Mortality and adverse events after protamine administration in patients undergoing cardiopulmonary bypass

We designed this study to determine whether adverse hemodynamic events after a protamine administration increase the risk of in-hospital mortality. Using a retrospective cohort study design, medical and anesthesia records of patients undergoing cardiopulmonary bypass (CPB) at the Hospital of the University of Pennsylvania, Philadelphia, between 1990 and 1994 were reviewed. Adverse events after a protamine administration were determined using strict, predefined criteria, and in-hospital mortality was assessed without knowledge of exposure status. Mortality was more frequent among the 53 patients with adverse events (13.2%) than the 223 patients without events (2.7%; crude odds ratio 5.50; 95% confidence interval, 1.49-20.6). After adjusting for confounders, the odds ratio was 6.98 (95% confidence interval, 1.36-35.9; P = 0.017). Those suffering severe events had the highest mortality (23.5%, compared with 8.3% among those with less severe events versus 2.7% among those without any event, P = 0.001 for trend). In addition, the odds ratio was largest when using the strictest definition for Protamine-related events. In conclusion, patients undergoing CPB who experience adverse events after a protamine administration have an increased risk of in-hospital mortality. Further studies to confirm these findings and development and testing of protamine alternatives or prophylactic therapies are required to determine if mortality can be reduced.