A patient develops sudden cardiovascular collapse with wide complex bradycardia immediately after injection of local anaesthetic for an infraclavicular brachial plexus block. The MOST appropriate immediate treatment is:

• A Intravenous epinephrine 1 mg bolus followed by adrenaline infusion
• B Intravenous sodium bicarbonate to alkalinise the blood
• C Immediate DC cardioversion
• D Intravenous lipid emulsion 20% at 1.5 mL/kg bolus followed by infusion ✓

Explanation

This presentation is consistent with local anaesthetic systemic toxicity (LAST), and intravenous lipid emulsion (ILE) 20% is the specific antidote. The proposed mechanism is a 'lipid sink' that sequesters the lipophilic local anaesthetic away from cardiac sodium channels, plus direct metabolic support to cardiac mitochondria. The AAGBI guidelines recommend 1.5 mL/kg bolus followed by 0.25 mL/kg/min infusion. Epinephrine, if used, should be in reduced doses (≤1 mcg/kg) in LAST as larger doses worsen the arrhythmia. Sodium bicarbonate may be adjunctive but is not first-line.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.