Proning

Proning is a treatment for refractory hypoxaemia in T1RF that:

Proning is a cornerstone of ARDS management. ARDS is covered in detail under Acute Respiratory Distress Syndrome.

• Promotes homogenous lung ventilation
  Creates a more uniform distribution of pleural pressure, which:
  • ↓ Cyclical atelectasis and atelectotrauma
  • Improves V/Q mismatch
• ↓ Lung deformation
  Relieves compression of the lungs from the mediastinum and abdominal contents.
• ↑ FRC
• Facilitates secretion drainage
• Reverses hypoxia due to shunt

Indications

Indicated with:

• Appropriate expertise
• Severe hypoxaemia (P/F <150) in lung pathologies that are:
  • Diffuse
  • Acute
  • Reversible
• Dorsal wounds
  • Burns
  • Surgical wounds

Contraindications

Prone position is contraindicated in patients with risk of:

• Turning
  • C-spine injury
  • Unstable T/L spine
  • Unstable pelvis
• Being supine
  • Facial trauma
  • Open chest
  • Open abdomen
  • Pregnancy
  • Intraabdominal hypertension
  • Ventral wounds

Principles

Proning is effective as:

• Lung parenchymal volume is larger posteriorly than anteriorly
• There is greater V/Q mismatch to posterior regions when supine due to:
  • Atelectasis and collapse
  • Dependent oedema
  • ↑ Pulmonary blood flow
• Prone ventilation
  • Recruits collapsed regions
  • ↑ Secretion drainage

Practice

• Consider prone ventilation early and often
  • 16 hours
  • 5 days or until no further response required
• Adjunct to lung protective ventilation and VV ECMO
• Timing of proning and de-proning should occur with experience staff present to manage any complications

Complications

• A
  • Airway loss
  • Sputum plugging
• C
  • Dislodgement of lines and devices
• D
  • Blindness
    • Ocular pressure injury
    • ↓ Retinal perfusion pressure
• E
  • Pressure areas

Key Studies

• PROSEVA (2013)
  • 474 Europeans with ARDS (PF <150mmHg), intubated for <36 hours at inclusion
  • Multicentre (experienced proning units), assessor-blinded, RCT
  • 456 patients gives 90% power for 15% ARR from control mortality of 60%
  • Randomised to proning vs. supine
    • Proning
      16 consecutive hours for 28 days, or until improvement.
    • Standardised ventilation and weaning strategy
  • Significant ↓ mortality (16% vs. 33%, OR 0.42 (0.26-0.66), NNT 6) in proning group
  • Over 2000 patients were not screened

PROSEVA was the definitive trial on proning.

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References

1. Guérin C, Reignier J, Richard JC, et al. Prone Positioning in Severe Acute Respiratory Distress Syndrome. N Engl J Med. 2013;368(23):2159-2168. doi:10.1056/NEJMoa1214103