In an ideal world we’d be able to sterilize any instrument safely, cost-effectively, and ready in a flash, with just one machine to do every job. But walk into any central service/sterile processing department today and you’ll most likely find a mix of sterilizing technologies – steam, ethylene oxide, paracetic acid, ozone, gas plasma – each uniquely advantageous to different device processing requirements.

Making the best choices in sterilants and disinfectants involves a multitude of parameters – the most important of which is efficacy, or the pro-duct’s effectiveness for the task at hand – killing bugs.

A basic background in the fundamentals of sterilization and disinfection is absolutely essential to selecting the right sterilant or disinfectant for the job. First, it’s important to differentiate between sterilization and disinfection. While sterilization is defined as the destruction of all microbial life, disinfection is categorized into various degrees of microbial kill with high-level disinfection destroying all microorganisms, except a high numbers of bacterial spores, and low-level disinfection not indicated for spore kill.

Both the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) recognize the Spaulding Classification System1 as a basis for determining the degree of sterilization or disinfection required for medical devices.

Using the Spaulding Classification, devices are categorized as critical, semi-critical or non-critical, based on the risk of infection involved with their use. Critical devices are those that enter normally sterile tissue or the vascular system, including surgical instruments and implants. Critical items require sterilization. Devices that are categorized as semi-critical are those that come into contact with intact mucous membranes and do not ordinarily penetrate sterile tissue, including flexible endoscopes and anesthesia equipment. Semi-critical devices require the use of either a sterilant or high-level disinfectant.

Honeywell Oxyfume sterilant tanks

"A CS/SPD or O.R. manager needs to first determine if he or she wants to sterilize or high-level disinfect the devices in question," said Tamara Struk, product manager, STERIS Corporation, Mentor, OH. "Once that determination is made, several criteria need to be considered, including but not limited to: The materials compatibility of the sterilant or disinfectant with the devices in question – will it damage any part of the device?; the degree of efficacy desired; the handling and use criteria of the disinfectant or sterilant – how easy and safe is it for their staff to use?"

Strategic planning

Among the many sterilization and high-level disinfection processes available today, some are more reliable than others, some are safer for workers and the environment, some are faster and some are more cost-effective.

What can help sterile processing managers in balancing their sterile processing/high-level disinfection needs with the limitations and capabilities of various sterilants and disinfectants?

"A plan," said Steve Conviser, sterilant manager, Honeywell (Morristown, NJ). "One that may involve the device-users, ICP, CS, engineering, quality control and other staff the healthcare center finds essential to these decisions. The plan should count for all of the facility’s re-usable instruments and their processing needs.

"Some questions the team often asks: Do we have the processes specified by the instrument manufacturers? What else do we need to know about each process? What sterility assurance can be acheived? How do we measure sterility? (BI, PCD, how often: how long to obtain BI results?) For how long can we store the sterile device? How does the product affect device service life, integrity and performance? How long to make the device ready for the next surgery? Trace-ability and record keeping? Operating and capital costs? Is managing this process onerous?
Is there and economic single-use option?"

"Goal priorities must be set," Conviser continued. "Instrument groupings can help. Daily reprocessing loads need to be determined. Future needs should be recognized. For example, if the facility is a research hospital, what types of new devices should CS be prepared to process? And, what, reasonably, will be required for sterility, device integrity and performance?"

These are just some of the questions a CS manager must answer when choosing steriliants and disinfectants.

"What makes life more complicated for people running central sterile these days, is they have a wider range of choices of processes, and these processes, including the estabished ones, often change," said Conviser. "So the people who plan sterilization have an increasingly difficult task."

"The varying exposure times, temperature settings, chemistry re-use periods and process monitoring requirements specified by different chemistry manufacturers allow for user variability. This, in turn, can create confusion and errors, and can jeopardize patient safety," said Struk.

Ann Hewitt, vice president sales and marketing for Quebec-based TSO3, notes, "Selection of the appropriate steam cycle is becoming more challenging, especially with the variation in recommendations on processing large orthopedic loaner trays. There is no guarantee that a steam cycle that differs from the manufacturer’s recommendation will actually sterilize those instruments."

