IMPACT OF MEMBRANE CHOICE AND BLOOD-FLOW PATTERN ON COAGULATION AND HEPARIN REQUIREMENT - POTENTIAL CONSEQUENCES ON LIPID CONCENTRATIONS

Background. We reasoned that procoagulant activity, and by implication heparin requirement, during haemodialysis are influenced, amongst oth er factors, by the type of membranes and the geometry of the blood lin e system. In addition, there are indications that heparin has dose-dep endent effects on the lipid status of chronic haemodialysis patients. Methods. In a parallel group design we compared patients treated with cuprophane (CU) and polycarbonate-polyether (PC-PE) plate dialysers. I n both groups, blood line geometry was varied by including in a first phase and omitting in a second phase drip chambers in the arterial blo od line. End-points were changes in coagulation parameters, i.e. throm bin-antithrombin III complex (TAT), plasmin-antiplasmin complex (PAP), and prothrombin fragment (F1 + 2) concentrations measured by sandwich ELISA. Subsequently all patients were switched to PC-PE dialysers for 6 months and the heparin dose was reduced in a stepwise fashion. Lipi d levels and coagulation parameters were monitored. Finally, in an anc illary study, the correlation between heparin dose and LDL/HDL ratio w as assessed in patients chronically exposed to PC-PE membranes and low doses of heparin.Results. Post-dialytic concentrations of coagulation and fibrinolysis parameters were significantly lower in the PC-PE gro up (TAT 31.0+/-4.4 mu g/l; PAP 1180+/-148 mu g/l; F1 + 2 4.2+/-0.4 nmo l/l) compared to the CU group (TAT 57.3+/-10.8 mu g/l; PAP 1789+/-185 mu g/l; F1 + 2 8.8+/-1.0 nmol/l), independently of the use of an arter ial drip chamber. Omission of the arterial drip chamber led to lower T AT in the CU group (42.2+/-5.8 mu g/l, P < 0.05), but not in the PC-PE group. In contrast, PAP and F1 + 2 concentrations did not change sign ificantly in either group. Down-titration of heparin dose (from 20.4+/ -1.1 to 9.4+/-0.9 IU/kg/h) was associated with a significant decrease in serum triglycerides (from 2.9+/-0.9 to 2.0+/-0.6 mmol/l, P < 0.05), LDL-cholesterol (from 3.4+/-0.2 to 2.7+/-0.4 mmol/l, P < 0.05) and LD L/HDL-ratio (from 3.2+/-0.3 to 2.0+/-0.3 P < 0.05) with no significant change of total or HDL-cholesterol after 6 months. In an ancilliary a nalysis, a correlation between lipid parameters (LDL/HDL ratio) and he parin dose was confirmed in 24 patients chronically exposed to PC-PE m embranes (r = 0.473, P < 0.05). Conclusions. In a prospective explorat ory study (i) heparin requirement is lower with the use of a polycarbo nate-polyether membrane compared to a cuprophane membrane, (ii) hepari n requirement is influenced by blood line geometry (decreased with omi ssion of an arterial drip chamber), and (iii) in patients on polycarbo nate-polyether membranes down-titration of heparin is associated with a reduction of serum triglycerides, LDL cholesterol, and LDL/HDL ratio . Our data suggest that reduction of heparin dose improves lipid profi le. These preliminary observations require confirmation by parallel gr oup controlled studies with controlled dietary intake.