Unrepaired VSD for adenotonsillectomy4-year-old boy, 13 kg, for elective adenotonsillectomy

The patient

The examiner asks

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1. Consider

   What are the issues?

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   • A 4-year-old with an unrepaired moderate VSD and apnoeas, for adenotonsillectomy. Patient
   • As a young child his output depends on heart rate, so bradycardia is poorly tolerated.
   • His shunt is left-to-right at 1.8:1, so I limit extra pulmonary flow. Disease
   • His poor growth makes me ask about sweating, fast breathing, poor feeding and chest infections.
   • Witnessed apnoeas mean obstructive sleep apnoea, with obstruction and desaturation after surgery. Surgery

2. Prepare

   How will you prepare?

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   • Recent echo for his shunt size, direction and pulmonary pressure. Disease
   • No endocarditis prophylaxis: his unrepaired acyanotic VSD isn't a highest-risk lesion.
   • Every IV line and syringe de-aired before it reaches him.
   • Oral midazolam 0.2–0.5 mg/kg so he arrives settled. Patient
   • Overnight stay with oximetry until he holds his saturation on air while asleep. After surgery

3. Plan

   How do you conduct the anaesthetic?

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   • Gas induction with sevoflurane, then IV access; his shunt barely changes the speed. Disease
   • No high oxygen or hyperventilation, which lower PVR and increase his shunt.
   • Avoid sharp rises in systemic resistance from light anaesthesia or pain.
   • Suction blood from his pharynx before extubation; blood triggers laryngospasm. Airway
   • Dexamethasone 0.15 mg/kg, ondansetron 50–100 mcg/kg, paracetamol 15 mg/kg IV. After surgery
   • OSA makes him opioid-sensitive, so I halve his opioid doses. Disease

4. Crisis

   At extubation he develops laryngospasm; SpO2 falls to 70% and HR to 58. What do you do?

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   • Laryngospasm with hypoxic bradycardia, HR 58: PALS bradycardia, and airway first. (Crisis)
   • Call for help; tight mask, 100% oxygen, CPAP 15–20 cmH2O, firm jaw thrust.
   • SpO2 70% already: suxamethonium 1–2 mg/kg IV, or 4–5 mg/kg IM.
   • His slow rate is hypoxic, so oxygen is the treatment; atropine 0.02 mg/kg goes with the suxamethonium.
   • Hypoxia also raises his PVR and can reverse flow across his VSD.
   • HR still under 60 and poorly perfused despite good ventilation: start CPR.
   • Bradycardia persisting once oxygenated: adrenaline 0.01 mg/kg IV.