WOUND-HEALING AND SOFT-TISSUE EFFECTS OF CO2, CONTACT ND-YAG AND COMBINED CO2-ND-YAG LASER-BEAMS ON RABBIT TRACHEA

Rabbit trachea was used as an experimental model to study tissue effec ts and healing of full-thickness tracheal lesions produced by CO2, con tact 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 l asers. 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(R). Histological specimens for light and transmission electron microscopy were prepared immediately and 1, 3, 5, 7, 14 and 21 days postoperativ ely. The wound with the most precise and fastest healing was produced by contact Nd:YAG laser. CO2 laser produced a moderate amount of charr ing and the largest amount of coagulated tissue with a slightly prolon ged healing period. In the acute phase, tissue defects produced by the Combolaser with power ratios 1:1 and 1.2 resembled the CO2 laser lesi ons but with slightly less charring. The power ratio 1:4 diminished th e cutting properties of the beam considerably. During the healing peri od the Combolaser produced the most intensive inflammation and granula tion tissue formation resulting in delayed regeneration of the lesion. In transmission electron micrographs the most severe damage to chondr ocytes was seen after using the Combolaser. These findings indicate th at the Combolaser produces deeper tissue damage than CO2 or contact Nd :YAG laser. However, the Combolaser appears to be suitable for tracheo bronchial operations, owing to its good simultaneous cutting and haemo static properties.