Proper Use of Lidocaine in Medical Treatment
Lidocaine should be administered using the lowest effective dose based on procedure type, patient factors, and administration route, with careful monitoring for signs of toxicity and strict adherence to maximum safe dosages. 1, 2
Dosage Guidelines
Intravenous Administration
- Loading dose: Maximum 1.5 mg/kg given as infusion over 10 minutes 1
- Maintenance infusion: 1.5 mg/kg/h, not exceeding 120 mg/h 1
- Maximum total dose: Should not exceed 300 mg for adults 2
- Weight calculation: Use ideal body weight for dose calculation 1
- Men: height (cm) - 100
- Women: height (cm) - 105
Topical Administration
- Maximum safe dosage: 3
- With epinephrine: 3.0-4.5 mg/kg for children, 7.0 mg/kg for adults
- Without epinephrine: 1.5-2.0 mg/kg
- Reduce dose by 30% for neonates and infants under 6 months
- Application time: Typically 30 minutes, varies by procedure 3
- Onset of action: Significant anesthesia in 25-30 minutes, optimal effect at 35-40 minutes 4
Special Populations
- Children: Maximum dose calculated using pediatric formulas (e.g., Clark's rule) 2
- Example: 5-year-old weighing 50 lbs should not exceed 75-100 mg
- Neonates/infants under 6 months: Reduce dose by 30% due to immature hepatic and renal function 3
- Contraindication: Not recommended for patients weighing <40 kg for IV administration 1
Administration Techniques
Specific Procedures
- Retrobulbar injection: 3-5 mL (120-200 mg) for a 70 kg person 2
- Transtracheal injection: 2-3 mL, rarely exceeding 5 mL (200 mg) 2
- Topical application for laryngoscopy/bronchoscopy: 1-5 mL (40-200 mg) 2
- Wound anesthesia: Provides excellent anesthesia in 20-30 minutes 3
Important Considerations
- Occlusion effects: Occlusive dressings can triple serum lidocaine levels 5
- Concentration vs. absorption: Higher concentrations don't necessarily mean higher absorption; formulation matters 6
- Application technique: Use smallest effective amount, avoid large areas or broken skin 3
Safety Precautions
Contraindications and Cautions
- Relative contraindications: 1
- Cardiac disease
- Electrolyte disorders
- Seizure disorders
- Renal or hepatic impairment
- Pregnancy/breastfeeding
- Neurological disorders
Drug Interactions
- Timing with other local anesthetics: 1
- Don't start IV lidocaine within 4h of nerve/fascial plane blocks
- No nerve/fascial plane blocks until 4h after IV lidocaine infusion
- No boluses into wound/epidural catheters until 4h after IV lidocaine
- Remove lidocaine plasters before starting IV lidocaine
Monitoring for Toxicity
- Signs of toxicity: 1, 3
- Early: Circumoral numbness, facial tingling, light-headedness, tinnitus
- Severe: Seizures, cardiac arrhythmias, myocardial depression, respiratory arrest
- Monitoring requirements: Continuous ECG, pulse oximetry, regular blood pressure checks 1
Management of Toxicity
- Immediate actions: 3
- Stop administration immediately
- Maintain airway
- Provide respiratory support if needed
- Treatment: 20% lipid emulsion for severe toxicity 3
Practical Applications
Formulation Selection
- IV lidocaine: Useful for postoperative pain management 1
- Topical preparations: Available in various concentrations (4% common) 5, 6, 4
- Combination with epinephrine: Prolongs anesthesia duration and decreases systemic absorption 3
Consent and Documentation
- Informed consent: Explain risks and benefits, especially for unlicensed indications 1
- Patient education: Inform about expected sensations and potential side effects 1
By following these guidelines, lidocaine can be used safely and effectively for various medical procedures while minimizing the risk of toxicity and adverse effects.