"Improper loading of a sterilization chamber can lead to aborted cycles, which cost the hospital time and a lot of money in re-packaging, using a new BI, and of course labor," she adds.

"Most CS professionals seem interested in streamlining their choices," said Hewitt. "Too many choices in cycle time, cycle temperature, temperature of disinfectant, etc., can lead to confusion and to errors that could compromise patient safety. Technologies need to be simple to use and have protection against making the wrong selection built into them."

"One of the biggest challenges is minimizing human error," said Mary Kundus, RN, BSN, CIC, supervisor, technical service, 3M Health Care, Sterilization Assurance, St. Paul, MN. "Customers tell 3M that education is one of the major contributors to achieving sterility assurance. It’s all about knowing the processes and procedures to follow and understanding why. Then, training is needed – baseline training for new employees and re-fresher training for experienced employees – so that every step, every detail, every day, the procedures are followed."

Above all, manufacturers’ instructions should be a CS manager’s ultimate guide.

"I agree with what CS managers always tell us. A good sterilization program starts with following written reprocessing instructions from the device manufacturer," said Conviser. "CS managers who do not have such written instructions should call the manufacturer and obtain them before processing."

"The few times that we have been brought in when sterilization was implicated in adverse patient health problems, the cause was the hospital following unclear or even incorrect reprocessing instructions." Conviser adds, "I would think that if the CS manager has been asked to sterilize instruments for which they cannot obtain clear written instructions or that require reprocessing by equipment not available to their facility, they need to discuss this with their manager or with the department that has specified that particular instrument."

Team CS/IC

Under the best circumstances, selection of sterilants and disinfectants should be a team effort between the central sterile and infection control departments.

"Infection control practitioners (ICPs) should be involved in the selection and then the ongoing measurement of efficacy of all processes used for sterilizing reusable medical equipment," said TSO3’s Hewitt. "Their understanding of microbiology coupled with their capacity to follow the patient through the spectrum of care – from procedure to discharge – provides them with a different perspective on the impact of various options than anyone else in the healthcare setting. Their expertise is vital to making good patient care decisions."

"Efficacy should be most important, of course. CS and IC professionals both need to be aware of the parameters for safe processing and the reasons behind those parameters," continued Hewitt. "If a disinfectant is not effective at a room temperature below 25°C and the processing room cannot be warmed above 21 degrees, the disinfectant won’t perform as it’s supposed to and should not be selected."

Likewise, infection control practitioners should consider device challenges and surgical case loads when evaluating sterilants and disinfectants. "Infection control should have an understanding of the types of processes being utilized for the cleaning, disinfection and sterilization of reusable devices. In addition, infection control should have a good understanding of what types of devices are being processed (e.g. scopes, implantable, etc.)," said 3M’s Kundus.

Kundus outlines a plan for fostering collaboration between infection control and sterile processing departments:

• Meet at least quarterly to review current practices and perform walk-throughs in the sterile processing area. This will promote open communication between the two departments and allow infection control to inspect the area for adherence to established protocols and provide feedback to sterile processing.

• Work as a team to update sterile processing’s policies and procedures using the most current recommended practice guidelines from AAMI and AORN.

• Use the Infection Control Committee, as appropriate, to review and approve updated policies and procedures in an effort to promote the use of best practice within the organization.

"Use of all three of the above components will facilitate a more cohesive working relationship between infection control and sterile processing resulting in improved patient safety," said Kundus.

Applied specifically to the selection of products, "infection control practitioners should be part of the team that evaluates potential sterilants and disinfectants used in sterile processing. This may take the form of a special ad-hoc committee or a product evaluation committee (e.g. value analysis committee). The infection control practitioner will be able to review pertinent technical data and studies on products, assess appropriateness for the intended use of the product and offer recommendations as to whether a potential sterilant or disinfectant should be submitted to the Infection Control Committee for a trial, if appropriate, or for approval to implement," she added.

"The infection control practitioner brings his/her expertise in epidemiology and infection prevention and control to the process that will ultimately promote best practice and improved outcomes for patients served," said Kundus.

Weighing options

While steam sterilization is the preferred and most common method of sterilization for its cost-effectiveness and safety, most delicate instruments such as endoscopes cannot tolerate the intense heat required to steam-sterilize. For these heat-sensitive items, many facilities use a sterilant gas technology such as ethylene oxide.

