Intraperitoneal pressure, peritoneal permeability and volume of ultrafiltration in CAPD.

Peritoneal permeability (PP), hydrostatic intraperitoneal pressure (IPP) and the overall volume of ultrafiltration (UF) were measured in 23 patients treated by CAPD under stable conditions. PP, IPP and UF were measured during the same exchange with a 2-liter bag with 3.86% glucose, dwell time of 2 hours. PP was evaluated with 3 indices: glucose peritoneal desaturation at 2 hours, urea peritoneal saturation at 2 hours, and crossing time of glucose and urea peritoneal equilibration curves. IPP was evaluated at inspiration (IPPinsp) and at expiration (IPPexp)-giving IPPmean-by measuring the height of the dialysis fluid in the PD line under atmospheric pressure, with point zero located on the axillary line of the subject in strict supine position. Net UF volume was inversely correlated with IPPmean. The net UF volume was strongly affected by IPP since a 1 cmH2O increase in IPPmean caused a decrease of 74 ml in global UF in 2 hours, probably by modification of the lymphatic reabsorption and perhaps of the transcapillary UF.