As I write this article, I am reminded how important my dog is to our family. She is an integral member, and I admire the professionals that support her health and well-being, along with that of pets everywhere. To that end, proper instrument sterilization helps ensure healthy outcomes in patients.
Let’s begin with best practices as far as the handling of instruments post-surgery. This part is critical to ensuring the procedures that follow are effective.
Keep instruments moist: Prior to cleaning, instruments should be kept moist to prevent blood from drying. This can be achieved in various ways, but should never be done with saline, as this can cause pitting. Keeping instruments moist ensures removal of blood and mucous during washing is optimized.
Scrub instruments: Next, wash the instruments in a sink. There are several products that can be used to break down blood, but make sure they comprise more than three per cent glutaraldehyde. Instruments should be scrubbed thoroughly with a soft brush. Careful cleaning is required before high-level disinfection and sterilization, as inorganic and organic materials remaining on the surfaces of instruments interfere with the effectiveness of these processes.
Also, if soiled materials dry or bake onto the instruments, removing them becomes more difficult and the disinfection or sterilization process less effective or ineffective. Surgical instruments should be presoaked or rinsed to prevent drying of blood and to soften or remove blood from them. There should be no blood visible to the naked eye.
Use an ultrasonic or thermal washer: To ensure instruments are properly prepared to be sterilized, place them in a thermal washer-decontaminator/disinfector or an ultrasonic cleaner with an enzymatic solution. This step is critical. Further, keep in mind some instruments (e.g. handpieces for animal dentistry and fixed scopes) cannot go in an ultrasonic cleaner, which means a washer must be used. Always check the instructions manual for the instruments you are processing to see what they recommend using. Either machine ensures all material is removed from cracks and crevices in the instrument; however, the thermal washer-decontaminator/disinfector is considered best practices.
Ultrasonic cleaning removes blood and other material by cavitation and implosion, meaning waves of acoustic energy are propagated in aqueous solutions to disrupt the bonds that hold particulate matter to surfaces. Thermal washer-decontaminators/disinfectors act like a dishwasher, using a combination of water circulation and detergents to remove material. These units sometimes have a cycle that subjects instruments to a heat process (e.g. 93 C [199 F] for 10 minutes). Thermal washer-decontaminators/disinfectors are generally computer-controlled units for cleaning, disinfecting, and drying solid and hollow surgical and medical equipment. Either machine ensures all material is removed from cracks and crevices in the instrument.
Once these procedures are done, you are ready to sterilize your instruments in an autoclave. There are many ways to achieve this, but steam sterilization is the preferred method due to cost and environmental impact. Although gas-based (e.g. hydrogen peroxide or ethylene oxide) low-temperature sterilization is used for instruments or trays made of plastic, there is a cost barrier and potential exposure of employees to harmful gas. That is the reason many consider steam sterilization to be the gold standard. Always check cleaning instructions of the instruments you are putting in the autoclave to ensure it is safe to do so.
Full steam ahead
There are three methods of steam sterilization: gravity, dynamic airflow removal, and pre- and post-vacuum.
1) Gravity is the common method for sterilizing with steam and is cost-effective when using less expensive autoclaves. The limitation is in the penetration of packs (or pouches) containing instruments, especially since veterinary staff tends to double wrap packs in cloth to ensure nothing (e.g. animal hair) gets into them. This, however, is not mandatory.
2) Dynamic airflow removal is a device featuring a pressurized chamber that pulses packs to penetrate them with steam to achieve sterilization.
3) Pre- and post-vacuum uses a vacuum to push and pull steam through packs and any hollow instruments longer than 6 inches where other methods of sterilization would fail. It is also faster, with steam penetrating packs regardless of how they are wrapped.
This method of steam sterilization dries packs completely, which is important to note.
Drying is the most challenging aspect of sterilization when packs are double-wrapped in cloth. When prepared this way, packs are damp or wet more often than not, which compromises sterilization. One proprietary line of autoclaves compensates for this by increasing the temperature during the drying cycle and by using a larger exhaust fan to remove moisture.
To properly store your packs, keep them in a covered cabinet to ensure they are not exposed to dander or pet hair. That consideration is also why sterilization should be done in a separate area, with the flow of the sterilization room going from dirty to clean.
The use of biological and chemical indicators is the final component to the sterilizing process. Each does a different thing. That said, both are vital to verifying your packs are sterilized and that your autoclave is functioning properly.
1) Chemical indicators alert technicians that packs or pouches have been exposed to steam. As such, they should be put inside every pouch or pack. There are many types of chemical indicators available on the market.
2) Biological indicators are placed inside the chamber when running a load to indicate all criteria have been met for sterilization, meaning temperature, steam, and exposure time. The liquid inside the indicator contains live bacteria that are killed when packs or pouches are sterilized correctly. They can also help determine whether the autoclave is functioning properly.
Sterilization and best practices should be a priority in any practice to help ensure the risk of post-surgical complications due to infection is mitigated.
Dan McGinley is the national sales manager for Tuttnauer USA. In addition to facilitating a partnership with American Society for the Prevention of Cruelty to Animals (ASPCA), he has trained veterinary practices on sterile processing and the potential risks associated with not adhering to accepted sterilization practices.