The expanding use of endoscopic technologies for diagnosis and treatment, coupled with the unfavorable epidemiological situation, has increased the relevance of the issue of endoscopic equipment reprocessing. Reprocessing endoscopes, particularly flexible endoscopes, is a problem not only in Russia. This topic has been studied and discussed in many countries for several decades. And in most of them, certain progress has been achieved, with the development of documents regulating this area. Professional organizations of endoscopists, nurses, and specialists in epidemiology and infection control are particularly active in the development of such documents. These organizations, as well as endoscope manufacturers, provide the same endoscope reprocessing algorithm, including pre-cleaning, final cleaning (mechanical cleaning), high-level disinfection, or sterilization. Pre-cleaning is performed immediately after the procedure (removal of the endoscope from the patient) and consists of wiping the insertion portion with a cloth moistened with water or a cleaning solution. Pumping water or a cleaning solution through the endoscope channels and cleaning the water/air supply channel are performed. After preliminary cleaning and before immersion in the cleaning solution, a leak test is performed in accordance with the equipment manufacturer's recommendations. If a leak is detected, follow the equipment manufacturer's instructions for further processing of the endoscope to prevent more serious damage. Final cleaning (mechanical cleaning) involves disconnecting all removable parts and components, soaking them in a cleaning solution, cleaning them with special brushes and wipes, and then thoroughly rinsing with water. The endoscope is completely (if permitted by the endoscope manufacturer) immersed in the cleaning solution, and its external surface is thoroughly cleaned. Then, the aspiration and biopsy channels are thoroughly cleaned with a brush. When the brush emerges from the opposite end of the channel, its end is thoroughly cleaned. Cleaning is continued until the brush is clean. Cleaning adapters are attached to the endoscope, the endoscope is immersed in the solution, and the channels are rinsed until no more contaminants are flushed from the channels. The cleaning stage is completed by rinsing the external surface, all channels, and removable components of the endoscope with running water to remove any remaining detergent. All channels are then blown with air, and the external surface of the endoscope is dried with wipes. Removing water is necessary to prevent dilution of the disinfectant. High-level disinfection or chemical sterilization is performed by immersing cleaned, rinsed, and dried endoscopes and removable components in a high-level disinfectant/sterilant. Using a cleaning adapter, fill all channels with the disinfectant/sterilant until air bubbles no longer appear. High-level disinfection/sterilization is performed according to the modes indicated on the product label, setting the timer for the required immersion time. High-level disinfection is used for endoscopes that do not enter sterile cavities, such as gastroscopes, colonoscopes, and bronchoscopes. High-level disinfection is acceptable for cystoscopes and hysteroscopes, although some recommend sterilization. Sterilization is used for endoscopes that enter sterile cavities and tissues, such as laparoscopes, arthroscopes, angioscopes, and neurofibroscopes. After the exposure period, all surfaces and channels of the endoscope and removable components are thoroughly rinsed with water to remove all traces of disinfectant, after which all channels are air-dried. Before storage, the endoscope must be thoroughly dried and all channels must be rinsed with 70-90% alcohol. This procedure facilitates the complete removal of moisture from the channels and prevents the growth of microorganisms that may be present in the water during storage. While endoscope types and their applications vary, they share common features. Firstly, there's the complexity of the design: multiple channels with a diameter of 2-4 mm and a length of 65 cm to 2.4 m, optics or video devices, a large number of components, and a combination of several different materials (metals, plastics, adhesives and cements, lenses, and others). During the procedure, contamination occurs not only on the outer surface of the working part inserted into the patient's body, but also on all channels, valves, and even the control unit. Secondly, endoscopes, especially flexible ones, are sensitive to various influences: physical, mechanical, and chemical. Thermal instability—sensitivity to high temperatures—is due to the inclusion of a large number of plastics, optical fibers, and other materials in the design. Rigid endoscopes (their metal parts) are generally autoclavable, as specified by the equipment manufacturer. However, most flexible endoscopes, such as those for the gastrointestinal tract and bronchi, cannot be subjected to high-temperature processing. Adverse mechanical stress is particularly noticeable during cleaning. Cleaning, like all other aspects of endoscope reprocessing, must be performed in strict accordance with the endoscope manufacturer's recommendations. Improper cleaning of the channels can cause serious damage to the integrity of the channel jacket. Excessive mechanical removal of dried or embedded contaminants is unacceptable, especially with hard brushes, metal mandrels, or other sharp or cutting objects. Chemical agents have different compatibility profiles with different materials. Data obtained from the endoscope manufacturer is based on extensive testing of specific equipment and is the key to its safety. Therefore, the products used for endoscope reprocessing must ensure effective cleaning, high-level disinfection, or sterilization without adversely affecting the materials. Given the large number of procedures involved, reprocessing time should be kept to a minimum and not exceed 1 hour. Cleaning agents based on various active ingredients are used. The cleaning mechanism when using