Prone multilevel spinal fusion: arrest and visual loss61-year-old man, 112 kg (BMI 37), for elective T10–S1 posterior instrumented fusion, prone

The patient

The examiner asks

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1. Consider

   What are your concerns?

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   • A 61-year-old obese smoker with diabetes, for a 7-hour prone multilevel fusion. Patient
   • He fits the ION profile: male, obese, long prone surgery, large expected blood loss. Disease
   • His obesity raises abdominal pressure when prone, adding venous congestion and bleeding. Patient
   • Motor evoked potentials are planned, and that shapes my anaesthetic. Surgery

2. Prepare

   How do you prepare him?

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   • Consent includes a small, unpredictable risk of visual loss. Disease
   • If it will run very long, I discuss staging the operation with the surgeon. Surgery
   • Arterial line, two large cannulas, crossmatched blood available. Disease
   • Tranexamic acid, which reduces bleeding in complex spine surgery. Surgery
   • TIVA, and no relaxant after intubation, so motor evoked potentials can be read.
   • A prone-arrest plan agreed with the surgeon before we turn him. Crisis

3. Plan

   Take me through positioning and maintenance.

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   • Eyes free of pressure and checked about every 15 minutes; head neutral, at or above heart level. Surgery
   • Abdomen hanging free, so his vena cava isn't compressed and epidural veins bleed less.
   • Shoulders abducted under 90 degrees; I pad axillae, iliac crests, genitals and knees.
   • Deliberate hypotension only case by case; I keep him near his baseline. Disease
   • Hb checked regularly; colloid alongside crystalloid if he bleeds heavily.
   • If the evoked potentials change: raise BP to baseline or 20% higher, then check depth and gases. Surgery

4. Crisis

   Four hours in, ETCO2 falls from 38 to 10 mmHg and the arterial trace goes flat; the ECG shows sinus rhythm at 110. What do you do?

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   • Adult arrest algorithm: PEA in a prone patient. (Crisis)
   • Call for help and start compressions prone now; turning him first wastes time.
   • Adrenaline 1 mg IV every 3–5 minutes; 100% oxygen.
   • His likely causes: air embolism through the open bone, or haemorrhage.
   • Surgeon floods the wound with saline; massive transfusion if he's bled.
   • Pack, close and turn him supine once that's feasible.

5. Crisis

   He is extubated, and next morning says he can't see out of his right eye; no pain. What do you do?

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   • Painless visual loss after prone spine surgery: ischaemic optic neuropathy until proven otherwise. Crisis
   • Urgent ophthalmology review today.
   • Optimise his haemoglobin, blood pressure and oxygenation.
   • MRI to rule out an intracranial cause.
   • No steroids, antiplatelets or eye-pressure drugs; they don't help ION.
   • Open disclosure with him and his family, and an incident report. After surgery