Sterilisation techniques for public health care facilities

Sterilisation is the elimination of all disease-producing micro-organisms, including spores (e.g. Clostridium and Bacillus species) and prions. Sterilisation is used on critical medical equipment/devices and, whenever possible, semi critical medical equipment/devices.

Methods of sterilisation

Sterilisation of the medical instruments can be achieved through:

• Thermal Sterilisation
• Chemical Sterilisation

Thermal Sterilisation

Thermal Sterilisation is performed via:

• Wet sterilisation: Exposure to steam saturated with water at 121°C for 30 minutes, or 134°C for 13 minutes in an autoclave. Please note these cycle parameters differ as per autoclave type (gravity/dynamic air removal) and need to follow as per type of autoclave.
• Dry sterilisation: Exposure to 160°C for 120 minutes, or 170°C for 60 minutes; this sterilisation process is often considered less reliable than the wet process, particularly for hollow medical devices. It should mainly be used for lab glassware and oils. Metal instruments are very likely damaged by this process.

Do not perform sterilisation for equipment which are not compatible to the heat sterilisation like endoscopes or fibro optic scopes and other related materials. It should be processed with use of HLDs. for 10–15 minutes kill bacteria but not viruses and spores. Electrical steriliser can be used for small instruments.

Chemical Sterilisation

This is sterilisation with the use of chemicals also known as cold sterilisation. This is often used for instruments likely to be damaged by heat. It is based on the premise that some HLDs would kill endospores after prolonged exposure (10-24 hours).

Chemical sterilisation may be achieved through use of 2-4% Glutaraldehyde Solution, by immersing the instruments for a minimum contact time of 10 hours.

Flash sterilisation

It is a modification of conventional steam sterilisation in which the flashed item is placed in an open tray or is placed in a specially designed, covered, rigid container to allow for rapid penetration of steam.Flash sterilisation is performed on unwrapped objects at temperature of 132^o C, with 27-28lbs pressure and for minimum exposure time of three minutes. Flash sterilisation should be used only in case of a dropped instrument during surgery and never as a routine method of sterilisation.

Endoscope Reprocessing

Endoscopes are medical devices which are problematic to clean and disinfect (long narrow channels, complex internal design, etc.). Products and/or processes used (chemical or thermo-chemical disinfection) may not be as reliable as sterilisation methods.

To reduce nosocomial transmission of micro-organisms by endoscopy, a standard reprocessing procedure should be systematically followed.

• Immediately after use, the air-water channel should be cleared with forced air, and treated tap water or detergent suctioned or pumped through the aspiration/biopsy channel(s) to remove organic debris
• All detachable parts (e.g. hoods and suction valves) should be removed and soaked in a detergent solution, and the external parts of the endoscopes gently wiped.
• All accessible channels should then be irrigated with treated tap water or detergent solution, brushed (using sterile or single use brush) and purged• Before any immersion, the endoscope should be leak-tested
• After pre-treatment and mechanical cleaning the endoscope needs to be cleaned and disinfected, either manually or automatically. In both cases, the complete cycle includes several stages:
• Cleaning using an approved detergent (this solution cannot be reused
• Rinsing (treated tap water is sufficient for this in-between rinsing stage)
• Disinfection. Using an approved, HLD
• Rinsing: The level of microbial purity of the water used depends on the further use of the endoscope (bacteriologically controlled water or sterile water)
• Drying: If the endoscope is not stored, this drying stage includes only air-blowing the channel to remove residual water.

Storage

Storage of instruments and equipment is a very important component to maintain its sterility or disinfection. Most instruments and equipment should be dry and packaged once they have been sterilised

• They should be stored in a clean, dry environment and protected from any damage
• Correct storage of sterile instruments and equipment are very crucial for keeping them sterile.

Maintaining sterility

Proper storage conditions are essential to maintain the integrity of sterilised items. Thus healthcare settings should have procedures for storage and handling of clean and sterile medical equipment/devices that include:

• The end-user should check the integrity of the package before use
• Sterile medical equipment/devices should be used before the expiration date
• Stock should be rotated, so that oldest stock can be used first
• Sterility should be maintained until used• Sterile packages that lose their integrity should be re-sterilised prior to use
• Equipment/devices should be handled in a manner that prevents recontamination of the item.

Source: Guidelines For Implementation Of "KAYAKALP" Initiative