Honeywell supplies non-flammable ethylene oxide sterilant blends, sold as Oxyfume. Why would a hospital choose to use Honeywell’s Oxyfume sterilant gas? "It handles large loads and large devices," explained Conviser. "Because it is non-flammable, Oxyfume can be used in much larger chambers [typically 30 cf.] than other chemical sterilants [typically used in small chambers [less than 5 cf.], he said. "With over 50 years of use, Oxyfume has been validated for more devices than any other process, giving the CS manager greater flexibility in scheduling devices for sterilization."

Conviser also notes that "whether or not the hospital uses Oxyfume, it may still need to use ethylene oxide. AdvaMed, the medical device manufacturer’s association, reported this year that ‘more than one third of medical devices used by hospitals... would become unusuable’ if the hospitals could not sterilize with ethylene oxide²."

Another boost to productivity and customer service, are faster turn-around times available through new Oxyfume sterilization cycles that have been shortened from 16 hours to 10 hours thanks to new Stericert EO controls.

Glutaraldehyde-based products are some of the most common liquid chemical sterilants used in facilities today and provide both high-level disinfection as well as sterilization when instruments are soaked for a specified time. The MetriCide family of sterilants from Metrex has a 20-year history, is available in three concentrations of gluatraldehyde, is noncorrosive and has an excellent instrument compatibility for the high-level disinfection of endoscopes as well as sterilization of heat-sensitive surgical instruments and other medical devices, explained Rossana Fernan-dez, marketing manager, medical products, Metrex (Orange, CA).

According to Fernandez, a common mistake is not testing sterilant before each use to ensure its effectiveness. "We recommend testing MetriCide Glutaraldehyde solution before each use with a MetriTest Strip. This will help guard against dilution, which may lower the level of the solution below its minimum effective concentration."

Cleaning is another component of sterility assurance. Fernandez suggests a pre-cleaning enzymatic spray that can be sprayed on instruments immediately after surgery.

"The presence of soil or organic material on medical devices can reduce disinfection or sterilization effectiveness. Use an effective enzymatic cleaning detergent that facilitates the cleaning of instruments prior to disinfection and sterilization. We recommend using EmPower Foam enzymatic foaming spray as an excellent start for dissolving bioburden immediately after use. The AAMI Guidelines on Safe Handling and Biological Decontamination of Reusable Medical Devices in Healthcare Facilities and in Non-Clinical Settings3 recommend products like EmPower Foam immediately after use to keep items moist in transport containers," said Fernandez.

Soaking instruments in EmPower or MetriZyme enzymatic detergents offers fast, thorough removal of proteinaceous debris before moving onto the disinfection and sterilization step, said Fernandez.

New technologies such as ozone are also gaining headway for their efficacy and other advantages. TSO3’s 125L Ozone Sterilizer is a general purpose low temperature sterilizer that can process a broad array of heat and moisture sensitive devices. It uses ozone as the sterilant, and makes that sterilant itself from water, oxygen and electricity. There is no sterilant to purchase or handle, and the cost is less than $1.00 per cycle. The 125L recently received FDA clearance on the largest variety of lumen sizes, highlighting the superior efficacy of the ozone process.

STERIS recently introduced its Reliance EPS Endoscope Processing system, which uses a single-use, pre-measured chemistry as part of a validated system, and monitors the critical parameters of each cycle without the need for manual intervention or setting changes, noted Struk. The dry germicide is pre-measured and packaged for single use, which assures the efficacy of each cycle and eliminates the variability and additional handling and work that is required with a reusable solution.

"A system approach, where the processor and chemistry are validated to perform together, provides the added assurance of a consistent, efficacious outcome. It eliminates the potential guesswork and fragmented approach of combining a processor from one manufacturer and chemistry from another," said Struk.

Safety and toxicity concerns

Robert Schattner, DMD, president and CEO, The Sporicidin Company (Rockville, MD), advises that safety in handling of sterilants and disinfectants by the end-user should include inhalation, dermal, eye, skin and oral toxicity concerns, as well as safety for instruments and equipment.

