Soaking Wounds in Lidocaine: Safety Concerns and Recommendations
Soaking wounds in lidocaine is not recommended due to significant risk of systemic toxicity with minimal benefit for pain control. This practice can lead to excessive absorption of lidocaine through open wound surfaces, potentially causing serious adverse effects including cardiovascular depression and seizures 1.
Safety Concerns with Wound Soaking in Lidocaine
Systemic Toxicity Risk
- Lidocaine has a narrow therapeutic window, with central nervous system toxicity occurring at plasma levels only slightly higher than therapeutic levels 1
- Open wounds provide direct access for rapid systemic absorption
- Toxicity symptoms progress from circumoral numbness and facial tingling to seizures and potentially fatal cardiovascular depression 1
- A patient death has been reported following postoperative lidocaine administration, prompting safety guidelines 1
Wound Healing Considerations
- While some studies show lidocaine can affect tissue vascularity and collagen formation 2, clinically relevant doses don't significantly impair overall wound healing 3
- High concentrations of lidocaine (above 100 μg/ml) can impair epithelial wound healing in a dose-dependent manner 4
Recommended Alternatives for Wound Pain Management
For Open Wounds
- Lidocaine-epinephrine-tetracaine (LET) combinations provide excellent wound anesthesia in 20-30 minutes when properly applied to the wound surface (not soaked) 1
- For children <17 kg: Use weight-based dosing of 0.175 mL/kg of LET solution 1, 5
- For children >17 kg: Maximum 3 mL of LET solution 1
- Application method: Place LET on open wound and cover with occlusive dressing or place cotton ball moistened (not soaked) with LET solution into wound for 10-20 minutes 1
For Wound Closure
- Buffered lidocaine injection using proper technique (small gauge needle, slow injection) for necessary anesthesia 1
- Consider tissue adhesives or Steri-Strips for low-tension wounds for essentially painless closure 1
- Topical 5% lidocaine cream may be used for painful wounds but should not be applied to large areas or broken skin 6, 7
Important Precautions
FDA Warnings for Topical Lidocaine
- Do not use on large areas of the body or on cut, irritated, or swollen skin 6
- Do not use on puncture wounds 6
- Do not bandage or apply local heat to the area 6
- Avoid contact with eyes and mucous membranes 6
When Using Any Lidocaine Product
- Do not use multiple sources of local anesthetics simultaneously 1
- Lidocaine should not be started within 4 hours of any nerve or fascial plane block 1
- Have 20% lipid emulsion readily available wherever lidocaine is used for potential toxicity treatment 1
- Use ideal body weight for dose calculation in patients with BMI >30 kg/m² 1
Special Populations
- For neonates and infants under 6 months: Decrease lidocaine doses by 30% due to immature hepatic and renal function 5
- Lidocaine should not be used in patients weighing <40 kg without careful weight-based dosing 1, 5
In conclusion, while lidocaine is valuable for wound anesthesia when properly applied, soaking wounds in lidocaine solution poses unnecessary risks of systemic toxicity with limited additional benefit. Safer alternatives like proper application of LET solution or buffered lidocaine injection should be used instead.