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Involving high-power lasers into clinic medicine significantly extended the possibilities of the endoscopic surgery, which in a number of cases becomes a serious competitor to the traditional surgical methods of treatment14. Endoscopic surgery lowers the intervention risk, reduces the terms of patient's hospital treatment, the patient's activity can be restored in a shorter post-operational period and a possibility appears of carrying out complex operations in ambulance conditions. Endoscopic operations nowadays are made using mostly a continuous YAG: Nd laser with operating wavelength 1.06 1um. However, there exist serious restrictions on use of this type of radiation for the endoscopic surgical interventions at the gastrointestinal organs. They are connected with wall perforation risk .Endoscopicusing of a CO2 -laser, which works as an excellent scalpel in general surgery, is connected with technical difficulties of 1.06Mm radiation transmission by a flexible light guide. Moreover, the the hemostatic properties of this kind of radiation are rather limited. The specified above reasons stipulated that the practical medicine be interested in solid YAG-Cr-Tm: Ho lasers with wavelength range of 2,um and their application in the endoscopic surgery. Few published (including our own) results of biological investigations of biological experiments on the exploration of 2,um laser radiation affect at different tissues9 allow us to talk about the following. This radiation approaches to 10.6 1tim CO2 -laser radiation by its cutting effect to the soft tissues. However, its properties are opposite to the effect of volumetric coagulation which is inherent in 1.06 1um YAG: Nd laser radiation. It is known that protein compounds, pigmental components and blood ifiling extent have a smaller impact on the absorption of medium 1.5-3 1um JR wavelength range in biological tissues than absorption of visible and near JR radiation. For the increasing wavelength the impact of water on the absorption process is predominant. For the 1.06 ,um wavelength radiation the coefficient of radiation absorption in water is --0.6 cm whereas for wavelength 2.09 um it is'° '5O cmi. Theoretical estimation for the penetration depth of visible and JR laser radiation demonstrates that for 1.06 4um radiation it may reach 5-10 mm, and for 2 1tim radiation it is no more than 1-1.5 mm (Fig.1). That is, a significant (comparing with 1.06 1iim radiation) surface localization of secondary heat supply in tissue during its irradiation by 2 1um radiation takes place, therefore, a higher absolute temperature values as well as temperature gradient in the tissue irradiation epicenter appear. So, one can create conditions with equal energy input for a more intensive thermal destruction of tissues, accompanied by processes which determine the efficiency of tissue dissection: water vaporization, protein component sublimation and active removal of interaction products from the application zone.
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