1.1. Water. The quality of water used for processing has a significant impact on the safety of the instrument. Water performs various functions during processing, for example: - acts as a solvent for detergents and other process chemicals; - transfers mechanical stress and temperature to the instrument surface; - dissolves water-soluble contaminants; - washes away process chemicals; - provides thermal disinfection during machine processing; - is used for steam sterilization. Poor water quality can negatively affect both the processing method and the appearance and material of the instruments. Therefore, it is necessary to ensure the required water quality and quantity already at the design stage of plumbing equipment. Substances contained in water and their effect during processing. Any natural water contains salts. The composition and concentration of substances contained in drinking water varies depending on the origin of the water and the method of its extraction. Substances contained in water can cause the following problems: Hardness salts (calcium and magnesium salts) Formation of plaque and scale due to calcium and magnesium bicarbonate Heavy and non-ferrous metals, such as iron, manganese, copper Formation of reddish-brown plaque Silicates, silicic acid Multi-colored thin surface layers like glaze Chlorides Ulcerative corrosion Dry residue Stains and plaque In addition to natural impurities, rust is sometimes present in drinking water. It usually gets there from rusty pipes. When processing tools, rust settles on their surface, forms rusty stains and causes secondary corrosion. Aluminum can be damaged by softened water. [ /upload/medialibrary/423/1.jpg ] Damage to material by softened water. Hardness salts. Depending on the water hardness and temperature, hardness salts can cause the formation of a difficult-to-remove deposit (scale). Under certain conditions, corrosion can even begin under the deposit layer. Heavy and non-ferrous metals. The presence of heavy and non-ferrous metals and their compounds in water, even in low concentrations, can cause the formation of a colored deposit. Silicates. Silicic acid and silicates, even in low concentrations, cause the surface of the instrument to become colored from golden-yellow to blue-violet. Chlorides. Particularly dangerous are chlorides dissolved in water, which in high concentrations can cause, for example, pitting corrosion, including on stainless steel instruments. Harmful effects of chlorides: [ /upload/medialibrary/92d/2.jpg ] Pitting corrosion of an instrument under the influence of chlorides. In general, the likelihood of pitting corrosion under the influence of chlorides increases with: — an increase in the chlorine content; — an increase in the temperature; — a decrease in the pH; — an increase in the exposure time; — insufficient drying of the tool; — increase in concentration as it dries. The causal relationship between the chloride content in water and pitting corrosion is often unpredictable. Experience shows that at room temperature and a chloride content of up to 120 mg/l (equivalent to 200 mg/l sodium chloride = NaCl), the likelihood of pitting corrosion is negligible. As the chloride content increases, the likelihood of pitting corrosion increases sharply. Dry residue. When water evaporates, the substances it contains may remain as a visible mineral deposit. This may cause staining and/or corrosion. Due to the presence of impurities, it is not recommended to use natural drinking water for all processing stages. Depending on the application, drinking water must be softened or desalinated. The following methods can be used: Water treatment methods. Softening. During softening, the calcium and magnesium cations (hardness salts) contained in the water are replaced by sodium ions. As a result, however, the total impurity content of the water (dry residue) does not decrease. The alkalinity of softened water, depending on temperature, time, and the carbonate hardness of the source water, can increase significantly due to the formation of sodium carbonate. Demineralization. Before demineralization, it is necessary to remove all mineral impurities from drinking water as much as possible. For this purpose, reverse osmosis technology is used, as well as cation and anion exchangers, including a combination of both, and in special cases, distillation. Substances contained in the water, such as silicic acid, can cause discoloration. [ /upload/medialibrary/d9c/3.jpg ] Stains resulting from the action of silicic acid in steam condensate. Comparative example of water quality: Drinking water Softened water Demineralized water Dry residue (ppm) 500 530 5 Electrical conductivity (µS/cm) 650 700 3 Total hardness (C6) 14 <0.1 <0.1 Sodium salts (mg/l) 20 160 <1 Chlorides (mg/l) 40 40 <1 Silicates (ppm 5I2) 12 12 <0.1 pH value 6.7 8 5.5 Softened water: Based on experience in the mechanical processing of instruments, the following