Analysis of epidermal/dermal temperature changes according to the different cryogen spray cooling conditions.

This study measured epidermal and dermal temperatures under different cryogen spray cooling (CSC) conditions to determine the optimum cooling conditions for skin rejuvenation. For this purpose, CSC conditions were applied before a laser transmission for varying spurt times of 50, 150, and 200 ms with delay times of 150 and 200 ms. A long-pulsed 1,064 nm Nd:YAG laser irradiated the skin surface of a pig with a condition of fluence of 26 J/cm2 and a spot diameter of 8 mm. The pulse duration was set to 30 ms during all experiments. This study found that all employed CSC conditions significantly decreased internal-external skin temperatures. Moreover, skin temperatures were influenced more by variations in spurt time of CSC compared with the delay times. Based on these experimental results, two spurt times were selected as the optimum CSC conditions for skin rejuvenation: 50 ms with delay time of 150 and 200 ms and 150 ms with a delay time of 150 and 200 ms.