Management of heparin therapy: Controlled prospective trial.

Among 100 consecutive patients receiving heparin in therapeutic dosage, major bleeding occurred in 21, and minor bleeding in 16. Two patients died from bleeding, and two had recurrent pulmonary embolism. Major bleeding occurred in 21% when therapy was regulated with whole-blood clotting time and in 20% when heparin was given without clotting tests. In a subsequent prospective trial patients received heparin by intermittent intravenous injection with or without laboratory control according to the partial thromboplastin time or continuously by intravenous infusion. Recurrent thromboembolism occurred once in each group. Major bleeding was seven times more frequent with intermittent injection than with continuous infusion. Control with the partial thromboplastin time did not prevent major bleeding in patients receiving intermittent injections. With continuous infusion, one-fourth less heparin was required than with intermittent injections. Administration of heparin by continuous infusion appears safer than intermittent injection with or without laboratory control and is no less effective for prevention of thromboembolism.