Effects of thermal conducting media on the skin surface during laser irradiation

To investigate the effects of thermally conductive, optically transparent media placed on skin during treatment with the flashlamp excited dye laser (FEDL). The use of higher energy densities to treat persistent cutaneous vascular lesions may result in a decrease in the number of treatment sessions. However, increased fluences can cause complications of scarring, hyperpigmentation, infection, skin texture changes, or hypopigmentation. The thermally conductive media should assist in dissipating surface thermal energy and thereby protect the skin from the complications.

This was a prospective laboratory study using an animal model. The results were verified in a prospective, pilot, human-use trial.

The threshold for acute skin damage and measurements of the thermal transients were made using a rabbit model. The threshold for purpura was noted with and without the use of a sapphire as a thermal conductor. The thermal transients were measured with small thermocouples placed subcutaneously. On a human subject, purpura intensities were photographed and measured using computer morphometrics after treatment with the FEDL and skin surface protection with air, glass, sapphire, and diamond as conductive media.

With the interposition of the sapphire thermal conductor during the FEDL treatment, excessive temperature increases of the epidermis were prevented during the laser pulse compared with glass and controls. Both sapphire and diamond resulted in decreased purpuric intensities with the applications of equivalent fluences. Wound recovery time for the purpura was decreased by approximately half a day when any of the surface conductors were used.

The decreased transient temperature and decrease in purpura seen with the use of sapphire and diamond protecting the epidermis during treatment with the FEDL should result in fewer untoward effects during treatment of vascular lesions and facilitate their management.