An in-vitro study of the timing between protamine sulfate administration and cardiotomy suction termination

Background: During cardiopulmonary bypass (CPB), anticoagulation of the blood is the paramount responsibility of a perfusionist. The perfusionist should ensure the termination of cardiotomy suction at the onset of protamine sulfate (protamine) administration to prevent compromising the integrity of the extracorporeal circuit (AmSect. Standards and Guidelines for Perfusion Practice. 2023. <ns0:ext-link ext-link-type="uri" ns4:href="https://www.amsect.org/Policy-Practice/AmSECTs-Standards-and-Guidelines">https://www.amsect.org/Policy-Practice/AmSECTs-Standards-and-Guidelines</ns0:ext-link>). Although coagulopathy causes the largest mortality risk in adult CPB cases, standardization is not seen universally, and practice often varies between institutions (Stammers et al. Perfusion. 2001;16(3):189–198. <ns0:ext-link ext-link-type="uri" ns4:href="https://doi.org/10.1177/026765910101600304">https://doi.org/10.1177/026765910101600304</ns0:ext-link>; Jansa et al. Ann Thorac Surg. 2022;113(2):506–510. <ns0:ext-link ext-link-type="uri" ns4:href="https://doi.org/10.1016/j.athoracsur.2021.04.059">https://doi.org/10.1016/j.athoracsur.2021.04.059</ns0:ext-link>). Methods: Activated clotting times (ACTs) were measured in five swine subjects that were heparinized and placed on CPB for a total of approximately 6 h each. Samples of blood were drawn from the CPB circuit; ACTs were measured before the administration of protamine, after a protamine test dose (PTD), and after 1/3 of the full protamine dose had been introduced to each sample. Protamine dosing was determined by a 1:100 ratio of protamine to heparin. Results: 60 blood samples were included in the final analysis. The mean ACT after the PTD was 290.4 s (seconds), and 147.5 s after 1/3 of the full protamine dose. ACTs after the PTD decreased significantly by an average of 38.2% (p < 0.0001), and by 50.8% (p < 0.0001) after 1/3 of the full protamine dose was given. Conclusion: This investigation demonstrated an analysis of heparin reversal via protamine administration. The findings revealed that in the majority of samples, the PTD was sufficient to decrease the ACT below 480 s, the determined benchmark upon which CPB can be safely conducted. After 1/3 of the full protamine dose was given, nearly every sample’s ACT reached a value considered unsafe for bypass. The interpretation of the data suggests that there are significant grounds for advocating for a more disciplined approach to cardiotomy suction termination to preserve the integrity of the CPB circuit and to safely conduct CPB.