I S S U E S B A C K G R O U N D E R For information contact: Joni Morford, Communicore 714/721-8081 jmorford@communicore.com ISSUES IN THE ADOPTION OF NEW STERILIZATION TECHNOLOGY: HOSPITAL SAFETY AND STERILITY ASSURANCE FOR THE 90s AND BEYOND Introduction Everyone entering a hospital, clinic, or doctor's office for diagnosis or treatment expects that all instruments used will be free of contamination. Infection control experts warn, however, that not all reusable medical instruments are in fact cleaned and decontaminated before their next use. Some are only disinfected. Sterilization is a process designed to inactivate all life-forms, including bacteria, viruses, and the difficult-to-inactivate bacterial spores that might be found on a used medical instrument or supply item. Disinfection, in contrast, may be defined as a process designed to inactivate most microorganisms--but not resistant bacterial or fungal spores that are a source of potential infection. Cleaning is the process of removing organic or inorganic material from a medical instrument by normal means, such as washing with cleanser and water. Although instrument cleaning must be performed prior to either sterilization or disinfection, it is not a substitute. Sterilization is preferable to disinfection, but current sterilization processes such as dry heat and steam can damage some instruments, while ethylene oxide (EtO) imposes additional worker safety problems as well as time and cost constraints. These issues contribute to the current disinfection versus sterilization debate within the healthcare community and underscore the importance of adopting an alternative sterilization technology. In the late 1950s, hospitals began using ethylene oxide to sterilize medical and surgical instruments after this gas was shown not to cause the heat and humidity damage of steam systems. Today, pure EtO is used as a sterilant, or it is mixed with flame-retardant "carrier" gases because of its high flammability. Until recently, the most common carrier gas contained chlorofluorocarbons (CFCs), commonly used in "12/88" sterilization systems that employ a combination of 12 percent EtO and 88 percent CFC. Effective December 31, 1995, however, CFCs were banned by the United States Environmental Protection Agency (EPA) because they have been shown to deplete the earth's ozone layer. Some institutions have chosen to incur the expense of retrofitting their 12/88 systems to use another carrier gas--containing hydrochlorofluorocarbons (HCFCs)-- which is commonly used in a configuration of approximately 10 percent EtO and 90 percent HCFC. Ethylene oxide may also be diluted with carbon dioxide. Despite the availability of these options, however, many hospitals are abandoning EtO-based systems in favor of new low-temperature sterilization technologies that are faster, more cost- effective, and safer for workers, patients, and the environment, and that meet regulatory requirements for the use of environmentally harmful carrier gases. Hospital Employee Safety The sterilization efficacy of EtO is well-established, but EtO use involves compromises. Classified as a pesticide by the EPA, it is a noxious gas that poses a toxic risk to both healthcare workers and patients if not carefully controlled. Ethylene oxide depresses the central nervous system, irritates the respiratory system, eyes, and skin, and has been linked to adverse reproductive events. Animal studies conducted by the National Institute of Occupational Safety and Health in 1977 indicated that EtO is carcinogenic, and in 1978, the EPA confirmed that EtO is a mutagen. Furthermore, the International Agency for Research on Cancer has recently reclassified EtO from a Class IIA "suspected" carcinogen to a Class IA "recognized" carcinogen. To protect workers and patients from these harmful effects, hospitals have been required to install federally mandated abatement and monitoring equipment to reduce the risk of EtO exposure. Some states have even more stringent requirements. Healthcare workers using EtO-based systems must also wear personal EtO monitors and special garments to protect themselves in the event of an EtO leak. Finally, extensive operating and safety training must be provided to those employees involved with EtO sterilization--at a considerable cost to the hospital. Storage and transport of EtO tanks is another safety concern. EtO is an explosive gas that is four times as flammable as propane and must be stored separately from the sterilization unit in a fireproof vault. Newer, single-use cartridges of 100 percent EtO are available, but they require the same protective storage as EtO tanks. Environmental Safety The CFCs and HCFCs used to retard flammability in most EtO-based systems present significant hazards of their own. In 1987, key governmental agencies representing 100 countries formulated the "Montreal Protocol," a multinational document calling for the worldwide ban of ozone-depleting chemicals. The EPA, recognizing CFCs as one of the leading causes of the depletion of atmospheric ozone, instituted a gradual phaseout of