guideline values ??are recommended: Total hardness: < 3 °C1 (< 0.5 mmol CaO/l) Total salt content: < 500 mg/l Chloride content: <100 mg/l pH value: 5-8 Caution! When using softened water, especially for thermal disinfection, the high pH of the final rinse can damage anodized aluminum surfaces. Demineralized water. For steam sterilization, the following maximum requirements for potable water quality according to EN 285 and ISO 17665 must be met: Contaminants in steam generator feedwater Substance/parameter Feedwater Dry residue < 10 mg/l Silicates (SiO2) < 10 mg/l Iron < 0.2 mg/l Cadmium < 0.005 mg/l Lead < 0.05 mg/l Heavy metals in sediment other than iron, cadmium and lead < 0.1 mg/l Chlorides (O) < 2 mg/l Phosphates (P,O5) 6 0.5 mg/l Conductivity (at 25 °C)* 5 5 µS/cm pH value (acidity) 5 to 7.5 Appearance colorless, transparent, without sediment Hardness I (alkaline earth metals) ions) 5 0.02 mmol/l * In contrast to this table, based on experience, a conductivity of about 15 µS/cm is acceptable. Since there are no standards for demineralized water for machine or manual processing, it is recommended to use boiled water in accordance with EN 285, Appendix B, for processing medical devices. Directions for use: It is recommended to use demineralized water for the final rinse for the following reasons: - no staining; - no increase in the content of corrosive impurities, such as chlorides; - no formation of dry crystalline sediment that could negatively affect the subsequent sterilization process; - protection and stabilization of anodized aluminum surfaces. To optimize the process and achieve consistent quality, it is recommended to use demineralized water at all stages of the program. If ion exchangers are used for demineralization, silicic acid transfer is possible, forming a glaze-type coating. Conductivity measurement for demineralized water is insufficient for identification purposes, as silicic acid does not impart conductivity to water. Experience has shown that silicic acid migration is possible even at conductivities <1 µS/cm. To minimize this risk, connecting two mixed-bed ion exchangers in series has proven effective. This series connection, after a reverse osmosis unit, optimizes the production of silicic acid-free demineralized water. A specialist should always be consulted. National recommendations must be followed to ensure compliance with the microbiological requirements for water used for instrument reprocessing. 1.2. Process Chemicals. Process chemicals for the reprocessing of medical instruments must be developed, tested, and manufactured in Europe in accordance with the European Medical Device Directive. — Cleaning, neutralizing, rinsing, and maintenance products are classified as Class I medical devices and bear the CE marking on their labels. — Process chemicals with disinfectant action belong to class IIa for the disinfection of medical devices and to class IIb for the disinfection of invasive medical devices. They are marked with the CE mark in combination with a four-digit number indicating the notified body ("Notified Body"). The manufacturer of process chemicals is obliged to optimize their composition already at the development stage, taking into account the results achieved during use, which include cleaning efficiency, disinfectant action, and qualities during care operations, taking into account compatibility with the materials used in the manufacture of instruments, as well as biocompatibility with patient tissue residues that may be present on the instrument used. The manufacturer of process chemicals is obliged, where necessary, to confirm the compatibility of materials with the manufacturer of the relevant medical instruments. Biocompatibility must be tested and assessed in accordance with ISO 10993 "Biological evaluation of medical devices". Optimum performance properties, material compatibility, and biocompatibility of process chemicals are achieved only under the conditions of use recommended by the manufacturer. The conditions of use must be described in detail by the manufacturer in the relevant documentation (label, technical information sheet) and must be observed by the user. Particular attention must be paid to the concentration of process chemicals in solutions, as well as the temperature and exposure time. The documentation for process chemicals is supplemented by safety data sheets and, at the user's request, certificates confirming material compatibility, effectiveness, environmental properties, and biological compatibility. Substances included in process chemicals may interact with each other. For example, components of a cleaning agent during machine processing, if they penetrate into the subsequent disinfection step, may have a negative effect on the disinfectant. Since this aspect must be taken into account by the manufacturer of process chemicals when testing their effectiveness, it is recommended to use only coordinated process chemicals from the same manufacturer in a closed-loop machine processing cycle. Interactions between components of pre-treatment agents and process chemicals used in subsequent machine processing are also possible, which may, for example, lead to the formation of a film. Therefore, the manufacturer's instructions must be strictly followed. 