Acute chest syndrome

Acute chest syndrome (ACS) is a potentially fatal complication of sickle cell anemia caused by vaso-occlusion of the pulmonary vasculature. Symptoms may include chest pain, shortness of breath, and fever. Diagnosis is based on clinical symptoms and chest imaging findings of a new pulmonary infiltrate. Management consists of antibiotics, supportive care with IV fluids and oxygen, and possibly a blood transfusion.

See also “Sickle cell disease.”

• Vaso-occlusion of the pulmonary vasculature
• Triggers include infection, asthma, surgery/general anesthesia
• Common cause of death in patients with sickle cell disease ^[1]

• Chest pain
• Fever
• Respiratory distress, cough, shortness of breath, wheezing
• Signs of vaso-occlusive crisis (e.g., pain in arms or legs)
• Rib or sternal pain
• See also “Complications” below.

ACS is a clinical diagnosis supported by characteristic clinical features and the presence of new pulmonary infiltrate on imaging. ^[1]

Diagnostic criteria for acute chest syndrome ^[2][3][4]

• Clinical findings of one or more of the following:
  • Chest pain
  • Cough
  • Temperature > 38.5°C
  • Tachypnea
  • Hypoxemia
  • Signs of increased work of breathing
  • Wheezing
  • Crackles
• PLUS a new pulmonary infiltrate on CXR that involves at least one lung segment and is not due to atelectasis ^[4]

Laboratory studies

• Routine
  • CBC: anemia, leukocytosis, thrombocytopenia ^[5]
  • Type and screen and crossmatch
  • BMP and LFTs: signs of multiorgan failure may be present
    • Elevated creatinine
    • Elevated AST and ALT
  • Sputum and blood cultures ^[6]
  • Arterial blood gas: Gold standard for determining partial pressure of oxygen and carbon dioxide ^[7]
• Additional
  • Consider PCR for viral panel and serologies for respiratory pathogens (e.g., Mycoplasma, Legionella): See pneumonia diagnostics.
  • Consider troponin to assess for myocardial injury.

Imaging

• Chest x-ray
  • Indication: all patients suspected of having ACS
  • Supportive findings:
    • New pulmonary infiltrate
    • Segmental, lobar, or multilobular consolidation with or without the presence of pleural effusion
    • If CXR is normal, it should be repeated in 24–48 hours if there is ongoing clinical suspicion for ACS. ^[6]
• CT pulmonary angiography: if there is a concern for pulmonary embolism (PE) ^[8]

Other

• ECG: Assess for acute myocardial injury (see diagnosis of myocardial infarction).
• Bronchoscopy with bronchoalveolar lavage: performed in refractory cases and/or in atypical presentations for assessment of viral or bacterial causes

General principles ^[1][4][9]

• All patients
  • Supportive care
  • Antibiotics
  • Evaluation for blood transfusion
  • Hospital admission with close monitoring and hematology consult
• Critically ill or rapidly progressing patients
  • Respiratory and hemodynamic support
  • Evaluation for urgent exchange transfusion
  • Admission to the ICU
• Patients with recurrent ACS
  • Allogenic stem cell transplantation may be indicated.
  • See “Long-term management of sickle cell disease”. ^[10]

Supportive care

• Respiratory support
  • Supplemental oxygen: target SpO₂ > 95%
  • Identify patients at risk of progression to respiratory failure. ^[1]
    • PaO₂ ≤ 60 mm Hg
    • Opioid-induced respiratory depression
    • Features of impending severe ACS (see “Monitoring”)
  • Initiate NIPPV or invasive mechanical ventilation as needed (see mechanical ventilation and management of ARDS). ^[1]
• Additional supportive care
  • Pain management: opioids administered as scheduled doses or continuous infusion via patient-controlled analgesia
  • IV fluids: Avoid overhydration, which can lead to pulmonary edema. ^[7]
    • For patients with hypovolemia: cautious use of normal saline bolus ^[11]
    • The choice of fluids depends on hydration status.
      • Isotonic fluids are recommended for urgent volume correction.
      • Hypotonic fluids are recommended otherwise, i.e., 5% dextrose in either water, 0.45% normal saline, or 0.22% normal saline.
    • Recommended rate: no greater than 1.5 times the maintenance fluid requirement
  • Bronchodilators (e.g., albuterol ): especially in patients with a history of asthma or evidence of acute bronchospasm
  • Incentive spirometry to prevent atelectasis
  • VTE prophylaxis ^[1]
  • Treatment of associated complications: See “Complications.”

Avoid overhydration in patients with acute chest syndrome because of the risk of pulmonary edema.

Antibiotic therapy ^[7]

• Obtain blood cultures (two sets) and sputum cultures before starting antibiotics.
• Start empiric antibiotics (see empiric antibiotic therapy for community-acquired pneumonia).
  • Suggested regimen
    • A third-generation cephalosporin (e.g., ceftriaxone ) ^[12][13]
    • PLUS a macrolide (e.g., azithromycin ) ^[4]

Blood transfusion

• Simple blood transfusion ^[4]
  • pRBCs indicated if hemoglobin concentration is > 1.0 g/dL below baseline
  • May not be indicated if the patient’s baseline hemoglobin is ≥ 9 g/dL
  • For HbSC or HbS/β-thalassemia, consult hematology.
• Urgent exchange transfusion ^[4]
  • Indications
    • Oxygen saturation < 90% even with supplemental oxygen
    • Worsening respiratory distress
    • Worsening pulmonary infiltrates
    • Hemoglobin concentration continuing to decline after a simple transfusion
  • Consult an apheresis specialist, if applicable.
  • Consider central venous access. ^[14]

Monitoring and disposition

• Monitoring
  • Continuous or frequent (e.g., every 4 hours) pulse oximetry monitoring
  • Consider continuous cardiac monitoring.
  • Consider frequent clinical assessments of patients with features of impending severe ACS. ^[4]
    • Multilobe disease on chest imaging
    • Pleural effusion
    • Respiratory distress
    • Persistent oxygen saturation < 95% despite supplemental oxygenation
    • Neurological features: seizure, stroke, altered mental status
    • Low platelets (< 200,000/mm³) ^[3]
    • History of cardiac disease ^[3]
  • Monitor for progression to multisystem organ failure.
  • Monitor closely for anemia and bronchospasm.
• Disposition
  • Admit all patients to the hospital. ^[4]
  • Admit/transfer to the ICU if the patient is at risk of progression to respiratory failure, is intubated, and/or requires an exchange transfusion.

• Acute ^[1][3][7]
  • Neurological: altered mental status, seizure, stroke, intracranial hemorrhage ^[1][3]
  • Pulmonary: PE, pulmonary hemorrhage, cor pulmonale
  • Splenic sequestration causing hypovolemic shock
  • Multisystem organ failure
• Chronic ^[1][3][7]
  • Chronic sickle lung disease
  • Pulmonary fibrosis
  • Premature mortality

We list the most important complications. The selection is not exhaustive.

• Pain management
• IV fluids: avoid overhydration
• Blood cultures (2 sets) and sputum cultures
• Start empiric antibiotics (see empiric antibiotic therapy for community-acquired pneumonia).
• Supplemental oxygen
• Rule out alternative causes (e.g., myocardial infarction, PE).
• Hematology consultation
• Evaluate the need for transfusion and obtain type and screen.
• Bronchodilators in patients with a history of asthma or evidence of acute bronchospasm ^[1]
• Incentive spirometry
• Hospital admission
• Transfer to ICU if the patient is at risk of progression to respiratory failure, intubated, and/or requires an exchange transfusion.