.7). The b r a c h i a l s y s t o l i c p r e s s u r e measured by the u l t r a s o n i c Doppler method ranged from 98 to 176 mm Hg on p o s t o p e r a t i v e day 3 (M=136.1 SD=3.8), 94 t o 180 on p o s t o p e r a t i v e day 4 (M=133.0 SD=3.8), and 100 t o 200 on the f i f t h p o s t o p e r a t i v e day (M=136.5 SD=4.2). T a b l e 4 B r a c h i a l S y s t o l i c P r e s s u r e R e c o r d i n g s by Method Postop P o s t o p P o s t o p mm Hg Day 3 Day 4 Day 5 T o t a l P e r c e n t S t e t h o s c o p e Diaphragm Method 90-99 1 1 1 3 3.0 100-109 2 3 3 8 9.0 110-119 6 2 2 10 11.0 120-129 2 5 8 15 16.0 130-139 5 9 2 16 17.0 140-149 7 4 5 16 17.0 150-159 3 5 4 12 13.0 160-169 3 0 4 7 8.0 170-179 1 1 1 3 3.0 180-189 0 1 0 1 1.0 190-199 1 0 0 1 1.0 200-209 0 0 1 1 1.0 S t e t h o s c o p e B e l l Method 80-89 0 0 1 1 1.0 90-99 2 1 1 4 4.0 100-109 3 3 3 9 10.0 110-119 4 4 3 11 12.0 120-129 3 5 3 11 12.0 130-139 5 7 5 17 18.0 140-149 4 6 5 15 16.0 150-159 5 2 5 12 13.0 160-169 2 1 1 4 4.0 170-179 2 1 2 5 5.0 180-189 0 1 1 2 2.0 190-199 1 0 0 1 1.0 200-209 0 0 1 1 1.0 U l t r a s o n i c Doppler Method 90-99 1 1 0 2 2.0 100-109 3 3 2 8 9.0 110-119 3 4 4 11 12.0 120-129 3 5 5 13 14.0 130-139 6 5 6 17 18.0 140-149 5 7 4 16 17.0 150-159 3 3 4 10 11.0 160-169 5 2 2 9 10.0 170-179 2 0 3 5 5.0 180-189 0 1 0 1 1.0 '1'9 0-199 0 0 0 0 0.0 200-209 0 0 1 1 1.0 T o t a l 31 31 31 93 100.0 45 T a b l e 5 Means and St a n d a r d D e v i a t i o n s of B r a c h i a l S y s t o l i c P r e s s u r e s by  Day and Method n=31 Postop P o s t o p P o s t o p Mean Method Day 3 Day 4 Day 5 (SD) S t e t h o s c o p e 136 .6 134 .0 136 .4 135 .6 Diaphragm (4. 2) (3 . 5) (4. 2) (3. 9) S t e t h o s c o p e 134 .0 132 .3 136 .4 134 .2 B e l l (4. 3) (3. 6) (4. 7) (4. 2) U l t r a s o n i c 136 .1 133 .0 136 .5 135 .2 Doppler ( 3 . 8) ( 3 . 8) (4. 2) (3 . 9) Mean (SD) 135 .9 133 .1 136 . 4 135 .0 (4. 1) (3. 6) (4. 4) (4. 0) The means f o r a l l methods and a l l o c c a s i o n s t h e r e f o r e ranged from 132.3 t o 136.6 mm Hg and the s t a n d a r d d e v i a t i o n s ranged from 3.5 t o 4.7 mm Hg (see Table 5 ) . Because the s t e t h o s c o p e diaphragm method i s the u s u a l method used to measure the b r a c h i a l s y s t o l i c p r e s s u r e , i t w i l l be used as t h e c o n t r o l a g a i n s t which the o t h e r p r e s s u r e s t a k e n by d i f f e r e n t methods a r e p r e s e n t e d . Table 6 i l l u s t r a t e s t h a t 61% of the p r e s s u r e s measured by the s t e t h o s c o p e b e l l method were w i t h i n ±5 mm Hg of the s t e t h o s c o p e diaphragm method, and 26% of these r e a d i n g s were the same r e a d i n g o b t a i n e d by the s t e t h o s c o p e diaphragm method. When the Doppler method was compared t o the s t e t h o s c o p e diaphragm method 67% of the p r e s s u r e s were w i t h i n +5 mm Hg of the s t e t h o s c o p e diaphragm method, and 17% of the s e r e a d i n g s were the same r e a d i n g as o b t a i n e d by the s t e t h o s c o p e diaphragm method. For the s t e t h o s c o p e b e l l method, 38% of the r e a d i n g s were more th a n 5 mm Hg d i f f e r e n t from the s t e t h o s c o p e 46 T a b l e 6 D i f f e r e n c e In B r a c h i a l S y s t o l i c P r e s s u r e s by Method of  Measurement (n=31) D e v i a t i o n s from P o s t o p Postop Postop S t e t h o s c o p e Day 3 Day 4 Day 5 T o t a l P e r c e n t Diaphragm Method i n mm Hg St e t h o s c o p e B e l l Method -21 t o -25 0 1 0 1 1.0 -16 t o -20 0 0 0 0 0.0 -11 t o -15 2 0 2 4 4.0 -6 t o -10 6 8 4 18 19.0 -1 t o -5 5 6 6 17 18.0 same 11 6 7 24 26.0 + 1 t o + 5 4 7 5 16 17.0 + 6 t o + 10 3 3 6 12 13.0 + 11 t o + 15 0 0 1 1 1.0 U l t r a s o n i c Doppler Method -36 t o -40 0 0 1 1 1.0 -31 t o -35 0 0 0 0 0.0 -26 t o -30 0 0 0 0 0.0 -21 t o -25 0 0 0 0 0.0 -16 t o -20 1 0 0 1 1.0 -11 t o -15 1 0 1 2 2.0 -6 t o -10 2 8 5 15 16.0 -1 t o -5 10 8 5 23 25.0 same 5 5 6 16 17 .0 +1 t o + 5 10 8 5 23 25.0 +6 t o + 10 2 2 2 6 6.0 +11 t o + 15 2 0 1 3 3.0 + 16 t o + 20 2 1 1 4 4.0 T o t a l 31 31 31 93 100.0 diaphragm method. U s i n g the Doppler method, 33% of the r e a d i n g s were over 5 mm Hg d i f f e r e n t t h a n those recorded u s i n g the s t e t h o s c o p e diaphragm method. To d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n the b r a c h i a l s y s t o l i c p r e s s u r e when the t h r e e methods were employed, w i t h i n -s u b j e c t two repeated-measures a n a l y s i s of v a r i a n c e (ANOVA) was used. As d e s c r i b e d i n the pr o c e d u r e s f o r d a t a a n a l y s i s the 47 a s sumptions were t e s t e d t o a s s u r e the a p p r o p r i a t e use of the two repeated-measures and a l l assumptions were met. I n the w i t h i n -s u b j e c t two repeated-measures procedure the s u b j e c t i s h i s / h e r own c o n t r o l . T h i s reduces the w i t h i n e r r o r v a r i a n c e and i d e n t i f i e s t he w i t h i n - s u b j e c t v a r i a t i o n . In o t h e r words, i t measures t h e v a r i a t i o n s i n each s u b j e c t ' s s c o r e a c r o s s the methods and o c c a s i o n s (W.B. B o l d t , p e r s o n a l communication, F e b r u a r y , 1991; Munro e t a l . , 1986) (see Table 7 ) . There was no s i g n i f i c a n t d i f f e r e n c e i n s y s t o l i c p r e s s u r e r e l a t e d t o method of t a k i n g the p r e s s u r e , the day t h a t the p r e s s u r e was t a k e n , nor the i n t e r a c t i o n between method and o c c a s i o n . T a b l e 7 A n a l y s i s of V a r i a n c e Summary Table f o r Measurement Method, Time  P e r i o d and S y s t o l i c P r e s s u r e n=31 Source Sum of Degrees of Mean F S i g . Squares Freedom Square O c c a s i o n 575, .45 2 287. .70 0, .67 0, .52 E r r o r 25881, .66 60 431, .36 Method 60, .59 2 30. .29 1, .52 0, .23 E r r o r 1195, .86 60 19 , .93 Method x O c c a s i o n 30, .51 4 7. ,63 0. .37 0. ,83 E r r o r 2479, .71 120 20, .66 p= .05 Q u e s t i o n 2. D i f f e r e n c e i n the A n k l e / B r a c h i a l Index by Method of  Me a s u r i n g the B r a c h i a l S y s t o l i c P r e s s u r e . P r i o r t o p r e s e n t i n g whether the method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e and/or o c c a s i o n made a d i f f e r e n c e t o the ABI, d e s c r i p t i v e i n f o r m a t i o n on the f r e q u e n c i e s and 48 d i s t r i b u t i o n o£ the d o r s a l i s p e d i s p r e s s u r e s , the p o s t e r i o r t i b i a l p r e s s u r e s and the ABI's u s i n g each v e s s e l w i l l be p r e s e n t e d . D o r s a l i s P e d i s P r e s s u r e s . The d o r s a l i s p e d i s p r e s s u r e s ranged from 44 t o 170 mm Hg on p o s t o p e r a t i v e day 3 (M=112.3 SD=4.7), 40 t o 160 mm Hg on p o s t o p e r a t i v e day 4 (M=107 SD=4.9) and 58 t o 165 mm Hg on p o s t o p e r a t i v e day 5 (M=114.4 SD=5.2) (see Ta b l e 8 ) . The means ranged from 106.9 t o 114.4 ram Hg and the SD ranged from 4.7 t o 5.2 mm Hg (see Table 9 ) . Ta b l e 8 D o r s a l i s P e d i s P r e s s u r e s on Each Day mm Hg Postop P o s t o p Postop T o t a l P e r c e n t Day 3 Day 4 Day 5 40-49 1 1 0 2 2.0 50-59 0 0 1 1 1.0 60-69 0 1 0 1 1.0 70-79 0 3 2 5 5.0 80-89 1 3 4 8 9.0 90-99 5 1 2 8 9.0 100-109 8 7 6 21 22.5 110-119 3 4 4 11 12.0 120-129 5 6 2 13 14.0 130-139 2 3 2 7 7 . 5 140-149 1 0 1 2 2.0 150-159 2 0 6 8 9.0 160-169 0 2 1 3 3.0 170-179 3 0 0 3 3.0 T o t a l 31 31 31 93 100.0 P o s t e r l o r T i b i a l P r e s s u r e s . The p o s t e r i o r t i b i a l p r e s s u r e s ranged from 4 4 t o 176 mm Hg on p o s t o p e r a t i v e day 3 <M= 109 SD=5.7), 44 t o 162 mm Hg on p o s t o p e r a t i v e day 4 (M= 109 SD=4.7) and 58 t o 165 mm Hg on the f i f t h p o s t o p e r a t i v e day (M= 114.6 SD=5.6) (see Table 10) . The means ranged from 109 t o 114.6 mm Hg and the s t a n d a r d d e v i a t i o n s from 4.7 t o 5.7 mm Hg (see Table 9 ) . 49 Ta b l e 9 Means and Sta n d a r d D e v i a t i o n s of D o r s a l i s P e d i s and P o s t e r i o r  T i b i a l P r e s s u r e s n=31 Postop P o s t o p P o s t o p Mean A r t e r y Day 3 Day 4 Day 5 (SD) D o r s a l i s 112 .3 107 .0 114 .4 111.2 Ped i s (4. 7) (4. 9) (5. 2) (4.9) P o s t e r i o r 109 .0 109 .0 114 .6 110.8 T i b i a l (5. 7) (4. 7) (5. 6) (5.3) T a b l e 10 P o s t e r i o r T i b i a l P r e s s u r e s on Each Day mm Hg Postop P o s t o p P o s t o p T o t a l P e r c e n t Day 3 Day 4 Day 5 40-49 1 1 0 2 2.0 50-59 1 0 1 2 2.0 60-69 2 1 1 4 4.0 70-79 2 2 1 5 5.0 80-89 1 3 3 7 8.0 90-99 3 4 4 11 12.0 100-109 5 5 4 14 15.0 110-119 7 2 5 14 15.0 120-129 2 5 3 10 11.0 130-139 1 2 1 4 4.0 140-149 0 4 0 4 4.0 150-159 4 0 6 10 11.0 160-169 1 2 2 5 5.0 170-179 1 0 0 1 1.0 T o t a l 31 31 31 93 99.0 D o r s a l i s p e d i s a n k l e / b r a c h i a l index (DPABI). Data on the DPABI w i l l be p r e s e n t e d u s i n g the p r e s s u r e s o b t a i n e d on the three days of d a t a c o l l e c t i o n . A d e s c r i p t i o n of the f r e q u e n c i e s and d i s t r i b u t i o n when a l l t h r e e methods were used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e w i l l be p r e s e n t e d f i r s t . T h i s w i l l be f o l l o w e d by a comparison of the DPABI when the b r a c h i a l s y s t o l i c p r e s s u r e was measured by d i f f e r e n t methods. The r e s u l t s of the p a r a m e t r i c t e s t i n g comparing the DPABI by o c c a s i o n and method w i l l then be p r e s e n t e d . The DPABI, by a l l methods t o measure t h e b r a c h i a l s y s t o l i c p r e s s u r e , ranged from 0.39 t o 1.30 mm Hg on p o s t o p e r a t i v e day 3 (M=0.843 SD=0.038), 0.36 t o 1.20 mm Hg on p o s t o p e r a t i v e day 4 (M=0.81 SD=0.038), and 0.41 t o 1.40 mm Hg on the f i f t h p o s t o p e r a t i v e day (M=0.84 SD=0.039) (see Table 1 1 ) . The DPABI u s i n g the s t e t h o s c o p e diaphragm method t o measure the b r a c h i a l s y s t o l i c p r e s s u r e ranged from 0.40 t o 1.20 mm Hg on p o s t o p e r a t i v e day 3 (M=0.84 SD=0.037), 0.41 t o 1.20 on p o s t o p e r a t i v e day 4 (M=0.80 SD=0.037), and 0.41 t o 1.30 on the f i f t h p o s t o p e r a t i v e day (M=0.85 SD=0.04) (see Table 1 2 ) . The DPABI u s i n g the s t e t h o s c o p e b e l l method t o measure the b r a c h i a l s y s t o l i c p r e s s u r e ranged from 0.42 t o 1.30 mm Hg on p o s t o p e r a t i v e day 3 (M=0.85 SD=0.04), 0.36 t o 1.17 on p o s t o p e r a t i v e day 4 (M=0.82 SD=0.04), and 0.41 t o 1.40 on the f i f t h p o s t o p e r a t i v e day (M=0.85 SD=0.04) (see T a b l e 1 2 ) . The DPABI u s i n g the u l t r a s o n i c Doppler t o measure the b r a c h i a l s y s t o l i c p r e s s u r e ranged from 0.39 t o 1.20 mm Hg on p o s t o p e r a t i v e day 3 (M=0.84 SD=0.037), 0.36 t o 1.19 on p o s t o p e r a t i v e day 4 (M=0.81 SD=0.037) and 0.43 t o 1.18 on the f i f t h p o s t o p e r a t i v e day (M=0.83 SD=0.037) (see Table 1 2 ) . Over the t h r e e day p e r i o d the means f o r a l l methods ranged from 0.80 t o 0.85 mm Hg and the s t a n d a r d d e v i a t i o n s ranged from 0.037 t o 0.040 mm Hg (see Table 1 3 ) . 51 T a b l e 11 D o r s a l i s P e d i s A n k l e / B r a c h i a l Index on Each Day by a l l Methods Index Postop P o s t o p P o s t o p T o t a l P e r c e n t i n mm Hg Day 3 Day 4 Day 5 0.36-0.40 2 4 0 6 2.0 0.41-0.45 1 5 2 8 3.0 0.46-0.50 0 0 3 3 1.0 0.51-0.55 3 5 7 15 5.0 0.56-0.60 3 1 1 5 2.0 0.61-0.65 10 4 5 19 7.0 0.66-0.70 8 7 10 25 9.0 0.71-0.75 9 14 8 31 11.0 0.76-0.80 9 1 2 12 4.0 0.81-0.85 4 11 9 24 9.0 0.86-0.90 7 7 7 21 7.5 0.91-0.95 5 6 7 18 6.5 0.96-1.00 7 6 7 20 7.0 1.01-1.05 8 10 7 25 9.0 1.06-1.10 8 3 9 20 7.0 1.11-1.15 1 3 2 6 2.0 1.16-1.20 7 6 5 18 6.