When is packed red blood cell (RBC) transfusion recommended?

Packed Red Blood Cell Transfusion Thresholds

For most hospitalized hemodynamically stable patients, transfuse when hemoglobin falls below 7 g/dL; for patients with cardiovascular disease or undergoing orthopedic/cardiac surgery, use a threshold of 8 g/dL or presence of symptoms (chest pain, orthostatic hypotension, tachycardia unresponsive to fluids, or heart failure). 1

General Hospitalized Patients

ICU Patients

• Transfuse at hemoglobin <7 g/dL in critically ill adult and pediatric ICU patients who are hemodynamically stable 1
• This restrictive strategy (7 g/dL) is as effective as liberal transfusion (10 g/dL) and does not increase mortality, myocardial infarction, stroke, or infection 1
• The most recent 2023 AABB guidelines strongly recommend this 7 g/dL threshold for hospitalized adults who are hemodynamically stable 2

Postoperative Surgical Patients

• Transfuse at hemoglobin <8 g/dL or for symptoms in postoperative patients 1
• Symptoms warranting transfusion include: chest pain of cardiac origin, orthostatic hypotension or tachycardia unresponsive to fluid resuscitation, or congestive heart failure 1
• For orthopedic surgery patients, the 2023 AABB guidelines support using 8 g/dL as the threshold 2

Mechanically Ventilated Patients

• Consider transfusion at hemoglobin <7 g/dL in critically ill patients requiring mechanical ventilation 1
• No benefit exists from liberal transfusion strategies (10 g/dL threshold) in this population 1

Patients with Cardiovascular Disease

Stable Cardiac Disease

• Transfuse at hemoglobin ≤8 g/dL or for symptoms in hemodynamically stable patients with preexisting cardiovascular disease 1
• The FOCUS trial demonstrated no difference in functional recovery or mortality between restrictive (8 g/dL) and liberal strategies in patients with cardiovascular disease 1
• The 2023 AABB guidelines recommend 8 g/dL for patients with preexisting cardiovascular disease 2

Acute Coronary Syndrome

• Transfusion may be beneficial when hemoglobin <8 g/dL in patients with acute coronary syndromes on hospital admission 1
• Exception: Avoid restrictive strategies in patients with active acute myocardial ischemia - this is the one population where the 7 g/dL threshold may not be safe 1
• Evidence is mixed: TRICC showed lower MI risk with restrictive transfusion, while FOCUS showed a non-significant trend toward higher MI risk 1

Cardiac Surgery Patients

• Use 7.5 g/dL threshold for patients undergoing cardiac surgery per the 2023 AABB guidelines 2
• Three trials in cardiac surgery patients showed no difference in mortality or cardiac outcomes between restrictive and liberal strategies 1

Special Clinical Situations

Hemorrhagic Shock and Active Bleeding

• Transfusion is indicated for hemorrhagic shock regardless of hemoglobin level 1
• Transfusion may be indicated for acute hemorrhage with hemodynamic instability or inadequate oxygen delivery 1
• In active hemorrhage, transfuse multiple units as needed; in stable patients without bleeding, give single units and reassess 1

Trauma Patients

• Consider transfusion at hemoglobin <7 g/dL in resuscitated critically ill trauma patients 1
• No benefit from liberal transfusion strategies in this population 1

Septic Patients

• Assess each septic patient individually - optimal transfusion triggers are unknown in sepsis 1
• No clear evidence that transfusion increases tissue oxygenation in sepsis 1
• The 2 g/dL threshold may be reasonable, but clinical context is critical 1

Pediatric Patients

• Transfuse at hemoglobin <7 g/dL in critically ill children who are hemodynamically stable without hemoglobinopathy, cyanotic cardiac conditions, or severe hypoxemia 2
• For children with congenital heart disease: use 7 g/dL (biventricular repair), 9 g/dL (single-ventricle palliation), or 7-9 g/dL (uncorrected disease) 2

Critical Decision-Making Principles

Never Use Hemoglobin Alone

• Do not base transfusion decisions solely on hemoglobin levels 1
• Incorporate: intravascular volume status, evidence of shock, duration and acuity of anemia, cardiopulmonary parameters, and signs of end-organ ischemia 1
• Look for: ST changes on ECG, chest pain, decreased urine output, elevated lactate, reduced mixed venous oxygen saturation 3

Transfusion Administration

• Give single units in the absence of active hemorrhage, then reassess 1
• Each unit increases hemoglobin by approximately 1-1.5 g/dL 3, 4
• Reassess clinical status and hemoglobin after each unit before giving additional blood 3, 4

Important Caveats and Pitfalls

Avoid Liberal Transfusion

• Do not transfuse when hemoglobin >10 g/dL - this increases risks without benefit 3, 4
• Liberal strategies increase nosocomial infections, multi-organ failure, transfusion-related acute lung injury (TRALI), and transfusion-associated circulatory overload 3, 4
• Restrictive strategies reduce RBC transfusion by approximately 40% without increasing mortality 3

Patients at Risk for ARDS

• Avoid transfusion after completion of resuscitation in patients at risk for or with acute lung injury/ARDS 1
• RBC transfusion is associated with respiratory complications including ALI and ARDS 1

Transfusion Risks

• Packed RBCs have limited ability to augment oxygen delivery to tissues 5
• Transfusion carries risks: infections (HIV 1:1,467,000; HCV 1:1,149,000; HBV 1:282,000-357,000), immunosuppression, and potentially worse clinical outcomes 3, 5