Protamine Administration Via the Ascending Aorta May Prevent Cardiopulmonary Instability.

OBJECTIVE: The method of protamine administration may influence adverse reactions. The authors investigated the effects of 3 different methods of protamine administration on cardiopulmonary function. DESIGN: Prospective, randomized clinical study. SETTING: Single university hospital. PARTICIPANTS: Human volunteer patients. INTERVENTIONS: Ninety-five patients undergoing cardiac surgery were randomized prospectively into 3 groups. Group central vein control (CVC) and group central vein (CV) received protamine via a central vein over 10 minutes and 2 minutes, respectively. Group ascending aorta (AA) received protamine via the ascending aorta over 2 minutes. Hemodynamic parameters were assessed at 7 intraoperative time points, and pulmonary parameters were assessed at 4 intraoperative time points. MEASUREMENTS AND MAIN RESULTS: The groups were similar regarding preoperative demographics, intraoperative care, and baseline cardiopulmonary function. However, both the CVC and CV groups exhibited decreased blood pressure and impaired pulmonary oxygenation after protamine administration; these changes were not observed in the AA group. Within-group changes in mean arterial blood pressure after protamine administration were significant in the AA group (mean increase 6.5 mmHg; p = 0.01) but not in the CVC (mean decrease 3.1 mmHg, p = 0.13) or CV (mean decrease 4.3 mmHg, p = 0.14) groups. Within-group changes in arterial oxygenation after protamine administration were significant in the CVC (mean decrease 85 mmHg; p<0.001) and CV (mean decrease 47 mmHg; p = 0.009) groups but not in the AA group (mean decrease 8 mmHg; p = 0.82). CONCLUSIONS: The results indicated that administration of protamine via the ascending aorta may be the preferred route. The potential ability of administering protamine via the ascending aorta to prevent cardiopulmonary instability in patients undergoing cardiac surgery deserves further clinical investigation.