detergents based on surface-active agents (surfactants) is as follows: surfactants promote water penetration into contaminants, causing them to swell and soften. These contaminants are then removed mechanically using special brushes. The quality of cleaning depends on how thoroughly contaminants are removed during mechanical cleaning. Due to the complex design of an endoscope, there are many areas where mechanical cleaning is extremely difficult, and sometimes even impossible. Products containing aldehydes and alcohols should not be used for cleaning complex, expensive equipment. These components cause protein fixation, negating the cleaning action of detergents such as surfactants. For cleaning endoscopes, it is recommended to use enzymatic detergents specially designed for endoscopes; their mechanism of action is based on the active breakdown of contaminants by enzymes. Surfactants included in the detergent facilitate better enzyme penetration into contaminant aggregates. These products remove not only fresh but also ingrained contaminants, cleaning hard-to-reach areas. There are monoenzyme products containing a proteolytic enzyme as the main active ingredient, and polyenzyme preparations that combine the action of various enzymes—protease, lipase, and amylase. Proteolytic enzymes are most often included in endoscope cleaning products, as most contaminants containing potentially dangerous pathogens are protein-based, such as blood. Products containing proteolytic enzymes are more effective if they are the only enzyme present. This is because when several enzymes are combined in a product, the more active protease breaks down other enzymes, as well as contaminants consisting of protein chains. As a result, both the overall cleaning activity of the product and the effectiveness of removing protein contaminants are reduced. Working solutions of cleaning products, especially enzymatic ones, are most active when they are freshly prepared and used only once. If the solution's appearance changes (flaking, color change, etc.), the detergent solution should be replaced. The effectiveness of high-level disinfection and chemical sterilization with solutions is influenced by factors related to the object being disinfected, such as the quality of the object's cleaning and the extent of organic contamination, the type and intensity of microbial contamination, the physical configuration of the object (e.g., the presence of depressions, joints, or gaps), as well as the parameters of the disinfectant solution and exposure time, such as the concentration of the active ingredient (AIO) in the solution, the solution temperature and pH, and the exposure time. For high-level disinfection, use products registered for chemical sterilization at a temperature of 20-25?C. In this case, only the exposure time—the concentration of the solution—is reduced. Its temperature and all other parameters remain the same as when the solution is used for sterilization. For high-level sterilization and disinfection solutions, the minimum effective concentration (MEC) must be determined. This is the minimum concentration of the active ingredient required to achieve the stated microcidal effect of the solution: for chemical sterilants, this is a 6-log reduction in spore counts; for high-level disinfectants, this is 100% destruction of Mycobacterium tuberculosis. Determining the MEC is necessary if the solution is approved for repeated use. As is well known, during the use of a sterilization or disinfection solution, it is diluted with water used to rinse the endoscope, contaminated with proteins poorly removed during cleaning, contaminated with cleaning solution remaining in the channels, and evaporation of some disinfecting agents, such as glutaraldehyde, from the solutions. All of this leads to a decrease in the microcidal activity of the disinfectant/sterilizing solution. The longer the time of use and the more treatments performed with it, the faster the decrease in the solution's activity. Therefore, for sterilizing/disinfecting solutions marketed for repeated use over a period of 1 day or more, not only an MEC is established but also a mandatory method for monitoring the active ingredient concentration in the solution. The shelf life of the working solution should not be confused with the maximum period of its reuse. The shelf life of the working solution is the period during which the initial solution parameters, such as active ingredient concentration, pH, and microcidal activity, are maintained prior to use, i.e., prior to the first immersion of an endoscope. From the moment of use, due to dilution and contamination, the solution parameters, especially the active ingredient concentration, will change, and with this, its microcidal activity will decrease. The shelf life of the working solution only guarantees that a solution stored but not used for the specified period has the same microcidal properties as a freshly prepared working solution. The rate at which the solution's activity will decrease after several treatments, even within the first 24 hours of preparation, cannot be predicted. The maximum reusability period of a solution determines the period during which the stated microcidal activity is maintained, and the active ingredient concentration does not fall below the maximum acceptable level (MAC). To determine this period, tests are conducted to confirm the microcidal activity of the solution both at its initial concentration and at the maximum acceptable level (MAC), including in the presence of a protein load, which reflects "worst-case" situations and massive organic contamination. The maximum reusability period provides only approximate guidelines: the solution lifespan will differ between two and fifteen endoscope reprocessings per shift. Only chemical methods can accurately determine the active ingredient concentration and the activity of a solution during repeated use. However, conducting such tests sometimes requires a well-equipped chemical laboratory. Furthermore, this would significantly delay the endoscope reprocessing process, which