[Instantaneous clearances: standard heparin versus low molecular weight heparin]

Standard heparin is still considered as a reference point for anticoagulation in CEC, although its use is not totally devoid of long-term and short term side effects, considering the risk of hemorrhage that patients undergo during dialysis. Numerous attempts have been made in the search for an alternative anticoagulating method. The recent discovery that low molecular weight fractions (LMWH) of standard heparin (UFH) assure the same antithrombotic effect but with a minor anticoagulating action, points to such a drug as an interesting alternative to the traditional use of heparin during dialysis. Our present task is to evaluate the purifying efficiency of different cuprophan and synthetic membranes with two LMWH and UFH, measuring the instantaneous ureic clearance of different dialysers at the start and end of each dialysis. N. 43 chronic patients were examined whilst undergoing different methods of treatment; using 12 different kinds of membrane, for a total of 22 filters. Every patient underwent a dialysis using each kind of heparin at least once, for a total of 189 dialysis. Neither the initial nor the final ureic clearances, nor the percentage of decreasing had changed by using different types of heparin and membranes with diverse thrombogenicity and ultrafiltration capacities. We may conclude from the results of the tests that the purifying efficiency of small molecules, judging from the istantaneous clearances, do not significant results compared to UFH.