Wound healing and collagen thermal damage in 7.5-μsec pulsed CO2 laser skin incisions

Abstract

Background and Objective: Wound-healing delays caused by lateral thermal damage to tissue remain a drawback of CO2 surgical lasers. This study compares the thermal damage and wound-healing properties of a 7.5-μs pulsed CO2 laser with scalpel and continuous wave (CW) CO2 laser incisions. Study Design/Materials and Methods: We created incisions on the dorsal pelts of rats with a 7.5-μs pulsed CO2 laser at 5-, 10-, or 15-Hz repetition rate, a conventional CW laser, or scalpel. Animals were euthanized at postoperative days 3, 7, 14, 21, and 80. Tissue was harvested and analyzed histologically and for wound tensile strength. In addition, tissue was harvested acutely and analyzed for acute thermal injury lateral to the incisions. Results: Incisions made with the pulsed laser had significantly higher tensile strength and histologic rankings than did CW laser incisions at days 3-21, producing 118 μm of thermal damage to tissue as compared with 333 μm for CW laser. Pulsed laser incisions were not statistically different than scalpel incisions at days 3-14 of healing. Mathematical modeling showed the pulsed laser to produce a wound healing delay of 1.0 day by tensiometry and 1.9 days by histology, compared with 3.2 days by tensiometry and 6.0 days by histology for CW laser. There were no significant differences in wound healing when the pulsed laser was used at repetition rates of 5-15 Hz. Conclusions: Using a 7.5-μs pulse duration, CO2 laser incisions healed at a rate similar to scalpel incisions and reduced the wound-healing delay seen with typical surgical CO2 lasers.