The Thermal Damage of Canine Vocal Fold by CO Laser Under Different Laser Emission Mode.

OBJECTIVE

The purpose of this study is to review the differences between continuous wave (CW) and UltraPulse (UP) on thermal damage of the laser with different power.

METHODS

Four adult beagle dogs underwent transoral laser microsurgery (TLM) using CO laser. The laser emission mode and power was CW (3 W, 5 W, and 8 W) and UP (3 W and 5 W), respectively. The tissue from 4 animals was evaluated histologically on postoperative days 1 and 3. The thermal damage of the laser was measured using slide scan system via SlideViewer version 1.5.5.2 software.

RESULTS

All dogs underwent TLM uneventfully. Under microscope examined, the laser damage area was composed of 2 parts: the vaporized zone (VPZ) and thermal damage area. The thermal damage area can be divided into thermal coagulative necrosis area (TCN) and hydropic degeneration area. The width of VPZ and TCN in UP mode was less than that in CW mode ( < .01). The data indicate that lower laser power created less thermal damage ( < .01). In addition, the width of VPZ on postoperative day 3 was less than that on postoperative day 1 ( < .01).

CONCLUSION

CO laser with UP and lower power could decrease the laser thermal damage and may offer more prompt wound healing.