Laser treatment of port-wine stains: reduced pain and shorter duration of purpura by epidermal cooling

The pulsed dye laser is the most efficient laser to treat port wine stains. Mathematical modeling predicts that the incident optical fluence required to coagulate small sized and/or deeply located vessels is larger than the threshold value for epidermal damage. Dynamic cooling has been reported to prevent epidermal damage caused by the absorption of laser energy in melanin. Further on, this cooling technique has proved to reduce the pain associated with laser therapy. The aim of our study was to examine possible clinical advantages of dynamic cooling. A flash lamp pumped dye laser emitting at 585 nm wavelength with pulse duration of 0.45 ms and a 5 mm diameter spot-size was used. In 12 port wine stains pairs of test sites were exposed to laser pulses with incident fluences of 6.0 to 10.0 J/cm2. In all stains one of the sites in each pair received 20 ms cryogen spurts immediately prior to laser admission. In the cooled areas laser induced pain was significantly reduced, and the time period with skin discoloration was shortened by an average of 5 days. Post treatment hyperpigmentation was not prevented. Future studies will aim at improving the cooling technique in order to achieve optical protection of the epidermis.