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Diagnosis, Prevention and Management of Thromboembolism

does not seem to result in excessive bleeding during or after surgery. Furthermore, it can be used on an extensive scale without straining hospital resources. However, final judgment on the value of this form of prophylaxis can only be established by unequivocal demonstration of a significant reduction in postoperative deaths from pulmonary embolism. This requires largescale studies involving thousands of patients and such a multicentre trial is already under way in the United Kingdom and abroad. Fifty-one centres in eleven countries are taking part in this study and a uniform protocol is being followed. Patients over the age of 40 having major operations are being randomly allocated to control or treatment groups. The incidence of fatal pulmonary embolism, confirmed at autopsy, is being recorded in both groups. The results are being analysed by computer. In the first nine months of the trial 2055 patients have been entered 1020 in the control group and 1035 in the heparin group. Computer analysis of these patients has shown that the two groups are well matched for age, sex, presence of malignancy, type of operation performed and other factors likely to influence the incidence of thromboembolism. Seven patients in the control group and one in the heparin group died due to acute, massive, isolated pulmonary embolism. In another 2 patients in each group pulmonary emboli were confined to the lobar or segmental branches and, though not thought to be the primary cause, did contribute to the patients' death. If these findings are confirmed in large numbers of patients, then low-dose heparin will provide an effective prophylactic method.