Question 10

a)    Discuss the use of prone positioning in critically ill patients with respiratory failure. Include in your answer the rationale, advantages and disadvantages of prone positioning in the critically ill in both awake and intubated patients.    (80% marks)

b)    Outline the important findings, strengths and weaknesses of the PROSEVA trial. (20% marks)

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College answer

Not available.


The average reader doing these papers to prepare for the CICM Second Part Exam will probably want to see a model answer representing something the average trainee could write in under 10 minutes, rather than an elaborate explanation of how and why prone ventilation works. That elaborate explanation is available on the prone ventilation page, and in the physiology-oriented CICM First Part Exam page dealing with the effects of positioning on the mechanics of breathing

  • Rationale
  • Advantages
    • Decreased oxygen requirements, therefore less oxygen toxicity
    • Low cost and low risk (especially in the awake patient)
    • Supported by more evidence than alternative rescue therapies (eg. inhaled pulmonary vasodilators)
    • Widely available, in contrast to other rescue strategies (eg. ECMO)
  • Disadvantages
    • Contraindicated in spinal/pelvic instability, open abdomen, ventral burns or wounds, abdominal compartment syndrome
    • Needs to be done early in the course
    • Oxygenation benefits are often reversed by de-proning
    • For awake patients:
      • Uncomfortable
      • Impedes communication
      • Often cannot be tolerated for periods which would have a therapeutic effect (eg. 12-16 hours)
    • For intubated patients:
      • Difficulty of positioning and increased nursing workload
      • Decreased airway and central line site safety
      • Pressure areas, facial oedema
      • Raised intraabdominal and intracranial pressure
      • Haemodynamic instability is exacerbated
  • PROSEVA trial:
    • ​​​​​​​Important findings:
      • Significant improvement in 28-day and 90-day mortality: 16% in prone vs. 32.8% in supine group
      • No increase in adverse events in prone group
    • Strengths:
      • Standardised ventilation and weaning strategy
      • Appropriate power calculation
      • Intention to treat analysis
    • Weaknesses:
      • 2015 patients not screened for inclusion, raising suspicion of selection bias
      • Some differences in baseline characteristics (eg. SOFA score)
      • All centres were very experienced in prone ventilation (reduces generalizability)


Sodhi, Kanwalpreet, and Gunjan Chanchalani. "Awake proning: current evidence and practical considerations." Indian journal of critical care medicine: peer-reviewed, official publication of Indian Society of Critical Care Medicine 24.12 (2020): 1236.

Messerole, Erica, et al. "The pragmatics of prone positioning." American journal of respiratory and critical care medicine 165.10 (2002): 1359-1363.

Koeckerling, David, et al. "Awake prone positioning in COVID-19." Thorax 75.10 (2020): 833-834.

Guerin, Claude, et al. "Effects of systematic prone positioning in hypoxemic acute respiratory failure: a randomized controlled trial." Jama 292.19 (2004): 2379-2387.