When to transfuse Packed Red Blood Cells (PRBCs)?

From the Guidelines

Packed Red Blood Cells (PRBCs) should be transfused when a patient's hemoglobin concentration decreases to < 7.0 g/dL in adults in the absence of extenuating circumstances, such as myocardial ischemia, severe hypoxemia, or acute hemorrhage. This recommendation is based on the strongest and most recent evidence from the Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016 1.

Key Considerations

• The decision to transfuse PRBCs should be guided by the patient's symptoms and hemoglobin level, rather than relying solely on hemoglobin concentration 1.
• A restrictive transfusion strategy is preferred over liberal transfusion because unnecessary transfusions carry risks including transfusion reactions, infection transmission, volume overload, and immunomodulation effects.
• For patients with cardiovascular disease or those undergoing orthopedic or cardiac surgery, a higher threshold of 8 g/dL is generally recommended 1.
• In cases of active bleeding with hemodynamic instability, transfusion should be initiated immediately without waiting for laboratory results.

Transfusion Protocol

• The standard dose is 1 unit of PRBCs for every 1 g/dL increase in hemoglobin needed, with each unit typically raising hemoglobin by approximately 1 g/dL in an average-sized adult.
• Before transfusion, proper type and cross-matching must be performed, and the patient should be monitored for vital signs, temperature, and transfusion reactions during and after administration.
• PRBCs are transfused to increase oxygen-carrying capacity in the blood, as red blood cells contain hemoglobin which binds and transports oxygen to tissues.

Evidence-Based Practice

The recommendation to transfuse PRBCs at a hemoglobin level of < 7.0 g/dL is supported by high-quality evidence from the Surviving Sepsis Campaign guidelines 1. This guideline provides a strong recommendation for restrictive transfusion strategies in hospitalized, stable patients. Additionally, the AABB clinical practice guideline from 2012 also recommends adhering to a restrictive transfusion strategy (7 to 8 g/dL) in hospitalized, stable patients 1.

From the Research

Indications for Transfusion of Packed Red Blood Cells (PRBCs)

• The decision to transfuse PRBCs should be based on the patient's hemodynamic status, comorbidities, risks and benefits of transfusion, and clinical setting 2, 3.
• A restrictive threshold of 7 g/dL is recommended in the new American Association of Blood Banks guidelines and multiple meta-analyses, and is supported in gastrointestinal bleeding, sepsis, critical illness, and trauma 2, 4.
• In patients with iron-deficiency anemia, alternative methods to improve hemoglobin levels should be tried first, and transfusion should be considered for hemoglobin levels less than 7 g/dL 3.
• In patients with acute coronary syndromes, symptoms and signs should guide the decision to transfuse, and in patients with ischemic heart disease, transfusion should be considered for hemoglobin levels less than 8 g/dL or if they are symptomatic 3.
• For patients with unimpaired cardiopulmonary and vascular function, transfusion is generally indicated at hemoglobin values of 6 g/dL or less 5.

Special Considerations

• Patients with chronic anemia may benefit from scheduled transfusions of PRBCs, but urgent transfusions have specific indications, and the appropriateness of transfusions should be assessed according to the American Association of Blood Banks (AABB) 2016 criteria 4.
• The age of transfusion products likely has no effect on products before 21 days of storage 2.
• Transfusion reactions and infections are rare but can have significant morbidity and mortality, and products stored for less than 21 days have the lowest risk of reaction and infection 2.

Clinical Setting and Patient Evaluation

• The clinician must evaluate and transfuse based on the clinical setting and patient hemodynamic status rather than using a specific threshold 2.
• Patients' symptoms and co-morbidities should be incorporated when considering whether to transfuse PRBCs 3.
• Organizational measures and training can reduce transfusion errors, such as overtransfusion, undertransfusion, and other transfusion errors 5.