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 1 0 1 2 1.0 1.31-1.35 0 0 0 0 0.0 1.36-1.40 0 0 1 1 0.5 T o t a l 93 93 93 279 100.0 Because the s t e t h o s c o p e diaphragm method i s the u s u a l method used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e i n d e t e r m i n i n g the a n k l e / b r a c h i a l i n d e x , i t was used as the c o n t r o l a g a i n s t which the o t h e r DPABI d e t e r m i n e d by d i f f e r e n t methods a r e p r e s e n t e d . T a b l e 14 i l l u s t r a t e s t h a t 84% of the DPABI's u s i n g the s t e t h o s c o p e b e l l method were w i t h i n +0.05 mm Hg of the s t e t h o s c o p e diaphragm method and 27% of t h e s e r e a d i n g s were the same as t h o s e o b t a i n e d by the s t e t h o s c o p e diaphragm method. When the Doppler method was compared t o the s t e t h o s c o p e diaphragm method 75% of the Doppler r e a d i n g s were w i t h i n +0.05 mm Hg of the s t e t h o s c o p e diaphragm method and 18% of the s e r e a d i n g s were the 52 T a b l e 12 D o r s a l i s P e d i s A n k l e / B r a c h i a l Index by Method of Mea s u r i n g the B r a c h i a l S y s t o l i c P r e s s u r e Index P o s t o p P o s t o p P o s t o p T o t a l P e r c e n t mm Hg Day 3 Day 4 Day 5 S t e t h o s c o p e Diaphragm Method 0.36-0.40 1 1 0 2 2.0 0.41-0.45 0 2 1 3 3.0 0.46-0.50 0 0 1 1 1.0 0.51-0.55 1 2 2 5 5.5 0.56-0.60 1 0 0 1 1.0 0.61-0.65 4 1 1 6 6.5 0.66-0.70 1 4 5 10 11.0 0.71-0.75 2 3 2 7 7.5 0.76-0.80 5 1 0 6 6.5 0.81-0.85 2 4 4 10 11.0 0.86-0.90 2 2 2 6 6.5 0.91-0.95 1 3 2 6 6.5 0.96-1.00 3 3 2 8 8.5 1.01-1.05 3 3 2 8 8.5 1.06-1.10 3 0 4 7 7.5 1.11-1.15 0 0 0 0 0.0 1.16-1.20 2 2 2 6 6.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 0 0 1 1 1.0 S t e t h o s c o p e B e l l Method 0.36-0.40 0 2 0 2 2.0 0.41-0.45 1 1 1 3 3.0 0.46-0.50 0 0 0 0 0.0 0.51-0.55 1 1 3 5 5.5 0.56-0.60 1 1 0 2 2.0 0.61-0.65 3 1 4 8 8.5 0.66-0.70 3 2 0 5 5.5 0.71-0.75 5 5 4 14 15.0 0.76-0.80 1 0 0 1 1.0 0.81-0.85 0 3 3 6 6.5 0.86-0.90 3 3 2 8 8.5 0.91-0.95 2 2 2 6 6.5 0.96-1.00 2 2 4 8 8.5 1.01-1.05 3 4 3 10 11.0 1.06-1.10 2 0 3 5 5.5 1.11-1.15 1 2 0 3 3.0 1.16-1.20 2 2 1 5 5.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 1 0 0 1 1.0 1.31-1.35 0 0 0 0 0.0 1.36-1.40 0 0 1 1 1.0 53 Tab l e 12 ( c o n t i n u e d ) Index Posto p P o s t o p Postop T o t a l P e r c e n t mm Hg Day 3 Day 4 Day 5 U l t r a s o n i c Doppler Method 0.36-0.40 1 1 0 2 2.0 0.41-0.45 0 2 0 2 2.0 0.46-0.50 0 0 2 2 2.0 0.51-0.55 1 2 2 5 5.5 0.56-0.60 1 0 1 2 2.0 0.61-0.65 3 2 0 5 5.5 0.66-0.70 4 1 5 10 11.0 0.71-0.75 2 6 2 10 11.0 0.76-0.80 3 0 2 5 5.5 0.81-0.85 2 4 2 8 8.5 0.86-0.90 2 2 3 7 7.5 0.91-0.95 2 1 3 6 6.5 0.96-1.00 2 1 1 4 4.0 1.01-1.05 2 3 2 7 7.5 1.06-1.10 3 3 2 8 8.5 1.11-1.15 0 1 2 3 3.0 1.16-1.20 3 2 2 7 7.5 T o t a l 31 31 31 93 100.0 Tab l e 13 D o r s a l i s P e d i s A n k l e / B r a c h i a l Index Means and S t a n d a r d D e v i a t i o n s  by Day and Method n=31 Method P o s t o p P o s t o p P o s t o p Mean Day 3 Day 4 Day 5 (SD) S t e t h o s c o p e 0, .84 0. .80 0, .85 0. .83 Diaphragm (0, ,037) (0, .037) (0, .040) (0. ,038) S t e t h o s c o p e 0, .85 . 0, .82 0, .85 0, .84 B e l l (0, .040) (0, .040) (0, .040) (0. .040) U l t r a s o n i c 0, .84 0, .81 0, .83 0, .83 Doppler (0, .037) (0, .037) (0, .037) (0. .037) Mean 0. .84 0. ,81 0, .84 0. ,83 (SD) (0. .038) (0. ,038) (0. .039) (0. ,038) 54 Ta b l e 14 D i f f e r e n c e s In D o r s a l i s P e d i s A n k l e / B r a c h l a l Index by Method of  Measurement D e v i a t i o n s from S t e t h o s c o p e Diaphragm Postop P o s t o p P o s t o p i n mm Hg Day 3 Day 4 Day 5 T o t a l P e r c e n t S t e t h o s c o p e B e l l Method -.06 t o -.10 1 2 3 6 6.5 -.01 t o -.05 6 9 9 24 26.0 same 10 6 9 25 27.0 +.01 t o + .05 10 11 8 29 31.0 +.06 t o + .10 4 3 2 9 9.5 U l t r a s o n i c Doppler Method -.36 to -.40 0 0 1 1 1.0 -.31 t o -.35 0 0 0 0 0.0 -.26 t o -.30 0 0 0 0 0.0 -.21 t o -.25 0 0 0 0 0.0 -.16 t o -.20 0 0 0 0 0.0 -.11 t o -.15 0 0 0 0 0.0 -.06 t o -.10 3 2 4 9 9.5 -.01 t o -.05 8 9 10 27 29.0 same 5 5 7 17 18.0 +.01 t o + .05 9 10 7 26 28.0 +.06 t o + .10 6 4 2 12 13.0 +.11 t o + .15 0 1 0 1 1.0 T o t a l 31 31 31 93 99.5 same as t h o s e o b t a i n e d by the s t e t h o s c o p e diaphragm method. With s t e t h o s c o p e b e l l method 16% of the DPABI r e a d i n g s were more than 0.05 mm Hg d i f f e r e n t from the s t e t h o s c o p e diaphragm method. For the Doppler method 25% of the r e a d i n g s were more than .05 mm Hg d i f f e r e n t from the s t e t h o s c o p e diaphragm method. To d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n the DPABI when the t h r e e methods were employed, a w i t h i n s u b j e c t two r e p e a t e d -measures a n a l y s i s of v a r i a n c e (ANOVA) was used. The assumptions were t e s t e d t o a s s u r e the a p p r o p r i a t e use of t h e two r e p e a t e d -measures procedure and a l l the assumptions were met (W.B. B o l d t , p e r s o n a l communication, F e b r u a r y , 1991; Munro e t a l . , 1986). There was no s i g n i f i c a n t d i f f e r e n c e i n the DPABI r e l a t e d t o method of t a k i n g the b r a c h i a l s y s t o l i c p r e s s u r e s , the day t h a t the measurements were r e c o r d e d , nor an i n t e r a c t i o n between method and o c c a s i o n (see Table 1 5 ) . Tab l e 15 A n a l y s i s of V a r i a n c e Summary Table f o r Measurement Method, Time  P e r i o d and D o r s a l i s P e d i s A n k l e / B r a c h i a l Index. n=31 Source Sum of Degrees of Mean F S i g Squares Freedom Square O c c a s i o n 0.070 2 0.351 1.24 0.29 E r r o r 1.695 60 0.028 Method 0.008 2 0.004 2.14 0.13 E r r o r 0.117 60 0.002 Method x O c c a s i o n 0.007 4 0.002 1.10 0.36 E r r o r 0.198 120 0.002 p= .05 P o s t e r i o r T i b i a l A n k l e / B r a c h i a l Index (PTABI) The d a t a < the PTABI w i l l be p r e s e n t e d u s i n g the s c o r e s o b t a i n e d on the t h r e e days of d a t a c o l l e c t i o n . A d e s c r i p t i o n of the f r e q u e n c i e s and d i s t r i b u t i o n u s i n g a l l t h r e e methods of d e t e r m i n i n g the b r a c h i a l s y s t o l i c p r e s s u r e w i l l be p r e s e n t e d f i r s t . T h i s w i l l be f o l l o w e d by a comparison of the r e s u l t s of the PTABI when the b r a c h i a l s y s t o l i c p r e s s u r e was measured by d i f f e r e n t methods. The r e s u l t s of the p a r a m e t r i c t e s t i n g comparing the PTABI by o c c a s i o n and method w i l l t hen be p r e s e n t e d . 56 T a b l e 16 P o s t e r i o r T i b i a l A n k l e / B r a c h l a l Index Measured on Each Day by a l l  Methods mm Hg Postop P o s t o p P o s t o p T o t a l P e r c e n t Day 3 Day 4 Day 5 0.36-0.40 2 2 0 4 1.5 0.41-0.45 4 1 7 12 4.0 0.46-0.50 5 0 2 7 2.5 0.51-0.55 6 3 5 14 5.0 0.56-0.60 9 8 1 18 6.5 0.61-0.65 5 11 2 18 6.5 0.66-0.70 2 2 8 12 4.0 0.71-0.75 7 13 5 25 9.0 0.76-0.80 7 2 9 18 6.5 0.81-0.85 3 3 3 9 3.0 0.86-0.90 4 5 10 19 7.0 0.91-0.95 6 9 9 24 9.0 0.96-1.00 9 10 7 26 9.0 1.01-1.05 5 7 4 16 5.5 1.06-1.10 7 5 13 25 9.0 1.11-1.15 4 8 2 14 5.0 1.16-1.20 7 4 3 14 5.0 1.21-1.25 0 0 0 0 0.0 1.26-1.30 1 0 2 3 1.0 1.31-1.35 0 0 0 0 0.0 1.36-1.40 0 0 1 1 0.5 T o t a l 93 93 93 279 99.5 The PTABI, by a l l methods t o measure the b r a c h i a l s y s t o l i c p r e s s u r e , ranged from 0.39 t o 1.30 mm Hg on p o s t o p e r a t i v e day 3 (M=0.82 SD=0.04), 0.37 t o 1.20 on p o s t o p e r a t i v e day 4 (M=0.84 SD=0.04) and 0.41 t o 1.40 on the f i f t h p o s t o p e r a t i v e day (M=0.85 SD=0.04) (see Table 1 6 ) . The PTABI, u s i n g the s t e t h o s c o p e diaphragm method t o measure the b r a c h i a l s y s t o l i c p r e s s u r e , ranged from 0.40 t o 1.20 mm Hg on p o s t o p e r a t i v e day 3 (M=0.81 SD=0.044), 0.44 t o 1.18 on p o s t o p e r a t i v e day 4 (M=0.85 SD=0.037), and 0.41 t o 1.30 on p o s t o p e r a t i v e day 5 (M=0.85 SD=0.042) (see Ta b l e 1 7 ) . T a b l e 17 P o s t e r i o r T i b i a l A n k l e / B r a c h i a l Index P r e s s u r e by Method of Measuring the B r a c h i a l S y s t o l i c Pressure Index P o s t o p P o s t o p P o s t o p i n mm Hg Day 3 Day 4 Day 5 T o t a l P e r c e n t S t e t h o s c o p e Diaphragm Method 0.36-0.40 1 0 0 1 1.0 0.41-0.45 1 1 3 5 5.5 0.46-0.50 2 0 0 2 2.0 0.51-0.55 3 1 2 6 6.5 0.56-0.60 2 2 0 4 4.5 0.61-0.65 2 5 1 8 8.5 0.66-0.70 0 1 2 3 3.0 0.71-0.75 2 4 2 8 8.5 0.76-0.80 3 0 3 6 6.5 0.81-0.85 0 1 1 2 2.0 0.86-0.90 3 3 3 9 10.0 0.91-0.95 2 3 3 8 8.5 0.96-1.00 1 3 3 7 7.5 1.01-1.05 2 2 0 4 4.0 1.06-1.10 4 2 5 11 12.0 1.11-1.15 1 2 1 4 4.5 1.16-1.20 2 1 1 4 4.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 0 0 1 1 1.0 S t e t h o s c o p e B e l l Method 0.36-0.40 0 1 0 1 1.0 0.41-0.45 2 0 2 4 4.5 0.46-0.50 2 0 1 3 3.0 0.51-0.55 1 1 1 3 3.0 0.56-0.60 3 3 1 7 7.5 0.61-0.65 2 3 1 6 6.5 0.66-0.70 1 0 3 4 4.5 0.71-0.75 3 6 0 9 10.0 0.76-0.80 1 0 4 5 5.5 0.81-0.85 2 1 1 4 4.5 0.86-0.90 0 1 3 4 4.5 0.91-0.95 2 3 3 8 8.5 0.96-1.00 3 3 2 8 8.5 1.01-1.05 2 3 2 7 7.5 1.06-1.10 3 1 4 8 8.5 1.11-1.15 1 5 0 6 6.5 1.16-1.20 2 0 2 4 4.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 1 0 0 1 1.0 1.31-1.35 0 0 0 0 0.0 1.36-1.40 0 0 1 1 1.0 58 T a b l e 17 ( c o n t i n u e d ) Index i n P o s t o p P o s t o p P o s t o p T o t a l P e r c e n t mm Hg Day 3 Day 4 Day 5 U l t r a s o n i c Doppler Method 0.36-0.40 1 1 0 2 2.0 0.41-0.45 1 0 2 3 3.0 0.46-0.50 1 0 1 2 2.0 0.51-0.55 2 1 2 5 5.5 0.56-0.60 4 3 0 7 7.5 0.61-0.65 1 3 0 4 4.5 0.66-0.70 1 1 3 5 5.5 0.71-0.75 2 3 3 8 8.5 0.76-0.80 3 2 2 7 7.5 0.81-0.85 1 1 1 3 3,0 0.86-0.90 1 1 4 6 6.5 0.91-0.95 2 3 3 8 8.5 0.96-1.00 5 4 2 11 12.0 1.01-1.05 1 2 2 5 5.5 1.06-1.10 0 2 4 6 6.5 1.11-1.15 2 1 1 4 4.5 1.16-1.20 3 3 0 6 6.5 1.21-1.25 0 0 0 0 0.0 1.26-1.30 0 0 1 1 1.0 T o t a l 31 31 31 93 100.0 The PTABI, u s i n g the s t e t h o s c o p e b e l l method t o measure t h e b r a c h i a l s y s t o l i c p r e s s u r e , ranged from 0.42 t o 1.30 mm Hg on p o s t o p e r a t i v e day 3 (M=0.82 SD=0.046), 0.38 t o 1.15 on p o s t o p e r a t i v e day 4 (M=0.84 SD=0.038), and 0.41 t o 1.40 on the f i f t h p o s t o p e r a t i v e day (M=0.85 SD=0.043) (see Ta b l e 17). The PTABI, u s i n g the u l t r a s o n i c Doppler method t o measure the b r a c h i a l s y s t o l i c p r e s s u r e , ranged from 0.39 t o 1.20 mm Hg on p o s t o p e r a t i v e day 3 (M=0.81 SD=0.044), 0.37 t o 1.20 on p o s t o p e r a t i v e day 4 (M=0.84 SD=0.039), and 0.43 t o 1.30 on the f i f t h p o s t o p e r a t i v e day (M=0.84 SD=0.037) (see Table 17). Over t h e 3 days of d a t a c o l l e c t i o n and f o r a l l methods t h e means t h e r e f o r e ranged from 0.81 t o 0.85 mm Hg and the s t a n d a r d 59 T a b l e 18 P o s t e r i o r T i b i a l A n k l e / B r a c h i a l Index Means and St a n d a r d D e v i a t i o n s by Day and Method n=31 Postop Postop P o s t o p Mean Method Day 3 Day 4 Day 5 (SD) S t e t h o s c o p e 0.81 0.83 0.85 0.83 Diaphragm (0.04) (0.037) (0.04) (0.04) S t e t h o s c o p e 0.82 0.84 0.85 0.84 B e l l (0.046) (0.038) (0.04) (0.04) U l t r a s o n i c 0.81 0.84 0.83 0.82 Doppler (0.04) (0.039) (0.037) (0.038) Mean 0.81 0.84 0.84 0.83 (SD) (0.04) (0.038) (0.039) (0.039) d e v i a t i o n s ranged from 0.037 t o 0.046 mm Hg (see Ta b l e 1 8 ) . The s t e t h o s c o p e diaphragm method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e was used as the c o n t r o l a g a i n s t which t h e o t h e r PTABI d e t e r m i n e d by d i f f e r e n t methods a r e p r e s e n t e d . Table 19 I l l u s t r a t e s t h a t 82% of the PTABI's u s i n g the s t e t h o s c o p e b e l l method were w i t h i n +0.05 mm Hg of the s t e t h o s c o p e diaphragm method and 29% of the s e r e a d i n g s were the same as t h o s e o b t a i n e d by the s t e t h o s c o p e diaphragm method. When the Doppler method was compared t o the s t e t h o s c o p e diaphragm method 77.5% of the Doppler r e a d i n g s were w i t h i n +0.05 mm Hg of the s t e t h o s c o p e diaphragm r e a d i n g s , and 21.5% of t h e s e r e a d i n g s were the same as tho s e o b t a i n e d by the s t e t h o s c o p e diaphragm method. For the s t e t h o s c o p e b e l l method 18% of the r e a d i n g s were more th a n .05 mm Hg d i f f e r e n t from the s t e t h o s c o p e diaphragm method. For the Doppler method 22.5% of the r e a d i n g s were more than .05 mm Hg d i f f e r e n t from the s t e t h o s c o p e diaphragm method. 