Nd:YAG laser irradiation in conjunction with cryogen spray cooling induces deep and spatially selective photocoagulation in animal models

Successful laser treatment of haemangiomas requires selective photocoagulation of subsurface targeted blood vessels without thermal damage to the overlying epidermis. We present an in vivo experimental procedure, using a chicken comb animal model, and an infrared feedback system to deliver repetitive cryogen spurts (of the order of milliseconds) during continuous Nd:YAG laser irradiation. Gross and histologic observations show deep-tissue photocoagulation is achieved, while superficial structures are protected from thermal injury due to cryogen spray cooling. Experimental observation of epidermis protection in chicken comb animal models suggests selective photocoagulation of subsurface targeted blood vessels for successful treatment of haemangiomas can be achieved by repetitive applications of a cryogen spurt during continuous Nd:YAG laser irradiation.