Hemodynamics of protamine administration. Comparison of right atrial, left atrial, and aortic injections

Protamine administration for heparin reversal after cardiopulmonary bypass on occasion is associated with mild to severe hemodynamic deterioration. The route of administration may modify these reactions. A prospective randomized study was done in 68 patients undergoing isolated coronary artery bypass grafting. The route of protamine administration was randomized in a balanced fashion between right atrium, left atrium, and aorta. The preoperative and operative characteristics of the three groups were similar. Hemodynamic measurements were recorded before cannulation, after removal of the venous drainage catheter, and 1 minute, 5 minutes, and 10 minutes after protamine administration. Hypotension occurred in 11 patients with no significant difference among the three groups. The hypotension was immediate in three patients in whom route of administration was the aorta. The overall hemodynamic changes observed for the three treatment groups were not significantly different. An analysis for type II error indicated that it was unlikely that an important difference had been missed. We conclude that the route of administration does not affect the hemodynamic changes associated with protamine administration. We did not observe a case of severe hemodynamic deterioration, so that we cannot assess the effect of route of administration on the severity of an anaphylactic reaction.