When is proning (positioning a patient in a prone position) necessary for a patient with respiratory distress?

When to Prone a Patient in Respiratory Distress

Prone positioning is strongly recommended in invasively ventilated patients with ARDS and impaired arterial oxygenation (PaO2/FiO2 < 150 mmHg), and should be implemented as soon as indicated for at least 12-16 hours per day. 1

Indications for Prone Positioning in Mechanically Ventilated Patients

• Severe ARDS: Prone positioning is recommended for patients with severe ARDS with PaO2/FiO2 < 150 mmHg 1, 2
• Early implementation: Prone positioning should be considered at an early stage (within 48 hours of starting mechanical ventilation) and implemented as soon as indicated 1, 2
• Duration: Prone positioning should be maintained for at least 12 hours, preferably 16 hours per day 1, 2
• Complete prone positioning: Complete (180°) rather than incomplete prone positioning is recommended as it has a stronger effect on oxygenation 1
• Patients with veno-venous ECMO: Prone positioning is suggested in ARDS patients receiving veno-venous ECMO therapy 1

Indications for Awake Proning in Non-Intubated Patients

• COVID-19 patients: Awake proning is recommended in non-invasively ventilated patients with COVID-19 and acute hypoxic respiratory failure 1, 3
• Non-COVID respiratory failure: Current guidelines cannot make a definitive recommendation for or against awake proning in non-invasively ventilated patients without COVID-19 1

Physiological Benefits of Prone Positioning

• Prone positioning improves oxygenation through:
  • More even distribution of gravitational gradient in pleural pressure 2, 4
  • Better distribution of ventilation to dorsal lung areas 2, 4
  • Improved ventilation-perfusion matching 2, 4
  • Reduced alveolar shunt 2
  • More homogeneous distribution of tidal volume, reducing ventilator-induced lung injury 2, 4

Pre-Prone Positioning Considerations

• Hemodynamic stabilization: Patients should be hemodynamically stabilized and volume status optimized prior to prone positioning 1
• Ventilation strategy: Apply lung-protective ventilation principles including limitation of tidal volumes, prevention of derecruitment, and integration of spontaneous breathing components 1, 2
• Pressure ulcer prevention: Careful examination of areas at risk for pressure ulcers is recommended 1

When to Terminate Prone Positioning

• Sustained improvement: Consider terminating prone positioning if improvement in supine oxygenation persists (PaO2/FiO2 ≥ 150 with PEEP ≤ 10 cm H2O and FiO2 ≤ 0.6) 4 hours after repositioning to supine 1, 2
• Unsuccessful attempts: Consider discontinuing prone positioning therapy if at least two positioning attempts have been unsuccessful in improving oxygenation 1

Special Considerations and Relative Contraindications

• Abdominal conditions: Consider prone positioning in patients following abdominal surgery, with abdominal pathologies, or abdominal obesity after individual consideration of benefits versus risks (increased intra-abdominal pressure) 1
• Increased intracranial pressure: Patients at risk of increased ICP should be monitored continuously during prone positioning, with the head positioned centrally and lateral rotation avoided 1
• Relative contraindications requiring interdisciplinary risk-benefit assessment:
  • Open abdomen 1
  • Spinal instability 1
  • Increased intracranial pressure 1
  • Cardiac arrhythmias with hemodynamic consequences 1
  • Shock 1

Evidence for Mortality Benefit

• The PROSEVA trial demonstrated a significant reduction in 28-day mortality from 32.8% in the supine group to 16.0% in the prone group in patients with severe ARDS 5
• Meta-analyses show prone positioning reduced mortality in trials with prone duration greater than 12 hours per day 6
• Mortality benefit is most pronounced in patients with severe ARDS (PaO2/FiO2 < 150 mmHg) 2, 6

Potential Complications

• Prone positioning is associated with risks including:
  • Endotracheal tube obstruction 6
  • Pressure sores 1, 6
  • Potential increases in intra-abdominal pressure 2

Alternative Positioning for Non-Intubated Patients with Mild Respiratory Distress

• The tripod position may be beneficial for conscious patients with respiratory distress who can maintain the position independently 7
• This position allows patients to use accessory muscles, particularly the pectoralis muscles, to stabilize the upper chest and shoulder girdle, enabling more efficient diaphragmatic function 7