Disinfection Processes and Chemicals PDF

Disinfection There are two types of disinfection, thermal and chemical. Thermal disinfection can be achieved in a thermal washer-disinfector by choosing the appropriate cycle. It is the simplest, most efficient and cost-effective disinfection method. Thermal disinfection equipment should allow you t...

Disinfection There are two types of disinfection, thermal and chemical. Thermal disinfection can be achieved in a thermal washer-disinfector by choosing the appropriate cycle. It is the simplest, most efficient and cost-effective disinfection method. Thermal disinfection equipment should allow you to monitor or record the length of time it was at a specific temperature, to make sure the microbes were killed. The effectiveness of chemical disinfection depends on a number of factors, including the initial number of microbes present, temperature, pH, and concentration. It can be achieved with a compatible RMD-grade disinfectant of the required level, used alone or with a chemical washerdisinfector. Rarely used in a CSSD setting, it can be seen regularly in areas that reprocess ultrasound probes and is the main disinfectant of choice in endoscopy units. In order to know if chemical disinfection processes were adequate, the processes are validated microbiologically, defining the concentration, contact time and minimum/ maximum temperatures for adequate disinfection. Disinfection eliminates many or all pathogenic micro-organisms on inanimate objects, with the exception of bacterial spores. It makes infectious agents inactive, using either thermal (moist or dry heat) or chemicals. The level of disinfection achieved depends on the temperature, exposure time and/or type of chemical disinfectant used. Highlevel disinfection (example used for thermo-labile endoscopes which you will learn about later) is the minimum treatment recommended for reprocessing medical devices that cannot be sterilized. These medical devices are used in semicritical sites or when there are specific concerns regarding contamination of surfaces. Low-level disinfection is the minimum treatment recommended for reprocessing non-invasive medical devices for use in non-critical sites. Decontamination Book.indb 124 27/02/2018 16:33 Medical Device Reprocessing (Decontamination Specialist) 125 Drying Drying minimizes rusting, and staining and reduces the risk of recontamination during inspection and assembly of RMD. Residual moisture interferes with the sterilization process. Place RMDs in a drying cabinet (Figure M5–18) and apply the following key considerations: Use a clean disposable lint-free, absorbent wipe when a drying cabinet is not available Take care not to exceed the temperature tolerances advised by the manufacturer Dry the RMD in a sloping position to facilitate drainage Do not use alcohol or other flammable liquids as drying agents, other than in automated equipment designed for this purpose, for example, some endoscope washer–disinfectors Process Chemicals We now know that thorough cleaning of used surgical devices prior to sterilization is critical. The main agent that affects cleaning is the process chemical used in the wash area of the CSSD. Chemicals such as detergents and disinfectants may have hazardous properties associated with them (may be irritant, corrosive, flammable), for example bleach and ammonia if mixed will release lethal chlorine gas. Process chemicals are potentially hazardous as they may cause irritation to the skin, eyes, respiratory tract and mucous membranes. Things to think about when dealing with process chemicals are choice of process chemicals, the controls required, safety data sheets and labeling. Choice of Process Chemicals Choose process chemicals that are compatible with: The medical device The decontamination equipment to be used and the intended use of the device Choose the least hazardous chemical that will fulfil the process requirement. Figure M5–18 Decontamination Book.indb 125 27/02/2018 16:33 126 Cleaning and disinfection According to the Association for the Advancement of Medical Instrumentation (AAMI) the characteristics of process chemicals are at minimum: Non-abrasive 222 Low-foaming Free-rinsing Biodegradable Non-toxic Able to dissolve/disperse soil easily Economical Dosage of process chemicals or detergent should be determined by Manufacturer IFU and validated during commissioning. Control of Process Chemicals Use defined, written procedures and methods for handling and storage of process chemicals. Clearly identify chemicals that should not be stored together. Figure M5–19 Cleaning and disinfection Type of DETERGENT Quality of WATER Type of INSTRUMENT Type of WASHER Decontamination Book.indb 126 27/02/2018 16:33 Medical Device Reprocessing (Decontamination Specialist) 127 Store chemicals below shoulder height. Make sure Safety Data Sheets (SDS) and labels are available to all staff in designated areas at all times, so that appropriate action can be taken in case of exposure to a hazardous substance. Read and follow the precautions and instructions given on the SDS and on the label prior to handling and use. Train all personnel who handle chemicals e.g. detergents, rinse aids, disinfectants, etc. Water Quality The quality of water used at all stages in the cleaning process is critical to the successful outcome of the process, as the water is the last thing to make contact with the RMD prior to the user procedure. Unfavorable water compositions can have an adverse effect on the reprocessing process and on the devices themselves. At each stage in the cleaning process the water quality should be compatible with the: Washer-disinfector (WD) construction materials Medical devices to be processed Process chemical to be used Process requirements of that particular stage Other factors to take into consideration are: pH and hardness—dissolved salts (lime scale) Temperature Ionic contaminants—heavy metals, phosphates and silicates leading to corrosion Microbial population Bacterial endotoxins