What are the recommended ventilatory settings for patients with Acute Respiratory Distress Syndrome (ARDS)?

ARDS Ventilatory Settings

For all patients with ARDS, use a tidal volume of 6 ml/kg predicted body weight (not actual weight) with plateau pressure maintained below 30 cmH2O, as this lung-protective strategy has been proven to reduce mortality. 1, 2

Core Ventilator Parameters

Tidal Volume and Pressure Limits

• Set tidal volume at 6 ml/kg predicted body weight for all ARDS patients, calculated using height and sex rather than actual body weight to prevent excessive volumes in obese patients 1, 3
• Maintain plateau pressure strictly <30 cmH2O to minimize ventilator-induced lung injury 1, 2, 4
• Evidence suggests there is no safe upper limit for plateau pressures between 30-35 cmH2O, so staying well below 30 cmH2O is critical 5
• Monitor driving pressure (plateau pressure minus PEEP) as it may be a superior predictor of outcomes compared to tidal volume or plateau pressure alone 1

PEEP Strategy (Severity-Based)

• For mild ARDS: Use lower PEEP strategy (<10 cmH2O) to optimize oxygenation while minimizing hemodynamic compromise 1
• For moderate to severe ARDS: Use higher PEEP strategy (>10 cmH2O, typically 10-15 cmH2O) to improve oxygenation and prevent atelectasis 1, 2, 4
• Titrate PEEP upward while monitoring for hemodynamic instability and worsening compliance 1

Respiratory Rate and Oxygenation

• Set respiratory rate between 20-35 breaths per minute to maintain adequate ventilation 3
• Target oxygen saturation of 88-92% to avoid oxygen toxicity while maintaining adequate tissue oxygenation 2
• Titrate FiO2 to achieve SpO2 of 88-95% rather than pursuing normoxemia 3

Severity-Specific Adjunctive Strategies

For Severe ARDS (PaO2/FiO2 <150 mmHg)

• Implement prone positioning for >12 hours per day as this significantly improves oxygenation and reduces mortality 1, 2, 4
• Consider neuromuscular blocking agents (cisatracurium) for ≤48 hours in patients with PaO2/FiO2 <150 mmHg to improve ventilator synchrony and reduce work of breathing 1, 4
• Consider recruitment maneuvers in moderate to severe ARDS to open collapsed alveoli 2

For Refractory Severe ARDS

• Consider extracorporeal membrane oxygenation (ECMO) for very severe ARDS despite optimized lung-protective ventilation 2, 4

Fluid Management

• Use a conservative fluid strategy for established ARDS without evidence of tissue hypoperfusion to avoid worsening lung edema and gas exchange 1, 2

Critical Pitfalls to Avoid

• Never use high tidal volumes (>8 ml/kg PBW) as they dramatically increase ventilator-induced lung injury risk 1, 3
• Do not use high-frequency oscillatory ventilation in ARDS as it does not improve outcomes 1, 2, 4
• Avoid beta-2 agonists for ARDS treatment unless bronchospasm is present 1
• Do not use actual body weight for tidal volume calculations in obese patients—always use predicted body weight 1
• Avoid excessive oxygen therapy; permissive hypoxemia (SpO2 88-92%) is safer than hyperoxia 2, 3

Supportive Care Measures

• Elevate head of bed 30-45 degrees to reduce ventilator-associated pneumonia risk 1
• Implement a weaning protocol when patients become arousable, hemodynamically stable, and have low ventilatory requirements 1
• Early application of lung-protective ventilation strategy improves outcomes compared to delayed implementation 6