Temperature and duration of cardiopulmonary bypass influence transfusion requirements

Study Objective: To determine the influence of temperature and duration of cardiopulmonary bypass (CPB) on blood loss and transfusion requirements. Design: Retrospective chart review. Setting: Tertiary care, academic medical institution. Measurements and Main Results: The charts of 378 patients who had undergone primary elective coronary artery bypass graft surgery were studied. Systemic perfusion of CPB had been conducted between 20°C and 37°C in all patients. Patient demographic temperature during CPB, duration of CPB, blood loss, and transfusion requirements were all recorded. Hypothermic CPB patients had minor increases in requirements for transfusion of red blood cells (RBC; p = 0.01), fresh frozen plasma (FFP; p = 0.01), platelets (PLT; p = 0.003), and total (allogeneic and autologous) blood products (p < 0.001). Multivariate analysis revealed that decreased temperature after adjusting for duration was predictive of allogeneic (RBC, FFP, PLT, and cryoprecipitate) and total (allogeneic and autologous) transfusion requirements. The duration of CPB correlated with decreased temperature (r = -0.455; p < 0.0001). After adjusting for temperature, duration was only predictive of total (allogeneic and autologous) transfusion requirements. Conclusions: The institution of warm CPB has many ramifications for clinical practice. The hypothermic induced platelet dysfunction and increased duration associated with cold CPB may contribute to the minor increases in transfusion requirements. However, temperature appears to be a weak factor, neither supporting nor refuting the use of warm or cold CPB.