A patient develops sudden cardiovascular collapse during interscalene brachial plexus block with bupivacaine 0.5%. The MOST likely mechanism and appropriate resuscitation is:

• A Vasovagal syncope; place supine and administer atropine
• B High neuraxial block from phrenic nerve spread; assist ventilation only
• C Anaphylaxis to bupivacaine; administer adrenaline 0.5 mg IM
• D Intravascular injection causing systemic local anaesthetic toxicity (LAST); administer 20% lipid emulsion IV ✓

Explanation

Sudden cardiovascular collapse during regional anaesthesia with bupivacaine suggests systemic local anaesthetic toxicity (LAST) from inadvertent intravascular injection. Bupivacaine is the most cardiotoxic of local anaesthetics due to high lipid solubility and tight binding to cardiac sodium and potassium channels, producing refractory ventricular arrhythmias and cardiac arrest. Treatment: stop injection, call for help, administer Intralipid 20% (1.5 mL/kg IV bolus, then infusion 0.25 mL/kg/min), and commence CPR. Adrenaline in large doses worsens cardiac toxicity in LAST; use only small doses (≤1 mcg/kg) during CPR.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.