Why is blood infusion important for a patient with anemia?

Blood Transfusion in Anemia: Importance and Clinical Considerations

Blood transfusions should be considered when hemoglobin concentration falls below 7 g/dL or when patients with anemia exhibit symptoms of inadequate tissue oxygenation, regardless of hemoglobin level. 1, 2

Indications for Blood Transfusion in Anemia

Hemoglobin-Based Criteria

• Transfusion is generally indicated when hemoglobin falls below 7 g/dL in critically ill patients 1
• Higher thresholds (7-8 g/dL) may be appropriate for patients with coronary heart disease 1
• Patients with severe symptoms may require transfusion regardless of hemoglobin level 2

Clinical Signs Indicating Need for Transfusion

• Tachycardia (heart rate >110 beats/min) suggesting compensatory response to inadequate oxygenation 2
• Tachypnea or dyspnea indicating respiratory compensation for anemia 2
• Postural hypotension suggesting inadequate circulatory compensation 2
• Confusion or altered mental status potentially indicating cerebral hypoxia 2
• Biochemical markers of tissue hypoxia (elevated lactate, metabolic acidosis) 2

Benefits of Blood Transfusion

• Provides rapid increase in hemoglobin and hematocrit levels, which no other treatment offers 1
• Immediate correction of severe or life-threatening anemia 1
• Improves tissue oxygenation in patients with abnormal baseline tissue oxygenation parameters 3, 4
• May improve exercise tolerance and quality of life in severely anemic patients 1
• Transfusion of 1 unit of packed red blood cells typically increases hemoglobin by approximately 1 g/dL 1

Risks and Limitations of Blood Transfusion

• Transfusion reactions including febrile non-hemolytic reactions 1
• Potential for circulatory overload and pulmonary edema, especially with rapid transfusion 1
• Risk of bacterial contamination and viral infections (though significantly decreased with modern screening) 1
• Increased risk of venous and arterial thromboembolism 1
• Transfusions do not correct the underlying pathology causing anemia and have no lasting effect 1
• Independently associated with increased ICU and hospital length of stay 1
• Potential relationship with acute lung injury and ARDS 1

Special Clinical Scenarios

Patients with Cardiovascular Disease

• Patients with symptomatic myocardial ischemia may require transfusion regardless of hemoglobin level 2
• A restrictive transfusion strategy (trigger hemoglobin 7-8 g/dL) is recommended even in patients with coronary heart disease 1
• The American College of Physicians does not support liberal use of blood transfusions in patients with mild to moderate anemia and cardiovascular disease 1

Critically Ill Patients

• Single-unit transfusions are recommended in hemodynamically stable patients, with careful monitoring and post-transfusion hemoglobin measurement 1
• No benefit has been demonstrated for a "liberal" transfusion strategy (transfusion when Hb is 10 g/dL) in critically ill patients requiring mechanical ventilation 1
• Transfusion may be appropriate for patients with severe symptoms regardless of hemoglobin level 2

Cancer and Chemotherapy-Induced Anemia

• Transfusion may be appropriate even without physiologic symptoms if a progressive decline in hemoglobin occurs after anticancer treatment 1
• Transfusion dependency in myelodysplastic syndromes is associated with shorter survival and increased risk of leukemic evolution 1

Best Practices for Transfusion

• Administer as single units in non-hemorrhaging patients to avoid overtransfusion 1
• Monitor for signs of transfusion-related complications 1
• Follow transfusions with intravenous iron supplementation when appropriate 1
• Consider alternatives to transfusion when appropriate, such as intravenous iron therapy for iron deficiency 5
• Recognize that the decision to transfuse should not be based solely on hemoglobin level but should incorporate clinical assessment of the patient's symptoms and comorbidities 2

Common Pitfalls to Avoid

• Transfusing based solely on a hemoglobin threshold without considering the complete clinical context 2
• Failing to evaluate for signs and symptoms of tissue hypoxia before deciding to transfuse 2
• Not considering the patient's volume status, as hemodilution can cause falsely low hemoglobin values 2
• Overlooking that transfusions are only a temporary solution and do not address the underlying cause of anemia 1
• Neglecting to investigate and treat the underlying cause of anemia while managing acute symptoms with transfusion 5