How to Order 1 Unit of Packed Red Blood Cells (PRBC)
Order PRBCs by the single unit with mandatory clinical reassessment after each transfusion before ordering additional units, ensuring proper crossmatching and patient identification protocols are followed. 1, 2
Pre-Transfusion Requirements
Blood Type and Crossmatch
- PRBCs must be crossmatched before transfusion to confirm ABO compatibility and screen for other antibodies in the recipient. 1
- This is a mandatory safety step that cannot be bypassed except in life-threatening emergencies where uncrossmatched O-negative blood may be used.
Patient Identification System
- Use a bar-coded wristband identification system that links the patient to the specific blood unit to prevent wrong-blood transfusions, which occur at a rate of approximately 1 per 10,000 units. 3
- The blood bag label should include the patient's ID number, the unit ID number, and a code identifying the product type (allogeneic or autologous). 3
- Scan both the patient's wristband and the blood bag barcode at bedside before administration to verify correct matching. 3
Ordering Protocol
Single-Unit Strategy
- Order exactly 1 unit of PRBCs at a time rather than ordering multiple units simultaneously. 1, 2
- This single-unit transfusion strategy is the standard recommended approach by the American College of Physicians and National Comprehensive Cancer Network. 2
- After the first unit is completed, reassess the patient clinically before deciding whether to order an additional unit. 1, 2
Transfusion Thresholds
- For hemodynamically stable patients without active bleeding, transfuse when hemoglobin is <7 g/dL. 2, 4
- For patients with cardiovascular disease or symptomatic anemia, transfuse when hemoglobin is <8 g/dL. 2, 4
- Do not transfuse solely based on hemoglobin numbers—always incorporate the patient's symptoms, comorbidities, and clinical status. 4
Administration Details
Premedication
- Premedication with acetaminophen or antihistamines is seldom required for patients not planned for long-term transfusion. 1
- If repeated transfusions are anticipated, consider leukocyte-reduced blood and premedication to minimize adverse reactions. 1
Monitoring Requirements
- Document baseline vital signs (temperature, heart rate, blood pressure, respiratory rate) before starting the transfusion. 2
- Monitor vital signs at 15 minutes after starting the transfusion and again at completion. 2
- These monitoring intervals are standard protocol to detect early transfusion reactions.
Expected Response and Reassessment
Hemoglobin Increment
- Each 300 mL unit of PRBCs typically raises hemoglobin by 1 g/dL or hematocrit by 3% in normal-sized adults without ongoing blood loss. 5
- Larger patients may require more blood volume to achieve the same hemoglobin increment. 5
Timing Between Units
- No mandatory waiting period exists between units for stable patients—the decision to transfuse additional units should be based on clinical reassessment, not arbitrary time intervals. 2
- In massive transfusion protocols for actively bleeding patients, PRBCs are given rapidly without gaps between units. 2
Common Pitfalls to Avoid
Volume Considerations
- Avoid routine volume reduction of PRBCs, as 15-55% of platelets are lost during additional centrifugation steps. 1
- Volume reduction should be limited to patients requiring severe volume restriction or neonates/children receiving ABO-incompatible platelets. 1
Iron Deficiency Management
- Do not assume transfusion corrects underlying iron deficiency—obtain pre-transfusion iron indices and provide supplemental iron therapy if needed in the 90 days following transfusion. 5
- The iron in transfused red cells (147-278 mg per unit) is not immediately available for erythropoiesis and is only released after the cells are phagocytosed at the end of their 100-110 day lifespan. 5