60 T a b l e 19 D i f f e r e n c e s I n P o s t e r i o r T i b i a l A n k l e / B r a c h i a l Index by Method of  Measurement D e v i a t i o n s from S t e t h o s c o p e Diaphragm P o s t o p P o s t o p P o s t o p In mm Hg Day 3 Day 4 Day 5 T o t a l P e r c e n t S t e t h o s c o p e B e l l Method -.06 t o -.10 1 1 4 6 6.5 -.01 t o -.05 6 9 8 23 25.0 same 12 6 7 25 27.0 + .01 t o + .05 8 11 9 28 30.0 + .06 to + .10 4 3 2 9 9.5 + .11 t o + .15 0 1 1 2 2.0 U l t r a s o n i c Doppler Method -.36 t o -.40 0 0 1 1 1.0 -.31 t o -.35 0 0 0 0 0.0 -.26 t o -.30 0 0 0 0 0.0 -.21 t o -.25 0 0 0 0 0.0 -.16 t o -.20 0 0 0 0 0.0 -.11 to -.15 1 0 0 1 1.0 -.06 t o -.10 2 2 4 8 8.5 -.01 to -.05 7 7 9 23 25.0 same 7 7 6 20 21.5 + .01 to + .05 11 9 9 29 31.0 + .06 t o + .10 3 6 2 11 12.0 T o t a l 31 31 31 93 100.0 To d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n the PTABI when the t h r e e methods were employed, w i t h i n - s u b j e c t two repeated-measures a n a l y s i s of v a r i a n c e (ANOVA) was used. The assumptions were t e s t e d t o a s s u r e the a p p r o p r i a t e use of the two repeated-measures procedure and a l l assumptions were met (W.B. B o l d t , p e r s o n a l communication, F e b r u a r y , 1991; Munro e t a l . , 1986). There was no s i g n i f i c a n t d i f f e r e n c e i n the PTABI r e l a t e d t o method of t a k i n g the b r a c h i a l s y s t o l i c p r e s s u r e s , the day t h a t the measurements were r e c o r d e d , nor an i n t e r a c t i o n between method and o c c a s i o n (see Table 2 0 ) . 61 T a b l e 20 A n a l y s i s of V a r i a n c e Summary Table f o r Measurement Method, Time  P e r i o d and P o s t e r i o r T i b i a l A n k l e / B r a c h i a l Index n=31 Source Sum of Squares Degrees of Freedom Mean Square F S i g O c c a s i o n 0.049 2 0.024 0. 54 0.59 E r r o r 2.720 60 0.045 Method 0.008 2 0.004 2. 88 0.06 E r r o r 0.083 60 0.001 Method x O c c a s i o n 0.011 4 0.003 1. 54 0.19 E r r o r 0.211 120 0.003 p=.05 D i s c u s s i o n of Sample The d i s c u s s i o n w i l l be d i v i d e d i n t o t h r e e s e c t i o n s . I n i t i a l l y t he c o m p a r a b i l i t y of the sample t o the t a r g e t p o p u l a t i o n and p o p u l a t i o n of p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s w i l l be p r o v i d e d . T h i s w i l l be f o l l o w e d by a d i s c u s s i o n of the b r a c h i a l s y s t o l i c p r e s s u r e and whether method or o c c a s i o n made a d i f f e r e n c e t o the p r e s s u r e . A d i s c u s s i o n of the ABI w i l l t hen be p r o v i d e d . The f i n d i n g s w i l l be examined i n l i g h t of the t h e o r e t i c a l f o r m u l a t i o n s , o t h e r e m p i r i c a l f i n d i n g s and the m e t h o d o l o g i c a l problems r e l a t e d t o the s t u d y . Comparison of the Sample w i t h the T a r g e t P o p u l a t i o n The r e s e a r c h e r wished t o det e r m i n e i f t h i s sample was comparable t o o t h e r p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s i n the h o s p i t a l where the s t u d y was conducted. The p a t i e n t i n f o r m a t i o n f o r the p e r i o d of J a n u a r y 1, 1989 t o December 31, 1990 were r e t r i e v e d from the o p e r a t i n g room r e c o r d s of t h a t h o s p i t a l . T h i s I n c l u d e d : age, gender and type of bypass s u r g e r y (see Table 21) . Age. I n b o t h the sample and t h e t a r g e t p o p u l a t i o n t h e l a r g e s t number of s u r g i c a l p r o c e d u r e s were performed f o r t h o s e between 6 and 80 y e a r s of age. The sample had a s m a l l e r p e r c e n t a g e of s u b j e c t s i n the 51 t o 60 y e a r age group and a h i g h e r p r o p o r t i o n i n the 61 t o 80 year age group than the t a r g e t p o p u l a t i o n . The sample had fewer s u b j e c t s i n the 31 t o 50 y e a r c a t e g o r y and the 81 t o 100 year group than the t a r g e t p o p u l a t i o n . The age d i s t r i b u t i o n was g e n e r a l l y comparable t o the t a r g e t p o p u l a t i o n even though the wide v a r i a n c e of ages seen i n the t a r g e t p o p u l a t i o n was not seen i n the sample, (see T a b l e 21 ) . C u r r e n t l i t e r a t u r e on the age of p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s c o u l d not be l o c a t e d . However, the Canada H e a l t h Report (1990) i n d i c a t e s t h a t i n the y e a r s 1987 t o 1988 the age range of p a t i e n t s a d m i t t e d t o Canadian h o s p i t a l s w i t h d i s e a s e s of the a r t e r i e s , a r t e r i o l e s and c a p i l l a r i e s i n c l u d e d : 33% between 45 t o 64 y e a r s of age, 33% between the ages 65 t o 74 y e a r s of age and 27% over 75 y e a r s of age (Canada H e a l t h R e p o r t , 1990). Owing t o t h e s m a l l sample s i z e of the c u r r e n t s t u d y , the d a t a r e g a r d i n g age groups s h o u l d be i n t e r p r e t e d c a u t i o u s l y . Gender. The gender of the sample i s comparable w i t h the t a r g e t p o p u l a t i o n which c o n s i s t e d of 62-65% males (see Table 21 ) . T h i s p e r c e n t a g e i s a l s o r e f l e c t e d i n the Canadian h o s p i t a l m o r b i d i t y f i g u r e s f o r d i s e a s e s of the a r t e r i e s , a r t e r i o l e s and c a p i l l a r i e s which averaged 66% male and 38% female ( H e a l t h Report 1989; H e a l t h R e p o r t , 1990). T a b l e 21 Comparison of Sample w i t h T a r g e t P o p u l a t i o n Sample T a r q e t P o p u l a t i o n J a n . 1/90 t o J a n . 1/89 t o Oct. -Nov/90 Dec. 31/90 Dec. 31/89 (n=31) (n=202) (n= 202) F r e q % F r e q % F r e q % Aqe Compar i s o n 31-40 0 0.0 2 1.0 3 1.5 41-50 2 6.0 14 7.0 9 4.5 51-60 3 10.0 32 16.0 40 20.0 61-70 13 42.0 79 39.0 65 32.0 71-80 12 39.0 65 32.0 59 29.0 81-90 1 3.0 10 5.0 24 12.0 91-100 0 0.0 0 0.0 2 1.0 Gender Comparison Male 18 58.0 125 62.0 131 65.0 Female 13 42.0 77 38.0 71 35.0 Type of Bypass S u r q e r y F e m o r a l - 10 33.0 47 23.0 46 22.5 P o p l i t e a l ( i n s l t u ) F e m o r a l - 10 33.0 57 28.0 48 23.5 P o p l i t e a l ( s y n t h e t i c ) A o r t a 3 10.0 28 14.0 24 12.0 B i - F e m o r a l F e m o r a l - 2 6.0 23 11.5 24 12.0 C r o s s o v e r F e m o r a l - 2 6.0 30 15.0 22 11.0 T i b i a l Abdominal 2 6.0 9 4.5 28 14.0 A o r t i c R e s e c t i o n P o p l i t e a l - 1 3.0 5 2.5 10 5.0 T i b l a l P o p l i t e a l 1 3.0 3 1.5 0 0.0 P e r o n e a l T o t a l 31 100.0 202 100.0 202 100.0 64 A r t e r i e s Bypassed and Type of S u r g e r y . The sample r e f l e c t e d the same f r e q u e n c y d i s t r i b u t i o n as the t a r g e t p o p u l a t i o n f o r a r t e r i e s bypassed. The most f r e q u e n t l y bypassed a r t e r y was the f e m o r a l a r t e r y as e v i d e n c e d by the number of f e m o r a l - p o p l i t e a l bypass s u r g e r i e s performed. Data from t h i s h o s p i t a l shows a h i g h e r p e r c e n t a g e of s u r g e r i e s t h a t bypass b l o c k a g e s In the f e m o r a l a r t e r y t h a n any o t h e r a r t e r y (see Table 21) . T h i s h i g h e r p r o p o r t i o n of f e m o r a l - p o p l i t e a l bypass s u r g e r y i s due t o a t h e r o s c l e r o s i s o c c u r r i n g a p p r o x i m a t e l y 50% of the time i n the s u p e r f i c i a l f e m o r a l a r t e r y ( B r e w s t e r , 1985; Fahey, 1988; V e i t h and c o l l e a g u e s , 1981). The second most f r e q u e n t l y bypassed a r t e r y was t h a t of the common i l i a c and s u r g i c a l p r o c e d u r e s i n c l u d e d the f e m o r a l - f e m o r a l c r o s s o v e r and the a o r t i c b i - f e m o r a l bypass (see Ta b l e 21). However, Fahey (1988) i n d i c a t e s t h a t the p o p l i t e a l a r t e r y i s the second most common a r t e r y t h a t i s bypassed. I n t h i s s t u d y s u r g e r y on the p o p l i t e a l a r t e r y ranked t h i r d and s u r g e r y t h a t bypassed the a o r t a ranked f o u r t h i n f r e q u e n c y (see T a b l e 2 1 ) . P r e v i o u s V a s c u l a r S u r g e r y . In the sample of 31 s u b j e c t s , 11 of the s u b j e c t s had p e r i p h e r a l v a s c u l a r s u r g e r y p r i o r t o the c u r r e n t s u r g e r y . S i x of thes e o p e r a t i o n s were on the same l e g . G r a f t r e placement i s not an uncommon re q u i r e m e n t f o r p a t i e n t s who have had p e r i p h e r a l v a s c u l a r bypass s u r g e r y . The f i v e - y e a r g r a f t s u r v i v a l ranges from 50-75% f o r o p e r a t i o n s performed above the knee and as low as 12% f o r g r a f t s i n s e r t e d below the knee (Fahey, 1988; V e i t h e t a l . , 1981). 65 M e d i c a l S t a t u s . The most p r e v a l e n t h e a l t h c o n d i t i o n s i n t h i s group of s u b j e c t s were d i a b e t e s m e l l i t u s and c a r d i o v a s c u l a r r e l a t e d p a t h o l o g i e s such as h y p e r t e n s i o n and c a r d i o m y o p a t h i e s . In t h e sample, 26% of the s u b j e c t s had d i a b e t e s m e l l i t u s which i s c o n s i s t e n t w i t h the t a r g e t p o p u l a t i o n ( J . R e i d , p e r s o n a l communication, F e b r u a r y , 1991). I n a s t u d y by G r e e n h a l g h , Jamieson, and N i c o l a i d e s (1986) t o a s s e s s the r i s k f a c t o r s t h a t e x e r t e d a s i g n i f i c a n t i n f l u e n c e on g r a f t f a i l u r e s f o r f e m o r a l -p o p l i t e a l bypass g r a f t s (n=119), 35% of t h e i r s u b j e c t s were d i a b e t i c . I n a s t u d y by S t e e r , C u c k l e , F r a n k l i n and M o r r i s (1983) on the i n f l u e n c e of d i a b e t e s m e l l i t u s on p e r i p h e r a l v a s c u l a r d i s e a s e , 30% of the s u b j e c t s were d i a b e t i c . T h e r e f o r e , the sample f o r the c u r r e n t s t u d y r e f l e c t s the d i a b e t i c p o p u l a t i o n of p e r i p h e r a l v a s c u l a r p a t i e n t s . In the sample 60% of the s u b j e c t s had a h i s t o r y of c a r d i o v a s c u l a r r e l a t e d p a t h o l o g i e s i n c l u d i n g h y p e r t e n s i o n , a n g i n a and p r e v i o u s m y o c a r d i a l i n f a r c t i o n s . T h i s i s comparable t o the e s t i m a t e of 50% of the t a r g e t p o p u l a t i o n who had a h i s t o r y of c a r d i a c problems ( J . R e i d , p e r s o n a l communication, F e b r u a r y , 1991). H y p e r t e n s i v e p a t i e n t s e x p e r i e n c e an I n c r e a s e i n the i n c i d e n c e of c o r o n a r y a r t e r y d i s e a s e , owing t o changes i n the a r t e r i a l l n t i m a (DeBakey, 1979). Brown (1981) a s s e s s e d the c a r d i a c h i s t o r y of 671 p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s , found t h a t 17% had a h i s t o r y of a n g i n a and 47% had a h i s t o r y of m y o c a r d i a l i n f a r c t i o n . H e r t z e r (1984) i n v e s t i g a t e d the p r e v a l e n c e of c o r o n a r y a r t e r y d i s e a s e i n 1000 p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s . He found t h a t 6% had normal c o r o n a r y a r t e r i e s w h i l e 94% had v a r y i n g degrees of c o r o n a r y d i s e a s e , owing t o the c l o s e a s s o c i a t i o n between c a r d i a c r e l a t e d p a t h o l o g i e s and p e r i p h e r a l v a s c u l a r d i s e a s e , the c u r r e n t sample appears t o be c o n s i s t e n t w i t h the t a r g e t p o p u l a t i o n on t h i s v a r i a b l e . M e d i c a t i o n . In the sample the most f r e q u e n t l y p r e s c r i b e d m e d i c a t i o n s were a n t i p l a t e l e t m e d i c a t i o n s (n=17) t o p r e v e n t e m b o l i z a t i o n of the g r a f t . P a t e n c y r a t e s f o r f e m o r a l - p o p l i t e a l bypass g r a f t s a r e s l i g h t l y b e t t e r f o r t h o s e p a t i e n t s a d m i n i s t e r e d a n t i p l a t e l e t m e d i c a t i o n s ( B r e w s t e r , 1985; V e i t h , e t a l . 