In a hemodynamically stable adult, at what hemoglobin (or hematocrit) level should a blood transfusion be given, and how do the thresholds change for patients with coronary artery disease, heart failure, cerebrovascular disease, undergoing major surgery, or in third‑trimester pregnancy?

Blood Transfusion Thresholds Based on Hemoglobin Levels

For hemodynamically stable adults without cardiovascular disease, transfuse when hemoglobin falls below 7 g/dL; for patients with coronary artery disease, heart failure, or cerebrovascular disease, use a threshold of 8 g/dL; for acute coronary syndrome, transfuse at hemoglobin <10 g/dL; and never transfuse when hemoglobin exceeds 10 g/dL in any population. 1, 2, 3

General Population (Hemodynamically Stable Adults)

• Transfuse at hemoglobin <7 g/dL in hospitalized adults without cardiovascular disease, as this restrictive strategy reduces transfusion exposure by 40% without increasing mortality, myocardial infarction, stroke, or renal failure. 2, 3

• Do not transfuse at hemoglobin >10 g/dL in any patient population, as liberal strategies increase complications including transfusion-related acute lung injury (TRALI), circulatory overload, nosocomial infections, and multi-organ failure without improving outcomes. 2, 3

• Hemoglobin <6 g/dL is an almost universal indication for urgent transfusion, especially when anemia is acute. 2, 3

Patients with Coronary Artery Disease or Heart Failure

• Transfuse at hemoglobin ≤8 g/dL for patients with established coronary artery disease, heart failure, or peripheral vascular disease, as these patients have reduced tolerance to anemia. 1, 2, 3

• The American College of Cardiology and American Association of Blood Banks both recommend this 8 g/dL threshold rather than the standard 7 g/dL used in other hospitalized patients. 1, 2

• Consider transfusion for symptomatic patients even at hemoglobin ≤8 g/dL, including those with chest pain, dyspnea, tachycardia unresponsive to fluids, or ECG changes suggesting ischemia. 1, 2

• A 2020 meta-analysis of critical care patients with chronic cardiovascular disease found no significant difference in mortality or acute coronary syndrome between restrictive (7 g/dL) and liberal strategies, but expert consensus supports the 8 g/dL threshold due to persistent uncertainty. 4

Acute Coronary Syndrome (Active or Recent)

• **Transfuse at hemoglobin <10 g/dL** in patients with acute coronary syndrome, as the Carson trial demonstrated significant reduction in 30-day mortality (1.8% versus 13%, p=0.032) with a liberal strategy targeting hemoglobin >10 g/dL compared to a restrictive strategy. 4

• Avoid restrictive strategies (hemoglobin >8 g/dL threshold) in acute coronary syndrome, as retrospective data suggest increased mortality when hemoglobin is maintained below 10 g/dL in this specific population. 4

• The European Society of Cardiology recommends withholding transfusion unless hemoglobin decreases below 8 g/dL, but the most recent trial evidence supports a 10 g/dL target. 1

Cerebrovascular Disease and Brain Injury

• Do not adopt a liberal transfusion strategy targeting hemoglobin >10 g/dL in brain-injured patients, as this does not decrease morbidity and mortality and may prolong hospital stay. 4

• A 2012 review of 537 patients with traumatic brain injury and subarachnoid hemorrhage found no mortality benefit with higher transfusion thresholds (9.3-11.5 g/dL) compared to lower thresholds (7.0-10.0 g/dL), but reported shorter hospital stays with restrictive strategies. 4

• Use a threshold of 7-8 g/dL for patients with cerebrovascular disease in the absence of active ischemia, as evidence does not support higher targets. 4

Major Surgery and Postoperative Patients

• For postoperative cardiac surgery patients, use a restrictive threshold of 7.5-8.0 g/dL (GRADE 1+ recommendation), as three large randomized trials with meta-analyses of >8,800 patients demonstrated no difference in 30-day or 6-month mortality between restrictive and liberal strategies. 4, 1

• Restrictive strategies in cardiac surgery reduce transfusion rates without increasing myocardial infarction, arrhythmias, stroke, acute renal failure, or infections. 4

• For other major surgery patients, use a threshold of 8 g/dL, particularly in orthopedic surgery. 2

Third-Trimester Pregnancy

• Evidence specific to third-trimester pregnancy transfusion thresholds is not provided in the available guidelines, but general principles suggest using a threshold of 7 g/dL for hemodynamically stable pregnant patients without cardiovascular disease, with consideration for the 8 g/dL threshold if cardiovascular compromise is present. 2, 3

Transfusion Protocol: Single-Unit Strategy

• Administer one unit of packed red blood cells at a time, then reassess clinical status, symptoms, and hemoglobin before giving additional units. 1, 2, 3

• Each unit should increase hemoglobin by approximately 1-1.5 g/dL. 2

• Target post-transfusion hemoglobin of 7-9 g/dL in most patients, as higher targets provide no additional benefit. 2

Clinical Assessment Beyond Hemoglobin Levels

• Never base transfusion decisions solely on hemoglobin concentration; always assess for symptoms of inadequate oxygen delivery including chest pain, tachycardia >110 bpm unresponsive to fluids, orthostatic hypotension, severe dyspnea, altered mental status, ST-segment ECG changes, elevated lactate, or low mixed-venous oxygen saturation. 1, 2, 3

• Hemodynamic instability or hemorrhagic shock mandates immediate transfusion regardless of measured hemoglobin level. 2, 3

• Consider the acuity of anemia: acute anemia is less physiologically tolerated than chronic anemia and warrants earlier transfusion. 3, 5

Critical Pitfalls to Avoid

• Do not use a 7 g/dL threshold in patients with active coronary artery disease or acute coronary syndrome—these populations require the 8-10 g/dL range depending on acuity. 4, 1

• Do not automatically order "2 units of PRBCs"—this outdated practice increases unnecessary exposure; modern guidelines favor single-unit transfusion with reassessment. 2, 3

• Do not delay transfusion in symptomatic patients waiting for hemoglobin to fall to a specific threshold—symptoms of inadequate oxygen delivery take precedence over numeric values. 1, 2, 3

• Avoid liberal strategies in any population, as transfusing to hemoglobin >10 g/dL increases complications (TRALI, volume overload, infections, immunosuppression) without mortality benefit. 2, 3