Medical instrument disinfection and sterilization

Proper cleaning and disinfection or sterilization of reusable medical instruments is critical in a hospital environment. Over their lifetime, such instruments are used on a progression of patients. Inadequate destruction or inactivation of pathogens (bacteria, fungi, viruses, spores, and other microorganisms) left on an instrument by one patient can result in serious adverse clinical outcomes, including death, in the next patient. The risk is particularly acute for instruments used invasively.

A variety of different microorganisms exists that require different methods to kill. There are also a number of different cleaning, disinfection and sterilization technologies available. The FDA certifies appropriate levels of disinfection or sterilization, and appropriate sterilization techniques on an instrument-by-instrument basis. Device manufacturers also make recommendations about the sterilization method(s) that work best with their products. Disinfection and sterilization practices are also the subject of extensive guidelines issued by the Centers for Disease Control (CDC) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO).

Primary Processes

The major steps involved in an organizational strategy for sterilization include:

Central sterilization/disinfection organization
Sterilization is generally managed by a central operation within a hospital. This group designs and implements processes and oversees all sterilization, disinfection and cleaning needs including training staff and monitoring results. Hospitals today generally do an excellent job of managing sterilization needs internally. Challenges tend to be infection risks coming in from outside the hospital, from health care workers or from patient to patient as well as the resistance of some infections to the sterilizers and disinfectants.

Healthcare facility design and construction
Many organizational infection risks can be controlled early in the design and construction stages of health care facilities. Early involvement in the conceptual phase helps ascertain the risk for susceptible patients and to minimize disruption of essential patient services. Decisions are made about numbers and types of isolation rooms, hand washing facilities and separation of patients with communicable diseases, for example. These decisions are predicated on an "infection control risk assessment." In addition, many microorganisms are introduced into a facility during construction. Strategic, proactive architectural design and construction planning can mitigate environmental sources of microbes and prevent infection, as well as accommodate the specific needs of the population served by the facility.[1]

Categorization of sterilization or disinfection needs
One way to classify the types of infections that patients can contract within a health care facility is to distinguish the source of infection as follows:

• Organizational: Infection introduced through the HVAC system, contaminated water systems, staff hygiene, physical layout of facility (e.g. compliance with hand hygiene, nurse-to-patient ratio, bed layout)
• Iatrogenic: infections introduced by a physician, health care worker or procedure- (e.g., intubation, indwelling vascular lines, urinary tract catheterization), antibiotic use and prophylaxis

It is also necessary to determine how serious an infection risk is. In a health care facility, not all risks of infection are the same. Infection risks can be divided into the following three categories.[2] Based on the category of infection risk, which is determined by the way an instrument is used, different sterilization methods are required.

• Critical: contact directly with internal fluids, such as with circulating blood though blood vessel walls, or contact directly with tissues through broken skin
• Semi-critical: contact with mucous membranes, or contact with broken skin
• Non-critical: contact with intact skin

Choosing the appropriate level of sterilization
Different microorganisms require different response levels in order to achieve the necessary degree of sterility.

• Sterilants are capable of completely eliminating or destroying of all forms of microbial life, including spores.
• Disinfectants form a less absolute category -- they will destroy some, but not necessarily all organisms. This category is further divided into subcategories, as follows:
• High-level disinfectants - destroy all microorganisms, with the exception of high numbers of bacterial spores.
• Intermediate-level disinfectants - inactivate even resistant organisms such as Mycobacterium tuberculosis, as well as vegetative bacteria, most viruses, and most fungi, but do not necessarily kill bacterial spores.
• Low-level disinfectants - kill most bacteria, some viruses, and some fungi, but cannot be relied on to kill resistant microorganisms such as tubercle bacilli or bacterial spores. (Source: APIC.)

Creating an inventory of devices and their agreed upon sterilization or disinfection methods
Since hospitals may use hundreds of different devices and equipment requiring cleaning, disinfection or sterilization, it is necessary to create a manageable recordkeeping system so that sterilization is done properly. Staff needs to be trained and records accessible to those that need them. Cleaning, disinfection and sterilization equipment as well as disposal or storage facilities for items to be reprocessed, need to be conveniently located.

To determine the kind of sterilization a device requires, the following questions can be asked:

• Is the device re-usable?
• If yes, can it be thoroughly cleaned?
• Is it heat sensitive?
• Does it have long thin lumens (tubing)?