"All sterilization requires the killing of germs. Anything that can kill germs can hurt people," said Honeywell’s Conviser. "All CS workers should be trained, frequently and diligently, about the hazards of each process, how to avoid accidents, and what to do in the event of an emergency. This is needed whether operating a sterilizer using high temperature steam or one using a toxic gas."

"For any chemical sterilant, know what is in the MSDS, and what regulations may apply to its safe use," he continued. "For ethylene oxide, comply with the OSHA ethylene oxide standard [29 CFR 1910.1047], which includes or references the key occupational standards regarding this chemical. Remember to review Federal and local environmental emission guidelines for any chemical the hospital uses. Standards can be changed; new ones may have been implemented."

"The fact that you can’t see or smell something doesn’t mean it’s not harmful," said Hewitt. "And the fact that something may be innocuous if used properly doesn’t mean it can’t cause harm if used improperly. We all know someone who’s suffered a burn from steam; likewise, there are healthcare workers who’ve suffered a burn or other skin damage from exposure to a concentrated level of gluteraldehyde or hydrogen peroxide. If a hospital can select a sterilant or disinfectant that minimizes storage, handling and disposal as well as minimizes the amount of toxic substance discharged to the air or water system, it should most certainly do that."

Among some of the safer new technologies on the market, TSO3’s Ozone sterilizer produces just water vapor and oxygen as byproducts, thus "there is no environmental impact," said Hewitt.

STERIS’ Reliance EPS uses a patented Reliance DG (dry germicide) formulation to achieve high-level disinfection. Reliance DG is an oxidative, generational chemistry that provides many safety benefits to healthcare workers and patients. The Reliance DG formula eliminates the staff exposure hazards that are associated with aldehyde-based HLD solutions. Using an oxidizing chemistry also eliminates the concern about aldehyde-induced colitis in patients. And because the active high-level disinfection solution is not generated until the Reliance DG dry formulation cup is sealed into the Reliance EPS processor and the cycle is initiated, this greatly diminishes chemical exposure concerns and means that the system does not require manual measuring, mixing pouring, or special venting.

"It is always important to refer to the sterilant or disinfectant package insert for specific use instructions, to assure appropriate measures are taken when using various chemistries," said Struk. "For example, some aldehyde-based disinfectant solutions carry specific exposure hazards (i.e. occupational asthma, headaches, etc.), so requirements such as appropriate ventilation, air exchanges and monitoring of solution exposure levels need to be taken into consideration."

Sporicidin Sterilizing Solution and High Level Disinfectant contains just 1% glutaraldehyde, the lowest level registered by FDA for sterilization. Glutaraldehyde at high levels is not only a concern for workers and the environment – causing tearing of the eyes, and irritation of nasal passages – but also can cause problems for endoscopes.

"At the 1% level, Sporicidin does not cloud lenses nor clog air/water channels of endoscopes," said Schattner. "Reduced glutaraldehyde makes it safer for instruments, equipment and the end-user." Lower glutaraldehyde levels also reduce the need for special ventilation. "The low level of glutaraldehyde does not have special requirements and can be disposed of in the regular drain," Schattner added.

The thing to remember is that by following the rules, you can safely use even the most dangerous chemicals to kill deadly bacteria. Honeywell’s Conviser cautions that new and increasingly harmful antibiotic-
resistant microbial strains such as MRSA, or so-called ‘super-bugs’ such as C. difficile, may become a growing concern for CS departments.

"What can happen, if super-bug problems persist – infection control teams, having eliminated the largest sources of hospital-acquired infection, such as inadequate hand washing, will review other possible sources, including central sterile, saying, ‘let’s double check all the disinfection and sterilization procedures and make sure we don’t have a problem there either,’" said Conviser. HPN

References:

1. Favero MS, Bond WW. Disinfection of medical and surgical materials. In: Block SS, ed. Disinfection, Sterilization, and Preservation. Philadelphia: Lippincott Williams & Wilkins; 2001:881-917.

2. Letter dated May 19, 2006 from AdvaMed to the Environmental Protection Agency, responding to Docket ID Number EPA-HQ-OPP–2005–0203, Ethylene Oxide Risk Assessment; Notice of Availability.

3. AAMI Guideline Transportation Section 6.2