Wound Healing and Soft Tissue Effects of CO², Contact Nd: YAG and Combined CO²-Nd: YAG Laser Beams on Rabbit Trachea

Abstract

Rabbit trachea was used as an experimental model to study tissue effects and healing of full-thickness tracheal lesions produced by CO₂, contact Nd : YAG and combined, coaxial CO₂-Nd : YAG (Combo) laser beams. Two power settings (10 W and 16 W)were used with CO₂ and contact Nd: YAG lasers. Three different CO₂/Nd : YAG power ratios (1:1, 1 : 2 and 1 :4) and power settings (12 W, 15 W and 16 W) were used with the Combolaser®. Histological specimens for light and transmission electron microscopy were prepared immediately and 1, 3, 5, 7, 14 and 21 days postoperatively. The wound with the most precise and fastest healing was produced by contact Nd : YAG laser. CO, laser produced a moderate amount of charring and the largest amount of coagulated tissue with a slightly prolonged healing period. In the acute phase, tissue defects produced by the Combolaser with power ratios 1 : 1 and 1 : 2 resembled the CO, laser lesions but with slightly less charring. The power ratio 1 : 4 diminished the cutting properties of the beam considerably. During the healing period the Combolaser produced the most intensive inflammation and granulation tissue formation resulting in delayed regeneration of the lesion. In transmission electron micrographs the most severe damage to chondrocytes was seen after using the Combolaser. These findings indicate that the Combolaser produces deeper tissue damage than CO, or contact Nd : YAG laser. However, the Combolaser appears to be suitable for tracheobronchial operations, owing to its good simultaneous cutting and haemostatic properties.

Key Words:

• laser surgery
• tissue damage
• wound healing