Effect of Power Density and Carbonization on Residual Tissue Coagulation Using the Continuous Wave Carbon Dioxide Laser

ABSTRACT

Ninety-eight incisions were made into the dermis of mongrel canines by an experienced laser surgeon and by a student to confirm previous studies demonstrating decreased thermal damage using pulses of a continuous wave carbon dioxide (CO₂) laser. This study was designed to examine the acute biologic effect. Power densities from 30 W/cm² to 19,000 W/cm² were used for incisional vaporization. Coagulation of the tissue adjacent to the vaporized crater was measured microscopically using hematoxolin and eosin histologic stains. Maximum and minimum depths of coagulation were measured. Pulsed mode of the continuous wave CO₂ laser caused a statistically decreased maximum and minimum coagulation than the continuous mode. The range between the maximum and minimum depths of coagulation overlapped at all power densities. Increasing thermal effect was noted with continuous mode at power densities of 4800 W/cm² and less and in the pulsed mode with power densities of 2375 W/cm² and less. This thermal coagulation increased as carbonization increased and was maximal with a 2700 μm depth of coagulation at 30 W/cm².