Maximum Dose of Lidocaine in Patients with Heart Problems
For patients with heart problems, the maximum dose of lidocaine as a local anesthetic should not exceed 4.4 mg/kg without epinephrine, and should be further reduced in patients with cardiac dysfunction. 1, 2
Dosing Guidelines for Local Anesthesia
General Maximum Doses
- For local anesthesia in adults with heart problems, lidocaine should not exceed 4.4 mg/kg without epinephrine 1
- With epinephrine, the maximum dose is 7.0 mg/kg in patients without severe cardiac dysfunction 1
- The absolute maximum dose for an adult should be kept below 300 mg in any case 2
Dose Adjustments for Cardiac Conditions
- Patients with myocardial infarction, heart failure, or cardiogenic shock require significant dose reductions due to altered pharmacokinetics 1
- In patients with cardiac failure, lidocaine's half-life increases to >20 hours (compared to 1-2 hours in normal subjects) 1
- In cardiogenic shock, the half-life is even longer, requiring appropriate reduction in dosing 1
Special Considerations
Intravenous Administration
- When lidocaine is administered intravenously (for arrhythmias), the dose should be decreased to 3-5 mg/kg 1
- For IV administration in cardiac arrhythmias, an initial bolus of 1 mg/kg (not exceeding 100 mg) is recommended 1, 3
- Maintenance infusion should be 20-50 μg/kg/min (1.4-3.5 mg/min in a 70 kg patient) 1, 3
Age-Related Adjustments
- Older patients (>70 years) with heart problems require lower doses due to decreased clearance 1, 2
- Doses should be reduced by approximately 30% in elderly patients with cardiac conditions 2, 4
Monitoring and Safety
Signs of Toxicity
- Monitor for cardiac toxicity signs: bradycardia, hypotension, sinus arrest 1
- CNS toxicity may precede cardiac toxicity: perioral numbness, dizziness, confusion, slurred speech 1, 5
- Toxic reactions are directly proportional to the total dose administered 2, 4
Treatment of Toxicity
- For lidocaine toxicity in cardiac patients, administer 1.5 mL/kg 20% lipid emulsion over ~1 minute 1, 5
- Follow with lipid infusion (0.25 mL/kg per minute) until circulation is restored 1
- Avoid vasopressin, calcium channel blockers, and β-blockers in treatment of toxicity 1
Common Pitfalls to Avoid
- Using standard doses in patients with heart failure or cardiogenic shock (requires significant reduction) 1
- Failure to calculate the maximum allowable safe dosage before administration 1
- Not recognizing enhanced sedative effects when combining local anesthetics with other sedatives or opioids 1
- Administering lidocaine too rapidly in patients with cardiac conditions 1, 4
- Using the same dose for elderly cardiac patients as for younger patients 2, 4
Remember that lidocaine is a cardiac depressant, and patients with pre-existing heart problems are at higher risk for adverse effects even at therapeutic doses 1.