1981). M e d i c a t i o n s such as a n t i a r r h y t h m i c s , c o r o n a r y v a s o d i l a t o r s , d i u r e t i c s , d i a b e t i c a g e n t s , a n t i h y p e r l i p i d i m i c s and a n t i h y p e r t e n s i v e s were n e c e s s a r y because of o t h e r m e d i c a l c o n d i t i o n s . A n t i h y p e r t e n s i v e m e d i c a t i o n s have an a d d i t i o n a l s i g n i f i c a n c e i n t h e c a r e of the p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t . The b l o o d p r e s s u r e must be m a i n t a i n e d a t a c o n s t a n t l e v e l s i n c e a s h a r p i n c r e a s e i n p r e s s u r e c o u l d r e s u l t i n an a n a s t o m o t i c l e a k w h i l e a sudden d r o p i n b l o o d p r e s s u r e c o u l d endanger g r a f t p a t e n c y (Fahey, 1988). A l t h o u g h the sample s i z e was s m a l l i t appears t o be comparable t o o t h e r p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r bypass p a t i e n t s i n the h o s p i t a l where the s t u d y was c o n d u c t e d . The comparable v a r i a b l e s i n c l u d e d : age, gender, a r t e r i e s bypassed, t y p e of s u r g e r y , m e d i c a l s t a t u s and p r e v i o u s p e r i p h e r a l v a s c u l a r s u r g e r y . D i s c u s s i o n of F i n d i n g s L e v e l o f B r a c h i a l S y s t o l i c P r e s s u r e P r i o r t o d i s c u s s i n g t h e f i n d i n g s r e l a t e d t o t h e d i f f e r e n c e s i n the b r a c h i a l s y s t o l i c p r e s s u r e b e t w e e n method and o c c a s i o n , some d i s c u s s i o n w i l l t a k e p l a c e on t h e l e v e l of t h e d i f f e r e n c e between th e l e f t a nd r 1ght arm p r e s s u r e s . Because i t i s a d v i s a b l e t o use the arm w i t h t h e h i g h e s t p r e s s u r e i n a s s e s s i n g the b r a c h i a l s y s t o l i c p r e s s u r e and ABI, I t i s n e c e s s a r y t o t a k e t h e p r e s s u r e s In both arms. I n t h i s sample, the f i n d i n g t h a t 61% had h i g h e r p r e s s u r e s In the r i g h t arm and 13% had e q u a l p r e s s u r e s i n b o t h arms i s not u n u s u a l ( K r i s t e n s e n , 1982). The d i f f e r e n c e i n r e a d i n g s was from 2 t o 48 mm Hg w i t h a mean of 10 mm Hg, t h e r e f o r e i n d i c a t i n g a c o n s i d e r a b l e d i f f e r e n c e f o r 15 s u b j e c t s . Of the 15 s u b j e c t s w i t h the d i f f e r e n c e g r e a t e r t h a n 10 mm Hg, 12 had a h i s t o r y of h y p e r t e n s i o n . T h i s i s comparable t o K r i s t e n s e n (1982) who found h y p e r t e n s i v e p a t i e n t s more l i k e l y t o have a d i f f e r e n c e between arm p r e s s u r e s t h a n n o rmotensive p a t i e n t s . Fahey (1988) and C a r t e r (1985) r e p o r t t h a t when the p a t i e n t has a t h e r o s c l e r o s i s of t h e u p p e r - e x t r e m i t y , the p r o x i m a l l e f t s u b c l a v i a n a r t e r y i s I n v o l v e d t w i c e as o f t e n as the r i g h t s u b c l a v i a n a r t e r y t h u s c o n t r i b u t i n g t o a more f r e q u e n t h i g h e r s y s t o l i c p r e s s u r e i n t h e r i g h t arm. The b r a c h i a l s y s t o l i c p r e s s u r e v a r i e d from 84 t o 200 mm Hg. w i t h an o v e r a l l mean of 135 mm Hg. The World H e a l t h O r g a n i z a t i o n d e f i n e s h y p e r t e n s i o n as s y s t o l i c p r e s s u r e s >_ 160 mm Hg (World H e a l t h O r g a n i z a t i o n T e c h n i c a l R e p o r t s , 1978). U s i n g t h i s f i g u r e , 15% of t h e r e a d i n g s f o r t h e s e s u b j e c t s were t h e r e f o r e i n t h e 68 hypertensive range. It is not unreasonable for there to be readings at t h i s l e v e l as eight of the nine subjects who recorded brachial s y s t o l i c pressures >160 mm Hg had a hist o r y of hypertension and were on antihypertensive medications. These subjects did not d i f f e r from the remainder of the sample in terms of age, hi s t o r y of diabetes, previous vascular surgery, or differences between pressures for right or l e f t arm. The higher readings were a one or two-day event for 6 of them but occurred on a l l three days for 3 of them. The ANOVA showed that there was no s i g n i f i c a n t difference in the brachial s y s t o l i c pressure related to the method of measuring the pressure. Although there was no s i g n i f i c a n t difference between methods, the stethoscope diaphragm and the ultrasonic Doppler seemed to r e f l e c t more sim i l a r pressures (see Table 5; Table 6). This finding i s comparable with r e s u l t s from other research studies (Garter, 1968; Tahir and Adriani, 1973; Theloosen-Kerstens et a l . , 1990; Yao et a l . , 1969). Possible explanations for the lack of a s i g n i f i c a n t difference related to a l l methods may have been the r e s u l t of technical problems, such as, f a m i l i a r i t y with the instruments used and manual dexterity required to operate the Doppler. Review of the l i t e r a t u r e indicates that the Doppler should record the higher pressures. Strandness et a l . (1967) stated that the ultraso n i c Doppler picks up the movement of the red blood c e l l before vibrations can be detected. When Theloosen-Kerstens et a l . (1990) compared noninvasive methods of measuring the brachial s y s t o l i c pressure they found that the Doppler and the stethoscope diaphragm had the best c o r r e l a t i o n . However, when they compared the Doppler and stethoscope diaphragm methods with invasive methods of measuring the brachial s y s t o l i c pressure they found that the Doppler had the better c o r r e l a t i o n with the Invasive methods. One explanation might be that the time lag between the detection of the movement of the RBC and the v i b r a t i o n of the artery is not s i g n i f i c a n t when using noninvasive methods to measure the s y s t o l i c pressure. Another explanation might be that the Doppler used in t h i s study f o r the conversion o£ u l t r a s o n i c sound to sonic sound required more energy for the conversion, therefore, the true magnitude of the ultrasonic sound wave was diminished. Another explanation might be that, although-the data c o l l e c t o r was trained, there are fewer variables to control when using the stethoscope diaphragm when compared to the Doppler method. The Doppler method requires more manual dexterity than the stethoscope method. For example, the Doppler method requires the operator to manipulate the Doppler probe on a s l i p p e r y surface and the sphygmomanometer valve at the same time. The increased number of variables to manipulate could res u l t in a pressure that i s below the actual pressure (0'Mara & Yao, 1982; Yao, 1985). Another explanation for the lack of a s i g n i f i c a n t difference related to the method of taking the brachial s y s t o l i c pressure might be that the nurse c o l l e c t i n g the data was more familiar with the stethoscope diaphragm and stethoscope b e l l methods of measuring the b r a c h i a l s y s t o l i c pressure and not as f a m i l i a r with 70 the Doppler method. Another e x p l a n a t i o n c o u l d be t h a t a l t h o u g h the s t e t h o s c o p e b e l l method i s b e t t e r a t d e t e c t i n g K o r o t k o f f sounds i t i s e a s i e r t o g e t a s e a l w i t h the diaphragm of the s t e t h o s c o p e on a rounded s u r f a c e ( C o n s t a n t , 1987). For t h e s u b j e c t s i n t h i s sample who had p r e s s u r e s which c o u l d be c o n s i d e r e d h y p e r t e n s i v e , t h e s t e t h o s c o p e b e l l r e c o r d e d the h i g h e s t p r e s s u r e 35% of t h e t i m e , the u l t r a s o n i c Doppler 23% of t h e ti m e and t h e s t e t h o s c o p e diaphragm 12% of t h e t i m e . The s t e t h o s c o p e , b e l l and Doppler r e c o r d e d the same p r e s s u r e 6% of the tim e and a l l t h r e e methods r e c o r d e d the same p r e s s u r e 6% of t h e t i m e . C o n s t a n t (1987) s t a t e s t h a t t h e s t e t h o s c o p e b e l l i s t h e o r e t i c a l l y b e t t e r t h a n t h e s t e t h o s c o p e diaphragm f o r d e t e c t i n g the low f r e q u e n c y K o r o t k o f f sounds as i t a m p l i f i e s the low f r e q u e n c y sounds b e t t e r t h a n t h e diaphragm. The d a t a from t h e c u r r e n t s t u d y appears t o i n d i c a t e t h a t the s t e t h o s c o p e b e l l method would be the b e t t e r one t o d e t e c t h y p e r t e n s i o n , but owing t o t he s m a l l sample s i z e t h i s d a t a s h o u l d be I n t e r p r e t e d c a u t i o u s l y . The ANOVA showed t h a t t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n the b r a c h i a l s y s t o l i c p r e s s u r e between p o s t o p e r a t i v e day 3, 4 and 5, a l t h o u g h t h e r e was a d e c l i n e i n t h e b r a c h i a l s y s t o l i c p r e s s u r e from p o s t o p e r a t i v e day 3 t o day 4 and then a r e t u r n t o the day t h r e e l e v e l s on f i f t h day. T h i s may have been due t o the s t r e s s response t o s u r g e r y . D u r i n g the f i r s t two p o s t o p e r a t i v e days f l u i d moves from t h e v a s c u l a r compartment t o t h e t i s s u e s . I n re s p o n s e t o t h i s d e c r e a s e i n i n t e r v a s c u l a r f l u i d the k i d n e y s r e t a i n water and sodium d u r i n g the t h i r d and f o u r t h p o s t o p e r a t i v e day. Then during the fourth to seventh postoperative day the f l u i d returns to the vascular compartment and the kidneys eliminate the excess f l u i d (Luckmann & sorensen, 1988). Ankle/Brachlal Index Since the ankle s y s t o l i c pressure i s the numerator of the ABI r a t i o , discussion of the l e v e l of the ankle s y s t o l i c pressure w i l l be given f i r s t . This w i l l be followed by a discussion of the ABI related to each artery and a comparison of the d o r s a l i s pedis ankle/brachial index (DPABI) with the p o s t e r i o r t i b i a l ankle/brachial index (PTABI). Level of Ankle S y s t o l i c Pressures. The means of the d o r s a l i s pedis and posterior t i b i a l pressures were within 3 mm Hg of each other and the range varied from approximately 44 mm Hg to 170 mm Hg with an o v e r a l l mean of approximately 111 mm Hg. The lack of a s i g n i f i c a n t difference between the pressures of these a r t e r i e s may be because the femoral-popliteal bypass graft was the most frequently performed surgery. With th i s type of graft the primary blockage i s in the femoral artery. Therefore, i t would not be unreasonable to see l i t t l e difference in the ankle s y s t o l i c pressures between the two a r t e r i e s as the flow d i s t a l to the primary blockage would not Improve one vessel more than the other once the blockage i s bypassed. Both ankle s y s t o l i c pressures had a lower range by about 30 to 40 mm Hg than the brachial s y s t o l i c pressure and showed a wider v a r i a t i o n than the brachial s y s t o l i c pressures (84 to 200 mm Hg). One possible explanation for t h i s discrepancy might be that the d o r s a l i s pedis or posterior t i b i a l artery may be a f f e c t e d by a t h e r o s c l e r o s i s , thus c o n t r i b u t i n g t o a d e c r e a s e d s u p p l y of b l o o d t h r o u g h t h e a r t e r y (Fahey, 1988). I f t h e r e a r e a t h e r o s c l e r o t i c p l a g u e s i n e i t h e r a r t e r y , t h e n t h e v e s s e l d i a m e t e r w i l l be d e c r e a s e d , r e s u l t i n g i n d i m i n i s h e d p r e s s u r e , f l o w and sound d i s t a l t o the p l a q u e s ( C a r t e r , 1985; Yao e t a l . , 1969). Another p o s s i b l e e x p l a n a t i o n might be t h a t 26% of the sample had d i a b e t e s m e l l i t u s . A t h e r o s c l e r o t i c l e s i o n s i n d i a b e t i c p a t i e n t s a r e f r e q u e n t l y l o c a t e d i n the medium and s m a l l a r t e r i e s below the knee (Rudermaut & Handench1Id, 1984). The a t h e r o s c l e r o t i c p l a q u e s i n e i t h e r a r t e r y can cause a d e c r e a s e i n the p r e s s u r e , f l o w and sound d i s t a l t o t h e p l a q u e s ( C a r t e r , 1985; Yao e t a l . , 1969). The World H e a l t h O r g a n i z a t i o n d e f i n e s h y p e r t e n s i o n as a s y s t o l i c p r e s s u r e >160 mm Hg (World H e a l t h O r g a n i z a t i o n T e c h n i c a l R e p o r t s , 1978). U s i n g t h i s f i g u r e , 6% of th e r e a d i n g s f rom b o t h t h e p o s t e r i o r t i b i a l and d o r s a l i s p e d i s a r t e r i e s of the s u b j e c t s were i n the h y p e r t e n s i v e range. A l l f i v e o f t h e s e s u b j e c t s had a h i s t o r y of h y p e r t e n s i o n , were on a n t i h y p e r t e n s i v e m e d i c a t i o n s and d i d not d i f f e r from the r e s t of the sample. Three s u b j e c t s had d o r s a l i s p e d i s and p o s t e r i o r t i b i a l p r e s s u r e s t h a t were h i g h e r t h a n t h e i r b r a c h i a l s y s t o l i c p r e s s u r e on a l l 3 p o s t o p e r a t i v e days. One p o s s i b l e e x p l a n a t i o n f o r t h i s c o u l d b e - c a l c i f i c a t i o n i n the p e r i p h e r a l a r t e r i e s which o c c u r s i n a p p r o x i m a t e l y 10% of p a t i e n t s w i t h p e r i p h e r a l v a s c u l a r d i s e a s e . C a l c i f i c a t i o n i n the a r t e r y a f f e c t s t h e c o m p r e s s i o n of t h e v e s s e l and r e s u l t s i n a f a l s e h i g h s y s t o l i c p r e s s u r e ( C a r t e r , 1968; Yao, 1985). 