| Aim:Following the development of all kinds of diagnostic technology, the fully exposure of laryngeal disease, even the little changes of the mucous membrane of vocal cord can be diagnosed. Especially following the development of the diagnosis of early glottic carcinoma, it precipitates the doctors to resect the process part in traditional medical treatment. And the doctors must consider and change the ideas of the Curative treatment of carcinoma and super Curative treatment. This kind of consideration and changes promoted emergence and development of phonomicrosurgery. At the same time , because of the maturation of laser's research and application in medical realm with each passing day, it is extensively applicated in clinical microsurgery treatment, moreover we accumulate a lot of effective cases. Using laser surgery to treat laryngeal disease is more than 30 years until now. The development of laser surgery is very fast. Applicating laser specially CO2 laser to resect early glottic carcinoma is the personification of clinical microsurgery treatment in head and neck tumor treatment. It not only has well treatment effect but also can satisfactorily protect laryngeal function . Recently, expect glottic carcinoma, it is reported that there are many successful cases abroad which utilize laser microsurgery to treat hypolarynx and supraglottic carcinoma. So it has superiority signification. It was accepted by more and more scholars to treat laryngeal glottic disease, especially laryngeal glottic precancerous lesion and early carcinoma. This test researches the response and biological effect of different energy of CO2 laser cutting and carbonizing for nomal tissue. It also directs the operation indication, ablated extend and the meaning to recover which using CO2 laser to treat laryngeal glottic benign lesion and early laryngeal carcinoma. And it contains the notices and methods in preoperative; intraoperative; postoperative.Methods:Choose a healthy hybrid dog to do the animal test. Use non-contact punctiform pulse laser to irradiate the dog's laryngeal mucous membrane tissue. It's irradiated by 2.8-11.1W power, 500Hz pulse frequency, 1.4mm light spot diameter, 50-250 pulse number. We can use the microscope to observe the sample at once after irradiating. Then measure the diameter of crater. Use acute scalpel to completely get the irradiated laryngeal. Fix it in 2% glutaraldehyde. Pathological observe biological effect the depth of thermal damage and the damaged degree for surrounding tissue. The judgement of acute thermal damage results: After laser irradiating, using naked eye to observe the changes of surface of mucous membrane. Use micrometer to measure the biggest diameter of ablation crater under the microscope. Then use this biggest diameter as the width of acute thermal damage. Cut it according to the central vertical surface of mucous membrane, and the bottom of the damaged tissue is comma. Use the basal part as the depth of acute thermal damage. Cut off about 1.5×1×lcm tissue of the damaged part,and fix it in 10% formalin. Routine paraffin section, HE staining, observe the biological effect, the depth of thermal damage and the damaged degree for surrounding tissue under light microscope at different parameter.Results:After irradiating, use naked eye to observe the results. Under less light, as the light dose increasing, tissue sample appears tissue dehydration in turn. Then there is white coagulation on the surface. The area of white coagulation adds more and more according to the light dose. The texture of the tissue becomes hard. Under more light dose, as the light dose increasing, light spot region uplifts, and the center of the caelate part appears blasting. It emerges ablation introcession. The edge of introcession has fuscescent burning. When ablation occurs, we can see spark and smog and hear crackling sound. Under more light dose, the spatter what suspected to be the tissue debris could be observed. The tissue will appear conspicuous contraction. The shape of ablation introcession of pulse laser is regular and planus. It is just like incident beam. Under two kinds of light dose, the diameter of ablation introcession is different. And they all occur burning. When radiant exposure is 324.7mJ/mm2, the diameter of ablation introcession becomes smaller. Burning mainly appears in the middle of the introcession. When radiant exposure is 1363.6mJ/mm2, the diameter of ablation introcession becomes bigger. Burning mainly appears at the edge, and the bottom of the introcession is very smooth. This test shows the diversify history of the depth of the ablation introcession which changes according to the light dose. At the same time this test shows the degrees of damage at each layer of vocal cord under different energy of CO2 pulse laser. In general, the depth of crater becomes larger and larger with the accrescence of light dose. The depth of the crater increase faster under less radiant exposure. When it reach a certain value, the increasing becomes gently .The depth of mucous membrane of vocal cord tissue thermal damage and the damage degree of the surrounding tissue is obviously different under different radiant exposure when we use light microscope to observe it . Following the accrescence of radiant exposure, the layers of thermal damage of mucous membrane of vocal cord becomes more and more and gradually from epithelial lining to muscular layer.Conclusions:Laser output radiant exposure has important significance for the ablation effect of glottic mucous membrane tissue. The depth and width of tissue thermal damage becomes accrescence with the increace of laser radiant exposure. There is linear relationship. Through animal test, this research preliminarily observes the relationship between CO2 laser radiant exposure and thermal damage for the tissue of laryngeal mucous membrane. Moreover, Laser output radiant exposure has important significance for the ablation effect of glottic mucous membrane tissue. During the dose of the experiment, in a certain exposed time, the width of thermal damage of the tissue and radiant exposure has linear relationship. But there isn't simple linear relationship between the depth of thermal damage of the tissue and laser radiant exposure. They all can predict the degree of thermal damage of the tissue under some radiant exposure through regression equation. Observing through light microscope, the depth of mucous membrane of vocal cord thermal damage of the tissue and the degree of surrounding tissue's damage are obviously different under different radiant exposure of laser. The relationship between radiant exposure of CO2 laser and the degree of laryngeal mucous membrane tissue ablation obtained in this research is different from the result of extent of ablation of soft tissue under CO2 laser irradiance reported in literature. This kind of difference mainly comes from the differences of laboratory apparatus and samples preparation. The result of the research showed that applying suitable pulse CO2 laser of dose parameter through non-contact irradiation is safe and effective in laser treatment. And this can obtain better effect of cutting and carburation. Through laser microsurgery, especially the technique of pulse and super pulse laser, we can adjust both its luminance and intensity. Moreover we must ensure the penetrating depth and precisely calculate the output power and the exposed time. The projection of laser light spot can contract very much, mini- cutting can only produce 5-100μm damage. This equals to 5 to 10 cells. The accuracy is very high and it can't make normal tissue's damage. CO2 laser is suitable for many kinds of laryngeal benign proliferative lesion and precancerous lesion and early stage of laryngeal carcinoma. According to the results in this research, we can use this CO2 laser device to select suitable energy for different lesion. It's possible to reserve the vocal function when we operate in cover layer of vocal cord and make the damage for Reinke's layer as little as possible during the treatment. |
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