UBC Theses and Dissertations
A new method of study of upper gastrointestinal transit time and secretion in ileostomy patients Dowell, Anthony James
There is a need for a simple, safe, reproducible and non-invasive method for studying upper gastrointestinal motility in humans. Existing methods, measuring electrical contractions and intraluminal pressure changes have limitations in their correlation with the physiology of what is actually happening to ingested food. Transit time has been suggested as a more physiologic means of studying gut motility; therefore a method was developed to measure transit time and secretory changes in response to ingested liquids, using ileostomy patients. 2.5 gm of polyethylene glycol (PEG) was added to 500 ml of normal saline, and given orally to volunteers with ileostomies. The ileostomy effluent was collected for 2 hours in 10 minute aliquots. PEG assay was performed by the turbidimetric method of Hyden, using Malawer's modification with an emulsifier. The following were measured: most rapid, mode, median, mean and total transit t imes. A study was then performed to determine if different foodstuffs -carbohydrate, fat, and protein - produce measurable changes in transit time. 2.5 gm of PEG was added to 500 ml of (a) 90 ml Lipomul in 410 ml normal saline (b) 5% dextrose (c) 100 ml of Travasol 10% in 400 ml distilled water. The volumes were chosen to produce isoosmolar test feeds. Validating studies showed satisfactory reproducibility and individual variation (r = 0.68 for volume recovery, r = 0.69 for PEG recovery, p = < 0.5) The recovery pattern of a test feed of 500 ml normal saline was found to follow a skew distribution, with mode, median and mean transit times all different. The most reproducible and easily measured was mode, or peak, transit time (average 40 minutes for volume and PEG recovery). Significant delays in all transit times were found (p = < 0.01) using each of the test feeds: (a) for Lipomul a peak volume recovery of 60 minutes and PEG recovery of 70 minutes; (b) for 5% dextrose a peak volume recovery of 90 minutes and PEG recovery of 90 minutes; (c) with Travasol, negligible amounts of ileostomy output were obtained over 2 hours. The most rapid transit time was consistently less than 10 minutes, as measured by PEG appearance from the ileostomy. This is far less than previously described by standard methods, but is in accordance with transit times measured to the ileocaecal valve in intact gastrointestinal tracts using the recently-introduced breath hydrogen method following lactulose ingestion. Comparison of total volume recovery with total PEG recovery over 2 hours indicates whether net absorption or secretion has occurred: (a) with normal saline a volume recovery of 62% and PEG recovery of 48% indicates net secretion; (b) with Lipomul a volume recovery of 66% and PEG recovery of 58% also indicates net secretion, with no significant difference from normal saline (p = < 0.05); (c) with 5% dextrose a volume recovery of 4% and PEG recovery of 13% indicates net absorption, significantly different from normal saline (p = < 0.01); (d) for Travasol a volume recovery of 1% and PEG recovery of 1% indicates no net absorption or secretion, but confirms the above finding of a very large delay in transit time. These studies have shown that isotonic solutions of normal saline, glucose, fat and protein result in widely different peak transit times in ileostomy patients. They also result in widely different fluid outputs from the ileostomy due to net absorption or secretion. These differences have not been described before.