A patient receiving a supraclavicular brachial plexus block for forearm surgery develops sudden hypotension, bradycardia, and reports ringing in the tinnitus, perioral tingling, and metallic taste 2 minutes after injection of 30 mL of 0.5% bupivacaine. What is the correct initial treatment?
- A Administer epinephrine 1 mg IV for anaphylaxis
- B Administer IV naloxone to reverse opioid-like effects of bupivacaine
- C Perform immediate DC cardioversion for suspected atrial fibrillation
- D Administer 20% lipid emulsion (Intralipid) 1.5 mL/kg IV bolus, followed by infusion; call for cardiac arrest team; do not use propofol as a substitute for lipid emulsion ✓
Explanation
The presentation is classic local anaesthetic systemic toxicity (LAST): perioral tingling, tinnitus, metallic taste, followed by cardiovascular collapse. Bupivacaine is particularly cardiotoxic as it has high affinity for cardiac sodium channels. Treatment follows ASRA (American Society of Regional Anesthesia) LAST guidelines: 20% Intralipid (lipid emulsion therapy, LET) at 1.5 mL/kg IV bolus over 1 minute, then 0.25 mL/kg/min infusion. Lipid acts as a 'lipid sink' sequestering lipophilic local anaesthetic. Standard ACLS applies simultaneously. Propofol is NOT a substitute for lipid emulsion (its lipid concentration is too low and it worsens cardiovascular depression). Epinephrine doses in LAST should be lower than standard ACLS doses (≤1 mcg/kg) to avoid arrhythmias.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.