Acute chest syndrome

Background

• The leading cause of death in patients with HbSS in the United States
• Occurs most commonly in the 2-4yr old age group and then declines with age
• Due to pulmonary ischemia and infarction; complication of pneumonia

Causes

• Pulmonary infection
  • Chlamydia pneumoniae and Mycoplasma pneumoniae are most common organisms
  • May also be caused by S. aureus, H. influenzae, Klebsiella, and viruses
    • Infection due to S. pneumoniae is now rare due to pneumococcal immunization and prophylactic penicillin therapy
• Fat emboli
  • Can cause microvasculature occlusion in the pulmonary circulation, leading to bone marrow infarction
  • Autopsies have shown bony slivers and marrow fat found in pulmonary vasculature of patients
• Rib infarction
• Overly aggressive IV hydration
• Vaso-occlusive pain crisis
• Asthma
• Iatrogenic
  • Opioid analgesics can lead to hypoventilation

Clinical Features

• New infiltrate on chest x-ray PLUS one of the following signs or symptoms
  • Fever >38.5°C (101.3°F)
  • Cough
  • Wheezing
  • Tachypnea
  • Chest pain

Complications

• Pulmonary Embolism (bone marrow, fat or thrombotic)
• Pneumonia
• CVA
• Sepsis

Differential Diagnosis

• Pneumonia
• Asthma
• Pulmonary hypertension

Sickle cell crisis

• Vaso-occlusive pain crisis
• Bony infarction
• Dactylitis
• Avascular necrosis of femoral head
• Acute chest syndrome
• Asthma
• Pulmonary hypertension
• Gallbladder disease
• Acute hepatic sequestration
• Infection
  • Meningitis
  • Pneumonia
  • Septic joint
  • Osteomyelitis
• Parvovirus B19
• Splenic sequestration
• CVA
• Cerebral aneurysm and ICH
• Priapism
• Papillary necrosis

Evaluation

Work-Up

• CBC
• Retic count
• VBG / ABG
• Blood culture /sputum cultures
• CXR

Evaluation

• New infiltrate seen on chest x-ray
  • Chest x-ray findings may lag behind clinical features
• Lung ultrasound to CXR or CT finding correlations
  • Consolidation seen as hyperechoic punctiform air bronchograms
  • Ground-glass opacities seen as coalescent B lines
  • Pleural effusion, defined as large if interpleural distance > 25 mm

Management

• O2
  • Titrate to pulse oximetry >92%
• Incentive Spirometer
• Hydration
  • Oral hydration preferred
  • IV hydration with hypotonic fluid if patient unable to tolerate PO
• Analgesia
  • Pulmonary toilet is important but avoid excessive sedation
• Bronchodilators
• Antibiotics
  • 3rd generation cephalosporin + macrolide
• Transfusion (leucocyte depleted)
  • Consider transfusion to goal of hemoglobin 11 / hematocrit 30 for:
    • O2 Sat <92% on room air
    • hematocrit 10-20% below patient's usual hematocrit or dropping hematocrit
• Exchange transfusion
  • Consider for:
    • Progression of acute chest syndrome despite simple transfusion
    • Severe hypoxemia
    • Multi-lobar disease
    • Previous history of severe acute chest syndrome or cardiopulmonary disease

See Also

• Sickle Cell Crisis

External Links

• IBCC Chapter on Acute Chest Syndrome

Video

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