1.2.1. Types of Process Chemicals. Pretreatment Agents. Pretreatment may include cleaning agents and antimicrobial agents, such as bacteriostatic agents or disinfectants, used prior to manual or, preferably, machine cleaning and disinfection, such as in the form of a foam aerosol, wet-packing agent, etc. Cleaning Agents. Cleaning agents are used to reduce the degree of contamination of the surface of a medical device to the level required for subsequent processing or use. Cleaning agents are used for both manual and machine processing. A distinction is generally made between: — pH-neutral cleaning agents, with or without enzymes — slightly alkaline cleaning agents, with or without enzymes — alkaline cleaning agents, with or without surfactants — cleaning agents with antimicrobial action (combined cleaning and disinfection agents). Disinfectants. Disinfectants are used both manually and, preferably, automatically for the final disinfection of heat-sensitive medical devices, such as flexible endoscopes. Disinfectants contain antiseptic substances or mixtures that reduce the number of viable microorganisms on the surface of the medical device to a level suitable for subsequent processing or use. Oxidizing agents and aldehydes, which act through chemical reactions with microorganisms, are the most preferred for final disinfection. These substances possess the spectrum of activity necessary for final disinfection even at room temperature. Examples of aldehydes include formaldehyde, glutaraldehyde, and ortho-phthalaldehyde. Key components of the oxidizing group include hypochlorous acid, chlorine dioxide, hydrogen peroxide, and peracetic acid and its salts. Active substances with other mechanisms of action do not possess the spectrum of activity necessary for final disinfection at room temperature. This disadvantage can in some cases be compensated for by increasing the temperature, which leads to increased stress on the material, especially for plastics and adhesive joints. These groups of active substances include, for example, alcohols, alkylamines, guanidines, and quaternary ammonia compounds. Neutralizing agents. These include agents based on citric or phosphoric acid, which can be added to the first rinse water during machine processing after alkaline cleaning to neutralize the alkalinity and improve cleaning agent rinsing. Rinsing agents. Rinsing agents are added to the final rinse water during machine processing to improve and accelerate drying. The active substances contained in the rinse agent reduce the boundary tension of the rinse water, thereby reducing the amount of moisture remaining on the surface. Care products. Care products for surgical instruments whose metal friction surfaces require lubrication consist of paraffin oil (Paraffinum Perfume) and emulsifiers. Other care products, such as those for anesthesia equipment, may also be based on silicone oil. 1.2.2 Properties and Evaluation of Components. Caustic alkalis. They can be included in alkaline cleaning agents (potassium or sodium hydroxide) and, due to their alkaline properties, decompose contaminating organic residues. Antimicrobial active ingredients. Aldehyde-based disinfectants, including formaldehyde, glutaraldehyde, and ortho-phthalaldehyde, are primarily used for terminal disinfection at temperatures up to 60°C. In this temperature range, they demonstrate good compatibility with the material of the instruments being processed. Due to their fixing effect on proteins, combined cleaning and disinfection agents based on this active ingredient are not recommended for cleaning. Alcohols are used extensively in disinfectants as antimicrobial active ingredients and, to a lesser extent, as solvents. Most instruments exhibit good material compatibility with alcohols at room temperature. When using aromatic alcohols, such as phenoxyethanol, for terminal disinfection at elevated temperatures, there are reports of damage to adhesive joints, particularly on flexible endoscopes. Alkylamines, in addition to their antimicrobial properties, also facilitate the cleaning process. Therefore, they are particularly suitable for use in combined cleaning and disinfection agents for instrument pretreatment and cleaning. In this group of active ingredients, material compatibility, particularly with elastomers and adhesive joints, depends significantly on the chemical structure of the active ingredient, making some agents unsuitable for reprocessing flexible endoscopes. Silicone elastomers may harden during prolonged exposure to disinfectants containing these active ingredients. Двуокись хлора используется