Can lidocaine (local anesthetic) with epinephrine (adrenaline) be used to numb an open wound on the plantar surface of the foot?

Use of Lidocaine with Epinephrine for Open Wounds on the Plantar Surface of the Foot

Lidocaine with epinephrine can be safely used to anesthetize open wounds on the plantar surface of the foot, as multiple systematic reviews and randomized controlled trials have demonstrated the safety of epinephrine in the digits, hands, and feet. 1

Evidence for Safety

The historical concern that epinephrine could cause tissue necrosis in terminal vascular areas like the digits, hands, and feet has been thoroughly refuted by modern research:

• Multiple systematic reviews and randomized controlled trials have found that adding epinephrine to local infiltrative anesthesia is safe for use in the digits, hands, and feet 1
• No cases of necrosis were reported in these studies, and epinephrine use resulted in:
  • Less need for tourniquets
  • Faster onset of anesthesia
  • Longer duration of anesthesia 1

Benefits of Using Lidocaine with Epinephrine

Adding epinephrine to lidocaine for plantar foot wounds provides several advantages:

1. Prolonged anesthetic effect - Epinephrine slows the absorption of lidocaine, extending its duration of action
2. Reduced systemic absorption - Lower peak blood levels of lidocaine reduce risk of toxicity
3. Improved hemostasis - Vasoconstriction helps control bleeding during wound assessment and repair
4. Reduced need for tourniquets - Decreases risk associated with mechanical tourniquets 1, 2

Administration Technique

For optimal results when anesthetizing plantar foot wounds:

• Use the lowest effective concentration of epinephrine (typically 1:100,000 or 1:200,000) 1
• Consider buffering the anesthetic with sodium bicarbonate to decrease pain during infiltration 1
• For neuropathic ulcers, debridement can often be performed without any local anesthetic 1
• For laceration repair:
  • Apply the anesthetic directly to the wound and cover with occlusive dressing or place a cotton ball soaked with solution into the wound
  • Allow 10-20 minutes for onset of action or until wound edges appear blanched 1

Special Considerations

Contraindications

• Allergy to amide anesthetics 1
• Grossly contaminated wounds 1

Dosing Precautions

• Maximum safe dose of lidocaine with epinephrine: 7 mg/kg 3
• For children: 3 mL for children >17 kg; 0.175 mL/kg in children <17 kg 1

Potential Concerns

While one older study from 1977 suggested that lidocaine might impair wound healing and that adrenaline could potentiate this effect 4, this concern has not been substantiated in more recent clinical practice and research. The benefits of proper pain control and hemostasis generally outweigh any theoretical risks to wound healing.

Conclusion

The traditional prohibition against using epinephrine in terminal areas like the plantar surface of the foot is not supported by current evidence. Modern research demonstrates that lidocaine with epinephrine can be safely and effectively used for anesthetizing open wounds on the plantar surface of the foot, providing better pain control, hemostasis, and potentially improving the conditions for wound assessment and repair.