DYNAMIC EPIDERMAL COOLING IN CONJUNCTION WITH LASER TREATMENT OF PORT-WINE STAINS - THEORETICAL AND PRELIMINARY CLINICAL-EVALUATIONS

The clinical objective in laser treatment of port-wine stains (PWS) is to induce selective photothermolysis of subsurface blood vessels with out damaging the overlying epidermis. This paper investigates the effe ctiveness of 'dynamic' cooling, where a cryogen is sprayed on the skin surface for an appropriately short period of time, to eliminate epide rmal thermal injury during laser treatment of PWS. Comparative measure ments of radiometric surface temperature from cooled and uncooled lase r irradiated (585 nm) PWS sites, and theoretical predictions of temper ature distributions within skin in response to dynamic cooling in conj unction with laser irradiation are presented. Rapid reduction of skin surface temperature and localization of cooling the epidermis are obta ined when a cryogen is sprayed on skin prior to laser irradiation. Suc cessful blanching of the PWS without thermal injury to the overlying e pidermis is accomplished.