Summary and conclusionsA total of 4352 patients were admitted to a prospective' randomised multicentre trial comparing the prophylactic efficacy of dextran 70 and low-dose heparin against fatal pulmonary embolism after elective operations for general, orthopaedic, urological, and gynaecological conditions. Out of 3984 patients correctly admitted, 1993 were allocated to receive dextran 70 and 1991 to receive low-dose heparin.Withdrawal of prophylaxis because of bleeding or technical difficulties occurred more often in the heparin group, but allergic reactions were more common in the dextran group. Of the 75 patients who died within 30 days after operation, 38 had been given dextran and 37 lowdose heparin. Necropsy was performed in 33 and 32 of these cases respectively. In six patients in each group pulmonary embolism was the sole or a contributory cause of death. Of these, five patients in the dextran group and two in the heparin group had received a full course of prophylaxis.There was no statistically significant difference between the two treatment groups in the incidence of fatal pulmonary embolism after a full course of prophylaxis.

The efficacy of dextran 70 or low dose heparin in preventing fatal postoperative pulmonary embolism was investigated in a multicentre randomized trial. 4352 patients over the age of 40 years undergoing elective major general, orthopaedic, urological or gynaecological surgery were included in the trial. The two groups were well matched for age, sex, weight and diagnosis. 75 patients died within 30 days after operation, 38 in the dextran and 37 in the heparin group. Autopsy frequency was 87 and 86% respectively. 5 patients in the dextran and 3 in the heparin group had pulmonary emboli as the only cause of death and 1 patient in the dextran and 3 in the heparin group had emboli which had contributed to death. The two methods of prevention thus seem to be equally effective in reduction of lethal pulmonary emboli. 2 cases with incidental pulmonary emboli were found in thex-tran and 4 in the heparin group. Wound haematoma and incomplete prophylaxie was more common in the heparin than in the dextran group. In 6 patients in the dextran and 94 in the heparin group prophylaxis was stopped due to bleeding. Side-effects occurred in 22 patients after dextran and in J patients aiter heparin. Most patients had mild reactions (skin erythema etc.) but in 5 dextran cases reactions were classified as severe.