CFC production, requiring hospitals to halt their use of CFCs by the end of 1995. HCFCs, which also have ozone-depleting properties, will be virtually eliminated in the United States by 2020. The urgency to eliminate these gases has been echoed by nations worldwide. At the December 1995 meeting of the Montreal Protocol signatories, 24 governments signed a declaration stating that they would take all appropriate measures to limit the use of HCFCs and phase out their use as soon as possible. Negotiators from the United States, which consumes approximately 50 percent of the world's production of HCFCs, fought off an attempt by some European nations to speed up the phaseout date. The European countries, which have a minor reliance on HCFCs, had proposed deeper consumption cuts for HCFCs and an accelerated phaseout date of 2015. Continued attempts to move up the date will likely persist as the parties of the Montreal Protocol meet for its 10th anniversary in Montreal in 1997. Economics For many years, hospitals have accepted the dangers of ethylene oxide sterilization because the gas was considered the only effective and economical low-temperature sterilization method available. While its efficacy remains consistent, budget-conscious hospitals have now realized that there are growing economic concerns related to the use of EtO-based systems. First is the problem of lengthy cycle times associated with EtO-based systems. Ethylene oxide systems require an 8-14-hour aeration period to allow remaining gas to dissipate from sterilized instruments, resulting in a total processing time as long as 12-16 hours. This extended processing time results in a slow turnover of sterilized equipment and instruments, requiring hospitals with busy surgical schedules to invest in multiple sets of instruments to ensure availability. Other hidden costs of EtO include expenses related to the need for abatement and monitoring equipment, protective attire for workers, and installation and maintenance of specialized ventilation, plumbing, electrical systems, and custom storage capabilities. Furthermore, both individual healthcare workers and the facilities that employ them must acquire permits to use EtO-based systems. If EtO is not handled according to strict regulations, hospitals may be subject to punitive fines by the Occupational Safety and Health Administration (OSHA). Hospitals may also be held liable if a worker, patient, or visitor is exposed to EtO. Sterilization Versus Disinfection Closely associated with the issue of economics is sterility assurance. As more institutions face financial concerns in a changing healthcare environment, emphasis is increasingly placed on the cost-effective use of both labor and materials. The increase in same-day outpatient surgeries over inpatient operations mandates faster sterilization turnaround to ensure that the appropriate instruments are available for each procedure. Consequently, some hospitals have resorted to the use of disinfection in lieu of sterilization because the process is significantly faster and less-expensive. While hospitals often substitute high-level disinfection for sterilization of instruments, the end result of the two processes is not the same. Sterilization is designed to inactivate all life forms. Disinfection, however, is a process that inactivates living microorganisms, except for bacterial or fungal spores that can also be a source of infection. While patients and the public may not be universally aware of the distinction between the two processes, recent best-selling books including "The Coming Plague" and "The Hot Zone" have brought attention to the importance of infection control by examining the continuing emergence of resistant strains of once-conquered lethal infections as well as new, previously unidentified, and sometimes very dangerous pathogens. At the 1994 International Symposium on Chemical Germicides, participants from the Association for Professionals in Infection Control and Epidemiology noted that continuing problems of nosocomial (hospital-acquired) infections are most often the result of inadequate cleaning, ineffective disinfection, and failure to follow recommended disinfection practices, particularly for endoscopic instruments. Sterilization, by definition, if preceded by properly cleaning, provides a much higher assurance that instruments are truly free of contamination. Low-Temperature Sterilization Alternatives In the last several years, a number of new low-temperature sterilization technologies have been developed in the United States, and several have now entered the market. The role these emerging sterilization technologies will have on the future of sterile processing is expected to be significant as traditional sterilization technologies are less relied upon in the years to come. Manufacturers of these new technologies are attempting to solve the problems associated with EtO use--with varying degrees of success. Healthcare facilities choosing a replacement for their EtO-based systems are basing their decisions on a variety of criteria including: * Efficacy: