Equipment (Medical and Surgical)
In the United States, annually there are about 46.5 million surgical and other invasive medical procedures including about 5 million gastrointestinal endoscopies. In each of these procedures, pathogenic organisms can be introduced into the body by means of the medical device or surgical instrument, thereby setting up a site of infection leading to potentially serious consequences for the patient and outbreaks of healthcare-associated infections caused by a break in procedure in the proper cleaning, disinfecting and, where necessary, sterilization of the equipment.
Sterilization is a process that destroys all forms of microbial life including spores and it may be accomplished by use of steam under pressure, dry heat, ethylene oxide gas, hydrogen peroxide gas plasma, or liquid chemicals. Disinfection is a process that eliminates all pathogenic microorganisms except bacterial spores on inanimate objects. Cleaning is the visible removal of all soil, either organic or inorganic, from objects and surfaces and can be accomplished either mechanically or by hand utilizing appropriate detergents. Decontamination results in the removal of pathogenic microorganisms from objects. The proper techniques utilized in any case include first meticulous cleaning and thorough rinsing, and then depending on the nature of the equipment, utilizing decontamination, disinfection, or sterilization techniques.
The Spalding technique which was set up as a rational approach to disinfection and sterilization of patient care items and equipment many years ago, although still being used in some areas, is considered to be an oversimplification, however the reader should understand what it is and how it works. The technique consists of dividing all patient care items and equipment into three categories including: critical items which enter sterile tissue or the vascular system and have to be sterile; semicritical items that come in contact with mucous membranes and non-intact skin including respiratory and anesthesia equipment and certain endoscopes which have to be free from all microorganisms but bacterial spores are allowed; and non-critical items that come in contact with intact skin but not mucous membranes such as bedpans, blood pressure cuffs, etc. and can be decontaminated on site without having to go to central supply for processing. One of the problems with implementing this procedure is the reprocessing of complicated medical equipment that is heat sensitive or the inactivation of certain infectious agents such as prions. Another problem is the processing of an instrument in the semi-critical category such as an endoscope that may be used with a critical instrument that comes in contact with sterile body tissues. The optimal contact time for high-level disinfection has not been defined and therefore there is no one Best Practice established for this type of procedure.
Factors that affect disinfection and sterilization include the number and location of the microorganisms and whether or not they produce spores; the resistance of the microorganisms; the concentration and potency of the disinfectants; the temperature, pH, relative humidity, and water hardness of the solution containing the disinfectants; the type and amount of organic and inorganic matter that is on the surface of medical equipment; the time of exposure of the equipment to the disinfecting solution; and the presence or absence of biofilms which are large groups of microorganisms that are tightly attached to surfaces and may be surrounded by additional materials and are difficult to remove.
Each of the major groups of instruments or pieces of equipment in use will be discussed and the most modern Best Practices will be stated as follows.
- 1. Endoscopes of all types are used to diagnose and treat various disorders. Endoscopes, which are heat sensitive, become contaminated when they enter body cavities. A prime example is the duodenoscope which has a very complex design and therefore may receive ineffective reprocessing. Multidrug-resistant microorganisms can be very difficult to destroy even if healthcare personnel properly follow the instructions established by the manufacturer. The reprocessing of endoscopes has four steps. They are: mechanically thoroughly clean all internal and external surfaces of the unit including brushing, with a detergent or enzymatic cleaner, thoroughly clean the internal channels and rinse very well with water and then test for leaks; disinfect by immersing the endoscope in an appropriate disinfectant or chemical sterilant, for example, 2% glutaraldehyde for 20 minutes; rinse the endoscope and all channels with sterile water or high-quality potable water; and rinse the insertion tubes with alcohol and dry with forced air after disinfection and before storage. A question that should always be asked prior to a procedure is “Do the benefits of the procedure outweigh potential risk due to the invasive nature of the task?”
- 2. Other instruments which can transmit a variety of infections from one patient to another include tonometers to measure eye pressure, cervical diaphragm fitting rings, cryosurgical instruments, and endocavity probes. The Food and Drug Administration (FDA) requires that the manufacturer lists at least one validated cleaning and disinfection/sterilization protocol in the labeling of each instrument. However, other than thorough cleaning, there is no consensus or significant research showing the best way to disinfect these types of equipment. It is recommended that further research be carried out in these areas.
- 3. Dental instruments that penetrate soft tissue or bone must be cleaned thoroughly and either sterilized after each use if heat stable or put in appropriate disposal containers. Covers can be used for other types of equipment and then disposed of after seeing the patients. Surfaces which are frequently touched should be cleaned and disinfected between patients.
- 4. Hepatitis B virus, hepatitis C virus, HIV, or TB-contaminated devices should be thoroughly cleaned and then treated with 2% glutaraldehyde solution for 20 minutes.
- 5. Disinfection of the hemodialysis unit includes the machines, water supply, water treatment systems, and distribution systems which have become infected with blood-borne viruses and pathogenic bacteria. Thoroughly clean all surfaces and properly disinfect all water. Use a hypochlorite solution or a disinfectant with a tuberculocidal agent for disinfection of the equipment. Disinfectants include peracetic acid, formaldehyde, glutaraldehyde, heat pasteurization, and chlorine-containing compounds. (See the most current recommendations for the reuse of hemodialyzers issued periodically by the Association for the Advancement of Medical Instrumentation.)