Disinfection and sterilization of endoscopes

Processing of flexible endoscopes

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

To prevent the spread of infection during bronchoscopy, the apparatus must undergo thorough sanitation, the rules and procedures of which are strictly regulated in the document "Prevention of infectious diseases in endoscopic manipulations".

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

1. Preliminary cleaning.
2. Check for leaks.
3. Cleaning.
4. Rinsing.
5. High level disinfection.
6. Rinsing.
7. Washing with alcohol and drying.
8. Storage.

Preliminary cleaning includes a set of measures, the purpose of which is to remove organic contaminants (protein and fat), biological films, as well as remnants of medicinal products used during the research. Preliminary cleaning is carried out immediately after the end of the procedure and extraction of the device from the bronchial tree. To remove visible traces of contamination, without disconnecting the endoscope from the light source, the injected part of the apparatus is wiped with a tissue moistened in a cleaning solution. Pumping the detergent through the biopsy channel and rinsing the air and water supply channels cleans them of the contents. The channels are washed to clean water, then purged with air. For pre-cleaning only detergents are used, designed specifically for flexible endoscopes.

Check for leaks - the next stage of sanitizing the endoscope. Leakage in the external or internal parts of the apparatus violates its integrity and waterproofness, as well as creates additional conditions for microbial contamination and damage to the instrument.

To carry out the leak test, the endoscope is disconnected from the light source, waterproof caps are put on the electrical connectors and a leak detector is attached. Despite the fact that the leak test is carried out in accordance with the instructions of the manufacturers of apparatus, there are general rules that should be followed when performing it.

Before immersing the endoscope in water it is necessary:

• Visually inspect the entire instrument for major damage.
• Create an over-pressure inside the instrument, which is controlled by the rubber membrane of its distal part to the eye or palpation.

After that, the endoscope is completely immersed in water and the air bubbles are controlled throughout the length of the apparatus. In the absence of leaks, the tool is removed from the water, the leak detector is removed and the pressure is released.

Mechanical cleaning is the most important stage of sanitary treatment, the quality of which determines the effectiveness of disinfection of the endoscope. Mechanical cleaning is the process of removing from the endoscope all foreign substances. As a rule, it is performed manually using water, brushes, applicators and detergents containing enzymatic preparations. All removable elements are disconnected and, together with the apparatus, are immersed in the cleaning solution. Removable parts and internal surfaces of the holes of the biopsy valve, air / water extraction valves and bioptic 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 fibers are removed mechanically or washed away. The procedure is repeated until the "purity of the brush bristles". After attaching adapters for cleaning and sealing the biopsy port, the device is completely immersed in the washing solution, which also fills all its channels. The soaking time depends on the detergent, usually it does not exceed 5 minutes.

Studies show that correctly performed mechanical cleaning with the use of detergent enzymes allows 99.99% of microorganisms to be removed from the endoscope.

After cleaning, the bronchoscope, its channels, as well as the removable parts, are thoroughly rinsed and washed with water. Then the channels are blown through with air to dry, and the outer surfaces of the tool are wiped with napkins. These measures allow the removal of residual washing solution and prevent dilution of the chemical for disinfection.

High level disinfection is a process in which all vegetative bacteria, viruses and fungi are destroyed except for the spores of certain bacteria. For these purposes apply:

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

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

After this stage of sanitization is completed, the tool, all its detachable parts and channels are rinsed and washed with a large amount of pure water to remove any remaining disinfectant solution.

Flushing with alcohol and drying the final stage of sanitary treatment of the endoscope, in which its channels are washed with 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 cloth.

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

Additional tools used during the endoscopic examination (forceps, loops, injection needles, catheters, etc.) are disinfected / sterilized in accordance with the manufacturer's recommendations. Thermally stable endoscopic equipment can be autoclaved after washing and mechanical cleaning. Thermolabile accessories are sterilized / disinfected by immersion in a disinfectant.

Thus, compliance with the rules for sanitizing devices and additional instruments almost completely eliminates the risk of infection and guarantees the safety of endoscopy.

[1], [2], [3], [4], [5], [6]