From the Guidelines
Red blood cell transfusions should be guided by symptoms and hemoglobin concentration, with a standard dosage of 1 unit of RBCs per transfusion in adults, and a weight-based dosage of 10-15 mL/kg in pediatric patients. A unit of red blood cells (RBCs) typically contains approximately 250-350 mL of packed red cells suspended in a preservative solution, with a total volume of about 300-400 mL. For adult patients, this standard dosage is expected to increase the hemoglobin level by approximately 1 g/dL or the hematocrit by about 3% 1. In pediatric patients, the dosage is calculated based on body weight, meaning a 20 kg child would receive about 200-300 mL of packed red cells, as suggested by guidelines that emphasize the importance of considering the patient's size and condition when determining transfusion volume 1.
Key Considerations for Transfusion
- The transfusion rate should be slower in patients at risk for volume overload, generally not exceeding 2-4 mL/kg/hour in stable patients.
- Red blood cell transfusions are indicated for treating symptomatic anemia or when hemoglobin levels fall below critical thresholds, typically 7-8 g/dL in stable patients, though thresholds may be higher in patients with cardiac disease or active bleeding 1.
- The goal of transfusion is to increase oxygen-carrying capacity of the blood when it has been compromised due to blood loss or decreased red cell production.
Guidelines for Practice
- The AABB recommends adhering to a restrictive transfusion strategy (7 to 8 g/dL) in hospitalized, stable patients, based on high-quality evidence 1.
- For pediatric patients, blood components should be prescribed by volume rather than number of units, as recommended by guidelines that aim to standardize and improve transfusion practices 1.
Clinical Decision Making
- Transfusion decisions should be influenced by symptoms as well as hemoglobin concentration, considering the individual patient's condition and needs 1.
- In cases of major hemorrhage, consideration should be given to transfusing red cells and other blood components as appropriate, with ongoing monitoring of the patient's condition and adjustment of the transfusion strategy as needed 1.
From the Research
Definition of One Unit of Red Blood Cells (RBCs)
- One unit of RBCs is approximately 250-450 mL 2
- A unit of packed red blood cells is approximately 300 mL 3
Indicated Dose in Adults
- The dose of RBCs transfused can vary depending on the patient's condition and the hospital's protocol
- Studies have shown that transfusion of one unit of RBCs can increase the hematocrit by approximately 1.9% +/- 1.2% 3
- In adults, the decision to transfuse RBCs is often guided by the patient's symptoms and hemoglobin concentration, with a restrictive transfusion strategy of 7 to 8 g/dL being as safe as a liberal transfusion strategy of 9 to 10 g/dL in many clinical settings 4
Indicated Dose in Pediatrics
- There is limited information available on the indicated dose of RBCs in pediatrics in the provided studies
- However, it is generally recommended that the dose of RBCs transfused be based on the patient's weight and the desired increase in hematocrit 5