What are the criteria for blood transfusion in adult and pediatric patients with anemia or significant bleeding?

Blood Transfusion Criteria

Primary Transfusion Thresholds

For hemodynamically stable hospitalized adults without cardiovascular disease, transfuse when hemoglobin falls below 7 g/dL. 1, 2 This restrictive strategy reduces transfusion exposure by approximately 40% without increasing mortality, myocardial infarction, stroke, or infection compared to liberal strategies targeting 9-10 g/dL. 1

Standard Adult Populations

• ICU patients (adult and pediatric): Transfuse at hemoglobin ≤7 g/dL 1, 2
• Postoperative surgical patients: Transfuse at hemoglobin ≤8 g/dL OR for symptoms (chest pain, orthostatic hypotension/tachycardia unresponsive to fluids, congestive heart failure) 1
• Orthopedic surgery patients: Use threshold of 8 g/dL 2
• Cardiac surgery patients: Use threshold of 7.5 g/dL 1, 2

High-Risk Cardiovascular Populations

For patients with preexisting cardiovascular disease or acute coronary syndrome, transfuse at hemoglobin ≤8 g/dL or for cardiac symptoms. 1, 3 The evidence shows that liberal transfusion strategies (targeting >10 g/dL) in acute coronary syndrome patients increase mortality (38% vs 13%, P=0.046) and composite cardiovascular endpoints. 1

• Acute coronary syndrome: Avoid liberal transfusion (>10 g/dL); restrictive strategy (≥8 g/dL) associated with lower 30-day mortality (1.8% vs 13%, P=0.032) 1
• Coronary artery disease/heart failure: Threshold of 8 g/dL 1, 3

Special Populations

Brain-injured patients: Do not adopt liberal strategy targeting >10 g/dL; restrictive thresholds (7-10 g/dL) result in shorter hospital stays without mortality difference 1

Pediatric patients:

• Critically ill children (stable, no hemoglobinopathy): Transfuse at hemoglobin <7 g/dL 4, 2
• Congenital heart disease: Use 7 g/dL (biventricular repair), 9 g/dL (single-ventricle), or 7-9 g/dL (uncorrected) 2
• Life-threatening anemia: Hemoglobin <5.5-6 g/dL almost always requires immediate transfusion 4, 5

Clinical Assessment Beyond Hemoglobin

Never use hemoglobin level alone as a transfusion trigger. 6, 3 Incorporate these clinical factors:

Signs Requiring Transfusion Regardless of Hemoglobin

• Hemorrhagic shock with hemodynamic instability 6, 7
• Active bleeding >30% blood volume (>1500 mL) 1, 7
• Symptomatic anemia: chest pain (cardiac origin), orthostatic hypotension/tachycardia unresponsive to fluids, congestive heart failure, shortness of breath, decreased exercise tolerance 1, 7
• ST-segment changes on ECG suggesting cardiac ischemia 1, 6

Markers of Inadequate Oxygen Delivery

• Elevated lactate indicating tissue hypoxia 6, 3
• Low mixed venous oxygen saturation (SvO2) 6, 3
• Metabolic acidosis 3
• Decreased urine output 6

Transfusion Administration Protocol

Transfuse one unit of packed RBCs at a time, then reassess clinical status and hemoglobin before administering additional units. 1, 6, 3 Each unit raises hemoglobin by approximately 1-1.5 g/dL. 6

Pediatric Dosing

• Standard formula: Volume (mL) = Weight (kg) × Desired Hb rise (g/dL) × 3 4
• Alternative approach: 10-15 mL/kg of packed RBCs 4
• Transfuse slowly over 2-4 hours to avoid volume overload 4

Target Post-Transfusion Hemoglobin

• Most patients: Target 7-9 g/dL 4, 6, 3
• Higher targets (>10 g/dL) provide no additional benefit and increase complications 4, 6, 3

Critical Pitfalls to Avoid

Liberal transfusion strategies (targeting hemoglobin >10 g/dL) increase mortality and complications without providing benefit. 1, 6, 3 Specific risks include:

• Transfusion-related acute lung injury (TRALI): Leading cause of transfusion-associated mortality 3
• Increased mortality: When Hb >10 g/dL at transfusion (OR 3.34,95% CI 2.25-4.97) 1
• Venous and arterial thromboembolism 3
• Transfusion-associated circulatory overload (TACO): Particularly dangerous in children and elderly 4, 6
• Infections: HIV (1:1,467,000), HCV (1:1,149,000), HBV (1:282,000-357,000) 6
• Immunosuppression and nosocomial infections 6

Do not transfuse asymptomatic patients with hemoglobin 7-10 g/dL without cardiovascular disease. 6 The body demonstrates physiologic compensatory adaptations to chronic anemia that make transfusion unnecessary. 8

Intraoperative Considerations

Monitor blood loss, hemodynamics, and end-organ perfusion during surgery. 1 Consider transfusion when:

• Blood loss exceeds 1500 mL 1
• ST-segment changes appear on cardiac monitoring 1
• Hemodynamic instability (BP, heart rate) despite fluid resuscitation 1

Use cell salvage and reinfusion of recovered red cells as part of blood conservation strategy. 1