Duchenne muscular dystrophy for scoliosis surgery15-year-old boy, 38 kg, for elective posterior spinal fusion with motor evoked potential monitoring

The patient

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1. Consider

   What are the key issues?

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   • A 15-year-old with Duchenne, severe scoliosis and cardiomyopathy, for long spinal fusion with neuromonitoring. Patient
   • As a child: blood volume about 70 mL/kg sets his transfusion triggers; his parents and he consent together.
   • Cobb 62° is past the 50° where thoracic curves need surgery. Surgery
   • Up to 70% of Duchenne boys have heart disease; his EF of 40% confirms it. Disease
   • Suxamethonium is out completely: rhabdomyolysis, hyperkalaemia and arrest. Stem trigger

2. Prepare

   How do you assess him?

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   • FVC 38%: under 40% predicts he'll need ventilation after surgery. Disease
   • Weak cough and pharyngeal weakness raise his aspiration risk at induction and emergence. Airway
   • ECG and echo: up to half have conduction defects, which can arrest during spine surgery. Disease
   • Years of prednisolone 10 mg suppress his adrenals; stress-dose hydrocortisone at induction.
   • ICU bed booked; his breathing can fail up to 36 hours later. After surgery

3. Plan

   What is your anaesthetic plan?

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   • Trigger-free TIVA, propofol and remifentanil; vaporisers removed and dantrolene in theatre. Stem trigger
   • Rocuronium for intubation only; no more relaxant, so motor evoked potentials stay readable. Surgery
   • Arterial and central lines plus large cannulae; cell salvage running.
   • Tranexamic acid: 10 mg/kg load and a 10 mg/kg/h infusion.
   • Prone, padded, and actively warmed; long exposed spine cases lose heat.
   • Planned ventilation in ICU after surgery, given his FVC and cardiomyopathy. After surgery

4. Crisis

   During instrumentation he loses 1.5 L in 20 minutes. BP 68/40, HR 140, Hb 6.8 g/dL. What do you do?

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   • Massive haemorrhage: over half his blood volume lost fast, in a boy with a weak heart. (Crisis)
   • Declare it, activate the massive transfusion protocol, and ask the surgeon to pack.
   • Plasma to red cells at 1:1 to 1:2, with salvaged blood returned.
   • Tranexamic acid running; all fluid and blood warmed.
   • Calcium checked often, as citrate in transfused blood lowers it.
   • Potassium checked with each gas; transfusion can push it up.

5. Crisis

   After 6 units, the ECG shows peaked T waves, then a broad-complex rhythm at 50. BP 55/30, K+ 7.6. What do you do?

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   • Hyperkalaemia from transfusion and perhaps rhabdomyolysis; Duchenne muscle releases potassium. Crisis
   • Calcium chloride 20 mg/kg IV slowly to protect his heart.
   • Insulin 0.1 units/kg, maximum 10 units, with glucose 10% 5 mL/kg.
   • Sodium bicarbonate 1–4 mEq/kg to drive potassium into cells.
   • If his pulse goes: turn supine, CPR, adrenaline 0.01 mg/kg every 3–5 minutes.
   • CK and urine for myoglobin, then ICU. After surgery