Severe ARDS with refractory hypoxaemia — FFICM MCQ

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HardVentilationSevere ARDS with refractory hypoxaemiaFFICM

A 54-year-old man with pneumococcal pneumonia is ventilated on ICU. He is on volume control ventilation, tidal volume 6 ml/kg predicted body weight, FiO2 0.85 and PEEP 14 cmH2O. Plateau pressure is 28 cmH2O, PaO2 is 8.0 kPa and PaCO2 is 6.2 kPa. He is deeply sedated, paralysed and has no contraindication to repositioning. What is the most appropriate ventilation strategy?

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Correct answer: D — Prone ventilation for at least 16 hours

The correct answer is D, prone ventilation for at least 16 hours. This man has severe ARDS from pneumococcal pneumonia, with a PaO2/FiO2 ratio of roughly 9.4 kPa (about 70 mmHg) despite lung protective ventilation, high FiO2 and adequate PEEP, meeting Berlin criteria for severe disease. He has no contraindication and is already deeply sedated and paralysed, the ideal state to commence proning early. Prone positioning improves ventilation perfusion matching, recruits dorsal lung units and reduces ventilator induced lung injury, and trial and Cochrane evidence show a mortality benefit when applied for 16 or more hours per day within 48 hours of onset in severe hypoxaemic respiratory failure. This is a first line adjunct in severe ARDS, not a last resort. Why the other options are wrong: C. Increase tidal volume to 8 ml/kg: this abandons lung protective ventilation and raises plateau and driving pressure, increasing volutrauma and barotrauma without treating the underlying oxygenation failure. B. Reduce PEEP to 5 cmH2O: this would derecruit already compromised alveoli, worsening shunt and hypoxaemia, when the current PEEP is appropriately titrated to his severity. E. Start high-frequency oscillation: trial evidence (OSCAR, OSCILLATE) showed no survival benefit and possible harm in adult ARDS, so it is not a routine strategy. A. Extubate to non-invasive ventilation: this is unsafe with a PaO2/FiO2 this low, since NIV risks delayed reintubation and increased mortality in severe hypoxaemic respiratory failure. Key point: In severe ARDS (PaO2/FiO2 under about 13.3 kPa or 100 mmHg) with no contraindication, early prone positioning for at least 16 hours a day is an evidence based intervention to reduce mortality, not a rescue therapy held back until other measures fail.

Reference: Intensive Care Society (ICS) / Faculty of Intensive Care Medicine (FICM), 'Prone position in adult critical care', https://ics.ac.uk/resource/prone-position-in-adult-critical-care.html