The longitudinal effect of a single peritonitis episode on peritoneal membrane transport in CAPD patients

Objective:To evaluate the longitudinal effect of a single peritonitis episo de on peritoneal membrane transport. Design: A prospective longitudinal study. Setting: Department of nephrology in a university hospital. Patients: Eighteen continuous ambulatory peritoneal dialysis patients with peritonitis. Methods: Peritoneal transport for low, middle, and high molecular weight (M W) solutes was evaluated by peritoneal equilibration test (PET). The first PET was performed on the day following the diagnosis of peritonitis. The te st was repeated at weeks 1, 2, 4, 12, and 24 and the results were compared to baseline PET data obtained before peritonitis. In addition, dialysate CA 125 concentration and leukocyte count were measured. Results: During peritonitis there were significant increases in dialysate-t o-plasma (D/P) ratios for all low, middle, and high MW solutes except potas sium, and decreases in D-4/D-0 glucose ratio and ultrafiltration (UF) volum e. Over the subsequent 2 weeks, solute transport gradually decreased to the baseline Values then remained unchanged during follow-up. Although net UF volume demonstrated a similar course during the study, it did not completel y return to the baseline value. No decrease in DIP sodium ratio was found a t 60 minutes during the PET performed 24 weeks after peritonitis. The perce nt change in solute transport during peritonitis compared to baseline value was significantly correlated with a solute's MW (r = 0.776, p = 0.014). Th e slope of the regression line for D/P ratios versus MW, in double logarith mic scale, before peritonitis (-0.73 +/- 0.09) was steeper than the slope d uring peritonitis (-0.59 +/- 0.08). Conclusions: These findings indicate that a single peritonitis episode does not permanently affect peritoneal solute transport. However, the loss of n et UF that accompanies peritonitis is not completely recovered, probably du e to impairment of transcellular water transport. The transport changes ass ociated with peritonitis may be due to the combined effect of increased eff ective peritoneal surface area and intrinsic permeability. Our findings sug gest that the latter mechanism seems to be more important.