What is the recommended dosage and administration of lidocaine (local anesthetic) for minor procedures?

Lidocaine Dosing for Minor Procedures

For minor dermatologic procedures in adults, administer no more than 4.5 mg/kg of lidocaine without epinephrine or 7.0 mg/kg of lidocaine with epinephrine as local infiltrative anesthesia. 1

Adult Dosing Parameters

Maximum Safe Doses

• Without epinephrine: 4.5 mg/kg maximum single dose 1
• With epinephrine: 7.0 mg/kg maximum single dose 1
• For a 70 kg adult, this translates to:
  • 315 mg (31.5 mL of 1% solution) without epinephrine 1
  • 490 mg (49 mL of 1% solution) with epinephrine 1

Special Circumstances

• Multistage procedures (e.g., Mohs surgery): Maximum 500 mg of 1% lidocaine solution (50 mL) delivered over several hours 1
• Obese patients: Calculate dose using ideal body weight, not actual body weight 2, 3

Pediatric Dosing Parameters

Maximum Safe Doses in Children

• Without epinephrine: 1.5-2.0 mg/kg maximum single dose 1
• With epinephrine: 3.0-4.5 mg/kg maximum single dose 1
• Do not use in children weighing less than 40 kg for intravenous formulations 2, 4

Administration Technique to Minimize Toxicity Risk

Critical Safety Steps

• Aspirate before each injection to avoid intravascular administration 1
• Use incremental injections rather than single large boluses 1
• Add epinephrine (1:100,000 to 1:200,000) when administering larger doses, unless contraindicated 1
• Inject slowly with small-caliber needles to reduce pain and improve safety 2
• Buffer with bicarbonate to reduce injection pain 2

Timing Restrictions

• Never administer lidocaine within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 2, 4
• Calculate the total dose of all local anesthetics administered when determining maximum safe dosage 2

High-Risk Situations Requiring Dose Reduction

Patient Factors

• Highly vascular areas: Use lower doses due to increased systemic absorption 2
• Cardiac disease, seizure disorders, hepatic/renal impairment: Use with caution and consider dose reduction 2
• Age >70 years or body weight <40 kg: Higher toxicity risk 2
• Pregnancy/breastfeeding: Use cautiously 2

Medication Interactions

• Beta-blockers: Reduce lidocaine metabolism 3
• Amiodarone: Decreases clearance, especially problematic with prolonged use 3

Early Recognition of Toxicity

Warning Signs (Plasma Concentration 5-10 μg/mL)

• Circumoral numbness and facial tingling 2, 3
• Tinnitus and auditory disturbances 2, 3
• Metallic taste and tongue/lip tingling 2, 4
• Light-headedness and slurred speech 2, 3

Severe Toxicity Signs (>10 μg/mL)

• Muscle twitching progressing to seizures 2, 3
• Loss of consciousness 2, 4
• Respiratory arrest 2, 4
• Cardiac arrhythmias and myocardial depression 2, 4

Immediate Management

• Discontinue administration immediately if any toxicity signs appear 2
• Have 20% lipid emulsion readily available for treatment of systemic toxicity 2, 3
• Maintain resuscitation equipment and trained personnel available 2

Alternative Anesthetics for Lidocaine Allergy

True lidocaine allergy is rare (1% of adverse reactions), but when present: 1

• Switch to ester-type local anesthetics (cross-reaction between amides and esters is rare) 1
• Use 1% diphenhydramine as alternative infiltrative anesthetic 1
• Use bacteriostatic normal saline for minor procedures 1

Common Pitfalls to Avoid

• Using actual body weight in obese patients instead of ideal body weight leads to overdosing 2, 3
• Combining multiple local anesthetic formulations without accounting for cumulative dose 2
• Administering nerve blocks too soon after topical or infiltrative lidocaine 2, 4
• Failing to aspirate before each injection increases intravascular injection risk 1