A 40-year-old man with sickle cell anaemia (HbSS) presents with severe acute chest syndrome: SpO₂ 88%, bilateral infiltrates, fever, chest pain, and Hb 5.8 g/dL (baseline 8 g/dL). Which is the most critical immediate intervention?
- A Emergency exchange transfusion targeting HbS fraction <30% ✓
- B Simple transfusion to raise Hb to 10 g/dL
- C Hydroxyurea 15 mg/kg/day urgently to reduce sickling
- D High-flow oxygen alone with IV hydration and incentive spirometry
Explanation
Severe acute chest syndrome (ACS) with respiratory failure (SpO₂ <90%) and rapid decline is a medical emergency requiring emergency exchange transfusion (erythrocytapheresis) to rapidly reduce HbS fraction below 30% while maintaining total Hb near baseline to avoid hyperviscosity. Simple transfusion risks hyperviscosity if Hb rises above 11 g/dL and does not sufficiently reduce HbS percentage. Hydroxyurea has no role in acute management. Supportive therapy (O₂, analgesia, incentive spirometry, empiric antibiotics) is essential but exchange transfusion is the definitive intervention for severe ACS.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.