Intraperitoneal phosphatidylcholine levels in patients on continuous ambulatory peritoneal dialysis do not correlate with adequacy of ultrafiltration.

A qualitative and quantitative study was undertaken to determine the lipid composition of dialysate effluent from patients maintained on continuous ambulatory peritoneal dialysis (CAPD). Effluent, after a 4-h, 2.27% dextrose dwell, was collected on ice, centrifuged and extracted for lipids with chloroform and methanol. Lipids were separated and identified by thin layer chromatography, and the constituent fatty acids were quantitated by gas liquid chromatography. Effluents from 10 patients were assayed at the commencement of CAPD treatment and again after 6 months of therapy. There was a significant fall in phosphatidylcholine and phospholipid concentrations (P < 0.007) with time, whereas the fatty acid compositions of these lipids remained constant. Dialysate phosphatidylcholine and phospholipid concentrations were not significantly different between seven patients with poor ultrafiltration and eight patients who had normal fluid removal. This study demonstrates that there is no relationship between dialysate phospholipid levels and the adequacy of filtration, although it corroborates previous reports of an inverse correlation between time on CAPD and dialysate lipid concentrations. These results do not support a rationale for ip phosphatidylcholine administration in patients with poor ultrafiltration.