Wound healing and collagen thermal damage in 7.5-microsec pulsed CO(2) laser skin incisions.

Abstract

Wound-healing delays caused by lateral thermal damage to tissue remain a drawback of CO(2) surgical lasers. This study compares the thermal damage and wound-healing properties of a 7.5-micros pulsed CO(2) laser with scalpel and continuous wave (CW) CO(2) laser incisions. We created incisions on the dorsal pelts of rats with a 7.5-micros pulsed CO(2) 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. 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 microm of thermal damage to tissue as compared with 333 microm 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. Using a 7.5-micros pulse duration, CO(2) laser incisions healed at a rate similar to scalpel incisions and reduced the wound-healing delay seen with typical surgical CO(2) lasers.