Blood Transfusion in Cardiac Surgery

Mr Corazon is a 78-year-old man with insulin-dependent diabetes mellitus and an ejection fraction of 40% who is postoperative day 2 from coronary artery bypass grafting. He has been extubated and feels good, but he remains on a low-dose epinephrine infusion to support his blood pressure. His cardiac index is 2.2 L/m2, and he has a mixed venous oxygen saturation of 59%. He has low filling pressures and marginal urine output. His hematocrit is 24%. His surgeon and his cardiologist confer and agree to transfuse him with 1 unit of red blood cells. They explain to him that he needs the blood transfusion and that the major risk of transfusion is the very low risk of viral infection. After the transfusion, his mixed venous oxygen saturation and urine output improve, and his epinephrine infusion is weaned off. He is transferred out of the intensive care unit the following day.Article p 2544 The rationale for transfusing Mr Corazon is understandable. Historically, patients were thought to benefit from transfusions that boosted their hematocrit to ≥30%, particularly if they were older and sicker. Transfused blood is an excellent volume expander and remains in the intravascular space better than other resuscitation fluids. Transfused patients often “look better.” It is possible that Mr Corazon’s transfusion allowed his hemodynamics to improve sufficiently to wean him more quickly from his inotropic support. We might even expect that his recovery has been accelerated and his length of stay reduced.How should we evaluate this decision making in light of the available evidence? The article by Murphy …