Over 13.8 million units of red blood cells are transfused to over 5 million patients in the United States in 2011; blood transfusion is one of the most common procedure codes recorded at discharge for hospitalized patients. It is estimated that 60% to 70% of these transfusions occur in relation to surgical procedures. For over 40 years it was generally assumed that patients benefitted from transfusions whenever the hemoglobin fell below 10 g/dL or if the hematocrit fell below 30% (the so-called “10/30 rule”). Controversy remains regarding the appropriate selection of patients requiring transfusion, as well as the recognition and management of adverse transfusion reactions.
Transfusion in the postoperative period generally occurs due to anemia. The prevalence of postoperative anemia is difficult to assess accurately, but it is undoubtedly common, particularly in critically ill patients. Hemoglobin concentrations on admission to the intensive care unit (ICU) are on average 11.0 to 11.3 g/dL in two large studies, with overall transfusion prevalence rates of 37% to 44%. Postoperative anemia can result from several factors, but acute and chronic blood loss is most frequently cited. While intraoperative or traumatic blood loss is generally replaced during the surgical procedure, a significant number of patients still leave surgery with some degree of anemia. Patients admitted to the ICU following surgery on average have hemoglobin levels ranging from 10.8 to 11.5 g/dL. Perhaps more insidious is the chronic blood loss that can occur during the postoperative period itself. Causes for this include ongoing bleeding from the surgical site (eg, chest tube drainage) and repeated blood collections for laboratory testing. It has been suggested that 40 to 60 mL of blood is routinely collected from ICU patients daily. While this daily blood loss may seem minimal, it is aggravated by the decreased production of erythropoietin (EPO), resistance to the effects of EPO, and an inability to utilize iron in red cell production, all of which have been documented in the postoperative period. In patients who display symptoms of anemia in the postoperative period, there are limited alternatives to transfusion. EPO and iron therapy are often ineffective in the postoperative period and are of little use in the patient with an acute need for blood.
Arguments in favor of conservative management of postoperative anemia without the use of blood products include:
Steps that may be taken include:
Minimize blood draws to tests that would influence management.
Assess the clinical need for transfusion in each individual patient and only transfusing patients likely to benefit from transfusion (ie, generally those with a hemoglobin <7 g/dL or those who are hemodynamically unstable with a hemoglobin <10.0 g/dL).
Several well-documented randomized controlled trials have demonstrated that a hemoglobin of 7.0 g/dL, when used as ...