73 Changes In the Ankle S y s t o l i c Pressures Over the Three Pays. For the d o r s a l i s pedis artery there was no s i g n i f i c a n t difference in the pressures between postoperative day 3, 4 and 5. However, there was a decline in the d o r s a l i s pedis pressures from postoperative day 3 to postoperative day 4 then an increase to the postoperative day three l e v e l on the f i f t h postoperative day. This appears to correlate with the brachial s y s t o l i c pressures on • those days. One possible explanation could be the- postoperative stress response causing a retention of sodium and water during the t h i r d to fourth day af t e r surgery followed by d i u r e s i s . Another possible explanation for^ the decrease i n pressure on postoperative day 4 is that the edema that r e s u l t s from s u r g i c a l manipulation in the groin area disrupts the lymphatic drainage from the leg. Edema i s most pronounced on postoperative day 4, owing to the patient's increased a c t i v i t y ( J . Reid, personal communication, February, 1991). This finding is not supported by Yao, et a l (1969), as they state that the ankle pressure usually reaches a maximum on the secondhand t h i r d postoperative days, but s l i g h t l y decreases on the fourth and f i f t h postoperative day. However, they did not indicate i n t h e i r study the subjects' a c t i v i t y l e v e l which contributes to dependent edema. The presence of edema greatly increases the distance the sound wave must cross over thus diminishing the sound that i s transmitted and- thus accounting for the decrease in the pressure measured (Frohlich et a l . , 1988). For the posterior t i b i a l artery there was no s i g n i f i c a n t difference in the pressures between postoperative day 3,4 and 5. The p o s t e r i o r t i b i a l p r e s s u r e s remained the same on p o s t o p e r a t i v e day 3 and 4. However, t h e r e was an I n c r e a s e i n t h e p o s t e r i o r t i b i a l p r e s s u r e s on the f i f t h p o s t o p e r a t i v e day. S i n c e the p r e s s u r e s d i d not change between p o s t o p e r a t i v e day 3 and 4 the f i n d i n g s on p o s t o p e r a t i v e day 4 d i d not c o r r e s p o n d w i t h e i t h e r t h e d o r s a l i s p e d i s or b r a c h i a l s y s t o l i c p r e s s u r e s f o r t h e f o u r t h p o s t o p e r a t i v e d a y . T h e i n c r e a s e I n the p o s t e r i o r t i b i a l p r e s s u r e s on p o s t o p e r a t i v e day 5 c o r r e s p o n d e d w i t h t h a t of t h e d o r s a l i s p e d i s and b r a c h i a l s y s t o l i c p r e s s u r e s f o r t h a t day. Perhaps edema and minor f l u c t u a t i o n s i n b l o o d p r e s s u r e do not p l a y as s i g n i f i c a n t a r o l e i n a f f e c t i n g the p o s t e r i o r t i b i a l p r e s s u r e s as t h e y do w i t h t h e d o r s a l i s p e d i s p r e s s u r e . L e v e l of A B I . Both the d o r s a l i s p e d i s and p o s t e r i o r t i b i a l i n d i c e s ranged from a p p r o x i m a t e l y 0.36 mm Hg t o 1.40 mm Hg over the t h r e e p o s t o p e r a t i v e days w i t h a m a j o r i t y of the i n d i c e s f a l l i n g between 0.66 t o 1.00 mm Hg. C a r t e r (1968) and Yao (1985) i n d i c a t e t h a t i f the a n k l e s y s t o l i c p r e s s u r e i s more th a n 20% lower t h a n t h e b r a c h i a l s y s t o l i c p r e s s u r e t h e n t h e f l o w of b l o o d t o t h e lower e x t r e m i t y i s compromised. Thus the c r i t i c a l v a l u e emphasized f o r ABI i s 0.80 mm Hg. A p p r o x i m a t e l y 45% of the r e a d i n g s were <0.80 mm Hg and 55% were >0.81 mm Hg. For most of t h e s e s u b j e c t s t h i s was a one or two day o c c a s i o n . However, 10 s u b j e c t s had b o t h ABI's >0.80 on a l l 3 p o s t o p e r a t i v e days. These s u b j e c t s d i d not d i f f e r from t h e remainder of t h e sample i n terms of age, gender, h i s t o r y of d i a b e t e s or p r e v i o u s p e r i p h e r a l v a s c u l a r s u r g e r y w i t h t h e e x c e p t i o n t h a t one s u b j e c t w i t h a low ABI was r e t u r n e d t o t h e o p e r a t i n g room on her f i f t h p o s t o p e r a t i v e 75 day a f t e r t he ABI's were measured. She vent f o r a r e v i s i o n of her f e m o r a l - p o p l i t e a l i n s i t u bypass g r a f t and d i d n o t d i f f e r from t h e r e s t of the sample i n r e l a t i o n t o age, m e d i c a l s t a t u s or s u r g i c a l s t a t u s . Some p o s s i b l e e x p l a n a t i o n s f o r ABI's below t h e c r i t i c a l l e v e l may be due t o changes In a r t e r i a l wave t r a n s m i s s i o n r e s u l t i n g from p o s s i b l e p r o x i m a l a r t e r i a l n a r r o w i n g , p r o g r e s s i v e i n c r e a s e i n s t i f f n e s s of p e r i p h e r a l a r t e r i e s , t he l a r g e r a r t e r i a l d i a m e t e r i n h y p e r t e n s i v e p a t i e n t s , or t h e degree o f edema i n t h e l o v e r e x t r e m i t y ( F r o h l l c h e t a l . , 1988; Hugue e t a l . , 1988). The ANOVA showed t h a t t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n the DPABI or PTABI r e l a t e d t o the method used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e . S i n c e 0.80 mm Hg i s t h e c r i t i c a l v a l u e emphasized f o r the ABI, methods t h a t do not d e t e c t t h a t c r i t i c a l v a l u e would be a c o n c e r n . I n terms o f t h i s c r i t i c a l v a l u e the s t e t h o s c o p e diaphragm and Doppler d e t e c t e d more ABI's below the c r i t i c a l v a l u e t h a n t h e s t e t h o s c o p e b e l l and seemed t o r e f l e c t t he more s i m i l a r r e s u l t s (see T a b l e s 12, 13, & 1 7 ) . o t h e r r e s e a r c h e r s f o u n d s i m i l a r r e s u l t s when n o n i n v a s i v e methods were used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e ( C a r t e r , 1968; T h e l o o s e n - K e r s t e n s , 1990; Yao e t a l . , 1969). Another p o s s i b l e e x p l a n a t i o n f o r the s t e t h o s c o p e diaphragm and Doppler methods o b t a i n i n g s i m i l a r r e s u l t s may be t h a t the- a c c u r a c y of the Doppler and s t e t h o s c o p e b e l l may be compromised by the number of v a r i a b l e s t o c o n s i d e r when t h e Doppler i s employed and the d i f f i c u l t y of o b t a i n i n g a s e a l w i t h the s t e t h o s c o p e b e l l ( C o n s t a n t , 1987; O'Mara & Yao, 1982). 76 Another p o s s i b l e e x p l a n a t i o n f o r the l a c k of s i g n i f i c a n t d i f f e r e n c e r e l a t e d t o the method c o u l d not o n l y be t h e i n c r e a s e d number of v a r i a b l e s t o c o n s i d e r when u s i n g the Doppler method but a l s o t h a t t h i s method r e q u i r e s more manual d e x t e r i t y t h a n does the o t h e r two methods (o'Mara & Yao, 1982; Yao, 1985). The ANOVA showed t h a t t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n the DPABI or the PTABI r e l a t e d t o the o c c a s i o n when the Index was measured. The c r i t i c a l v a l u e emphasized f o r ABI i s 0.80 mm Hg because below 0.80 mm Hg i n d i c a t e s d e c r e a s e d f l o w t o the e x t r e m i t y ( C a r t e r , 1968; Vancouver G e n e r a l H o s p i t a l V a s c u l a r Lab, 1980). Based on t h i s f i g u r e , the DPABI r e a d i n g s by a l l m e t h o d s , f l u c t u a t e d over the t h r e e p o s t o p e r a t i v e days and c o r r e s p o n d e d w i t h the d o r s a l i s p e d i s and b r a c h i a l s y s t o l i c p r e s s u r e s . The PTABI r e a d i n g s , by a l l methods, c o r r e s p o n d e d w i t h t h e p o s t e r i o r t i b i a l p r e s s u r e s but d i d not s i g n i f i c a n t l y f l u c t u a t e w i t h the b r a c h i a l s y s t o l i c p r e s s u r e over the t h r e e p o s t o p e r a t i v e days. S i n c e t h e PTABI r e a d i n g s d i d not s i g n i f i c a n t l y f l u c t u a t e t h i s c o u l d a c c o u n t f o r t h e i n c r e a s e i n the DPABI on t h e f o u r t h p o s t o p e r a t i v e day. I f the b r a c h i a l s y s t o l i c p r e s s u r e d e c r e a s e s and t h e p o s t e r i o r t i b i a l p r e s s u r e does not t h i s would r e s u l t i n an i n c r e a s e i n the PTABI on the f o u r t h p o s t o p e r a t i v e day. Summary of F i n d i n g s In t h i s c h a p t e r a d e s c r i p t i o n of the sample i n terms of t h e s u b j e c t ' s age, gender, s u r g i c a l s t a t u s and m e d i c a l s t a t u s was p r e s e n t e d . A l t h o u g h the sample was s m a l l , i t appeared t o be comparable t o o t h e r p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r p a t i e n t s i n t h e h o s p i t a l where the s t u d y was c o n d u c t e d . The. sample c o n s i s t e d 77 o£ 18 males and 13 f e m a l e s w i t h an average age of 67.6 y e a r s . The f i n d i n g s and a d i s c u s s i o n o f t h o s e f i n d i n g s i n r e l a t i o n t o each o f the two r e s e a r c h q u e s t i o n s were p r e s e n t e d . The r i g h t arm had a h i g h e r s y s t o l i c p r e s s u r e t h a n t h e l e f t arm 61% o f t h e t i m e . Nine of the s u b j e c t s were h y p e r t e n s i v e which i s not un r e a s o n a b l e owing t o t h e p r e v a l e n c e of h y p e r t e n s i o n w i t h i n t h e sample. There was no s i g n i f i c a n t d i f f e r e n c e i n t h e b r a c h i a l s y s t o l i c p r e s s u r e r e l a t e d t o the method of measuring the p r e s s u r e ( s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and- D o p p l e r ) . T h i s f i n d i n g i s c o n s i s t e n t w i t h p r e v i o u s r e s e a r c h but does not appear t o be s u p p o r t e d by S t r a n d n e s s e t a l . , as t h e y s t a t e d t h a t the Doppler p i c k s up the movement o f the RBC b e f o r e v i b r a t i o n s w i t h i n the a r t e r y can be d e t e c t e d . The a u t h o r of t h i s c u r r e n t s t u d y proposed t h a t perhaps the time l a g between d e t e c t i o n o f the movement of t h e RBC and t h e v i b r a t i o n s w i t h i n t h e a r t e r y i s not s i g n i f i c a n t when n o n i n v a s i v e methods a r e employed. I n a d d i t i o n , t h e Doppler used i n t h i s s t u d y may have r e q u i r e d more energy t o c o n v e r t u l t r a s o n i c sound t o s o n i c sound. Another e x p l a n a t i o n f o r t h e l a c k of a s i g n i f i c a n t d i f f e r e n c e i n p r e s s u r e s was t h a t the Doppler* method has more v a r i a b l e s t o c o n s i d e r and r e q u i r e s more manual d e x t e r i t y when compared t o t h e s t e t h o s c o p e method. In a d d i t i o n , the nurse c o l l e c t i n g the d a t a was more f a m i l i a r w i t h the s t e t h o s c o p e method t h a n t h e Doppler method. There was no s i g n i f i c a n t d i f f e r e n c e i n t h e b r a c h i a l s y s t o l i c p r e s s u r e r e l a t e d t o the o c c a s i o n when the p r e s s u r e was measured. 