Acute limb ischaemia from embolism for embolectomy82-year-old woman, 58 kg, for emergency right femoral embolectomy; cold, pale

The patient

The examiner asks

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1. Consider

   What are your concerns?

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   • An 82-year-old with AF and heart failure, for emergency embolectomy of an acutely ischaemic leg. Patient
   • At 82 with heart failure and an ischaemic leg, delirium is likely; I note her baseline cognition.
   • Time-critical: the limb's outcome depends on how fast flow returns. Stem trigger
   • ACC/AHA: emergency surgery, so straight to theatre; her failure and AF shape the anaesthetic. Disease
   • Her potassium is already 5.1, with reperfusion still to come.

2. Prepare

   What anaesthetic will you choose?

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   • No spinal or epidural on therapeutic heparin; the haematoma risk is too high. Disease
   • Femoral exposure can be done under local infiltration, sparing her failing heart. Surgery
   • Surgeon's lidocaine within 4.5 mg/kg plain; propofol sedation 25–75 mcg/kg/min if needed.
   • Bisoprolol continues; arterial line under local for beat-to-beat pressure. Disease
   • Calcium chloride, insulin and glucose drawn up before the clot comes out.

3. Plan

   How do you manage her through reperfusion?

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   • If general anaesthesia is needed: etomidate 0.15–0.2 mg/kg and rocuronium. Airway
   • No suxamethonium: it raises potassium by about 0.5 mmol/L. Disease
   • Surgeon warns me before flow returns; I watch the ECG and send a gas.
   • Reperfusion washes out acid and potassium from the ischaemic leg.
   • Dark urine means myoglobin: fluids and bicarbonate to alkalinise the urine. After surgery
   • A tense calf after reperfusion means compartment syndrome and urgent fasciotomy.
   • Heparin resumes after surgery to stop the clot propagating.

4. Crisis

   As flow returns, T waves become peaked and the QRS broadens; HR falls to 42, BP 84/50. What do you do?

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   • Bradycardia algorithm with a clear cause: hyperkalaemia on reperfusion, slow and hypotensive. (Crisis)
   • Treat the cause first: calcium chloride 500–1000 mg IV over 3 minutes.
   • Insulin 10 units with 50 g glucose IV.
   • Sodium bicarbonate for her acidosis, which also lowers potassium.
   • Still slow: atropine 1 mg every 3–5 minutes, up to 3 mg.
   • No response: adrenaline 2–10 mcg/min or transcutaneous pacing.

5. Crisis

   Minutes later the ECG becomes a broad sine wave and she has no pulse. What do you do?

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   • Adult arrest algorithm: PEA with a sine wave from hyperkalaemia; CPR started now. Crisis
   • Non-shockable rhythm: give adrenaline 1 mg straight away, repeating every 3–5 minutes.
   • Insulin-glucose, with calcium and bicarbonate considered; benefit in arrest is uncertain.
   • Shock at once if it turns into VF.
   • Other causes for her: acidosis, bleeding into the wound, and hypoxia.
   • After return of circulation: ICU, repeated potassium and limb checks. After surgery