для заключительной дезинфекции, в особенности гибких эндоскопов, в автоматических дезинфекторах в качестве двухкомпонентной системы. В зависимости от состава вещества известны случаи воздействия на эндоскопы, например, изменения цвета черной вводимой части, которые, возможно, имеют лишь косметический характер. При воздействии данного активного вещества нельзя исключить сокращение срока службы пластмасс и клеевых соединений Надуксусная кислота и ее соли в зависимости от значения рН могут использоваться в качестве средств для очистки и дезинфекции, а также для заключительной дезинфекции. Совместимость материалов в значительной степени зависит от состава дезинфицирующего средства, а также от условий применения, в том числе от значения рН, концентрации активного вещества и температуры. По этой причине должны строго соблюдаться подтвержденные испытаниями данные изготовителя. Четвертичные соединения аммиака, а также соединения гуанидина преимущественно используются в комбинированных средствах для очистки и дезинфекции. Они характеризуется хорошей совместимостью материалов. Активные вещества данной группы имеют склонность к адсорбции на поверхностях пластмасс, что при недостаточной промывке после очистки может приводить к образованию налета. По причине широкого спектра воздействия применение веществ из данных групп без использования других средств для заключительной дезинфекции не рекомендуется. Если эти активные вещества используются в сочетании с ароматическими спиртами для заключительной дезинфекции при повышенной температуре, описаны случаи повреждениях клеевых соединений эндоскопов. Хлорноватистая кислота образуется в автоматических дезинфекторах в результате процесса электролиза и используется для заключительной дезинфекции, в особенности гибких эндоскопов. Совместимость материалов в значительной степени зависит от значения рН используемого раствора и от концентрации активного вещества. В отдельных случаях рекомендуются дополнительные меры (покрытие) для защиты пластмассовых деталей эндоскопов. При воздействии данного активного вещества нельзя исключить сокращение срока службы пластмасс и клеевых соединений в зависимости от условий применения. Перекись водорода используется в качестве отдельного вещества или в сочетании со средствами для очистки и дезинфекции для заключительной дезинфекции, а также для низкотемпературной стерилизации. При комнатной температуре активное вещество в обычно используемых концентрациях демонстрирует хорошую совместимость с материалами. При повышенной температуре и других условиях применения данное активное вещество по причине своих окислительных свойств применительно к совместимости материалов классифицируется как восприимчивое. По этой причине должны строго соблюдаться подтвержденные испытаниями данные изготовителя. Энзимы. Такие энзимы, как протеаза, амилаза и липаза, представляют собой протеины, которые при мягких условиях применения в результате каталитических реакций разлагают загрязняющие компоненты, в том числе белки, углеводы и жиры, делая их растворимыми в воде. Комплексообразующие вещества. Они нейтрализуют соли жесткости в воде и повышают эффективность действия средств для очистки. Окислители. Они основаны, например, на перекиси водорода или на гипохлорите натрия и могут путем окисления разлагать особо стойкие загрязняющие органические остатки. Парафиновое масло. Оно входит в состав средств по уходу за инструментами, которые используются для предотвращения фрикционной коррозии на инструментах с металлическими поверхностями скольжения. Фосфаты. Фосфаты служат для связывания жесткости воды и за счет своей способности препятствовать отложению загрязнений способствуют процессу очистки. Фосфатные заменители. Фосфатные заменители, например, глюконаты и фосфонаты, повышают жесткость воды, но могут лишь частично заменить способствующее очистке действие фосфатов. Кислоты (лимонная и фосфорная кислота). Препараты на основе лимонной и фосфорной кислоты служат нейтрализаторами, но также находят применение на этапах кислотной очистки в методах машинной обработки. Силикаты. Они служат в щелочных средствах для очистки в целях защиты от коррозии, например, для легких металлов. Силиконовые масла. Их рекомендуется использовать в качестве компонентов средств для ухода за принадлежностями для анестезии. Поверхностно-активные вещества. Поверхностно-активные вещества в средствах для очистки уменьшают пограничное и поверхностное натяжение, что в сочетании с их эмульгирующим и диспергирующим действием способствует очистке и позволяет избежать редепозиции. Соответствующие поверхностно- активные вещества при машинной очистке подавляют пенообразование, обусловленное, например, большим количеством крови. Кроме того, поверхностно-активные вещества с соответствующей биологической совместимостью в качестве основных компонентов ополаскивателей снижают пограничное и поверхностное натяжение промывочной воды, улучшая тем самым условия сушки обработанных медицинских изделий.