Acute chest syndrome — exchange transfusion thresholds

This is acute chest syndrome (ACS) — a new pulmonary infiltrate plus a respiratory symptom/sign (fever, chest pain, hypoxia) in sickle cell disease; ACS is the leading cause of death in SCD.^[2]

First-hour management

• Oxygen targeting saturation greater than 95 per cent; monitoring; 0.9% saline at no more than maintenance once euvolemic.
• Parenteral opioids within 30 minutes of triage, reassess every 15–30 min; meperidine only if it is the sole effective opioid; consider PCA (lower morphine consumption than continuous infusion).^[5]
• Antibiotics: intravenous cephalosporin + oral macrolide.
• Incentive spirometry; bronchodilators if wheeze; escalate respiratory support (HFNC/NIV) for hypoxia.
• Panel: FBC, reticulocytes, film, haemolysis markers, G&S, cultures, gas, CXR.

Transfusion strategy^[1][4]

• Simple transfusion (10 mL/kg) when haemoglobin is more than 10 g/L below baseline (may not be required if baseline ≥90 g/L); do not simple-transfuse SCA above 100 g/L.^[1]
• Urgent exchange transfusion for rapid progression (saturation below 90 per cent despite oxygen, increasing distress, progressive infiltrates, and/or haemoglobin falling despite simple transfusion). When exchange is performed, AABB usual goals are HbS not more than 30 per cent and haematocrit under 30 per cent. HbS below 30 per cent immediately prior to the next unit is the STOP chronic programme goal.
• Haematology early; HDU/ICU for severe ACS.

Watch for VOC→ACS evolution from chest-wall splinting; this presentation already meets ACS criteria.^[2]