Lidocaine Dosing for Ventricular Tachycardia
For hemodynamically stable monomorphic VT in adults, give lidocaine 1-1.5 mg/kg IV bolus over 2 minutes, followed by repeat doses of 0.5-0.75 mg/kg every 5-10 minutes as needed up to a maximum cumulative dose of 3 mg/kg, then start a maintenance infusion at 1-4 mg/min (or 20-50 mcg/kg/min). 1
Initial Bolus Dosing
- First dose: 1-1.5 mg/kg IV push (typically 100 mg for average adult)
- Repeat doses: 0.5-0.75 mg/kg IV every 5-10 minutes if VT persists
- Maximum cumulative dose: 3 mg/kg total 1
For practical purposes, the 2000 British guidelines specify giving 50 mg IV over 2 minutes, repeated every 5 minutes to a total dose of 200 mg 2. This aligns with the AHA recommendation but provides a simpler fixed-dose approach.
Maintenance Infusion
Once VT is terminated:
- Standard rate: 1-4 mg/min continuous infusion 1
- Weight-based: 20-50 mcg/kg/min 1
- Continue for 6-24 hours, then reassess need
Critical Context: Lidocaine is Second-Line
Amiodarone is now preferred over lidocaine for hemodynamically stable VT. The 2010 AHA guidelines list amiodarone first, with lidocaine as an alternative 1. The 2018 focused update reinforces this, noting that while neither drug improves long-term survival, amiodarone shows better short-term outcomes (ROSC, hospital admission) 3. Recent 2023 data from in-hospital cardiac arrest actually favors lidocaine over amiodarone for survival and neurological outcomes 4, but this contradicts the out-of-hospital data that informed current guidelines.
Route-Specific Considerations
- IV route strongly preferred: A 2020 analysis found intravenous amiodarone and lidocaine significantly improved survival versus placebo, but intraosseous administration showed no benefit 5
- Endotracheal route (last resort): If no vascular access, give 2-3 mg/kg (double or triple the IV dose) via ETT, followed by 5 mL saline flush and 5 ventilations 6
Dose Adjustments for High-Risk Patients
Reduce infusion rates by 50% in:
- Age >70 years
- Heart failure or cardiogenic shock
- Hepatic dysfunction
- Severe renal impairment 7
The bolus dose should be based on lean body weight, not actual weight 7.
Maximum Safe Dosing
- Total 24-hour maximum: Do not exceed 3 mg/kg cumulative bolus dose
- Infusion maximum: 4 mg/min standard (50 mcg/kg/min weight-based)
- Absolute ceiling: Keep total lidocaine <300 mg in initial dosing for most patients 8
Toxicity Warning Signs
Monitor for CNS toxicity (occurs before cardiac toxicity):
- Slurred speech, drowsiness, disorientation
- Muscle twitching, tremors
- Seizures
- Bradycardia and hypotension (late signs) 1, 6
Stop infusion immediately if neurological symptoms develop. Lidocaine toxicity is more likely with poor cardiac output, which reduces hepatic clearance.
When NOT to Use Lidocaine
- Complete heart block (contraindicated)
- Wide complex tachycardia from accessory pathways (e.g., WPW with atrial fibrillation) 9
- Polymorphic VT with prolonged QT (torsades de pointes)—use magnesium instead 1
- No effect on SVT—lidocaine is ventricular-specific 2
Practical Algorithm
- Confirm stable VT (pulse present, BP adequate)
- Give lidocaine 1-1.5 mg/kg IV (or 100 mg) over 2 minutes
- Wait 5-10 minutes—assess rhythm
- If VT persists: Give 0.5-0.75 mg/kg (or 50 mg) IV, repeat every 5 minutes up to 3 mg/kg total
- If VT terminates: Start infusion at 2-4 mg/min
- If VT continues after max dose: Switch to amiodarone or consider cardioversion 1, 2
Comparative Effectiveness
Procainamide is actually more effective than lidocaine for terminating monomorphic VT (78% vs 27% success rate in one trial) 10, but requires slower infusion (20-50 mg/min to max 17 mg/kg), making it impractical during acute arrest. Amiodarone terminated shock-resistant VT in 78% vs 27% for lidocaine in another study 11. However, the 2023 in-hospital cardiac arrest data showed lidocaine associated with better survival to discharge than amiodarone (AOR 1.19) 4.
Bottom line: Use the dosing above, but recognize amiodarone is guideline-preferred for stable VT, while lidocaine remains reasonable and may actually be superior for in-hospital arrests based on emerging data.