What is the typical volume of a unit of Packed Red Blood Cells (PRBC) for transfusion?

Typical Volume of a Unit of Packed Red Blood Cells (PRBC) for Transfusion

A standard unit of packed red blood cells (PRBC) typically has a volume of approximately 300 mL. 1

Composition and Characteristics of PRBC Units

PRBCs are the preferred blood product for transfusion to correct anemia and are derived from whole blood through centrifugation or collected via apheresis. The standard unit has the following characteristics:

• Volume: Approximately 300 mL per unit 1
• Hematocrit: Ranges from 50% to 80% 1
• Hemoglobin content: Contains 42.5-80 g of hemoglobin per unit 1
• Iron content: 147-278 mg of iron per unit 1
• Pure RBC volume: 128-240 mL of pure red blood cells 1
• Storage: Stored at controlled temperatures with appropriate preservatives

Expected Clinical Response to Transfusion

When administering PRBC transfusions, clinicians can expect:

• A single unit (300 mL) of PRBCs typically increases hemoglobin by approximately 1 g/dL 1
• Hematocrit typically increases by about 3% per unit in a normal-sized adult who is not actively bleeding 1
• For pediatric patients, approximately 1 cc/kg of PRBC transfused results in a 1% increase in hematocrit 2

Variations in PRBC Units

It's important to note that there may be variations in PRBC units:

• Some blood centers now supply units with higher numbers of platelets or different volumes 1
• Apheresis-derived platelets may have different characteristics than those from whole blood 1
• Volume reduction may be performed for specific patient populations (e.g., pediatric patients) 1

Clinical Considerations for PRBC Transfusion

When administering PRBC transfusions:

• PRBCs should be transfused one unit at a time with reassessment after each unit in stable patients 1
• Single-unit transfusions are recommended for hemodynamically stable patients without active bleeding 1
• Crossmatching must be performed before transfusion to confirm ABO compatibility 1
• A 170-200μm filter giving set should be used for administration 1

Potential Risks of PRBC Transfusion

Clinicians should be aware of potential risks:

• Volume expansion that may exacerbate conditions like portal hypertension 1
• Transfusion-related reactions (febrile, allergic) 1
• Potential for bacterial contamination and viral infections 1
• Immunologic complications including transfusion-related lung injury 1
• Development of HLA antibodies that may impact subsequent transfusions or transplantation 1

Common Pitfalls in PRBC Transfusion Practice

• Fixating on hemoglobin/hematocrit numbers alone without considering patient symptoms and comorbidities 3
• Failing to reassess after single-unit transfusions in stable patients 1
• Overlooking the need for special blood products (leukoreduced, irradiated, etc.) for specific patient populations 1
• Not accounting for the variability in hematocrit response to transfusion, which can have a standard deviation of ±1.2% per unit 4

Understanding the typical volume and expected response to PRBC transfusion is essential for appropriate transfusion practices that optimize patient outcomes while minimizing unnecessary exposure to blood products.