The optimal administration regimens of low molecular weight heparins (LMWHs) have not yet been established. The aim of this study was to compare the efficacy and safety of 2500 and 5000 XaI units of the LMWH dalteparin in patients undergoing elective general surgery for malignant and benign abdominal disease. Prophylaxis was started in the evening before surgery and given once-daily every evening thereafter. The study was designed as a prospective, randomized, double-blind, multicentre trial. Some 66.4 per cent of patients were operated on for a malignant disorder. The primary endpoint was deep vein thrombosis (DVT) detected with the fibrinogen uptake test. Bleeding complications were recorded and classified. Analysis was made both on an intention to treat basis and in patients given correct prophylaxis (86.3 per cent). A total of 2097 patients were randomized and 27 excluded after randomization. A technically correct fibrinogen uptake test was obtained in 1957 patients. The incidence of DVT was significantly lower in patients given 5000 XaI units, this being true for both correct prophylaxis (6.8 versus 13.1 per cent, P < 0.001), on an intention to treat basis (6.6 versus 12.7 per cent, P < 0.001), and in patients with malignant disease (8.5 versus 14.9 per cent, P < 0.001). Sixty-seven patients (3.2 per cent) died within 30 days with no difference between the groups. There were two cases of fatal pulmonary embolism. The frequency of bleeding complications in the whole series was higher in patients randomized to 5000 XaI units (4.7 versus 2.7 per cent, P = 0.02), although this was not the case in those operated on for malignant disease (4.6 versus 3.6 per cent, P not significant). Dalteparin in the dose of 5000 XaI units started in the evening before surgery has a good thromboprophylactic effect in high-risk general surgery at the cost of a small bleeding risk. In patients with malignant disease there was no increased risk of bleeding. The overall frequency of fatal pulmonary embolism with dalteparin is extremely low, even in this high-risk group of patients.

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Aspirin induces a haemorrhagic diathesis that persists for at least 1 week after discontinuation of the drug. The effect of the vasopressin analogue desmopressin was studied in 12 patients treated with aspirin who were undergoing cholecystectomy. Desmopressin was given to six of these patients. There were five postoperative bleeding complications; all occurred in patients who had not received desmopressin (P < 0.05). The bleeding time was prolonged in aspirin-treated patients and normalized by desmopressin (P < 0.05). Desmopressin can be used safely to prevent bleeding induced by aspirin.

Two hundred and twelve total hip replacements performed in one clinic over 1 year were reviewed. The mean operative time was 89 min and mean total blood loss 1090 ml. Homologous blood was administered to 74% of the patients. Blood loss was dependent on sex, body weight and height, but these correlations were eliminated when blood loss was related to estimated blood volume. There was no correlation to age. There was a positive correlation between operative time and intraoperative blood loss, but not between any of these factors and postoperative blood loss. Operative time varied significantly between surgeons, but there was no correlation between surgeon's experience and operative time or blood loss. Despite a mean of only 12 total hip replacements per surgeon, both operative time and blood loss were small compared to what was found in other studies. The use of a posterior approach is believed to contribute to a shorter operative time as well as to moderate blood loss. Intraoperative blood loss was less under epidural than under general anaesthesia, but in contrast to others we found higher postoperative blood loss after epidural anaesthesia.

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SummaryTwelve patients undergoing total hip replacement, with regional anaesthesia and with dextran infusion for plasma expansion and thromboprophylaxis, were given the vasopressin analogue desmopressin (DDAVP) or placebo in a randomized, double-blind prospective study. In controls (n = 6) we found a prolongation of the bleeding time, low factor VIII (FVIII) and von Willebrand factor (vWF) and a decrease in antithrombin III to levels known to be at risk for venous thrombosis. Desmopressin shortened postoperative bleeding time, gave an early FVIII/vWF complex increase, prevented antithrombin III from falling to critically low values and appeared to activate the fibrinolytic system, both by tPA increase and PAI-1 decrease.Thus in the controls we found changes in both coagulation and fibrinolysis indicating a haemorrhagic diathesis as well as a risk for thromboembolism. Desmopressin induced factor changes that possibly reduce both risks.

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