Cutaneous pain effects induced by Nd:YAG and CO 2 laser stimuli

The near infrared laser technique can activate cutaneous nociceptors with high specificity and reproducibility and be used in anti-riot equipment. This study aimed to explore cutaneous pain effect and determine the threshold induced by Nd:YAG and CO 2 laser stimuli. The corresponding wavelength was 1.32μm and 10.6μm. The pain effect was assessed in three healthy subjects (1 woman and 2 men) on the skin of dorsum of both hands. The energy of each pulse and whether the subjects felt a painful sensation after each stimulus were recorded. A simplified Bliss Method was used to calculate the pain threshold which were determined under three pulse durations for Nd:YAG laser and one pulse duration for CO 2 laser. As a result the pain thresholds were determined to be 5.6J/cm 2 , 5.4J/cm 2 and 5.0J/cm 2 respectively when using Nd:YAG laser, 4.0mm beam diameter, 8ms, 0.1s and 1s pulse duration. The pain threshold was 1.0J/cm 2 when using CO 2 laser, 4.0mm beam diameter and 0.1s pulse duration. We concluded that the threshold of cutaneous pain elicited by 1.32μm laser was independent upon the pulse duration when the exposure time ranged from 8ms to 1s. Under the same exposure condition, the threshold of cutaneous pain elicited by 1.32μm laser was higher than that elicited by 10.6μm laser.