Prospective randomized clinical study in general surgery comparing a new low molecular weight heparin with unfractionated heparin in the prevention of thrombosis

A prospective, randomized, controlled clinical trial was performed comparing the antithrombotic efficacy of the low molecular weight heparin LMWH 21-23, (Braun) with an unfractionated heparin in elective general surgical patients over an observation period of 7 postoperative days. A total of 230 patients were admitted: 103 (group I) received low molecular weight heparin and 100 (group II) low-dose unfractionated heparin treatment given subcutaneously. In group I 41 patients (46%) were operated on for malignant disease and in group II 54 patients (54%). Due to the large amount of great abdominal procedures the intra- and perioperative application of hydroxyethyl starch was allowed for volume substitution. None of the patients died due to fatal pulmonary embolism. In group I four patients revealed positive 125I-labeled fibrinogen uptake (3.9%); two patients belonged to the hydroxyethyl starch subgroup. In group II five patients displayed a positive fibrinogen uptake (5%); two belonged to the hydroxyethyl starch subgroup. The results of the hemostaseological investigations (e.g., prothrombin time, activated partial thromboplastin time, thrombin clotting time, fibrinogen, antithrombin III, protein C, plasminogen, alpha 2-antiplasmin, tissue-type plasminogen activator, plasminogen activator inhibitor) revealed no statistically significant differences between groups I and II or their subgroups, although a tendency to prolonged clotting times was observed. The antifactor Xa activity values, however, displayed a statistically significant difference between the two groups (P < 0.05). The antifactor Xa activity measured up to 0.16 U/ml for the low molecular weight heparin (group I) and 0.05 U/ml for the unfractionated heparin (group II) in the postoperative period.