Synopsis
Recognise and treat local-anaesthetic systemic toxicity promptly while preventing excessive or intravascular exposure during adult regional anaesthesia and infiltration.
- Stop injection and all pumps immediately when LAST is suspected; call for senior help, the cardiac-arrest trolley and the lipid rescue pack.
- Give 100% oxygen, maintain or secure the airway and ventilate effectively while avoiding hypercarbia, which can worsen toxicity.
- Use 20% lipid emulsion: initial 1.5 mL/kg intravenous bolus over 2–3 minutes, then 15 mL/kg/hour infusion, following the QRH repeat and maximum-dose instructions.
Key red flags
Sudden agitation, altered mental state, loss of consciousness or tonic-clonic seizure after local anaesthetic requires immediate treatment for possible toxicity.
Bradycardia, conduction block, ventricular arrhythmia, hypotension or asystole may be the first recognised manifestation under sedation or general anaesthesia.
Toxicity can appear after the injection, through cumulative infiltration or during a continuous infusion; finishing the block does not end surveillance.
Propofol is not a substitute for 20% lipid emulsion in the LAST rescue regimen.
During LAST cardiac arrest, the Association QRH specifies smaller adrenaline doses of no more than 1 microgram/kg and avoidance of vasopressin.
Children, pregnancy, frailty, critical illness and cardiac, renal or hepatic dysfunction increase risk and require specialist dosing rather than routine adult extrapolation.
Sudden altered consciousness or tonic-clonic convulsion during or after local anaesthetic should trigger the LAST drill.
Bradycardia, conduction delay, wide complexes, ventricular arrhythmia, hypotension and asystole indicate life-threatening myocardial and electrical toxicity.
Reasoning priorities
Detect airway failure, seizure, arrhythmia and circulatory collapse while treatment begins.
Diagnosis is clinical and treatment should not wait for a confirmatory concentration; relate deterioration to the injection timeline and all administered drugs.
Worked reasoning
An adult becomes agitated and convulses seconds after local-anaesthetic injection.
- Stop injection and any infusion, call for help, summon the arrest trolley and lipid pack, give 100% oxygen and establish effective airway ventilation and intravenous access.
- Control seizure with small incremental benzodiazepine doses and assess rhythm and perfusion; begin 20% lipid emulsion promptly if severe toxicity is suspected.
- Give an initial 1.5 mL/kg lipid bolus over 2–3 minutes and start 15 mL/kg/hour, then follow the QRH repeat-bolus, doubled-infusion and 12 mL/kg cumulative ceiling instructions.
- If arrest occurs, start continuous CPR, use adrenaline doses no greater than 1 microgram/kg, avoid vasopressin and consider prolonged resuscitation with bypass support.