Disinfection and sterilization of endoscopes

Processing of flexible endoscopes

All flexible endoscopes come into contact with intact mucous membranes and are classified as semi-critical. They should not contain any microorganisms, but may contain spores of some bacteria. According to statistics, gram-negative bacteria and mycobacteria are most often transmitted during bronchoscopy.

To prevent the spread of infection during bronchoscopy, the devices must undergo thorough sanitization, the rules and procedures of which are strictly regulated in the document “Prevention of infectious diseases during endoscopic manipulations”.

Flexible endoscopes have a complex design, so their sanitization includes the following steps:

1. Pre-cleaning.
2. Checking for leaks.
3. Cleaning.
4. Rinsing.
5. High level disinfection.
6. Rinsing.
7. Rinse with alcohol and dry.
8. Storage.

Preliminary cleaning includes a set of measures aimed at removing organic contaminants (protein and fat), biological films, and residues of drugs used during the examination from the working part of the device. Preliminary cleaning is carried out immediately after the procedure is completed and the device is removed from the bronchial tree. To remove visible traces of contamination, without disconnecting the endoscope from the light source, the inserted part of the device is wiped with a napkin soaked in a cleaning solution. Pumping detergent through the biopsy channel and flushing the air and water supply channels cleans them of their contents. The channels are flushed until the water is clean, then blown with air. Only detergents developed specifically for flexible endoscopes are used for preliminarily cleaning.

Checking for leaks is the next stage of endoscope sanitization. A leak in the external or internal parts of the device disrupts its integrity and water resistance, and also creates additional conditions for microbial contamination and damage to the instrument.

To perform a leak test, the endoscope is disconnected from the light source, waterproof caps are placed on the electrical connectors, and a leak detector is attached. Although leak testing is performed according to the manufacturer's instructions, there are general rules that should be followed when performing it.

Before immersing the endoscope in water, it is necessary to:

• Visually inspect the entire instrument for major damage.
• Create excess pressure inside the instrument, which is controlled by the rubber sheath of its distal part by eye or palpation.

After this, the endoscope is completely immersed in water and the release of air bubbles is monitored along the entire length of the device. If there are no leaks, the instrument is removed from the water, the leak detector is removed and the pressure is released.

Mechanical cleaning is the most important stage of sanitization, the quality of which determines the effectiveness of endoscope disinfection. Mechanical cleaning is the process of removing all foreign substances from the endoscope. As a rule, it is performed manually using water, brushes, applicators and detergents containing enzymatic preparations. All removable elements are disconnected and immersed in a cleaning solution together with the device. The removable parts and internal surfaces of the biopsy valve openings, air/water suction valves and biopsy port are cleaned with a brush. Each time the brush comes out of the distal end of the instrument or the light guide connector, the contents of its bristles are removed mechanically or washed off. The procedure is repeated until the "brush bristles are clean". After connecting the adapters for cleaning and sealing the biopsy port, the device is completely immersed in a cleaning solution, which also fills all its channels. The soaking time depends on the detergent, usually it does not exceed 5 minutes.

Research shows that properly performed mechanical cleaning using enzymatic detergents allows removing 99.99% of microorganisms from the endoscope.

After cleaning, the bronchoscope, its channels, and removable parts are thoroughly rinsed and washed with water. The channels are then blown with air to dry, and the outer surfaces of the instrument are wiped with napkins. These measures remove residual cleaning solution and prevent dilution of the chemical disinfectant.

High-level disinfection is a process that destroys all vegetative bacteria, viruses and fungi, with the exception of some bacterial spores. The following are used for this purpose:

• Glutaraldehyde.
• Peracetic acid.
• Hydrogen peroxide.
• Orthophthalic aldehyde.

Disinfection can be carried out manually or automatically in a washer-disinfection machine. During manual disinfection, the endoscope and its removable parts are immersed in a disinfectant solution, and all the instrument channels are filled with it. The soaking time depends on the type of preparation used. During automatic disinfection, the device is inserted into the machine, and connecting tubes for supplying the disinfectant are connected to all channels. The machine operating time is set in accordance with the preparation used.

After completing this stage of sanitization, to remove any remaining disinfectant solution, the instrument, all its removable parts and channels are rinsed and washed with plenty of clean water.

Rinsing with alcohol and drying is the final stage of sanitizing the endoscope, during which its channels are rinsed with a 70% solution of ethyl or isopropyl alcohol and dried by forced air blowing. The outer surfaces of the instrument are wiped with a clean towel made of soft fabric.

To prevent contamination, the tool prepared for work is stored vertically suspended in a special cabinet.

Additional instruments used during endoscopic examination (forceps, loops, injection needles, catheters, etc.) are disinfected/sterilized in accordance with the manufacturers' recommendations. Heat-resistant endoscopic equipment can be autoclaved after washing and mechanical cleaning. Heat-labile accessories are sterilized/disinfected by immersion in a disinfectant.

Thus, compliance with the rules for the sanitary treatment of devices and additional instruments almost completely eliminates the risk of infection and guarantees the safety of endoscopic examination.

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