SLR - September 2017 - Kevin Garfield
Reference: Diaz DC, Iglesias ME, Diaz MC, Vallejo RB. Enhanced Removal of Phenol with Lidocaine vs. Alcohol: An In Vitro Study. JAMA Dermatol. 2017 Apr 1;153(4):325-326. doi:10.1001/jamadermatol.2016.5244Scientific Literature Review
Reviewed By: Kevin Garfield, DPM
Residency Program: Beaumont Health, Farmington Hills, MI
Podiatric Relevance: Partial or total nail avulsion with chemical destruction of the matrix is one of the most common office procedures performed by podiatrists. Phenol is a commonly used acid for matrix ablation. After the phenol has destroyed the matrix tissue, the excess phenol must be neutralized or washed away because it is a destructive irritant to surrounding skin. This study compared the effectiveness of irrigation with three solutions readily available in a podiatry office. The results suggest that two percent lidocaine is more effective at removing phenol than 94 percent isopropyl alcohol or 0.9 percent saline.
Methods: This is an in vitro study using fresh cadaveric halluces. The donor halluces were placed in an automated cell diffusion system, and 50 microliters of hydroalcoholic phenol solution (95 percent) was applied to the matrix tissue for three minutes, then irrigated twice with 1 mL aliquots of either 96 percent isopropyl alcohol, 0.9 percent saline or two percent lidocaine. The irrigation solution was collected, and the amount of phenol remaining in the irrigation solution was determined. The experiment was performed in triplicate for each irrigation solution.
Results: The percent of phenol recovered from a single 1 mL irrigation of each solution was 64.06 percent recovered in 94 percent isopropyl alcohol, 72.95 percent recovered in 0.9 percent saline and 81.76 percent recovered in the two percent lidocaine. The percent of phenol recovered from the second 1 mL irrigation of the same tissue sample of each solution was 7.92 percent recovered in 94 percent isopropyl alcohol, 7.81 percent recovered in 0.9 percent saline, and 7.2 percent recovered in the two percent lidocaine. The total phenol recovered in both irrigations was 71.89 percent recovered in 94 percent isopropyl alcohol, 80.4 percent recovered in 0.9 percent saline and 88.96 percent recovered in the two percent lidocaine.
Conclusions: This study shows that two percent lidocaine is significantly more effective in removing excess phenol after matrixectomy. Phenol is a caustic substance, and prolonged exposure due to poor irrigation could cause unintended tissue damage to surrounding skin, which has the potential to cause ulceration leading to increased risk of infection. The phenol that was recovered in each of the irrigation solutions was active, indicating that the phenol is not neutralized but only diluted, so it is important to remove as much as possible.