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 episode 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 (MW) solutes was evaluated by peritoneal equilibration test (PET). The first PET was performed on the day following the diagnosis of peritonitis. The test 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 CA125 concentration and leukocyte count were measured.

RESULTS

During peritonitis there were significant increases in dialysate-to-plasma (D/P) ratios for all low, middle, and high MW solutes except potassium, and decreases in D4/D0 glucose ratio and ultrafiltration (UF) volume. 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 completely return to the baseline value. No decrease in D/P sodium ratio was found at 60 minutes during the PET performed 24 weeks after peritonitis. The percent change in solute transport during peritonitis compared to baseline value was significantly correlated with a solute's MW (r = 0.776, p = 0.014). The slope of the regression line for D/P ratios versus MW, in double logarithmic scale, before peritonitis (-0.73 +/- 0.09) was steeper than the slope during 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 net UF that accompanies peritonitis is not completely recovered, probably due to impairment of transcellular water transport. The transport changes associated with peritonitis may be due to the combined effect of increased effective peritoneal surface area and intrinsic permeability. Our findings suggest that the latter mechanism seems to be more important.