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, 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. Major bleeding complications were not encountered in this study. Fundamental for the low incidence of thrombosis, the additive administration of hydroxyethyl starch appeared in almost one-third of the patients in both study groups.Abbreviations APTT activated partial thromboplastin time - aXa anti-factor Xa - DVT deep venous thrombosis - FUT ¹²⁵I-labeled fibrinogen uptake test - HES hydroxyethyl starch - LMWH low molecular weight heparin - PE pulmonary embolism - UFH unfractioned heparin