78 A l t h o u g h not s i g n i f i c a n t , t h e r e was a d e c l i n e i n the b r a c h i a l s y s t o l i c p r e s s u r e on t h e f o u r t h p o s t o p e r a t i v e day, and a r e t u r n t o t he t h i r d - p o s t o p e r a t i v e day l e v e l s on the f i f t h p o s t o p e r a t i v e day. T h i s might be e x p l a i n e d by p o s t o p e r a t i v e f l u i d s h i f t s t h a t might have o c c u r r e d . The d o r s a l i s p e d i s s y s t o l i c p r e s s u r e appeared t o f o l l o w t h i s same p a t t e r n over t h e t h r e e days of d a t a c o l l e c t i o n and might be e x p l a i n e d by f l u i d s h i f t s and p o s t o p e r a t i v e edema. The p o s t e r i o r t i b i a l s y s t o l i c p r e s s u r e remained the same on t h e t h i r d and f o u r t h p o s t o p e r a t i v e day and i n c r e a s e d on the f i f t h p o s t o p e r a t i v e day. These f i n d i n g s r e g a r d i n g t h e d o r s a l i s p e d i s and p o s t e r i o r t i b i a l s y s t o l i c p r e s s u r e s do not appear t o be s u p p o r t e d by Yao e t a l . , however, t h e y d i d not i n d i c a t e the s u b j e c t ' s a c t i v i t y l e v e l , which i s a c o n t r i b u t i n g f a c t o r t o p o s t o p e r a t i v e dependent edema. The a n k l e s y s t o l i c p r e s s u r e s of the d o r s a l i s p e d i s and p o s t e r i o r t i b i a l a r t e r i e s were w i t h i n 3 mm Hg of each o t h e r . Because the m a j o r i t y of the s u b j e c t s had f e m o r a l - p o p l i t e a l bypass g r a f t s i t would not be u n u s u a l t o observe l i t t l e d i f f e r e n c e i n t h e s e p r e s s u r e s . A p p r o x i m a t e l y 45% of t h e a n k l e s y s t o l i c p r e s s u r e s were >20% lower than the b r a c h i a l s y s t o l i c p r e s s u r e r e s u l t i n g i n a p p r o x i m a t e l y 45% of t h e ABI's l e s s t h a n t h e c r i t i c a l v a l u e of 0.80 mm Hg. The low a n k l e s y s t o l i c p r e s s u r e and ABI may have been due t o compromised f l o w t h r o u g h t h e d i s t a l a r t e r i e s owing t o changes i n the a r t e r i a l wave t r a n s m i s s i o n r e s u l t i n g from p r o x i m a l a r t e r i a l n a r r o w i n g , p r o g r e s s i v e i n c r e a s e i n t h e s t i f f n e s s of t h e p r o x i m a l a r t e r y and the degree of edema i n the lower e x t r e m i t y . 79 These f a c t o r s can c o n t r i b u t e t o a d e c r e a s e In the f l o w t o and t h e t r a n s m i s s i o n of sound from t h e d i s t a l a r t e r i e s t h u s p r o d u c i n g a low a n k l e s y s t o l i c p r e s s u r e and ABI. No s i g n i f i c a n t d i f f e r e n c e i n t h e ABI's r e l a t e d t o the method used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e was found. Nor was t h e r e any s i g n i f i c a n t d i f f e r e n c e i n the ABI's r e l a t e d t o the o c c a s i o n when the index was measured. However, the s t e t h o s c o p e diaphragm and Doppler d e t e c t e d more ABI's below t h e c r i t i c a l v a l u e of 0.80 mm Hg and seemed t o r e f l e c t more s i m i l a r ABI r e s u l t s . Other r e s e a r c h e r s found s i m i l a r r e s u l t s and i d e n t i f i e d v a r i a b l e s w i t h i n the equipment employed t h a t c o u l d compromise the measurements o b t a i n e d . S i n c e t h e PTABI r e a d i n g d i d not f l u c t u a t e on the o c c a s i o n s when t h e i n d e x was measured t h i s c o u l d a c c o u n t f o r t h e i n c r e a s e i n t h e PTABI on the f o u r t h p o s t o p e r a t i v e day. 80 CHAPTER FIVE Summary, C o n c l u s i o n s , I m p l i c a t i o n s and Recommendations I n t r o d u c t i o n T h i s s t u d y was d e s i g n e d t o dete r m i n e the d i f f e r e n c e i n t h e b r a c h i a l s y s t o l i c b l o o d p r e s s u r e when the p r e s s u r e was measured w i t h the s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and u l t r a s o n i c Doppler and t o de t e r m i n e which method was more a c c u r a t e i n measuring t h e a n k l e / b r a e h i a l index. T h i s c h a p t e r presents an o v e r v i e w of the s t u d y , f o l l o w e d by c o n c l u s i o n s , i m p l i c a t i o n s f o r n u r s i n g p r a c t i c e , n u r s i n g i n - s e r v i c e e d u c a t i o n and t h e o r y and recommendations f o r f u r t h e r r e s e a r c h . Summary I t was not c l e a r from the l i t e r a t u r e or from d i s c u s s i o n w i t h v a s c u l a r surgeons which method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e i s more a c c u r a t e when d e t e r m i n i n g t h e a n k l e / b r a c h i a l i n d e x (ABI) which i s an Important t o o l i n a s s e s s i n g g r a f t p a t e n c y f o r p a t i e n t s who have had p e r i p h e r a l v a s c u l a r s u r g e r y . T h i s s t u d y was d e s i g n e d t o compare the b r a c h i a l s y s t o l i c p r e s s u r e s when measured by s t e t h o s c o p e diaphragm, s t e t h o s c o p e b e l l and Doppler methods. These p r e s s u r e s were th e n used i n the c a l c u l a t i o n of the ABI. The ABI was t h e n compared by method and time s i n c e s u r g e r y . The t h e o r e t i c a l framework f o r t h i s s t u d y was drawn from the t h e o r i e s on sound g e n e r a t i o n , t r a n s m i s s i o n and measurement. Review of the l i t e r a t u r e on sound t r a n s m i s s i o n and measurement of s y s t o l i c b l o o d p r e s s u r e p r o v i d e d i n f o r m a t i o n on t h e f a c t o r s t o c o n s i d e r when measuring t h e s y s t o l i c p r e s s u r e . T h i s l i t e r a t u r e 81 p r o v i d e d v a r i o u s v i e w p o i n t s on which method o£ measuring the s y s t o l i c p r e s s u r e would be the most a c c u r a t e . F a c t o r s a f f e c t i n g the g e n e r a t i o n of sound w i t h i n an a r t e r y i n c l u d e d the magnitude of the f o r c e c r e a t i n g the sound wave and the d i s t a n c e from the i n i t i a l s o u r c e of g e n e r a t i o n . F a c t o r s a f f e c t i n g the t r a n s m i s s i o n of sound i n the a r t e r y i n c l u d e d the d i a m e t e r of t h e v e s s e l , vasomotor t o n e , p a t e n c y of the v e s s e l and the gap between the so u r c e of t h e sound wave and the i n s t r u m e n t used t o d e t e c t t h a t sound. The measurement of sound can be a f f e c t e d by human e r r o r , a r t e r i a l d i s e a s e , s t a t e of r e p a i r of the i n s t r u m e n t s , c h o i c e of i n s t r u m e n t s and how the i n s t r u m e n t s a r e used. Review of the l i t e r a t u r e s u g g e sted t h a t t h e Doppler would d e t e c t the s y s t o l i c p r e s s u r e sooner t h a n the o t h e r two methods as the Doppler d e t e c t s the movement of the RBC b e f o r e v i b r a t i o n s can be d e t e c t e d w i t h i n the a r t e r y . S t u d i e s by C a r t e r (1968), T h e l o o s e n - K e r s t e n s e t a l . (1990) and Yao e t a l . (1969), found the s t e t h o s c o p e diaphragm and Doppler produced comparable r e s u l t s , but were conducted under c o n t r o l l e d c o n d i t i o n s i n a l a b o r a t o r y . A l t h o u g h the l i t e r a t u r e a l s o s u g g e s t e d t h a t the s t e t h o s c o p e b e l l would be more a c c u r a t e t h a n the s t e t h o s c o p e diaphragm i n measuring the s y s t o l i c p r e s s u r e no p u b l i s h e d r e s e a r c h s t u d i e s c o u l d not be l o c a t e d t o s u p p o r t t h i s c l a i m . T h e r e f o r e , t h i s s t u d y was d e s i g n e d t o de t e r m i n e i f t h e r e was a d i f f e r e n c e i n the ABI when t h e b r a c h i a l s y s t o l i c p r e s s u r e was measured by d i f f e r e n t methods. The s t u d y used a two-r e p e a t e d measures d e s i g n i n which t h e s u b j e c t s s e r v e d as t h e i r own c o n t r o l s and was conducted In a 82 l a r g e t e r t i a r y c a r e h o s p i t a l i n Western Canada. A nurse r e s e a r c h a s s i s t a n t measured t h e b r a c h i a l s y s t o l i c p r e s s u r e s by t h r e e methods on the t h i r d , f o u r t h and f i f t h p o s t o p e r a t i v e day. The d o r s a l i s p e d i s and p o s t e r i o r t i b i a l p r e s s u r e s were measured by the Doppler on t h o s e same o c c a s i o n s . The sample was composed of 31 p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r s u b j e c t s . They were between 47 and 82 y e a r s of age w i t h 81% of the s u b j e c t s between 61 and 80 y e a r s of age (M=67.6). There were 18 males and 13 males i n the s t u d y . The s u b j e c t s had a v a r i e t y of h e a l t h problems i n a d d i t i o n t o a r t e r i a l b l o c k a g e such as h y p e r t e n s i o n and d i a b e t e s . The o p e r a t i v e p r o c e d u r e performed on t h e s e s u b j e c t s was p r i m a r i l y a f e m o r a l - p o p l i t e a l bypass. The sample was comparable t o the t a r g e t p o p u l a t i o n a t the h o s p i t a l where the s t u d y was co n d u c t e d . The d a t a were t e s t e d t o a d d r e s s each o f the two r e s e a r c h q u e s t i o n s . An ANOVA s p e c i f i c t o the two - r e p e a t e d measures d e s i g n was used t o t e s t t he two r e s e a r c h q u e s t i o n s . There was no s i g n i f i c a n t d i f f e r e n c e , a t t h e p=.05 l e v e l , i n t h e b r a c h i a l s y s t o l i c p r e s s u r e r e l a t e d t o method of t a k i n g the p r e s s u r e , t h e day t h a t t h e p r e s s u r e was measured, nor any i n t e r a c t i o n between the method and o c c a s i o n . The l a c k o f a s i g n i f i c a n t d i f f e r e n c e s u g g e s t s t h a t a l l t h r e e methods were comparable when t h e y were used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e . When measuring the b r a c h i a l s y s t o l i c p r e s s u r e i t was found t h a t the r i g h t arm had a h i g h e r s y s t o l i c p r e s s u r e than the l e f t arm 61% of t h e t i m e . The m a j o r i t y of s u b j e c t s w i t h p r e s s u r e s more th a n 10 mm Hg d i f f e r e n c e between the r i g h t and l e f t arms were 83 h y p e r t e n s i v e , which i s r e a s o n a b l e and c o n s i s t e n t w i t h r e s e a r c h f i n d i n g s . A l t h o u g h t h e s t e t h o s c o p e diaphragm and Doppler method p r o v i d e d more comparable p r e s s u r e s t h a n the s t e t h o s c o p e b e l l method t h e r e was not a s i g n i f i c a n t d i f f e r e n c e . When the methods were compared on the h y p e r t e n s i v e s u b j e c t s i n the sample (n=9), i t was found t h a t t h e s t e t h o s c o p e b e l l method r e c o r d e d the h i g h e s t s y s t o l i c p r e s s u r e more f r e q u e n t l y t h a n the o t h e r two methods. T h i s c o u l d i n d i c a t e t h a t t h e s t e t h o s c o p e b e l l method would be the b e t t e r method t o d e t e c t h y p e r t e n s i o n . However, the s m a l l sample s i z e r e s t r i c t s the i n t e r p r e t a t i o n of t h i s f i n d i n g . There were no s i g n i f i c a n t d i f f e r e n c e s i n the b r a c h i a l s y s t o l i c p r e s s u r e r e l a t e d t o t h e p o s t o p e r a t i v e day when t h e p r e s s u r e was measured. A l t h o u g h the means of the b r a c h i a l s y s t o l i c p r e s s u r e f l u c t u a t e d over t h e t h r e e p o s t o p e r a t i v e days t h i s was not s i g n i f i c a n t and c o u l d be a t t r i b u t e d t o the s t r e s s response t o s u r g e r y . An o v e r a l l e x a m i n a t i o n of the a n k l e s y s t o l i c p r e s s u r e s showed t h a t t h e r e was l i t t l e d i f f e r e n c e between the l e v e l of the d o r s a l i s p e d i s p r e s s u r e and t h e p o s t e r i o r t i b i a l p r e s s u r e . T h i s l a c k of a s i g n i f i c a n t d i f f e r e n c e i s not u n u s u a l i n p a t i e n t s w i t h p e r i p h e r a l v a s c u l a r d i s e a s e and may be due t o t h e v a r i a b i l i t y i n the degree of a t h e r o s c l e r o s i s i n e i t h e r the d o r s a l i s p e d i s or p o s t e r i o r t i b i a l a r t e r i e s . Another e x p l a n a t i o n may be because t h e f e m o r a l - p o p l i t e a l bypass g r a f t was the most f r e q u e n t l y performed s u r g e r y . With t h i s t y pe of s u r g e r y the p r i m a r y b l o c k a g e i s i n t h e f e m o r a l a r t e r y and once the b l o c k a g e I s bypassed f l o w t o the more 84 d i s t a l a r t e r i e s would resume. The s l i g h t variations between the d o r s a l i s pedis and posterior t i b i a l pressures related to the occasion when the pressure was measured were not s i g n i f i c a n t . No s a t i s f a c t o r y explanation could be located to support t h i s finding. When the ankle s y s t o l i c pressures were compared to the brachial s y s t o l i c pressure the ankle s y s t o l i c pressure readings had a lower range by about 30-40 mm Hg and had a wider v a r i a t i o n than the brachial s y s t o l i c pressure. Some possible explanations for t h i s finding could be the atherosclerotic plaques in the artery, increased s t i f f n e s s in peripheral a r t e r i e s and edema of the lower extremity. Research question number two explored the difference in the ABI when the brachial s y s t o l i c pressure was measured by d i f f e r e n t methods. There was