Experimental Research On Different Power CO₂Laser For Benign Lesions Of Vocal Cords

Objective To explore the suitable CO₂laser power used in treatment of laryngealbenign lesions by observing the different CO₂laser power surgery on benign lesions ofvocal cords of dogs. At the same time, the experiment provides certain experiment basis forCO₂laser treatment of laryngeal benign lesions.Methods Thirty experimental dogs were randomly divided into A, B, C, D, E fivegroups. There were six dogs in one group; vocal sub-mucosal resection under the sameirradiation time （0.1s）, irradiation mode （ultra pulse mode）, different output power （1w,3w,5w and8w） of the CO₂laser （light spot diameter is0.1mm-0.2mm） and cold instruments.Remember to respectively observe the wound and repair in general form under electronlaryngoscope in2hours after operation.1st week and4th week, we each executed two dogs,by cutting the vocal cord tissues, partly by HE staining, VG staining and Periostinimmunohistochemistry staining observation of inflammatory cells, fibroblasts, capillarydensity and the content and distribution of collagen fibers. Another part by scanning andtransmission electron microscopy observation of microvilli on the surface of the vocal cordsand the change of vocal cord structure at all levels.Results electronic laryngoscope: healing of the wound of C （5w）, D （8w） groups isheavier and slower than that of A （1w）, B （3w）, E （cold equipment） groups. Pathologicalsection microscopically: the damage depth of the vocal cords of A, B, E groups are limited tothe mucosa and sub-mucosa; while deep shallow or middle ligament injury of C, D groups.The density of inflammatory cells, the density of fibroblasts, capillary density and collagenfiber determination: C, D groups higher than that in groups of A, B, E, with significant difference （all P <0.05）; no significant difference （P>0.05） in A, B and E groups. VGstaining and Periostin immunohistochemistry staining observed under scanning andtransmission electron microscopy: A, B, E groups of vocal cord repair process, there were nosignificant difference;compared with C, D groups, there were obvious difference.Conclusions Postoperative analysis of CO₂laser （1w） group, B （3w） group and E（cold equipment） for vocal sub-mucosal resection of dogs: no difference between the set ofmacroscopic observation, and microscopic tissue repair process is similar. Sub-mucousresection of the vocal cords with tiny flare （0.1⁰.2mm） in diameter, low power （1³w）、ultra pulse mode CO₂laser, the tissue damage are lighter, similar to cold equipment operationby the naked eye and microscope tissue repair process. The conclusion clinically has a highreference value on CO₂laser treatment of laryngeal benign lesions.