The purpose of this study was to determine the influence of hydrostatic intraperitoneal pressure (IPP) and cardiac function (CF) on the lymphatic absorption rate (LAR) in 9 patients on continuous ambulatory peritoneal dialysis (CAPD). The LAR was measured by estimation of the intraperitoneal disappearance of dextran 70 added to 2 L of 2.5% dextrose dialysis solution. The patients remained in the supine position during the 4-hour dwell. The IPP was obtained by measuring a column of dialysate in the peritoneal dialysis line, immediately before the drainage of the peritoneal cavity. The pressure was measured at the level of the umbilical cicatrix with point zero located on the mid axillary line of the patient. IPP was measured at inspiration and expiration, and the average of these two measurements was taken. These patients also underwent an echocardiographic examination. The LAR was 0.46 +/- 0.25 mL/minute, and the IPP was 13.07 +/- 2.61 cm H2O. The IPP correlated positively with the LAR (r = 0.80, p < 0.05). The intraperitoneal volume at the 4-hour dwell correlated inversely with the IPP (r = -0.68, p < 0.05). The left ventricular circumferential shortened fraction was 36 +/- 6% (27%-43%) and did not correlate with the LAR. These data suggest that the LAR is higher in patients with more elevated IPP. In addition, the CF, in the range studied, does not affect the lymphatic absorption rate.