Does the system destroy a broad spectrum of microorganisms as determined by biological testing? * Healthcare worker and patient safety: Does the technology present little or no health risk to system operators or patients? * Environmental safety: Are potential hazards to the environment minimal or absent? * Cost effectiveness: Can the process provide rapid instrument sterilization turnaround with reasonable installation and operational costs? * Materials compatibility: Can the technology sterilize without damaging or corroding sensitive and expensive medical instrumentation? New and emerging low-temperature sterilization alternatives for medical instrumentation include peracetic acid, ozone, vapor phase hydrogen peroxide, and gas plasma systems. Peracetic Acid Peracetic acid is listed by the Centers for Disease Control and Prevention (CDC) as both a high-level disinfectant and a chemical sterilant, and it has been available commercially for sterilization in healthcare facilities since 1988. Because concentrated peracetic acid is corrosive and can be irritating to the skin and mucous membranes, manufacturers have designed systems that use the substance in sealed, single-use containers. Peracetic acid liquid chemical sterilization systems have one of the fastest processing times (approximately 30-40 minutes), but are severely limited in use to only immersible instruments. Furthermore, liquid chemical sterilization systems are able to process only a few items at one time. These instruments are exposed directly to the sterilant without protective packaging. Sterility cannot be maintained after the instruments are removed from the sterilizer. Therefore, instruments must be used immediately to maintain sterility since they cannot be stored sterile. While there is concern that the corrosive properties of peracetic acid can be damaging to instruments, an even larger question centers on the lack of monitoring of the process. To date, there is no biological indicator (BI) available to test the sterilizing efficacy of this liquid sterilization system. Studies suggesting that spore strips currently used as BIs for EtO and steam could be used to monitor peracetic acid sterilization have been challenged by the CDC. As long as there is no established sterility monitoring technique, routine efficacy of peracetic acid sterilization cannot be checked by the hospital. Ozone Although still investigational, an ozone sterilizer has been developed for use in healthcare applications. The system applies an electrical discharge to oxygen, converting the oxygen molecules (containing two atoms of oxygen) into ozone. Ozone molecules contain three atoms of oxygen, and they are highly unstable. In the sterilization systems, the reactive ozone gas is combined with water vapor and dispersed throughout the sterilization chamber, where it reacts with and inactivates microorganisms. The ozone then naturally degrades back to oxygen. Sterilization cycles last from 30-120 minutes. A major limitation of ozone sterilizers is materials compatibility. Ozone gas can be corrosive to medical instruments and can damage plastics and rubber materials. The high chamber humidity required (75-95 percent) can also be damaging to moisture-sensitive items. The medical use of this technology has been very limited to date. Vapor Phase Hydrogen Peroxide A vapor phase hydrogen peroxide sterilization system has been developed for rigid endoscopes, but is not yet commercially available for the hospital market in the United States. The endoscopes are placed into custom containers that are loaded into a sterilization chamber. A deep vacuum is created, and a 35 percent solution of hydrogen peroxide is vaporized inside the chamber. The vacuum and injection phases are subsequently alternated in the 90-minute cycle, creating a vacuum pulse that routes the sterilant into the channels of the endoscopes. Unlike liquid chemical sterilizers, the containers used in the vapor phase hydrogen peroxide system can maintain the sterile condition over a period of time, allowing for sterile storage and transport. The endoscope sterilizer does not meet hospitals' immediate needs for general sterilization, however, and although a general-use sterilizer is also in the early stages of development, neither system has received clearance for commercialization in the United States. Gas Plasma Sterilization Scientists refer to the plasma state--not to be confused with blood plasma--as the fourth state of matter, different from solids, liquids, and gases. Plasmas can occur naturally in outer space as a cloud-like body of ions, electrons, and neutral atomic and molecular species. One of the more prominent plasmas in nature is the aurora borealis or "northern lights." An everyday example of a gas plasma is neon lights. Initiating a low-temperature plasma requires a closed chamber, a deep vacuum, a chemical precursor on which to base the plasma, and a source of electromagnetic energy, such as radio frequency (RF) energy. Mixed Chemical Plasma A mixed chemical plasma (MCP) system became available in the United States