Heparin therapy during extracorporeal circulation. I. Problems inherent in existing heparin protocols.

Five heparin protocols, representative of about 30 presently used throughout the country, were analyzed. The adequacy of anticoagulation during and the precision of protamine neutralization at the conclusion of extracorporeal circulation were studied. In each of 50 patient's age, height, weight, or surface area was of no help in predicting heparin kinetics. The study group consisted of the 2 patients with the longest and the 2 patients with the shortest heparin half lives, as well as the 2 patients who showed the greatest sensitivity to heparin and the 2 who showed the least. By computer simulation, each was managed according to the five protocols and by a monitoring procedure. The protocols failed to provide safe anticoagulation or precise protamine neutralization, whereas the simplified monitoring approach was uniformly successful.