The relationship of different power settings and fiber geometries to thermal tissue damage created by the superpulse Nd:YAG laser.

We attempted to quantify the amount of thermal damage that was created to surrounding tissues when an incision was made with the superpulse neodymium:yttrium-aluminum-garnet (Nd:YAG) laser with the optical fiber in contact. Light micrographic studies of several incisions, at different laser power settings and with different fiber geometries, were made in the anterior abdominal wall of 16 Sprague-Dawley rats. The specimens were collected immediately postoperatively and at 48 hours postoperatively. Several laser power settings (2-50 W) and seven different optical fiber geometries were studied. The micrographs showed minimal damage (<0.1 mm) to surrounding tissues at all laser power settings in both the immediate and the 48-hour studies. The superpulse Nd:YAG laser with optical fiber contact limited laser thermal damage to the surrounding tissues to less than 0.1 mm in the range of power settings studied. Higher power settings minimally increased the damage. The geometries of the optical fiber created no significant alteration in thermal damage. The results suggest that the superpulse Nd:YAG laser creates both thermal and photodisruptive effects in tissue.