Lidocaine (IV — Regional Anaesthesia)

How it works

Lidocaine is an amide local anaesthetic that blocks voltage-gated sodium channels, preventing nerve impulse conduction; systemically it also has analgesic and anti-hyperalgesic effects.

Prescribing in practice

• The principal hazard is local anaesthetic systemic toxicity (LAST) — perioral numbness and tinnitus progressing to seizures, cardiac arrhythmia and arrest — so respect maximum doses, use a functioning tourniquet for Bier's block and have lipid emulsion and resuscitation immediately available.
• For intravenous regional anaesthesia the tourniquet must not be released prematurely, as sudden systemic release of the agent can precipitate toxicity.
• Use with caution and reduced dosing in hepatic impairment, low cardiac output, the elderly and those with conduction defects; avoid in severe heart block.

Monitoring

Monitor ECG, blood pressure, conscious level and for early signs of systemic toxicity throughout administration.

Counselling the patient

• Report ringing in the ears, tingling around the mouth, a metallic taste or dizziness immediately.
• The tourniquet (cuff) stays inflated for a set time for your safety.
• This provides numbness and pain relief for your procedure.

Evidence & guidelines

AAGBI/Association of Anaesthetists guidance on managing severe local anaesthetic systemic toxicity underpins safe intravenous lidocaine use and immediate lipid-emulsion availability.