Response to Reader Comment: Continuing the Quest for Hemostasis: Can Factor Eight Inhibitor Bypassing Activity (FEIBA) Bypass Post-Pump Coagulopathy?

We thank Allred et al for their interest in our recently published work ¹ and their insightful comments. To clarify, our endpoint was not “pre-FEIBA transfusion volumes” but instead post-cardiopulmonary bypass post-protamine transfusion volumes as stated in the manuscript. ¹ We elected to match the patients who received Factor Eight Inhibitor Bypassing Activity (FEIBA) with the retrospective cohort of patients who did not receive FEIBA based on their preoperative characteristics. Although we would be interested to learn which postoperative variables Allred et al would like to add to the propensity score, we would be hesitant to do that to avoid further reduction in the study group.

As correctly noticed by Allred et al, our practice has changed over the years, and we listed the changes in the supplemental table. Of note, we did not use Hepcon for protamine dose calculation; we used it mainly for the determination of heparin concentration in the blood while on cardiopulmonary bypass.

We certainly would like to have a quick and easy laboratory test indicating that FEIBA is needed. Realistically, however, it takes approximately 45 min in our institution to release the values of prothrombin time (PT), activated partial thromboplastin clotting time (APTT), and international normalized ratio (INR). Meanwhile, when the patient is bleeding, hemostatic efforts must be initiated without delay. Therefore, to rule out potential post-bypass deficiencies of coagulation factors and thrombocytopenia, we obtain heparinized thromboelastography R-value, fibrinogen level, and platelet count after rewarming before separation from cardiopulmonary bypass. We clinically assess microvascular bleeding after protamine and 10 to 15 mL/kg of platelets and cryoprecipitate. Based on that data and taking into consideration the complexity of surgical repair we decide whether to give FEIBA.

Without a doubt, many aspects of hemostatic profile and management of hemostasis after cardiopulmonary bypass require further investigation, and more research is needed in the area.