Relationships among haemoglobin level, packed red cell transfusion and clinical outcomes in patients after cardiac surgery

Objective: To identify associations among haemoglobin (Hb) concentrations, blood transfusions, and clinical outcomes in patients after cardiac surgery, especially in those who undergo valve replacement or bypass surgery. Design: Prospective observational trial. Setting: Surgical intensive care unit in a tertiary-level university hospital. Patients: 1216 Consecutive patients. Measurements: Haemoglobin at admission and 6, 12, 24, and 48 h later, and then, every 24 h while patients remained in the intensive care unit (ICU); number of transfusions and clinical events. Results: Patients were divided into quartiles according to minimal haemoglobin, the first and second of which (Hb <8.10 and <8.91 g/dL, respectively) differed significantly (P < 0.001) from the other two quartiles in terms of more organ failure, longer ICU stay, and higher mortality. We found associations between being transfused >= 4 packed red cells (PRCs) and a worse clinical outcome and higher mortality. The associated mortality rate was higher for patients who underwent bypass surgery when they had Hb <= 8.9 g/dL and for those who underwent valve replacement when they had Hb <= 8.9 g/dL and were transfused >= 4 PRCs. Conclusions: Low haemoglobin concentrations and transfusions in patients undergoing cardiac surgery are associated with increased morbidity and mortality. Also, anemia and transfusions are associated with poor outcome. Therefore, intra-and postoperative bleeding seem to be a risk factor in patients undergoing cardiac surgery.