Is it safe for Max to use lidocaine (lido) with epinephrine (epi)?

Safety of Lidocaine with Epinephrine (Lido with Epi)

Lidocaine with epinephrine is safe to use in most clinical situations with proper dosing, though specific precautions should be observed regarding maximum doses and anatomic locations.

Maximum Safe Dosing

Lidocaine with epinephrine has well-established safety parameters:

• For adults: Maximum safe dose is 7.0 mg/kg of lidocaine with epinephrine 1
• For children: Maximum safe dose is 3.0-4.5 mg/kg of lidocaine with epinephrine 1
• Without epinephrine: Maximum doses are lower at 4.0-4.5 mg/kg for adults and 1.5-2.0 mg/kg for children 1

The addition of epinephrine to lidocaine provides two key benefits:

1. Prolongs the duration of anesthesia (90-200 minutes vs. 45-60 minutes for plain lidocaine) 1, 2
2. Decreases systemic absorption of lidocaine, reducing toxicity risk 1

Anatomic Considerations

Contrary to traditional teaching, modern evidence supports that lidocaine with epinephrine can be safely used in most anatomic locations, including:

• Digits (fingers and toes) - historical concerns about digital necrosis have not been substantiated with modern commercial preparations 3
• Face and scalp
• Trunk and extremities

Precautions and Contraindications

Exercise caution in the following situations:

• Cardiac patients: The majority of patients receiving intraosseous injection of lidocaine with epinephrine (67%) experience a transient increase in heart rate, though this is typically not clinically significant in healthy patients 4
• Vascular tissues: Lower doses should be used when injecting into highly vascular areas 1
• Avoid concurrent use with other local anesthetics within their period of action 2
• Monitor for signs of toxicity: Circumoral numbness, facial tingling, slurred speech, metallic taste, auditory changes, and hallucinations are early warning signs 1

Practical Administration Tips

To maximize safety and efficacy:

• Aspirate before injection to avoid intravascular administration 1
• Use incremental injections rather than bolus administration 1
• For dermatologic procedures: Maximum dose of 500 mg lidocaine delivered incrementally over several hours (e.g., during Mohs surgery) has been shown to be safe 1
• Buffering the solution with sodium bicarbonate (1:9 or 1:10 ratio) and warming to approximately 40°C can decrease injection pain 2, 5
• Refrigeration maintains stability of buffered lidocaine with epinephrine for up to 2 weeks 5

Management of Toxicity

If signs of local anesthetic systemic toxicity (LAST) develop:

1. Stop administration immediately
2. Maintain airway and provide respiratory support if needed
3. Have 20% lipid emulsion available for treatment of severe toxicity 2
4. Monitor vital signs closely

In summary, lidocaine with epinephrine is a safe and effective local anesthetic when used within established dosing guidelines and with appropriate precautions for specific patient populations.