Pressure profiles in ileal pouch outlets

Water-perfused open-tip catheters were used to measure the pressure profiles in the nipple valve of the continent ileostomy. In in vitro studies the conditions required to measure the yield pressure in collapsed vessels like the nipple valve were determined. Flow rates below 4--5 ml/min should not be used when measuring the pressure with open-tip catheters size Ch 8. At lower flow rates the yield pressure was underestimated. When appropriate flow rates were used, a moderate increase of the perfusional flow rate did not increase the measured pressure notably. Measurements were performed in 31 patients with continent or incontinent ileostomy reservoirs. Nineteen patients had outlets with a nipple valve, and 12 patients outlets without such a valve. In most cases it was possible to distinguish a pressure zone in the outlet. The length of the pressure zone was fairly constant in consecutive measurements, whereas the pressure varied, presumably owing to contractile activity, in the outlet. In continent patients with nipple valve outlets the pressure was significantly higher than in patients who were incontinent owing to nipple valve sliding. In patients who were incontinent owing to fistula formation the pressure was of the same order of magnitude as in continent patients.