The Assessment of Peritoneal Function Using a Single Hypertonic Exchange

Peritoneal ultrafiltration, creatinine clearance and glucose absorption were measured in 56 CAPD patients using a single hypertonic exchange with a four-hour dwell. The intraindividual coefficient of variation for these parameters was less than 5 % and the results obtained correlated significantly with those obtained using a six-hour dwell. Ultrafiltration capacity was independent of clearance values but glucose absorption correlated directly with clearance and inversely with ultrafiltration levels (p < 0.001). Multiple regression analysis showed a decline in four-hour clearance values with time on CAPD (p < 0.001), and an increase in glucose absorption after four hours with Frezenius hypertonic solution (p < 0.02) but no other effect of patient age, sex, body surface area, serum albumin, duration of CAPD treatment, peritonitis history or dialysate brand on these indices of peritoneal function. It is important to monitor peritoneal function in patients treated by CAPD and these results indicate that a single, timed, hypertonic exchange is a reproducible test of ultrafiltration, clearance and glucose absorption. Loss of peritoneal function is reported as a cause of failure of CAPD (1–5) although we have limited information concerning sequential changes in the peritoneal membrane with time (6–8) and no agreement over the most appropriate investigation to monitor its permeability (9–11). The International Co-operative Study measured ultrafiltration capacity using a four-hour, two-litre hypertonic exchange (9). This study examines the reliability of such a single, timed exchange to measure peritoneal clearance, glucose absorption and ultrafiltration and evaluates the influence of demographic factors on these parameters.