is highly undesirable. To facilitate the determination of the active ingredient concentration in a solution used multiple times, rapid testing devices in the form of indicator test strips have been developed. This is a quantitative and qualitative method that allows one to quickly determine whether the active ingredient concentration in a solution has dropped below the MEC by observing the color change of the indicator pad. Indicator test strips cannot be used to extend the shelf life of the solution beyond the stated expiration date. This means that a solution with a shelf life of 7 days must be discarded after this period, even if the indicator strips indicate that the active ingredient concentration exceeds the MEC. This is because the properties of a solution are determined not only by the active ingredient concentration but also by other parameters. While the microcidal properties of the solution may be maintained, its effect on materials and other properties may change. When selecting a high-level sterilization and disinfection agent, where the quality of treatment is crucial for patient safety, it is important to consider the possibility of repeated use of these solutions. Only reuse of solutions for which the MEC has been determined and for which active ingredient monitoring tools and methods, such as test strips, have been developed can be considered safe for patients. For other solutions, a single use is recommended as a sterilization or high-level disinfectant. Glutaraldehyde solutions are most widely used for high-level sterilization and disinfection. Most aqueous glutaraldehyde solutions are acidic and require activation (alkalinization to a pH of 7.5–8.5) to achieve sporicidal activity. Acidic glutaraldehyde preparations that do not require activation are also available; however, studies have shown that their antimicrobial activity is lower than that of alkaline preparations. Unlike many disinfectants, glutaraldehyde is highly resistant to the inactivating action of organic contaminants. The shelf life of activated solutions is up to 14 days. The MEC for glutaraldehyde is 1.5%. Solutions with a glutaraldehyde concentration of 1% or less do not guarantee the destruction of atypical and resistant forms of mycobacteria. The initial concentration of alkaline glutaraldehyde solutions used for chemical sterilization and high-level disinfection and subject to repeated use should not be below 2%. Studies have shown a decrease in glutaraldehyde concentration from 2.4 to 1.5% within 10 days of use, as well as below 1%, and even to 0.27%, on the fourth day of repeated use. Therefore, when using glutaraldehyde solutions repeatedly, to ensure effective disinfection and sterilization, it is imperative to monitor the concentration of the active ingredient using indicator test strips. Indicator strips are generally designed to detect glutaraldehyde concentrations above 1.5%. The frequency of measurements depends on how frequently the solutions are used; optimally, before each immersion of the endoscope. The solution should be considered unsafe even for single use if the measured glutaraldehyde concentration does not exceed 1%. Орто-фталевый альдегид является новым продуктом, разрешенным для проведения дезинфекции высокого уровня. Препарат широко применяется в США и других странах. В отличие от глутарового альдегида, представляющего собой летучую жидкость, орто-фталевый альдегид — твердое вещество, хорошо растворимое в воде. Природой действующего вещества объясняются высокая активность средства, особенно в отношении микобактерий, отсутствие резкого запаха, устойчивость к разведению водой и загрязнению органикой, стабильность раствора в широком диапазоне рН — от 3 до 9, отличная совместимость с материалами. Для дезинфекции высокого уровня используется готовый раствор с концентрацией орто-фталевого альдегида 0,55%. Максимальный срок повторного использования составляет 14 дней. Для контроля концентрации орто-фталевого альдегида при повторном использовании растворов разработаны и используются индикаторные тест-полоски. МЭК для орто-фталевого альдегида составляет 0,3%. Количество циклов обработки, проведенных в одном и том же растворе орто-фталевого альдегида до момента снижения концентрации АДВ до МЭК, в два раза превышает таковое для 2% раствора глутарового альдегида. В настоящее время орто-фталевый альдегид считается одним из наиболее перспективных заменителей глутарового альдегида, обладающих необходимыми активностью и безопасностью оборудования и для человека. Обработка эндоскопического оборудования была и остается сложной для решения задачей. Эффективность этой процедуры зависит от многих факторов: тщательности выполнения каждого из этапов обработки, правильности выбора средства для очистки и дезинфекции высокого уровня, правильности использования растворов выбранных средств. Только при понимании всех особенностей процедуры обработки и соблюдении всех требований возможно обезопасить пациента от инфицирования в ходе эндоскопической манипуляции и сохранить дорогостоящее оборудование. Библиография: 1. Alvarado C., Reichelderfer M. APIC guideline for infection prevention and control in flexible endoscopy, — American Journal of Infection Control, 1994. — Vol. 2, pp. 19-38. 2. MacDonald E. Rigid Endoscopes: Proper Care and Maintenance. — Journal of the Association of Operating Room Nurses, 1984. — Vol. 39, № 7, pp. 1236-1244. 3. Rutala W., 1994, 1995, and 1996 APIC Guidelines Committee. APIC guideline for selection and use of disinfectants. — American Journal of Infection Control, 1996. — Vol. 24, pp. 313-342 4. Rutala, W.A., Weber, D.J., Disinfection of Endoscopes: Review of new chemical sterilants used for high-level disinfection. — Infection Control and Hospital Epidemiology, 1999. — Vol. 20, pp. 69–76. 5. Systchenko R., Marchetti B. et al. and the Council of the French Society of Gastrointestinal Endoscopy. Guidelines of the French Society for Digestive Endoscopy: Recommendations For Setting Up Cleaning and Disinfection Procedures In Gastrointestinal Endoscopy. — Endoscopy, 2000. — Vol. 32, № 10, pp. 807 — 818.