no s i g n i f i c a n t difference in either the do r s a l i s pedis or posterior t i b i a l ankle/brachial Indices related to method of measuring the brachial s y s t o l i c pressure, the time that the measurement was recorded, nor an interaction between method and occasion. There were no s i g n i f i c a n t differences in either the PTABI or DPABI related to when the pressure was measured. The s l i g h t variations between the d o r s a l i s pedis and posterior t i b i a l ABI's related to method of measuring the brachial s y s t o l i c pressure were not s i g n i f i c a n t . The lack of s i g n i f i c a n t difference related to the methods of measuring the ankle and brachial s y s t o l i c pressure could be attributed to the Increased number of variables to consider when 85 the Doppler method was employed compared t o t h a t of the a u s c u l t a t o r y method. In a d d i t i o n , the r e s e a r c h a s s i s t a n t was more f a m i l i a r w i t h the a u s c u l t a t o r y methods t h a n t h e Doppler method used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e . C o n c l u s i o n s A l t h o u g h the sample was s m a l l i t d i d c o n s i s t of 80% of the p a t i e n t s a d m i t t e d f o r p e r i p h e r a l v a s c u l a r s u r g e r y over the two month p e r i o d and i t seemed f a i r l y r e p r e s e n t a t i v e of th o s e who had p e r i p h e r a l v a s c u l a r s u r g e r y a t t h a t h o s p i t a l . T h e r e f o r e , the f i n d i n g s of t h i s s t u d y can be g e n e r a l i z e d t o p o s t o p e r a t i v e p e r i p h e r a l v a s c u l a r p a t i e n t s who a r e not obese, have p a t e n t and a c c e s s i b l e a r t e r i e s of both arms, a r e hemodynamically s t a b l e and i n t h e i r t h i r d , f o u r t h and f i f t h p o s t o p e r a t i v e day. A l t h o u g h t h e f i n d i n g s d i d not show any s i g n i f i c a n t d i f f e r e n c e s r e l a t e d t o method or o c c a s i o n , t h e y do suggest some c o n c l u s i o n s . A l t h o u g h the p r e s s u r e s r e c o r d e d by the s t e t h o s c o p e diaphragm were more s i m i l a r t o t h e Doppler t h a n the p r e s s u r e s r e c o r d e d by the s t e t h o s c o p e b e l l t h e r e appears t o be no major d i f f e r e n c e i n the p r e s s u r e s by method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e f o r s t a b l e p a t i e n t s . I t i s not u n u s u a l t o f i n d d i f f e r e n c e s of 30 t o 40 mm Hg between the b r a c h i a l and a n k l e s y s t o l i c p r e s s u r e s i n p a t i e n t s w i t h p e r i p h e r a l v a s c u l a r d i s e a s e owing t o t h e e x t e n t of t h e i r o c c l u s i v e d i s e a s e . O v e r a l l , a l a r g e p o p u l a t i o n of p a t i e n t s w i t h p e r i p h e r a l v a s c u l a r d i s e a s e o f t e n have a s y s t o l i c p r e s s u r e t h a t d i f f e r s between t h e r i g h t and l e f t arm. N e i t h e r the d o r s a l i s p e d i s or p o s t e r i o r t i b i a l A B l ' s showed a s i g n i f i c a n t d i f f e r e n c e when t h e b r a c h i a l s y s t o l i c p r e s s u r e was 86 measured by d i f f e r e n t methods. T h e r e f o r e , any of the t h r e e methods used t o measure the b r a c h i a l s y s t o l i c p r e s s u r e can be used In the d e t e r m i n a t i o n of the ABI. I m p l i c a t i o n s w h i l e t h e s t u d y ' s r e s u l t s showed no s i g n i f i c a n t d i f f e r e n c e i n method or o c c a s i o n i n d e t e r m i n i n g t h e b r a c h i a l s y s t o l i c p r e s s u r e or t h e a n k l e s y s t o l i c p r e s s u r e , t h e y do su g g e s t i m p l i c a t i o n s f o r n u r s i n g p r a c t i c e , e d u c a t i o n and t h e o r y . N u r s i n g P r a c t i c e and I n - S e r v i c e E d u c a t i o n . Because t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n t h e b r a c h i a l s y s t o l i c p r e s s u r e when measured by d i f f e r e n t methods t h e r e a r e i m p l i c a t i o n s f o r the use of n u r s i n g manpower. Assessment of t h e ABI i s done a t the same time t h a t the b l o o d p r e s s u r e i s measured. The Doppler i s used t o measure t h e s y s t o l i c p r e s s u r e whereas the s t e t h o s c o p e i s used t o measure b o t h the s y s t o l i c and d i a s t o l i c p r e s s u r e . T h e r e f o r e , the Doppler method would r e q u i r e the nurse t o measure t h e s y s t o l i c p r e s s u r e t w i c e — o n e measurement f o r the ABI ( D o p p l e r ) and one measurement f o r t h e b l o o d p r e s s u r e ( s t e t h o s c o p e ) . T h e r e f o r e , the s t e t h o s c o p e method of measuring the b r a c h i a l s y s t o l i c p r e s s u r e i n d e t e r m i n i n g the ABI r e d u c e s the manpower time r e q u i r e d . Because no d i f f e r e n c e was found In the p r e s s u r e s when t a k e n by d i f f e r e n t methods, i t i s p o s s i b l e t h a t the nurse might not need t o use a l l methods t o a s c e r t a i n the ABI. S i n c e the Doppler t e c h n i q u e t a k e s the more ti m e and r e q u i r e s more p r a c t i c e one c o u l d p r o b a b l y omit t h a t method of d e t e r m i n i n g the b r a c h i a l s y s t o l i c p r e s s u r e . 87 Because the Doppler method has m u l t i p l e v a r i a b l e s t o c o n s i d e r and r e q u i r e s more manual d e x t e r i t y , t h e r e i s more p o t e n t i a l f o r e r r o r t h a n w i t h the a u s c u l t a t o r y method. T h e r e f o r e , i n s e r v i c e e d u c a t i o n and p e r i o d i c s k i l l c h e c k i n g of the nurse a r e r e q u i r e d when the Doppler method i s employed. I n a d d i t i o n , the measurement of the ABI s h o u l d be r e s t r i c t e d t o a r e a s where the nurse has s u f f i c i e n t knowledge and p r a c t i c e t o m a i n t a i n the s k i l l of u s i n g t h e D o p p l e r . Because t h e r e was a d i f f e r e n c e i n t h e s y s t o l i c p r e s s u r e s between the r i g h t and l e f t arm of some p a t i e n t s i t i s i m p o r t a n t f o r t h e nurse t o be t a u g h t t o a s s e s s t h e s y s t o l i c p r e s s u r e s i n bo t h arms and then t o document and c o n s i s t e n t l y use the arm w i t h t h e h i g h e s t s y s t o l i c p r e s s u r e when d e t e r m i n i n g t h e ABI. Choice of the arm w i t h the lower s y s t o l i c p r e s s u r e would r e s u l t i n a f a l s e h i g h ABI. A c c u r a t e n u r s i n g assessment of the p a t i e n t ' s p e r i p h e r a l g r a f t p a t e n c y i n f l u e n c e s the s u r g i c a l outcome f o r the p a t i e n t . Because t h i s assessment i n v o l v e s t h e i d e n t i f i c a t i o n of a drop i n the ABI below 0.80 mm Hg or a d e c r e a s e i n ABI of 0.20 mm Hg from t h e p r e v i o u s r e a d i n g i t i s t h e r e f o r e Important t o t e a c h n u r s e s t o a c c u r a t e l y and c o n s i s t e n t l y use e i t h e r the s t e t h o s c o p e diaphragm or Doppler i n measuring t h e b r a c h i a l s y s t o l i c b l o o d p r e s s u r e . Because the d o r s a l i s p e d i s and p o s t e r i o r t i b i a l p r e s s u r e s were not s i g n i f i c a n t l y d i f f e r e n t i t might be c o n c l u d e d t h a t e i t h e r a r t e r y c o u l d be used t o check the p a t e n c y of a f e m o r a l -p o p l i t e a l bypass g r a f t . However, i t i s i m p o r t a n t t o check the ABI of b o t h d i s t a l a r t e r i e s and th e n t o document and c o n s i s t e n t l y use 88 the d i s t a l a r t e r y w i t h the h i g h e s t p r e s s u r e when d e t e r m i n i n g the pa t e n c y of f e m o r a l - p o p l i t e a l bypass g r a f t s . C h o i c e of a d i f f e r e n t a r t e r y each time c o u l d l e a d t o f a l s e c o n c l u s i o n s r e g a r d i n g the pa t e n c y of t h e f e m o r a l - p o p l i t e a l bypass g r a f t . Because a n o i s y environment can a f f e c t the d e t e c t i o n of sound i t i s i m p o r t a n t t o c o n t r o l t h i s v a r i a b l e when measuring the s y s t o l i c p r e s s u r e s or a f a l s e h i g h or low ABI w i l l be r e c o r d e d . Theory. The r e s u l t s of t h i s s t u d y p r o v i d e s u p p o r t f o r t h e use of the t h e o r y of sound when d e t e r m i n i n g the s y s t o l i c p r e s s u r e . T e s t i n g of t h e t h e o r y of sound i n the c l i n i c a l s i t u a t i o n added t o the knowledge base of sound t r a n s m i s s i o n and measurement. Because the t h e o r i e s of sound g e n e r a t i o n , t r a n s m i s s i o n and measurement p r o v i d e a u s e f u l framework w i t h which t o a s s e s s the v a r i a b l e s t h a t may i n t e r f e r e w i t h the a c c u r a t e measurement of the s y s t o l i c b l o o d p r e s s u r e , knowledge of t h i s framework would a s s i s t the nurse t o e v a l u a t e the s y s t o l i c p r e s s u r e . F a c t o r s t h a t e f f e c t t h e g e n e r a t i o n , t r a n s m i s s i o n and measurement of sound a r e i m p o r t a n t and need t o be i d e n t i f i e d by the n u r s e . For example, i n t h i s s t u d y t h e r i g h t arm r e c o r d e d h i g h e r p r e s s u r e s more f r e q u e n t l y t h a n the l e f t arm due t o a t h e r o s c l e r o s i s i n the l e f t s u b c l a v i a n a r t e r y . The a t h e r o s c l e r o s i s i n t h e v e s s e l r e s u l t e d i n a d e c r e a s e i n the p a t e n c y and d i a m e t e r of t h a t v e s s e l and thus the sound t r a n s m i t t e d from t h e a r t e r y was dampened. The n u r s e ' s knowledge of and a b i l i t y t o use the I n s t r u m e n t s w i l l e f f e c t the a c c u r a c y of t h e r e a d i n g s o b t a i n e d from the i n s t r u m e n t s employed t o measure sound. 89 To measure the u l t r a s o n i c and I n f r a s o n i c sound waves e m i t t e d from the a r t e r y t h e s e waves had t o be c o n v e r t e d t o s o n i c sound waves i n o r d e r f o r them t o be measured. In the c o n v e r s i o n p r o c e s s some of t h e energy of t h e sound wave i s d i s s i p a t e d . The equipment used i n t h i s s t u d y t o c o n v e r t the sound was of the type t h a t would be used by n u r s e s i n t h e b e d s i d e m o n i t o r i n g of s y s t o l i c p r e s s u r e s . T h e r e f o r e , when u s i n g t h i s t y pe of equipment f o r the c o n v e r s i o n p r o c e s s , the amount of sound wave energy t h a t i s d i s s i p a t e d may r e s u l t i n not measuring the t r u e magnitude of the sound wave. S t u d i e s by C a r t e r (1968), T h e l o o s e n - K e r s t e n s e t a l . (1990), and Yao e t a l . (1969), as w e l l as the c u r r e n t s t u d y found t h a t the s t e t h o s c o p e diaphragm and Doppler methods a r e comparable when e x t e r n a l methods a r e used t o measure the sound t r a n s m i t t e d from the b r a c h i a l a r t e r y . T h e r e f o r e , t h e a u t h o r c o n c l u d e d t h a t when e x t e r n a l methods a r e used t o measure the s y s t o l i c p r e s s u r e the d i f f e r e n c e between u l t r a s o n i c and i n f r a s o n i c sound waves a r e t o o s m a l l t o be d e t e c t e d . Recommendations f o r F u r t h e r R e s e a r c h Recommendations f o r f u r t h e r r e s e a r c h i n c l u d e t h e f o l l o w i n g : The c u r r e n t s t u d y was done on the t h i r d , f o u r t h , and f i f t h p o s t o p e r a t i v e days when the s u b j e c t s were i n a s t a b l e c o n d i t i o n and o n l y one of the s u b j e c t s was r e t u r n e d t o s u r g e r y on t h e f i f t h p o s t o p e r a t i v e day a f t e r t h e ABI was measured. T h e r e f o r e , a s t u d y on p e r i p h e r a l v a s c u l a r s u r g e r y p a t i e n t s measuring the ABI p r e o p e r a t i v e l y t h e n c o l l e c t i n g d a t a from the immediate more u n s t a b l e p o s t o p e r a t i v e p e r i o d t h r o u g h t o the f i f t h p o s t o p e r a t i v e 90 day is recommended. This type of study would provide data regarding the use of these methods during the more unstable postoperative period for peripheral vascular surgery patients and provide a comparison of the preoperative and postoperative ABI. When the subjects had brachial s y s t o l i c pressures >_160 mm Hg the stethoscope b e l l method recorded the highest pressure more frequently than the stethoscope diaphragm or Doppler methods. Because t h i s sub-sample was small, further research on the brachial s y s t o l i c pressures of hypertenisve patients comparing the stethoscope b e l l and stethoscope diaphragm methods is recommended. 