Introduction. The problem of phonosurgery remains relevant today since the prevalence of benign and tumor-like laryngeal lesions is up to 55%–70% among diseases of the upper respiratory tract. Photoangiolytic lasers are actively used among laser systems in phonosurgery today. A new 445 nm surgical laser (TruBlue, A.R.C. Laser Company), having a high hemostatic and resection effects, was certified for the medical market in 2018. TruBlue laser operation is possible in an atmosphere of inert gas (helium) by connecting the optional Flow Control unit. To date, there are very few works in foreign and Russian literature devoted to the use of that laser device in ENT practice, particularly, in laryngology. Objective. To select the optimal 445 nm laser mode for use in phonosurgery based on an experimental study of biological material. Material and methods. An experimental study was conducted on a model of the larynx (chicken muscle tissue) using a 445 nm laser in contact constant and pulsed modes, including an atmosphere of an inert gas (helium). The zones of destruction, coagulation necrosis, and ischemia were measured by histological examination using a morphometry system. The total number of experiments was 142, the total number of micro-preparations studied was 284. Results. While working in continuous wave mode, we received an extensive zone of thermal exposure, which in clinical practice correlates with deep damage of the vocal fold and violation of its vibratory function. This confirms the axiom that the optimal mode for laryngeal surgery is a pulsed one. According to the evaluation results of the pulse mode at standard laser settings (without helium supply), the parameters with the smallest pause between pulses—that is, 8 W pulse 10–20 ms, 9–10 W pulse 10 ms with a pause of 150 ms—were the most optimal for practical activity in terms of combined resection and coagulation effect. These parameters are acceptable for use in phonosurgery since the maximum destruction zone does not exceed 600 nm. While working in an inert gas atmosphere, we recommend using a laser at a power of 6–8 W with a pulse duration of 10 ms and a pause of 100–130 ms; with an increase in the pulse, lengthen the pause 6–7 W 20 ms 120–130 ms, 8 W 20 ms with a pause of 130 ms. Conclusion. During the experiment, blue laser showed high resection and coagulation effects. According to the results of the study, the parameters of laser exposure were obtained, which are optimal for the surgical treatment of benign and tumor-like laryngeal lesions.
Compliance with standardized conditions for the use of lasers and the development of modes in experimental conditions is one of the main factors that make it possible to safely use a laser in surgical practice. To date, a new 445 nm blue laser has now become available for otorhinolaryngologists. The use of this type of laser in rhinosurgery requires some both experimental and clinical studies that will help signal the possibilities and limitations of the use of this laser. Objectives: Choose the safest and most sparing mode of exposure to a laser with a wavelength of 445 nm for rhinosurgery. Materials and methods: The experimental part of the study was carried out on samples of biological tissues with optical properties close to the tissues in the nasal cavity. As a biological model, preparations of chicken muscle tissue and preparations of chicken liver tissue were selected. A new laser with a wavelength of 445 nm was used. The results of the microscopic picture were evaluated by histological examination. The study was carried out using a biological microscope Biolam M-1 (JSC “LOMO”, Russia), with standard magnification of 100 times. Staining of histological preparations was carried out according to hematoxylin-eosin, trichrome according to Masson. To measure the specified parameters, the VIDEOTEST system for morphometry was used. Conclusion: A laser with a wavelength of 445 nm in the experiment showed the possibility of using it in a constant contact mode. The obtained results of the maximum depth of damage when using a laser with a wavelength of 445 nm suggest the most sparing and safe modes of using the laser in surgical practice.
Intraoperative bleeding impairs visualization of the surgical field. Working in a practically bloodless operating field reduces the duration of surgery and reduces the need for cautery use, which reduces pain in the postoperative period and the risk of delayed bleeding after tonsillectomy.Objective – to select the parameters of a diode laser with a wavelength of 970 nm in order to get optimal hemostatic effect and to develop a technique for safe preventive coagulation of vessels in the surgical wound using diode laser with a wavelength of 970 nm for their bloodless section.Materials and methods. 47 Wistar rats weighing 300–400 g were used in the experiment. After preparation of the surgical field, three groups of vessels were isolated from each rat. The rat vascular bed was used as a model of tonsillar vascular bed in the patients undergoing tonsillectomy. All animals were divided into groups, depending on the laser power. For the experiment we used a diode surgical laser with a wavelength of 970 nm in a constant mode, a fiber diameter of 400 microns. After coagulation of each vessel, a visual and microscopic assessment of the vessels was performed. The study of the possibility of vascular coagulation was evaluated after the vessel was cross-sectioned with a scalpel.Results. Damage to the walls of blood vessels was not observed at powers from 5.0 W to 7.0 W. At the same time, at the laser power from 5.0 W to 6.0 W there was no hemostasis after crossing the vessels. At a power of 6.5 W, adequate hemostasis was observed only in 42 % of cases. The coagulation mode of a diode laser with a wavelength of 970 nm, which is the most effective and safe for surrounding tissues, was observed at a power of 7.0 WConclusions. Exceeding the power levels of a diode laser with a wavelength of 970 nm leads to the formation of carbonization of the surrounding tissues, to a damage of the vascular wall. In order to prevent bleeding, arteries with a diameter of more than 1.5 mm must be stitched. Small vessels with a diameter of less than 0.4 mm do not require preventive coagulation and can be coagulated during the incision with a laser fiber.
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