Local Anaesthetic Systemic Toxicity
This is an anaesthetic crisis. Priority is to:
- Maintain oxygenation
- Control seizures
- Manage arrhythmias or CVS arrest
- Give intravenous lipid emulsion
Excessive systemic levels of local anaesthetic. LAST presents:
- With CNS or CVS signs
Up to and including seizures and cardiac arrest. - Variably
Presentation may be:- In PACU, the ward, or after hospital discharge
- Obscured by other perioperative events
Emergency Management
Priorities:
- Cease LA injection
- Call for help
Early consideration of CPB or ECMO, if available. - Support physiology
Maintain oxygenation and ventilation, and consider intubation. - Intralipid emulsion
Specific management:
- Control seizures
- Benzodiazepine preferred
- Propofol reasonable alternative
Note potential haemodynamic instability.
- Arrhythmia
- Start ALS if required
Consider ECMO. - Reduce dose adrenaline
⩽1μg/kg. - Avoid:
- Vasopressin
- Calcium-channel blockers
- β-blockade
- Start ALS if required
- Give intravenous lipid emulsion
- 1.5mL/kg bolus
Repeat if unstable. - Commence infusion at 15mL/kg/hr
Double rate if unstable. - Up to 12ml/kg total volume.
- Continue at least 15 minutes after haemodynamic stability achieved.
- 1.5mL/kg bolus
Epidemiology and Risk Factors
LAST:
- Occurs in ~1/1,000-1/10,000 regional techniques
- Cardiac arrest in ~1/25,000
- Associated with:
- Upper limb and PVB blockade
- ↑ LA dose
- Reduced patient body weight
- Use of lignocaine
- Protective factors
- Use of ultrasound
Pathophysiology
Aetiology
Clinical Manifestations
History
Examination
Diagnostic Approach and DDx
Investigations
Management
Preventative Management
- Use the lowest effective dose of LA required
- Use ultrasound
- Monitor LA spread during injection
- If not seen, suggests intravascular injection
- Consider use of adrenaline in the block
Gives a marker for inadvertent intravascular injection.