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J . , Gupta, S.K., Samson, R.H., Scher, L.A., F e l l , S.C., Weiss, P., Janko, G., Flores, S.W., R i f k i n , H., Bernstein, G., Haimovicl, H., Gliedman, M.L. & Sprayregen, S. (1981). Progress i n limb salvage by reconstructive a r t e r i a l surgery combined with new or improved adjunctive procedures. Annals of Surgery, 194, 386-399. Winter S . s . (1967). The Physical Sciences: An Introduction. New York: Harper Row. World Health Organization, Geniva (1978). A t r i a l hypertension. - World Health organization Technlclal Reports. Series 628 Yao, J.S.T., Hobbs, J.T., & Irvine, W.T. (1969). Ankle s y s t o l i c pressure measurements in a r t e r i a l disease a f f e c t i n g the • lower extremities. B r i t l s h Journal of Surgery, 56, 676 -679. Yao, J.S.T. (1985). Noninvasive techniques of measuring lower limb a r t e r i a l pressures. In E.F. Bernstein (Ed.). Noninvasive Diagnostic Techniques in Vascular Disease (3rd ed.), (pp.83-90). St. Louis: C.V. Mosby Company. Yao, J.S.T. (1985). Surgical use of pressure studies In peripheral a r t e r i a l disease. In E.F. Bernstein (Ed.). Noninvasive Diagnostic Techniques in Vascular Disease (3rd ed.), (pp.545-551). S t . L o u i s : C.V. Mosby Company. APPENDIX A MERCURY DESK MODEL: 300 MM W.A. Braum Co. 95 J-430 Mercury Desk Model: 300 MM: This mercury manometer i s a rugged and extremely accurate instrument. Complete with 300mm scale, s p e c i a l lock valve to prevent loss of mercury, velcro cuff i n f l a t i o n system and metal case. 96 APPENDIX B PORTABLE ULTRASONIC DOPPLER: MODEL 812 PARKS MEDICAL ELECTRONICS, INC. MODEL 812 97 APPENDIX C DATA COLLECTION SHEET SUBJECT # AGE: GENDER: ARTERY BYPASSED: ; TYPE OF SURGERY: OTHER HEALTH CONDITIONS: ( I n c l u d i n g p r e v i o u s v a s c u l a r o p e r a t i o n s ) RESULTS OF VASCULAR LAB STUDIES: ( i f done) MEDICATIONS: INITIAL SYSTOLIC PRESSURES ( s t e t h o s c o p e diaphragm method) OF: RIGHT ARM: LEFT ARM:. OPERATIVE LEG: RIGHT LEFT SYSTOLIC PRESSURES ( B r a c h i a l s y s t o l i c p r e s s u r e s t o be t a k e n on arm w i t h h i g h e s t s y s t o l i c p r e s s u r e . A n k l e s y s t o l i c p r e s s u r e s t o be t a k e n on o p e r a t i v e l e g ) PRESSURES ABI DP ABI PT POSTOPERATIVE DAY 3 | ~~| BRACHIAL: STETHOSCOPE DIAPHRAGM STETHOSCOPE BELL DOPPLER ANKLE: DORSALIS PEDIS (DP) •. POSTERIOR TIBIAL (PT) POSTOPERATIVE DAY 4 BRACHIAL: STETHOSCOPE BELL DOPPLER STETHOSCOPE DIAPHRAGM ANKLE: DORSALIS PEDIS , POSTERIOR TIBIAL POSTOPERATIVE DAY 5 BRACHIAL: DOPPLER STETHOSCOPE BELL STETHOSCOPE DIAPHRAGM ANKLE: DORSALIS PEDIS POSTERIOR TIBIAL 98 APPENDIX D PATIENT INFORMED CONSENT My name Is I v y O'Flynn. I am a R e g i s t e r e d Nurse and I am c u r r e n t l y e n r o l l e d i n t h e Master of S c i e n c e i n N u r s i n g Program a t the U n i v e r s i t y of B r i t i s h C o lumbia. I am i n t e r e s t e d i n s t u d y i n g the f l o w of b l o o d t h r o u g h g r a f t s t h a t a r e used t o bypass b l o c k a g e s i n l e g s . The procedure used t o measure the f l o w of b l o o d t h r o u g h t h e g r a f t a f t e r s u r g e r y i s done r o u t i n e l y by the nurs e s and p h y s i c i a n s . The u s u a l procedure i n v o l v e s t a k i n g the b l o o d p r e s s u r e i n t h e arm and f o o t and the n comparing t h e s e two b l o o d p r e s s u r e s t o a s s e s s the b l o o d f l o w t h r o u g h the g r a f t . In t h i s s t u d y a n u r s e , who i s my r e s e a r c h a s s i s t a n t , w i l l a p p l y a r e g u l a r b l o o d p r e s s u r e c u f f t o the arm and the n t a k e a r e a d i n g of the b l o o d p r e s s u r e by l i s t e n i n g f o r the b l o o d p r e s s u r e u s i n g t h r e e d i f f e r e n t methods. The t h r e e d i f f e r e n t methods t h a t w i l l be used t o l i s t e n t o the b l o o d p r e s s u r e i n c l u d e : a s t e t h o s c o p e b e l l , s t e t h o s c o p e diaphragm and a Do p p l e r . A f t e r t a k i n g the t h r e e b l o o d p r e s s u r e r e a d i n g s on t h e arm t h e nurse w i l l t h e n wrap the b l o o d p r e s s u r e c u f f around the l e g j u s t above the a n k l e and ta k e a b l o o d p r e s s u r e r e a d i n g of t h e two a r t e r i e s of the f o o t u s i n g a Do p p l e r . A l l of these r e a d i n g s w i l l be done on each of the 3 r d , 4th and 5 t h day a f t e r s u r g e r y . I a n t i c i p a t e t h a t t h i s s t u d y w i l l p r o v i d e i n f o r m a t i o n t h a t w i l l h e l p n u r s e s t o de t e r m i n e the b e s t method of a s s e s s i n g the b l o o d f l o w t h r o u g h g r a f t s . I would l i k e t o i n v i t e you t o p a r t i c i p a t e i n t h e s t u d y . Your i n v o l v e m e n t w i l l i n c l u d e r e s t i n g f o r 5 minutes b e f o r e h a v i n g t h e s e b l o o d p r e s s u r e s t a k e n . The r e s e a r c h a s s i s t a n t w i l l t a k e t h e s e b l o o d p r e s s u r e between 10 a.m. and 12 noon on the 3 r d , 4 t h , and 5 th day a f t e r s u r g e r y and w i l l r e q u i r e a p p r o x i m a t e l y 20 minutes of your time on each of thos e days. I would l i k e t o c o l l e c t s p e c i f i c I n f o r m a t i o n from your c h a r t t h a t has a b e a r i n g on t h i s s t u d y , such as type of s u r g e r y , day of s u r g e r y , any p r e v i o u s s u r g e r i e s and any o t h e r h e a l t h problems you may have. Complete c o n f i d e n t i a l i t y w i l l be m a i n t a i n e d . Your name w i l l not appear on any document o t h e r than the t h r e e c o p i e s of t h i s Consent. A s i g n e d copy of the Consent i s p l a c e d on your c h a r t , a n o t h e r s i g n e d copy Is r e t a i n e d by m y s e l f , and the l a s t s i g n e d copy i s f o r you. I w i l l be happy t o answer any q u e s t i o n s r e l a t e d t o t h i s s t u d y . You can c o n t a c t me by t e l e p h o n e or by l e a v i n g a message f o r me a t t h e n u r s i n g s t a t i o n . I f you do agree t o p a r t i c i p a t e , you a r e f r e e t o withdraw a t any t i m e . Your p a r t i c i p a t i o n i s c o m p l e t e l y v o l u n t a r y and p a r t i c i p a t i o n or n o n - p a r t i c i p a t i o n w i l l have no e f f e c t on a c c e s s n u r s i n g c a r e or m e d i c a l t r e a t m e n t and s e r v i c e s . I have r e a d and u n d e r s t o o d t h i s consent and the i n f o r m a t i o n Sheet, and hereby c o n s e n t t o p a r t i c i p a t e i n t h i s s t u d y . 100 APPENDIX E Procedure For Determining The Brachial S y s t o l i c Pressure I n i t i a l l y the brachial SP of both arms w i l l be checked by a nurse using the "stethoscope diaphragm" method described below. The arm with the highest s y s t o l i c BP w i l l be used on subsequent readings taken on the three occasions. Stethoscope Diaphragm Follow these i n s t r u c t i o n when taking the s y s t o l i c BP using the stethoscope diaphragm: 1. Prior to taking the reading, situate the patient in a supine position in bed with the arm resting at heart l e v e l for 5 minutes. 2. Place the mercury manometer at eye l e v e l , s u f f i c i e n t l y close to read the c a l i b r a t i o n marking the column. 3. Select the appropriate sized c u f f . Bladder width should be 40% of arm circumference; bladder length should be at least 80% of arm circumference. 4. Palpate the brachial artery. 5. Wrap the cuff smoothly and snugly around the arm, centring the bladder over the brachial artery. The lower margin of the cuff should be 2.5 centimetres above the antecubltal space. 6. Determine the l e v e l of maximal I n f l a t i o n by observing the pressure at which the r a d i a l pulse i s no longer palpable as the cuff Is r a p i d l y Inflated (palpate s y s t o l i c ) , and then add 30 mm Hg. 7. Rapidly and s t e a d i l y deflate the cuff . Then wait 1 minute before r e l n f l a t l n g 8. Position the stethoscope over the palpated brachial artery below the cuff at the antecubital fossa. Ear pieces should point forward in the ears. The diaphragm of the stethoscope should be applied with l i g h t pressure to ensure skin contact at a l l points. Heavy pressure may d i s t o r t sounds. 9. Rapidly and s t e a d i l y Inflate the cuff to maximal i n f l a t i o n l e v e l , as determined in step 6. 10. Release the a i r in the cuff so that the pressure f a l l s at a rate of 2-3 mm per second. 11. Note the s y s t o l i c pressure at the onset of at least two consecutive beats. 12. Record the brachial s y s t o l i c pressure to the nearest 2 mm Hg murk on I;lie manometer. Stethoscope B e l l If the stethoscope b e l l i s the f i r s t of the three methods to be used then follow steps 1-7 in the procedure "stethoscope diaphragm", otherwise, wait 2 minutes before proceeding with steps 8-12. Use the stethoscope b e l l Instead of the diaphragm in step 8. Doppler If the Doppler i s the f i r s t of the three methods to be used then follow steps 1-7 in procedure "stethoscope diaphragm", otherwise, wait 2 minutes before proceeding with t h i s method. Adjust the procedure as follows: 8. Apply gel over the brachial artery below the cuff in the antecubital space. Place the probe of the Doppler in the gel at a 45-60 degree angle to the brachial artery and pointed toward the 102 d i r e c t i o n of blood flow. The probe should be applied with l i g h t pressure ensuring that i t i s embedded in the g e l . Li s t e n for a d i s t i n c t tapping sound that corresponds with the r a d i a l pulse. Venous sounds do not have a clear c r i s p sound and vary with resp i r a t i o n s . 9. Follow steps 9-10 as in stethoscope diaphragm method 11. Note the s y s t o l i c pressure at the onset of a clear tapping sound from the Doppler speaker. 12. Record the brachial s y s t o l i c pressure to the nearest 2 mm Hg on the manometer. 103 APPENDIX F Pr o c e d u r e F o r D e t e r m i n i n g The A n k l e S y s t o l i c P r e s s u r e 1. A f t e r t a k i n g the t h r e e measurements o£ t h e b r a c h i a l SP p l a c e the b l o o d p r e s s u r e c u f f around the l i m b of the o p e r a t i v e l e g 2.5 c e n t i m e t r e s above t h e a n k l e . 2. A p p l y a s m a l l amount of g e l on t h e d o r s a l i s p e d i s p u l s e s i t e . 3. P l a c e the probe of the Doppler i n the g e l a t a 45-60 degree a n g l e t o t h e a r t e r y and p o i n t e d toward the d i r e c t i o n of b l o o d f l o w . The probe s h o u l d be a p p l i e d w i t h l i g h t p r e s s u r e e n s u r i n g t h a t i t i s embedded i n t h e g e l . 4. L i s t e n f o r a d i s t i n c t t a p p i n g sound t h a t c o r r e s p o n d s w i t h the r a d i a l p u l s e . 5. With t h e Doppler s i t u a t e d over the p u l s e s i t e , i n f l a t e t h e c u f f u n t i l sound from the Doppler d i s a p p e a r s . 6. S l o w l y d e f l a t e the c u f f so t h a t the p r e s s u r e f a l l s a t a r a t e of 2-3 mm per second. 7. Note t h e p r e s s u r e on the manometer a t the onset of a c l e a r t a p p i n g sound heard from the D o p p l e r - - t h i s i s the a n k l e SP f o r the d o r s a l i s p e d i s a r t e r y . 8. Record the a n k l e SP t o the n e a r e s t 2 mm Hg mark on the manometer. 9. Now r e p e a t s t e p s 2-8 u s i n g t h e p o s t e r i o r t i b i a l a r t e r y . 104 APPENDIX G PROCEDURE FOR DETERMINING THE ANKLE/BRACHIAL INDEX 1. D i v i d e the d o r s a l i s p e d i s s y s t o l i c p r e s s u r e by b r a c h i a l SP when the b r a c h i a l SP i s d e t e r m i n e d by: a) s t e t h o s c o p e b e l l b) s t e t h o s c o p e diaphragm c) u l t r a s o n i c D o p p l e r . 2. D i v i d e t h e p o s t e r i o r t i b i a l s y s t o l i c p r e s s u r e by the b r a c h i a l SP when t h e b r a c h i a l SP i s d e t e r m i n e d by: a) s t e t h o s c o p e b e l l b) s t e t h o s c o p e diaphragm c) u l t r a s o n i c Doppler 

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