in January 1995. The system uses a two-phase sterilization cycle that is repeated six times during the sterilization process. In the first phase, a chemical vapor is formed by evaporating a peracetic acid chemical solution into the sterilizer. In the second phase, a mixture of gases including hydrogen and oxygen is exposed to an electromagnetic field to create a plasma that is flowed into the sterilization chamber. The entire process as cleared for U.S. use takes more than three hours. The MCP system is limited in that it is not indicated for use on instruments with lumens or hinges and does not eliminate handling of toxic chemicals. Workers must periodically load bottles of peracetic acid for the first phase of the sterilization cycle, and special venting is required for the elimination of remaining peracetic acid vapor. Hydrogen Peroxide Gas Plasma Hydrogen peroxide gas plasma sterilization has been recommended as a viable alternative to EtO sterilization by the Association of Operating Room Nurses (AORN). Unlike mixed chemical plasma or other low-temperature sterilization systems, it does not require workers to handle toxic chemicals and there is no need for gas tanks, abatement and monitoring equipment, or protective gear. Instead, hydrogen peroxide is injected into the sterilization chamber from a self-contained cassette inserted into the sterilizer by the user. The hydrogen peroxide solution vaporizes and diffuses throughout the sterilization chamber, surrounding the items to be sterilized and initiating the inactivation of microorganisms encountered in the sterilization chamber. After a period of hydrogen peroxide diffusion, the pressure is reduced in the chamber and the formation of a low-temperature gas plasma is initiated by applying radio frequency (RF) energy to create an electromagnetic field. In the plasma state, the hydrogen peroxide molecules break apart into reactive species that include free radicals. The combination of the hydrogen peroxide diffusion pretreatment phase and the plasma phase acts to disrupt the life functions of the microorganisms, including viruses and bacterial spores, on instruments and other surfaces within the chamber, thereby sterilizing the instruments, and to convert the hydrogen peroxide to non-toxic products, primarily harmless oxygen and water vapor, so that the items are ready for use. When the process is complete, the RF energy is turned off, the vacuum is released, and the chamber is returned to atmospheric pressure by the introduction of filtered air. After 10 sterilization cycles, the hydrogen peroxide cassette self-ejects into an internal receptacle for future disposal. A low-temperature hydrogen peroxide gas plasma sterilization system has been commercially available in Europe since 1992 and in the United States since October 1993. A key advantage of the system is its short cycle time--lasting about one hour--after which sterilized items are immediately ready for use. In addition, since no toxic chemicals remain at the end of the sterilization cycle, aeration is not required. The hydrogen peroxide cassettes make the system safe and easy to use, and there are no special plumbing or siting requirements for installation. An adapted electrical outlet is all that is needed for installation, making the system well-suited for placement wherever it is needed within a healthcare facility, including the surgical suite. The sterilization unit is mounted on rollers, providing the added convenience of mobility. Studies have shown the hydrogen peroxide gas plasma system to be effective in sterilizing a majority of items traditionally sterilized by EtO, with the exception of cellulosic materials that can be easily and economically sterilized with steam. Hydrogen peroxide gas plasma is currently capable of sterilizing instruments with lumens less than or equal to 31 cm in length and larger than or equal to 6 mm in diameter. An accessory that facilitates sterilization of longer, more narrow lumens, such as those of flexible endoscopes, is available in many countries worldwide, but it is not cleared for marketing in the United States. Conclusion For years, hospitals have relied on EtO-based sterilization systems for their low-temperature sterilization needs. Because these systems were the only available option for heat and moisture-sensitive instruments, hospitals were forced to accept several unpalatable compromises in safety, cost, and convenience. Today, however, environmental and safety requirements and increasing cost pressures are leading hospitals to investigate alternatives. Hydrogen peroxide gas plasma has emerged as the most promising alternative to EtO because it can effectively sterilize instruments without compromising the safety of healthcare workers, patients, or the environment. Furthermore, with sterilization cycle times of about one hour, hospitals no longer need to rely on high-level disinfection in lieu of sterilization. Instruments can be processed quickly, ensuring that hospitals have sterilized instruments available for every patient in each procedure. End of document.