Desaturation in the prone position52-year-old man, 124 kg, for elective L4–S1 posterior fusion, prone on a spinal frame

The patient

The examiner asks

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1. Consider

   What concerns you before he turns prone?

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   • A 52-year-old, 124 kg, with severe OSA on CPAP, prone for an elective lumbar fusion. Patient
   • Prone, his airway is out of my reach; if the tube comes out, I can't simply reintubate. Airway
   • His tube is taped carefully and disconnected during the turn, so the move doesn't pull it out.
   • A long prone case, so I confirm and note a cuff leak both before and after.
   • His OSA means awake extubation, full reversal, and recovery on his side or sitting up. Disease

2. Crisis

   Two hours in, the surgeon moves the head ring. SpO2 falls to 84% and the capnograph trace goes flat. What do you do?

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   • Flat trace: tube out, disconnected, or kinked or blocked until proven otherwise. Crisis
   • 100% oxygen, bag by hand, summon help; the surgeon pauses.
   • I trace the circuit from oxygen supply to tube, check the mark at his lips, and pass a suction catheter.
   • Bag empty, no trace: he's extubated, so a second-generation supraglottic airway goes in while prone. Airway
   • Meanwhile the wound is packed and covered, and the trolley comes alongside for turning. Crisis
   • If the supraglottic airway fails, we turn him supine and I intubate with a videolaryngoscope. Airway
   • No more than three attempts, each one changed, then a fourth by the most experienced person.

3. Crisis

   He is reintubated supine and turned prone again. Now peak pressure is 42 cmH2O, there is wheeze, and the capnograph upslopes. SpO2 91%. What now?

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   • Before calling it bronchospasm, I pass a suction catheter and listen to both sides. (Crisis)
   • Tube clear and in the right place: bronchospasm, so I deepen anaesthesia with propofol or volatile.
   • Salbutamol via the tube: 4–8 puffs first, 2 more each 10 minutes.
   • Ipratropium as the second inhaler: 6 puffs, then 2 each 10 minutes.
   • Still severe: adrenaline 1 mcg/kg IV bolus.
   • Magnesium 2 g IV over 20 minutes as a single dose if it persists.
   • Any rash or hypotension and I treat it as anaphylaxis instead.

4. Plan

   Surgery finishes. How do you manage his recovery?

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   • Extubated only when fully awake, with full reversal confirmed, because of his OSA. (After surgery)
   • He recovers semi-upright or on his side, not flat on his back.
   • His own CPAP machine goes on in recovery and stays on for the ward.
   • On the ward his saturation is watched continuously while he remains at risk.
   • Opioid-sparing analgesia; small sedative doses can stop his breathing.
   • We debrief the head-ring move and how his tube was secured.