What are the diagnostic criteria and treatment options for Acute Respiratory Distress Syndrome (ARDS)?

Diagnosis and Management of Acute Respiratory Distress Syndrome (ARDS)

The diagnosis of ARDS is based on the Berlin Definition criteria, which include the development of bilateral opacities on chest radiography indicative of pulmonary edema within 1 week of a known clinical insult, combined with impaired oxygenation (PaO2/FiO2 ratio ≤300 mmHg) despite at least 5 cmH2O of PEEP, where cardiac failure does not fully explain the clinical presentation. 1, 2

Diagnostic Criteria for ARDS

• ARDS is defined by the following Berlin criteria:

  • Onset within 1 week of a known clinical insult or new/worsening respiratory symptoms 2
  • Bilateral opacities on chest radiography not fully explained by effusions, lung collapse, or nodules 2
  • Respiratory failure not fully explained by cardiac failure or fluid overload 2
  • Impaired oxygenation with minimum PEEP of 5 cmH2O 2

• ARDS severity classification based on PaO2/FiO2 ratio:

  • Mild: 200-300 mmHg 3, 2
  • Moderate: 100-200 mmHg 3, 2
  • Severe: ≤100 mmHg 3, 2

Management of ARDS

First-Line Interventions (For All ARDS Patients)

• Implement lung-protective ventilation strategies:

  • Use low tidal volumes (4-8 mL/kg predicted body weight) 1, 3
  • Limit plateau pressures to <30 cmH2O 1, 3
  • Apply appropriate PEEP to prevent alveolar collapse 1

• Use higher PEEP without lung recruitment maneuvers for moderate to severe ARDS 1, 3

  • The American Thoracic Society suggests higher PEEP without lung recruitment maneuvers (conditional recommendation, low to moderate certainty) 1
  • Avoid prolonged lung recruitment maneuvers in moderate to severe ARDS (strong recommendation) 1

• Consider corticosteroids for patients with ARDS 1, 3

  • The American Thoracic Society suggests corticosteroid use (conditional recommendation, moderate certainty of evidence) 1

Additional Interventions Based on ARDS Severity

• For severe ARDS (PaO2/FiO2 ≤100 mmHg):

  • Implement prone positioning for >12 hours per day 3, 1
  • Consider neuromuscular blocking agents in early severe ARDS 1, 3
    • The American Thoracic Society suggests using neuromuscular blockers (conditional recommendation, low certainty of evidence) 1
  • Consider venovenous extracorporeal membrane oxygenation (VV-ECMO) for refractory cases 1, 3
    • The American Thoracic Society suggests VV-ECMO for selected patients with severe ARDS (conditional recommendation, low certainty of evidence) 1

• For moderate ARDS (100 < PaO2/FiO2 ≤ 200 mmHg):

  • Apply higher PEEP strategies 1, 3
  • Consider prone positioning if oxygenation worsens (PaO2/FiO2 <150 mmHg) 3

Supportive Care Measures

• Implement conservative fluid management to reduce pulmonary edema in patients without tissue hypoperfusion 1
• Provide prophylaxis for stress ulcers and venous thromboembolism 4
• Provide appropriate nutritional support (enteral nutrition is preferred) 1
• Treat the underlying cause of ARDS (e.g., antibiotics for pneumonia, source control for sepsis) 1, 4

Common Pitfalls and Considerations

• Underdiagnosis of ARDS - clinician interpretation of chest radiographs and origin of edema may be unreliable, leading to missed diagnoses 5

• Delayed implementation of evidence-based strategies - particularly prone positioning in severe ARDS, which should be initiated early 3

• Excessive tidal volumes and inspiratory pressures - can worsen ventilator-induced lung injury 3

• Inappropriate patient selection for advanced therapies:

  • VV-ECMO should only be performed at experienced centers and after other evidence-based strategies have been tried 1, 3
  • Consider factors such as duration of mechanical ventilation, severity of hypoxemia, and presence of other organ failures 3

• Failure to recognize ARDS heterogeneity - ARDS presents with significant variation on aetiological, physiological, and biological levels, which may impact treatment response 1

Long-Term Considerations

• Survivors of ARDS are at risk for decreased functional capacity, psychological sequelae, and reduced quality of life 4, 6
• As the patient's condition improves, implement daily spontaneous breathing trials to assess readiness for ventilator weaning 3
• Consider tracheostomy when prolonged mechanical ventilation is anticipated 3