UBC Theses and Dissertations
Physical activity measurement strategies in advanced chronic lung disease Dhillon, Satvir Singh
Background: Physical activity may reduce mortality risk in advanced chronic lung disease by optimizing functional capacity, which is a major prognostic indicator in lung transplantation candidates. There is uncertainty as to the optimal method to measure physical activity in this patient population. We assessed different commercially-available physical activity measurement techniques (flex heart rate monitoring (FHR); pedometry; tri-axial accelerometry; and multi-sensor technology) by investigating their agreement with indirect calorimetry (IC) in adult lung disease patients (chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), and cystic fibrosis (CF)) with advanced pulmonary impairment. Methods: This is a cross-sectional method comparison study conducted on two separate days. We recruited consecutive COPD, ILD, and CF patients with physician diagnosis of advanced pulmonary impairment. On day one, participants performed cardiopulmonary exercise testing until exhaustion with measurements of oxygen uptake (VO₂) and heart rate (HR) collected. On day two, subjects had their VO₂ and HR measured during standardized resting and sub-maximal activity. Simultaneous VO₂ and HR measures from both days were used to develop individual regressions for FHR-derived energy expenditure (EE). We then simultaneously measured each subject’s EE using a variety of index measures of physical activity and IC during standardized “free-living” type activities and varying intensities of sub-maximal cycle exercise. Results: In a sample of eight participants (CF, n=5; COPD, n=2; ILD, n=1), Flex HR methods using submaximal (FMSUB) and CPET-derived (FMCPX) calibrations showed the best agreement and interchangeability with IC during free-living and cycling activities compared to the SenseWear (SW) and ActiCal (AC) devices as evidenced by lower mean differences with IC and widths of limit of agreement (LOA) + 95% confidence interval (CI). For the secondary index methods assessed, the Tractivity and DigiWalker devices significantly over and underestimated IC EE respectively (p<0.05), whereas the Dynaport device did not differ from IC (p>0.05) over the entire protocol. Conclusion: Our study found that the Flex HR method for EE estimation had the lowest bias and variability during free-living activities and exercise. EE estimation using Flex HR methods may be potentially useful clinical tools to ensure metabolic energy balance and activity monitoring in advanced lung disease groups.
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