When should a hospitalized patient be transfused?
Case
A 65-year-old male nursing home resident is sent to the emergency room with a productive cough, fever, and low blood pressure, and is diagnosed with community-acquired pneumonia. He has a history of tobacco abuse, hypertension, and a right middle cerebral artery stroke. His admission labs show a hemoglobin level of 9.0 g/dL. The day after admission his hypotension has resolved and he reports feeling much better after two liters of intravenous fluids and antibiotics. However, his hemoglobin level is 7.9 g/dL. There is no evidence of bleeding. Should this hospitalized patient be transfused?
Overview
When to give a red blood cell transfusion is a clinical question commonly encountered by hospitalists. Individuals with acute blood loss, chronic blood loss, anemia of chronic disease, and hemolytic anemia often are given transfusions. Hospitalists serving as consultants may be asked when to transfuse patients perioperatively.
It is estimated up to 25% of the red blood cells transfused in the U.S. are inappropriate.1-4 Many physicians transfuse based on a number, rather than on objective findings. Overuse is common because of the wide availability of red blood cells, the belief complications are infrequent, and an unfounded fear of adverse outcomes if a patient is not transfused.
Tachycardia, low blood pressure, and declining oxygen saturations are signs clinicians can use when making the decision to transfuse. Electrocardiographic changes associated with tissue hypoxia can occur at a hemoglobin level <5 g/dL in healthy adults. Studies show mortality and morbidity increase rapidly at levels <5.0 to 6.0 g/dL.5 Currently, no diagnostic serological test exists for tissue hypoxia, which is the physiologic reason to give red blood cells.
Red blood cell transfusion can be a life-saving therapy; however, it is not a benign intervention. It is estimated 10% of transfusion reactions will have some adverse event.6 Red blood cell use exposes patients to hemolytic transfusion reactions, infections, and transfusion related acute lung injury.7,8 Additionally, unnecessary economic expenses are incurred and a scarce resource is diverted from other patients.
Hospitalists should be able to describe the indications for red blood cell transfusion and understand the evidence for and against its use. Physicians who appreciate the risks and benefits of red blood cell use tend to transfuse less blood that those who less informed. 9, 10
Review of the Data
General outcomes: Despite the long history of red blood cell transfusion, which dates back to 1818, when James Blundell successfully saved a woman exsanguinating from a postpartum hemorrhage, little evidence has been accumulated for its appropriate use. In the 1980s, the discovery of the human immunodeficiency virus sparked blood product safety concerns. This stimulated research and a debate over red blood cell transfusion practices, with a growing body of literature unsupportive of transfusion for an arbitrary trigger, for example the “10/30 rule,” which referred to 10 g/dL hemoglobin or hematocrit of 30%.9