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Packed Red Blood Cells (PRBCs): Composition, Indications, Transfusion Thresholds, and Safety

Packed Red Blood Cells (PRBCs, pRBCs, or "packed cells") are the most commonly transfused blood component, prepared by removing 200–250 mL of plasma from a unit of whole blood.

Product Specifications

ParameterStandard Unit (US)
Volume250–350 mL (Hct 55–65%)
Hemoglobin≥43 g/unit (typically 50–65 g)
Residual Leukocytes<5×10⁶/unit (leukoreduced; universal in US since 1990s)
Storage1–6°C in CPDA-1 (35 days) or Adsol/AS-3/AS-5 (42 days)
Additive SolutionsExtend shelf life; reduce viscosity; maintain 2,3-DPG/ATP
Irradiation25 Gy — prevents TA-GVHD (for immunocompromised, directed, HLA-matched)
WashedRemoves plasma proteins, K⁺, cytokines — for IgA deficiency, severe allergic reactions

Indications for Transfusion (AABB/ASA Guidelines)

Restrictive Strategy (Preferred for Most)

  • Hb ≤7 g/dL: Stable, non-cardiac inpatients (including ICU).
  • Hb ≤8 g/dL: Cardiovascular disease, orthopedic surgery, preexisting cerebrovascular disease.
  • Symptomatic anemia: Acute coronary syndrome, active bleeding, hemodynamic instability — transfuse regardless of Hb.

Liberal Strategy (Select Populations)

  • Acute coronary syndrome (some guidelines: Hb <8–9 g/dL).
  • Severe thrombocytopenia with bleeding.
  • Massive transfusion protocol (MTP): 1:1:1 PRBC:FFP:Platelets.

Dosing and Expected Response

  • 1 unit PRBC → ↑ Hb ~1 g/dL (10 g/L), ↑ Hct ~3% in 70 kg adult (non-bleeding).
  • Pediatric: 10–15 mL/kg → ↑ Hb 2–3 g/dL.
  • Transfuse over 1–4 hrs (max 4 hrs from issue); warmer if rapid/large volume.

Compatibility and Testing

  • ABO/Rh compatibility mandatory (electronic crossmatch if valid type & screen).
  • Antibody screen → if positive, full crossmatch + antigen-negative units.
  • Emergency release: O-negative (universal RBC) or type-specific uncrossmatched — documentation required.

Adverse Reactions (Per 100,000 Units)

ReactionIncidenceKey Features
Febrile Non-Hemolytic (FNHTR)1–3%Temp ≥38°C / Δ1°C; chills; cytokines, recipient antibodies
Allergic (Urticaria)1–3%Hives, pruritus; anti-plasma protein IgE
Anaphylaxis1:20,000–50,000Hypotension, angioedema, bronchospasm; IgA deficiency + anti-IgA
TRALI1:5,000–10,000Acute respiratory distress ≤6 hrs; donor HLA/HNA antibodies
TACO1–6% (high-risk)Volume overload; BNP ↑, pulmonary edema; diurese, slow rate
Hemolytic (Acute/Delayed)1:40,000–100,000ABO mismatch (acute); alloantibody anamnestic (delayed)
Infection (Bacterial)1:100,000 (platelets); <1:1M (RBC)Sepsis; skin flora (Staph) or Yersinia
Viral (HIV, HCV, HBV)<1:1–2MNAT testing; window period residual risk

Special Modifications

  • CMV-seronegative: For pregnant, immunocompromised, transplant (or leukoreduction equivalent).
  • HbS-negative: For sickle cell patients (prevent sickling).
  • Phenotype-matched: For sickle cell, thalassemia, alloimmunized (Rh, Kell, Duffy, Kidd).

Patient Blood Management (PBM)

  • Pre-op: Iron (IV/oral), EPO, optimize Hb.
  • Intra-op: Cell salvage, antifibrinolytics (TXA), meticulous hemostasis.
  • Post-op: Restrictive thresholds, single-unit policy, reassess after each unit.

PRBC transfusion is a lifesaving but not benign therapy. Evidence-based restrictive thresholds, PBM, and meticulous compatibility testing maximize benefit and minimize harm.

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