Local Anaesthetic Systemic Toxicity (LAST)

You will infiltrate local anaesthetic for sutures, drains, lines and lumbar punctures — which makes you both the likeliest cause and the likeliest first finder. Toxicity presents as circumoral tingling, metallic taste, tinnitus and agitation…

AAGBI Lipid Rescue

The pathway

1 · Stop injecting

Immediately, at the first symptom
Early features: perioral tingling, metallic taste, tinnitus, visual disturbance, agitation or odd behaviour
Onset may be delayed up to 60 minutes — a patient who feels odd 30 minutes after a block has LAST until proven otherwise

2 · Call for help

Emergency call. Say "local anaesthetic toxicity"
Ask for the lipid emulsion by name and for anaesthetic support
Every theatre and ED should hold 20% lipid emulsion — know where yours is

3 · Airway, breathing, circulation

100% oxygen, secure the airway, ensure adequate ventilation
Hyperventilation may help by raising plasma pH in the presence of metabolic acidosis
IV access, continuous ECG monitoring

4 · Control seizures

Benzodiazepine first line — midazolam or lorazepam
Avoid large doses of propofol if there is any cardiovascular instability: it is a myocardial depressant and it is not a substitute for lipid emulsion
Small doses of thiopental or propofol are acceptable if cardiovascularly stable

5 · Give 20% lipid emulsion — bolus

1.5 ml/kg over 1 minute (≈100 ml in a 70 kg adult)
Start immediately in cardiovascular collapse; do not wait for arrest

6 · Start the lipid infusion

15 ml/kg/hr (≈1000 ml/hr in a 70 kg adult)
Continue while resuscitation proceeds

7 · If stability is not restored after 5 minutes

Repeat the bolus up to twice more, 5 minutes apart
Double the infusion to 30 ml/kg/hr
Maximum cumulative dose 12 ml/kg, and never more than 840 ml total

8 · Modified cardiac arrest management

Standard ALS, but expect it to be prolonged — over an hour may be required and recovery is well described
Do not use lidocaine as an antiarrhythmic — it is a local anaesthetic
Expect arrhythmias to be very refractory to standard treatment
ASRA additionally advises reducing adrenaline to small boluses (≤1 microgram/kg) and avoiding vasopressin, calcium channel blockers and beta blockers — this is not in the AAGBI 2010 poster
Consider cardiopulmonary bypass if available

9 · After the event

Transfer to a critical care area — recurrence and propofol-related issues can follow
Report it: to the National Patient Safety Agency and at www.lipidrescue.org
Exclude pancreatitis: clinical review plus daily amylase or lipase for two days
Propofol is not a substitute for lipid emulsion at any point

Drugs

Drug	Dose	Route	Notes
Lipid emulsion 20%	1.5 ml/kg bolus, then 15 ml/kg/hr	IV	≈100 ml bolus then 1000 ml/hr in a 70 kg adult. Up to 2 further boluses 5 min apart (3 including the first); may double infusion to 30 ml/kg/hr. Max cumulative 12 ml/kg and 840 ml total.
Midazolam	2–5mg	IV	Seizure control, titrated. Lorazepam is an equally reasonable first line.
Adrenaline	≤1 microgram/kg boluses	IV	ASRA advises reduced doses in LAST; the AAGBI 2010 guideline does not specify. Follow your local protocol and the arrest team lead.
Lidocaine — maximum safe dose	3 mg/kg (7 mg/kg with adrenaline)	Infiltration	Prevention. 1% = 10mg/ml, so 3mg/kg is only ~21ml of 1% in a 70kg adult. Calculate before you draw up.
Bupivacaine — maximum safe dose	2 mg/kg	Infiltration	The most cardiotoxic of the common agents. Cardiac arrest may precede seizures.

When to escalate

Any suspected LAST — call before you are certain,Seizures, arrhythmia or hypotension after local anaesthetic,Cardiovascular collapse — start lipid emulsion immediately, do not wait for arrest,Arrest requires prolonged CPR and cardiopulmonary bypass consideration,All cases need critical care follow-up and formal reporting

Reference: AAGBI / Association of Anaesthetists — Management of Severe Local Anaesthetic Toxicity

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