What are the key components of managing acute respiratory distress syndrome (ARDS)?

Diagnosis and Management of Acute Respiratory Distress Syndrome (ARDS)

The management of ARDS should include lung-protective ventilation strategies, systemic corticosteroids, prone positioning for severe cases, and consideration of neuromuscular blockade and venovenous extracorporeal membrane oxygenation (VV-ECMO) in selected patients with severe ARDS. 1, 2

Diagnosis of ARDS

ARDS is diagnosed based on the following criteria:

• Onset within one week of a known insult or new/worsening respiratory symptoms
• Bilateral pulmonary opacities on chest imaging
• Respiratory failure not explained by cardiac failure or fluid overload
• Profound hypoxemia classified by PaO₂/FiO₂ ratio:
  • Mild: 201-300 mmHg
  • Moderate: 101-200 mmHg
  • Severe: ≤100 mmHg 2, 3

Core Management Strategies

1. Mechanical Ventilation

Lung-protective ventilation is the cornerstone of ARDS management:

• Tidal volume: 4-8 mL/kg predicted body weight 1
• Plateau pressure: ≤30 cmH₂O 2
• Driving pressure: Ideally <15 cmH₂O 2
• PEEP strategy:
  • Higher PEEP without lung recruitment maneuvers for moderate to severe ARDS
  • Lower PEEP (5-10 cmH₂O) for mild ARDS 1, 2
• Target oxygenation: PaO₂ 70-90 mmHg 2

CAUTION: Avoid prolonged lung recruitment maneuvers in moderate to severe ARDS as they are associated with increased mortality 1

2. Pharmacological Interventions

• Corticosteroids: Suggested for all ARDS patients to reduce inflammatory response, decrease pulmonary edema, and improve survival 1, 2
• Neuromuscular blocking agents: Suggested for early severe ARDS (first 48 hours) to prevent patient-ventilator dyssynchrony and excessive transpulmonary pressure 1, 2

3. Positioning Therapy

• Prone positioning: Recommended for severe ARDS (PaO₂/FiO₂ <150 mmHg)
  • Should be applied for 16-20 hours per day
  • Reduces mortality in severe ARDS 2

4. Advanced Therapies

• VV-ECMO: Suggested for selected patients with severe ARDS who fail conventional therapy
  • Improves gas exchange and modestly improves survival by allowing for lung rest 1, 4

Severity-Based Management Algorithm

Mild ARDS (PaO₂/FiO₂ 201-300 mmHg):

1. Lung-protective ventilation (4-8 mL/kg PBW)
2. Lower PEEP (5-10 cmH₂O)
3. Consider corticosteroids
4. Target PaO₂ 70-90 mmHg

Moderate ARDS (PaO₂/FiO₂ 101-200 mmHg):

1. Lung-protective ventilation (4-8 mL/kg PBW)
2. Higher titrated PEEP
3. Corticosteroids
4. Consider prone positioning
5. Target PaO₂ 70-90 mmHg

Severe ARDS (PaO₂/FiO₂ ≤100 mmHg):

1. Lung-protective ventilation (4-8 mL/kg PBW)
2. Higher titrated PEEP
3. Corticosteroids
4. Prone positioning for 16-20 hours/day
5. Consider neuromuscular blockade in first 48 hours
6. Consider VV-ECMO if refractory hypoxemia persists
7. Target PaO₂ 70-90 mmHg 1, 2, 4

Hemodynamic Management

• Fluid management: Conservative approach to avoid worsening pulmonary edema
• Vasopressors: Initiate norepinephrine to maintain MAP ≥65 mmHg in patients with hypotension
• Monitor for right ventricular failure: Can limit efficacy of fluid administration 2, 5

Supportive Care

• DVT prophylaxis
• Stress ulcer prophylaxis
• Nutritional support
• Regular assessment of sedation requirements 2

Weaning from Mechanical Ventilation

• Daily assessment for weaning readiness
• Use spontaneous breathing trials in patients ready for weaning
• Follow structured weaning protocol to minimize risk of failure 2

Complications to Monitor

• Ventilator-associated pneumonia
• Barotrauma, volutrauma, and atelectrauma
• Acute cor pulmonale (occurs in 20-25% of ARDS cases)
• Physical debility and neurocognitive deficits 2, 4, 5

IMPORTANT: Even with optimal management, severe ARDS carries a high mortality rate (46-60%). Early recognition and implementation of evidence-based strategies are crucial to improve outcomes 3