Risk of complications during intravenous heparin therapy.

The records of all patients to whom heparin was dispensed by the pharmacy of the University of California Medical Center, San Diego, during the year 1979 were reviewed. A total of 131 patients above age 15 met the inclusion criteria-they had received more than 10,000 units of heparin per 24 hours for at least 24 hours. All 131 patients were administered heparin by continuous intravenous infusion by peristaltic pump. All heparin was porcine heparin from a single commercial source. The daily mean minimum dose averaged 19,700 units, the maximum, 25,600 units. The activated partial thromboplastin time, usually measured once a day, was the only test used to monitor the dose. Major complicating events occurred in 13 patients (10 percent), and minor complicating events occurred in 10 patients (7.6 percent). All major complicating events occurred in patients with serious concurrent diseases. In subpopulations of 58 patients without concurrent disease, and of 24 in whom heparin was initiated for suspicion of thromboembolism that was not confirmed, no major complicating events occurred. These data indicate that continuous, intravenous administration of heparin is associated with minimal risk, and that risk is concentrated among older patients with serious concurrent disease.