Thermal and fluid characteristics during cryogen spray cooling

Cryogen spray cooling (CSC) is a technique to protect the epidermis from non-specific thermal injury during laser treatment of various dermatoses. Successful application of CSC in conjunction with laser treatment of heavily pigmented individuals, and high radiant exposures which may be required for effective therapeutic outcomes, requires enhancement of heat removal. We have investigated the thermal mechanisms, and effects of droplet size, density and velocity on heat removal during CSC. Our results suggest that although the inherent thermal diffusivity of skin may be a limiting factor in heat removal, parameters such as droplet size, density, and velocity are important, and should be optimized for maximum heat removal.