The influence of surgical trauma on factor XaI and IIaI activity and heparin concentration after a single dose of low-molecular-weight heparin

To study the influence of surgical trauma on the XaI and IIaI activity after injection of a low-molecular-weight heparin (LMWH) 24 patients undergoing elective cholecystectomy received one subcutaneous injection of the LMWH Fragmin. Each group of eight patients received either 2,500 or 5,000 XaI U 2 h before operation or 5,000 XaI U 10 h before surgery. For comparison an additional eight patients received 5,000 IU unfragmented heparin (UH) before operation. Laboratory analyses included amidolytically measured XaI- and IIaI-activities and direct measurements of heparin. Dose-dependent increase in the XaI- and IIaI-activity with maximal levels about 3-4 h after injection was seen. Patients given the LMWH 2 h before operation had lower levels of XaI-activity 2 h after injection than those receiving it 10 h before surgery, despite the same dose given. This correlated with the heparin concentrations, where the highest concentration was measured in patients given the LMWH 10 h before surgery. In conclusion, the surgical trauma of a cholecystectomy does not seem to have any major influence on the XaI- or IIaI-activity after administration of the studied LMWH. Alterations of the absorption and/or elimination rates cannot, however, be ruled out, but are related to factors other than the operative trauma per se, such as effects of premedication or circadian rhythmic variations

Thromboprophylactic effect of low molecular weight heparin started in the evening before elective general abdominal surgery: a comparison with low-dose heparin

A prospective randomized double-blind trial was performed comparing conventional low-dose heparin with a LMWH fragment (Kabi 2165, Fragmin) for thromboprophylaxis in elective general abdominal surgical patients. The first dose of the fragment was given in the evening before surgery, and thereafter every evening. There were 1002 analyzable patients, 826 having received correct prophylaxis. Sixty three percent of the patients were operated on for malignant diseases. The frequency of DVT was significantly reduced among patients with correct prophylaxis with the heparin fragment (9.2 to 5.0%, p = 0.02). In patients with malignancies the reduction was from 11.2 to 6.4% (p = 0.06). The frequency of bleeding was 6.7% among the heparin fragment patients and 2.7% among the patients given conventional heparin (p = 0.01). The corresponding frequencies for patients with malignancies were 3.2 and 2.8%, respectively (p = 0.28). All bleedings were minor and of no clinical significance. Local pain at the injection site was reported significantly less often among patients with the fragment. Twenty patients died, 13 with malignant disease, mortality being the same in the two groups. It is concluded that heparin fragment administered in the evening before surgery and then every evening is a practically acceptable alternative to prevent postoperative DVT in patients undergoing elective abdominal surgery, also when the histology shows malignancy. Thus, the advantages of using LMWH compared with conventional low-dose heparin are simplified administration routines, better thromboprophylactic effect, and less local pain at injection sites. A disadvantage is the slight increase in hemorrhagic side effects, all of minor clinical importance and not seen in patients undergoing surgery for malignancy

Low molecular weight heparin given the evening before surgery compared with conventional low-dose heparin in prevention of thrombosis

A prospective randomized double-blind trial was performed comparing conventional low-dose heparin with a low molecular weight heparin fragment for thromboprophylaxis in elective general abdominal surgical patients. The first dose of the heparin fragment was given the evening before surgery, and further doses were given thereafter every evening. There were 1002 analysable patients, 826 having received correct prophylaxis. Of these 1002 patients, 64 per cent were operated on for malignant disease. A total of 20 patients died, 10 in each group. The frequency of deep vein thrombosis was significantly reduced among patients with correct prophylaxis with the heparin fragment (9.2-5.0 per cent, P = 0.02) [corrected]. The frequency of bleeding was 6.7 per cent among the heparin fragment patients and 2.7 per cent among the patients given conventional heparin (P = 0.01), but all bleeds were of minor degree and there was no difference in the reoperation rate for bleeding, or in the transfusion requirements. Local pain at the injection site was reported significantly less often among patients given the heparin fragment