Pulsed exposure mode of the 445 nm semiconductor laser in phonosurgery: an experimental study

The study presents the results of an experimental study devoted to the choice of the most optimal mode of pulsed contact laser exposure of semiconductor laser with a wavelength of 445 nm in phonosurgery, which implies maximum preservation of anatomically and functionally significant structures of the larynx combined with a radical approach to the pathological process. From the standpoint of the mucoundular theory of voice formation, wave-like oscillations of the vocal folds are possible due to the mobility of the cover layer of the vocal fold (epithelium, superficial layer of the lamina propria) relative to its body (deep layer of the lamina propria, vocal muscle). Thus, any injury at the level of the integumentary layer is associated with the risk of excessive scarring and loss of the ability to wave-like sliding. Pig vocal folds, according to a number of authors, have a structure similar to human ones in terms of both histological structure and acoustic parameters, which justifies the rationality of their use as an experimental model. In a series of experiments using a 445 nm laser, contact pulsed impacts on a biological model were carried out with pulse durations of 10, 20, 50, and 100 ms, followed by evaluation of the following parameters based on the data of histological sections: the depth and width of the ablation crater, the width of the zone of lateral thermal damage. Thus, the most optimal for phonosurgical interventions modes of pulsed laser exposures with a wavelength of 445 nm are described.