Red Blood Cell Transfusion in the Emergency Department

Brit Long, MD; Alex Koyfman, MD

Disclosures

J Emerg Med. 2016;51(2):120-130. 

In This Article

Abstract and Introduction

Abstract

Background: Transfusion of red blood cells (RBCs) is the primary management of anemia, which affects 90% of critically ill patients. Anemia has been associated with a poor prognosis in various settings, including critical illness. Recent literature has shown a hemoglobin transfusion threshold of 7 g/dL to be safe. This review examines several aspects of transfusion.

Objective: We sought to provide emergency physicians with an updated review of indications for RBC transfusion in the emergency department.

Discussion: The standard hemoglobin transfusion threshold was 10 g/dL. However, the body shows physiologic compensatory adaptations to chronic anemia. Transfusion reactions and infections are rare but can have significant morbidity and mortality. Products stored for <21 days have the lowest risk of reaction and infection. A restrictive threshold of 7 g/dL is recommended in the new American Association of Blood Banks guidelines and multiple meta-analyses and supported in gastrointestinal bleeding, sepsis, critical illness, and trauma. Patients with active ischemia in acute coronary syndrome and neurologic injury require additional study. The physician must consider the patient's hemodynamic status, comorbidities, risks and benefits of transfusion, and clinical setting in determining the need for transfusion.

Conclusions: RBC transfusion is not without risks, including transfusion reaction, infection, and potentially increased mortality. The age of transfusion products likely has no effect on products before 21 days of storage. A hemoglobin level of 7 g/dL is safe in the setting of critical illness, sepsis, gastrointestinal bleeding, and trauma. The clinician must evaluate and transfuse based on the clinical setting and patient hemodynamic status rather than using a specific threshold.

Introduction

Transfusion of red blood cells (RBCs) has been a standard of care for the management of anemia for >100 years. RBC transfusion is common, with approximately 15 million units transfused annually in the United States (US), with 85 million units transfused worldwide.[1,2] It was thought that patients would not tolerate anemia and regular transfusion would improve outcomes with little risk. The definition of anemia includes hemoglobin (Hgb) <12 g/dL in females and 13 g/dL in males.[3] In fact, anemia affects almost 90% of patients in the intensive care unit during their admission, with 30% of intensive care unit (ICU) admissions possessing a Hgb <9 g/dL and 70% <12 g/dL at the time of admission.[4–6] Approximately 40% of critical patients will receive a transfusion during hospitalization, receiving on average 2 to 5 units of RBCs.[7,8] Anemia in the setting of older age, critical illness, trauma, and surgery has been associated with poor prognosis, as indicated in several studies.[9–16]

Patients in the setting of critical illness have multiple causes of anemia, including active hemorrhage, blunted erythropoietin production, inflammatory cytokine production, increased hepcidin, iron deficiency, and underlying disease (e.g., renal failure). RBC transfusion in anemia can increase oxygen delivery, increase cell mass, and potentially resolve anemic symptoms; however, transfusion can contribute to fluid overload, fever, reaction, immunomodulation, multiple organ dysfunction, hypothermia, and coagulopathy.[17]

The standard level for transfusion was considered to be Hgb of 10 g/dL or hematocrit (Hct) <30%.[15,18–20] Therefore, many transfusions occurred in patients with little to no symptoms in an effort to maintain Hgb levels above this number, considered a liberal strategy for transfusion. Several recent studies have questioned the liberal transfusion threshold in patients with sepsis, gastrointestinal (GI) bleeding, acute coronary syndrome (ACS), and trauma, as well as other components of product transfusion, including the physiologic effects of transfusion, product reactions, and effect of RBC product age.

The question for providers caring for patients ultimately revolves around the threshold for transfusion. Within emergency medicine, critical care, and in-hospital settings, little debate currently exists on restrictive strategy for hemodynamically stable admitted patients. Most would also agree that transfusion can be life-saving in patients with hypoperfusion and severe bleeding. This review will discuss the recent literature on these points and provide emergency physicians with an evidence-based review on the indications for RBC transfusion.

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