EFFECTS OF DIFFERING RATES OF PROTAMINE REVERSAL OF HEPARIN ANTICOAGULATION

Background. Protamine sulfate reversal of heparin anticoagulation may be associated with adverse cardiovascular side effects. The purpose of this study was to determine whether diminished systemic oxygen consum ption and hemodynamic changes were more likely to accompany rapid vers us slow protamine administrationMethods. Fifteen patients undergoing a bdominal aortic aneurysm resection in, a prospective randomized double -blinded study received intravenous protamine (1.5 mg/kg) rapidly duri ng a 3-minute period (group I; n = 7) or slowly during a 15-minute per iod (group II, n = 8). Systemic oxygen consumption (VO2) and hemodynam ic parameters were assessed for up to 20 minutes after protamine admin istration began. Results, Blood pressure declines (millimeters of merc ury) were greatest in group I with rapid protamine administration (-19 systolic and -9 diastolic) compared with group II with slow protamine administration (-12 systolic and -1 diastolic). Heart rate fell marke dly in, both groups I and II. Cardiac output (CO) declined in group I at virtually all time periods. Similar CO declines in, group II occurr ed 10 minutes after protamine infusion had begun and persisted for 3 m inutes after protamine administration was complete. Maximum VO2 decrea ses were -16% (60 seconds into protamine infusion) and -13% (1.5 minut es after protamine infusion) in groups I and II, respectively, with st atistically significant declines (p < 0.05) occurring only in group I compared with baseline values. Statistically significant differences ( p < 0.01), however, were found when mean declines during and after pro tamine infusion were compared with controls for both CO and VO2 in bot h groups. Conclusions, Significant declines in, systemic VO2 and hemod ynamic perturbations accompany protamine reversal of heparin anticoagu lation during aortic surgery. Rapid protamine administration increases the magnitude of these adverse responses.