Do ventilator settings need to be adjusted after prone positioning?

Ventilator Settings After Prone Positioning

When patients are placed in prone position, ventilator settings should maintain the generally recommended principles of optimized ventilation, including limitation of tidal volumes, prevention of derecruitment, and integration of spontaneous breathing components, rather than requiring routine adjustment solely due to position change. 1

Ventilation Strategy During Prone Positioning

Key Principles to Maintain

• Tidal volume limitation: Continue using lung-protective ventilation strategies with tidal volumes ≤8 ml/kg predicted body weight, with evidence suggesting that lower tidal volumes provide even greater benefit 1
• PEEP management: Maintain appropriate PEEP to prevent derecruitment
  • Prone positioning and PEEP have an additive effect on improving oxygenation 1
  • No specific evidence mandates routine PEEP adjustment after transitioning to prone position
• Spontaneous breathing: Can be maintained during prone positioning despite common practice of deep sedation 1

Monitoring After Position Change

• Assess oxygenation parameters within 1-2 hours after prone positioning
• Monitor for improvement in PaO₂/FiO₂ ratio, which typically increases significantly with proning 2
• Evaluate for potential hemodynamic changes, though prone positioning is generally hemodynamically well-tolerated 1

Duration and Efficacy Assessment

• Minimum duration: Maintain prone position for at least 12 hours, preferably 16 hours daily 1, 3
• Continuation criteria: Continue prone positioning until:
  • Improvement in supine oxygenation persists (4 hours after repositioning to supine: PaO₂/FiO₂ ≥150 with PEEP ≤10 cmH₂O and FiO₂ ≤0.6) 1
  • Consider discontinuing after two unsuccessful attempts if no improvement in oxygenation is observed 1

Special Considerations

Synergistic Effects

• The combination of prone positioning with appropriate ventilator settings has shown significant mortality benefits in severe ARDS 3, 2
• In patients with severe ARDS (PaO₂/FiO₂ <150 mmHg), early application of prolonged prone positioning significantly decreases 28-day and 90-day mortality 3

Airway Pressure Release Ventilation (APRV)

• APRV with unsupported spontaneous breathing may enhance improvement in oxygenation in response to prone positioning after 24 hours compared to conventional ventilation modes 4

Common Pitfalls to Avoid

• Inadequate duration: Prone sessions shorter than recommended 12-16 hours may limit effectiveness 1
• Delayed implementation: Early application of prone positioning (within 48 hours of mechanical ventilation initiation) shows better outcomes 1
• Improper patient selection: Most beneficial in severe ARDS with PaO₂/FiO₂ <150 mmHg 1, 3
• Failure to maintain lung-protective ventilation: The mortality benefit from prone positioning requires limitation of tidal volume 1
• Premature termination: Continue prone positioning until clear improvement criteria are met rather than using arbitrary timeframes 1

By maintaining appropriate ventilator settings and following these guidelines, prone positioning can significantly improve outcomes in patients with severe ARDS.