With answers to these questions, a system can be put into place that insures that each device is sterilized, re-processed or used once as is appropriate. Once an inventory is prepared, documentation can be created and staff trained.

Sterilization of equipment [3]
Many steps are required to ensure that instruments are appropriately sterilized. These include pre-cleaning, cleaning, milking, inspection, packaging, wrapping, autoclaving and maintaining the autoclave.

• Pre-cleaning needs to be done at the point of use to prevent the drying of organic material. This can be accomplished by either wiping the instrument with a wet cloth or placing the instrument in an enzymatic cleaner.
• Cleaning includes many steps. Staff should wear appropriate personal protection equipment and follow approved procedures to prevent BBP (blood borne pathogen) exposure. They must be sure all instrument surfaces, including hinges, are scrubbed with an approved enzymatic cleaner and thoroughly rinsed. If an ultrasonic machine is used, care should be used to be sure all the manufacturer's recommendations are followed.
• Milking: After cleaning, instruments with moveable parts need to be immersed in a milk solution and removed without rinsing. All instruments should be inspected before wrapping. It is important to ensure that hinged instruments open easily and that the jaws are properly aligned. Sharp instruments should be inspected for sharpness. All instruments should be inspected for cracks, chips or worn spots, with any instruments found with defects removed from service and sent for repair.
• After inspection, wrap instruments in a single pouch of an appropriate size. Store all instruments in the open position with any curved tips pointed in the same direction. A steam indicator should be placed in the center of the pack with one end visible when the pack is opened. Secure the packet with steam indicator tape and labeled with the date of sterilization, the load number and the initials of the person preparing the package.
• Autoclaving or other sterilization methods should be done following manufacturer's directions. Keep a log that details each time the equipment is run, every time a biological indicator is sent and every time maintenance is performed. Staff should be able to verbalize the recall/resterilization procedure in case of failure of the biological indicator, visible condensation seen in a package, indicators that do not appropriately change color, and package integrity concerns or compromised storage and handling conditions.

Surveillance
Demonstration of quality health care includes documentation of outcomes of care. Surveillance is a comprehensive method of measuring outcomes and related processes of care, analyzing the data, and providing information to members of the health care team to assist in improving those outcomes. Surveillance is an essential component of effective clinical programs designed to reduce the frequency of adverse events such as infection or injury.

To ensure quality of surveillance, the following elements must be incorporated:

• A written plan should serve as the foundation of any surveillance program. The plan should outline important objectives and elements of the surveillance process so that resources can be targeted appropriately.
• Thoroughness or intensity of surveillance for an area of interest must be maintained at the same level over time. Fluctuations of a surveillance rate have no meaning unless the same level of data collection is maintained. External rate comparisons are meaningless unless the systems used have comparable intensity.
• All the elements of surveillance should be used with consistency over time. This includes application of surveillance definitions and rate calculation methods.
• Personnel resources need to be appropriate for the type of surveillance being performed. This includes trained professionals who understand epidemiology and surveillance and who have access to continuing professional education opportunities.
• Other resources essential to surveillance include computer support, information and technology services, clerical services, and administrative understanding and support to maintain a quality program.
• As a means of ensuring quality control and accuracy, the data and process of surveillance should undergo periodic evaluation and validation.[4]

Conduct on-going risk assessment, identify, and implement interventions and strategies to reduce infection risks:
Using information gained from the surveillance program and a model for continuous improvement, hospital administrators can continue to refine and improve upon the infection record in the facility. Some of the tasks that can facilitate reduced infection rates are:

• Periodic review and selection of the best sterilization products available
• Periodic critical analysis of facility design, especially local exhaust and HVAC systems
• Scheduled evaluation of staff competency and skills and training needs

Sources:
[1] "The role of infection control during construction in health care facilities" http://www.apic.org/AM/Template.cfm?Section=Home&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=6369.
[2] Sterilants and disinfectants in healthcare facilities, Hospitals for a Healthy Environment, http://h2e-online.org/hazmat/steril.html.
[3] Proper Sterilization of Instruments is Essential to Patient Safety, http://www.apic.org/Content/NavigationMenu/Publications/
InfectionConnection/Proper_Sterilization.htm.
[4] Recommended Practices for Surveillance, American Journal of Infection Control, http://www.apic.org/AM/Template.cfm?Section=Surveillance_Definitions_Reports_and_Recommendations
&Template=/CM/ContentDisplay.cfm&ContentFileID=2710.