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Poisoning – Acute Guidelines for Initial Management
For 24 hour advice, contact Victorian Poisons Information Centre 131126
Local anaesthetic toxicity generally occurs as a result of therapeutic error. Situations leading to toxicity include inadvertent venous or arterial injection as well as too high a dose of ingested or topically administered local anaesthetic-containing preparations. Although there is extensive first-pass metabolism, there are reported fatalities following the ingestion of lignocaine-containing local and topical preparations.
The toxic mechanism is via local anaesthetic agent binding reversibly to sodium channels. There may be other effects, including blockade of potassium and calcium channels, interaction with cholinergic or N-methyl-D-aspartate (NMDA) receptors and interference with cellular metabolic processes.
Clinical manifestations correspond to the concentration in the systemic circulation. This in turn depends on a number of factors, including
Most local anaesthetics are eliminated by hepatic metabolism. Most agents have elimination half-lives of 2 hours, but bupivacaine has a longer elimination half-life (5 hours or longer).
Intentional overdose or accidental
Co-ingestants eg paracetamol
The following table outlines the maximum recommended doses for various local anaesthetic agents. Please note that toxicity can still occur with doses lower than these when given via intravenous or intra-arterial injection. Larger doses can safely be given with adrenaline.
Maximum dose (mg/kg)
1 – 2.5
Lignocaine / lidocaine
4 – 5
4 – 5
5 – 7
2.5 - 3
Bupivocaine is particularly cardiotoxic.
Early clinical features include:
More severe toxicity manifests by:
Cardiac arrest may be the first clinical manifestation following massive intravenous overdose.
Always check for Medicalert bracelet in any unconscious patient, or any other signs of underlying medical condition (fingerprick marks etc)
UEC, arterial blood gas, methaemoglobin concentration
Serial ECGs looking for evidence of sodium channel blockade (prolonged PR and QRS intervals, large terminal R wave in aVR)
Immediately cease administration of the local anaesthetic
Call for help
Recovery from local-anaesthetic induced cardiac arrest may take > 1hr
Precautions - hypersensitivity to egg yolk, soya or peanut protein
Adverse events reported after lipid emulsion infusion:
Administration of lipid emulsion therapy with 20% lipid emulsion
Wait 5 Minutes, then
Ongoing care and monitoring
Children who have ingested lignocaine-containing teething gels and other topical preparations require hospital assessment if > 6mg/kg or there are symptoms.
Ongoing care should be in a high-dependency or intensive care setting.
Admission should be considered for all children and young people with an intentional overdose.
Contact Victorian Poisons Information Centre 131126 for advice
Any patient with local anaesthetic toxicity
For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.
Intentional self –harm: Referral to local mental health services eg Orygen Youth Health: 1800 888 320
Recreational poisoning: Referral to YoDAA, Victoria's Youth Drug and Alcohol Advice service: 1800 458 685
Call the duty anaesthetist on ext. 52000 for advice.
Bottles of 20% lipid emulsion are kept in the central drug room in the emergency department as well as in theatre.
Lipid emulsion is kept in the main drug room in the adult side of the emergency department.
More is available from ICU.
Last Updated October 2018