Methodology for estimating instantaneous heat removal from human skin in response to cryogen spray cooling

Cryogen spray cooling (CSC) reduces epidermal damage during laser treatment of various dermatoses. The goal of this study was to determine the instantaneous surface heat removal from skin by CSC. Thermocouples were imbedded in four substrates with a range of thermal diffusivities, greater than three orders of magnitude in difference, to measure internal temperature profiles in response to CSC. An inverse heat conduction model was subsequently used to quantify the instantaneous heat removal from the substrates using the measured temperatures. The ratio of the average values of the instantaneous heat removal among pairs of substrates was plotted as a function of the ratio of the thermal diffusivity among the pairs. The resulting correlation was then used to estimate the instantaneous heat removal from skin. This work will aid in the modeling of heat transfer in skin during laser irradiation in conjunction with CSC.