What is the recommended protocol for lipid emulsion therapy in a patient with severe lignocaine toxicity?

Lipid Emulsion Therapy for Severe Lignocaine (Lidocaine) Toxicity

For severe lignocaine toxicity with cardiovascular collapse or refractory seizures, immediately administer 20% lipid emulsion as a 1.5 mL/kg bolus over approximately 1 minute, followed by continuous infusion at 0.25 mL/kg/min until circulation is restored. 1

Immediate Recognition and Initial Management

Signs of Severe Toxicity Requiring Lipid Emulsion

• Cardiovascular collapse: Hypotension, bradycardia, ventricular arrhythmias, or cardiac arrest 1
• Refractory seizures: Seizures not responding to benzodiazepines 1
• Early CNS symptoms: Peri-oral tingling, tinnitus, light-headedness, restlessness, dysarthria, hallucinations 1, 2

First-Line Actions (Before Lipid Emulsion)

1. Call for help immediately and alert the nearest facility with cardiopulmonary bypass capability 1
2. Ventilate with 100% oxygen and secure the airway if needed 1
3. Begin standard resuscitation: Chest compressions if pulseless, airway management, ventilatory support 1
4. Treat seizures with benzodiazepines first (e.g., midazolam 0.1-0.2 mg/kg IV) - avoid propofol if cardiovascular instability present 1

Lipid Emulsion Protocol

Dosing Regimen

Initial bolus: 1.5 mL/kg of 20% lipid emulsion over approximately 1 minute 1

Continuous infusion: 0.25 mL/kg/min immediately after bolus 1

Repeat boluses: Give 1.5 mL/kg bolus once or twice more for persistent cardiovascular collapse 1

Infusion adjustment: Double the infusion rate to 0.5 mL/kg/min if blood pressure remains low 1

Duration: Continue infusion for at least 10 minutes after attaining circulatory stability 1

Maximum dose: Recommended upper limit is approximately 10 mL/kg total 1

Evidence Supporting Use

The 2010 International Consensus on CPR found that five case reports demonstrated return of spontaneous circulation (ROSC) soon after lipid emulsion in patients with cardiac arrest from local anesthetic toxicity who were refractory to conventional advanced life support 1. Five controlled animal studies showed lipid emulsion was more effective than placebo for achieving ROSC in local anesthetic intoxication models 1.

Modified Resuscitation During Lipid Therapy

Medications to Avoid or Reduce

• Avoid: Vasopressin, calcium channel blockers, β-blockers, or additional local anesthetic 1
• Reduce epinephrine doses: Use smaller than standard doses as lipid emulsion may enhance epinephrine effects 1

Supportive Measures

• Fluid resuscitation: 10-20 mL/kg balanced salt solution bolus may be needed for peripheral vasodilation 1
• Vasopressor support: Phenylephrine infusion (0.1 μg/kg/min to start) if hypotension persists 1
• Prolonged resuscitation: Be prepared for extended CPR efforts as recovery may take time 1

Availability and Preparation

Lipid emulsion 20% must be readily available wherever IV lidocaine is used, and all staff should know its location 1. This is a critical safety requirement for any facility using local anesthetics 1.

Monitoring Requirements

During Treatment

• Continuous cardiac monitoring and ECG 1
• Frequent vital signs (every 15 minutes initially) 1
• Neurological assessment using Glasgow Coma Scale 3, 2
• Observation for at least 10 minutes after circulatory stability achieved 1

Post-Treatment

• Patients should be managed in a monitored bedspace (HDU/level 2 care) 1
• Continue monitoring for delayed effects or recurrence 1

Critical Pitfalls to Avoid

Do not delay lipid emulsion administration while waiting for laboratory confirmation of toxicity - treat based on clinical presentation 1

Do not use propofol for seizure management if cardiovascular instability is present, as it may worsen hemodynamic compromise 1

Do not give standard or high-dose epinephrine - reduce doses as lipid emulsion may potentiate catecholamine effects 1

Do not stop resuscitation prematurely - prolonged efforts may be required for successful recovery from severe local anesthetic toxicity 1

Refractory Cases

If the patient remains in cardiac arrest or refractory shock despite lipid emulsion therapy, consider venoarterial extracorporeal membrane oxygenation (VA-ECMO) as a rescue therapy 4. This should be arranged early if lipid emulsion does not produce rapid improvement 4.

Evidence Limitations

While lipid emulsion has become standard therapy based on case reports and animal studies, one controlled human study found that lipid emulsion did not affect subjective CNS toxicity symptoms or EEG changes from lidocaine in volunteers 5. However, this study used non-toxic doses and did not evaluate cardiovascular effects 5. The overwhelming case report evidence of successful resuscitation from otherwise fatal toxicity supports its use in severe cases 1, 3, 6, 2.