Laser surgery in otolaryngology: interaction of CO2 laser and soft tissue.

The sequence of histological change induced by CO2 laser irradiation was discussed in terms of two factors: the physiomechanical factor and the physiochemical factor. At sufficiently high heat energy levels, the immediate findings are characterized by crater formation resulting from rapid vaporization of the water and ejection of the solid component. In the immediate vicinity of the crater edge, the maximum tissue temperature rise is 65 degrees C above the 32 degrees C ambient tissue temperature and it decreases to the primary tissue temperature within a distance of 2 mm. The healing process of CO2 laser induced lesions proceeds with minimal delay. The lymphatic and vascular channels are occluded in the marginal area of coagulation resulting in a marked hemostatic effect. This sealing effect increases the margin of safety in preventing possible dissemination of tumor cells. By selecting the appropriate power, time, and focus cone angle, precise destruction of preselected areas of tissue can be achieved with an extraordinary hemostatic effect without damaging the underlying tissue. These advantages are especially helpful in function-preserving surgery.