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Difficulty: HardHematology and Oncology

A 22-year-old man presents to the emergency department complaining of severe chest pain and difficulty breathing for the past 48 hours. He has a known history of homozygous sickle cell disease (HbSS). Vital signs show a temperature of 39.1°C (102.4°F), blood pressure of 92/58 mm Hg, heart rate of 128/min, and respiratory rate of 34/min. Pulse oximetry is 83% while receiving high-flow oxygen via a non-rebreather mask. Physical examination reveals severe respiratory distress, scleral icterus, and bilateral dullness to percussion with widespread crackles. A portable chest radiograph displays new diffuse, multilobar alveolar infiltrates.

Laboratory analysis reveals the following:

Laboratory TestResult
Hemoglobin6.9 g/dL (baseline 8.5 g/dL)
Leukocytes24,000/mm³
Platelets380,000/mm³
Reticulocytes15%

The patient has been started on intravenous fluids, broad-spectrum antibiotics (ceftriaxone and azithromycin), and adequate pain management. Which of the following is the most appropriate next step in management?

  1. A
    Administer intravenous furosemide
  2. B
    CT angiography of the chest
  3. Exchange blood transfusionAnswer
  4. D
    Simple red blood cell transfusion
  5. E
    Switch to intravenous piperacillin-tazobactam

Answer

Exchange blood transfusion is the most appropriate next step in management for this patient with severe acute chest syndrome.
The correct answer is exchange blood transfusion. This patient is presenting with acute chest syndrome (ACS), a life-threatening complication of sickle cell disease characterized by fever, chest pain, new pulmonary infiltrates, and hypoxemia. His presentation is severe, evidenced by multilobar infiltrates and profound hypoxemia (83% on a non-rebreather mask). The management of severe ACS requires an exchange blood transfusion. This procedure removes the patient's sickled red blood cells (HbS) and replaces them with normal red blood cells (HbA), rapidly improving oxygenation and halting the vaso-occlusive cycle without significantly raising overall blood viscosity. Simple transfusion is typically reserved for mild cases where the hemoglobin has dropped significantly but hypoxemia is less severe.

Step-by-Step Solution

1
Identify the primary diagnosis based on the clinical presentation.
The patient with sickle cell disease presents with fever, chest pain, new pulmonary infiltrates, and severe hypoxemia, establishing the diagnosis of Acute Chest Syndrome (ACS).
Recognizing ACS is critical as it is a major cause of mortality in sickle cell patients and requires specific, rapid intervention.
2
Determine the severity of the acute chest syndrome.
The presence of multilobar infiltrates, severe hypoxemia (SpO2 83% on high-flow oxygen), and hemodynamic instability indicates severe ACS.
Severity classification dictates the choice between a simple red blood cell transfusion and an exchange transfusion.
3
Select the appropriate targeted intervention for severe ACS.
Exchange blood transfusion is indicated rather than a simple transfusion.
Exchange transfusion rapidly decreases the percentage of hemoglobin S and improves oxygen-carrying capacity without significantly increasing overall blood viscosity, avoiding the exacerbation of vaso-occlusion.

Key Concept

Severe acute chest syndrome in sickle cell disease requires exchange blood transfusion to rapidly reduce hemoglobin S levels and improve oxygenation without causing hyperviscosity.
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Topics

Hematology and Oncology

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