STERILIZATION

The process of sterilization, despite being implemented in healthcare functions for several decades is still ambiguous to many individuals. Hence, by developing comprehension regarding the most usual sterilization methodology which is implemented prevalently; healthcare personnel would be able to optimize the gains from present technology along with enhancing their understanding which will enable them to effortlessly comprehend the future innovative advancement in this particular field.

Numerous challenges have been stimulated by the present healthcare environment:
Healthcare industry has been propelled to reduce expenditures due to the fact that there has been a decline in reimbursements regarding health insurance. This predicaments leads to a lesser number of full-time personnel; therefore, every individual is compelled to work rigorously which leaves insufficient time for training. Lack of training will ultimately jeopardize the patient’s safety as the personnel are not adequately trained for the sterilization procedure.
Since the past fifteen years, lesser number of invasive methodologies have been implemented whilst novel and less invasive methodologies have been formulated. Therefore, this tendency has spurred an escalated level of utilizing sophisticated devices which are usually heat sensitive and intricate. Hence, sterilizing these particular devices could be of intricate nature.
Hospital managements are undertaking swift rotation of OR to facilitate the structuring of further methodologies so as to augment the revenues. This particular demand when coalesced with inadequate and expensive inventory of paraphernalia instigates additional sterilization complexities.
These particular complexities accentuate the necessity of comprehending the fundamental theory and methodologies pertaining to apposite sterilization procedure which will be beneficial in saving time, reducing threats, and enhance the efficiency of these procedures. This paper presents a tutorial as well as an initial reference for the healthcare personnel.

Sterilization Basics
With the aim of conducting an adequate sterilization procedure, it is obligatory to satisfy the two essential stipulations, which are as under:
1. It is necessary to decontaminate the paraphernalia scrupulously without which a sterilization procedure could never be successful. Sterilizer manufactures presume that the contamination level or bioburden will be significantly lessened from the paraphernalia’s plane before being placed inside the sterilizer. Therefore, depending on this attribute manufacturers recommend an adequate exposure time which is referred as “kill time”. It the paraphernalia is not sanitized adequately then the mentioned exposure time will certainly be insufficient for sterilizing that particular paraphernalia.
2. Every single plane of the equipment should be contacted by the sterilant. This accentuates that the paraphernalia should be disintegrated as per manufacturers’ guidelines; hence, every single plane will easily be contacted by the sterilant.
Sterilization is also influenced by the following factors:
The dehydrated state of the paraphernalia which will be sterilized
The humidity and temperature level of the surrounding area
Whether the paraphernalia was adequately organized and placed inside the sterilizer or not
Whether the sterilant was effectively conveyed in the system or not
Sterilizer’s maintenance and condition protocol
Whether appropriate and accurate sterilization methodologies and procedures were implemented or not

Methods of Sterilization
Presently, in the healthcare industry four general methodologies are implemented:
1. Steam sterilization
2. Peracetic acid liquid sterilization
3. Ethylene oxide sterilization
4. Hydrogen peroxide sterilization


High-level disinfectants which are capable of sterilizing are presently being implemented. They involve extensive immersion time span (twelve to thirty-six hours). These particular sanitizers are generally implemented for high-level disinfections; therefore, for this particular rationale, these solutions would not be discussed in this paper.


Adequate preparation and sanitizing are the two crucial aspects associated to the above stated sterilizing methodology. The aim is to eradicate every single observable inorganic and organic “soil” automatically or manually from the paraphernalia before positioning it inside the sterilizer. Pre-cleaning measures facilitate the personnel in safely handling and packing paraphernalia along with enabling the sterilant to contact every single plane throughout the sterilizing methodology.

Steam Sterilization

In the year 1880, steam sterilization procedure was initially launched. The procedure utilized moist heat under pressure, similar to pressure cookers. The steam sterilizer which was launched commercially utilized saturated steam under pressure and in the year 1933, it was sold in America. Presently, not a single sterile processing methodology is ideal but steam sterilization has undoubtedly reached a position which is unprecedented as well as unmatched. Furthermore, it is economical, fast, eco-friendly, and non toxic.


The organisms are obliterated by the steam through coagulating cell proteins. An everyday instance of coagulating proteins is boiling an egg. The steam should contact every single plane of the paraphernalia so as to obliterate the microbes entirely.


Only those planes are sterilized which are contacted by the steam. The predicaments which are encountered in this procedure are mainly caused by air pockets, as they avert the steam from contacting the planes. These air pockets are generally instigated by inappropriate loading and packing assembly.


The two chief kinds of prevalently utilized steam cycles are: dynamic air removal and gravity displacement and they incorporate steam flush pressure pulse (SFPP) and prevacuum cycles. The initial kind of cycle which was implemented in hospitals was the gravity displacement steam sterilization.

This kind of cycle is utilized in operating rooms for the purpose of “flash” sterilization.
When the air in the form of steam enters inside the chamber then gravity is utilized to displace it. The air is removed more effectually by prevacuum cycle on the basis of mechanical procedure. Mechanical air removal over the atmospheric pressure is implemented by SFPP cycle. Furthermore, these cycles entail three stages:
1. Conditioning phase: air is eradicated, steam penetrates into the chamber; the paraphernalia instigates to heat up according to a fixed temperature.
2. Exposure phase: the time span involved in this particular phase is fixed on scientific basis. It entails actual kill time, heating time, additionally a safety element which is equivalent to 50 percent of kill time.
3. Exhaust phase: when the exposure phase ends, steam is swapped with air which enables the chamber to settle down to a level equal to the atmospheric pressure.
The sole predicament associated to the steam sterilization incapacitates numerous heat sensitive paraphernalia and specially endoscopes to be sterilized due to the fact these equipments are not capable of withstanding the level of heat of this methodology.

Peracetic Acid Liquid Sterilization
Peracetic acid liquid sterilization was developed in response to the increased demand of heatsensitive devices’ quick turnaround time. The heat sensitive devices are being processed by Ethylene oxide gas for a very long time, however, the slowness in this method is attributed to the aeration time, which is required for gas removal at the cycle’s end.

During low concentrations, Peracetic acid was sporicidal. The quality of water solubility was also witnessed, hence, no residue was found when rinsed. There were no negative environmental or health impacts. In reality, for sterilization method, peracetic acid was adopted by the food industry as the nature of this was quite safe and advantageous. The bonds in enzymes and proteins were disrupted due to the method of Peracetic acid. The rupture of cell walls served as a mean for interfering cell membrane transportation. This may also mean that necessary enzymes may be oxidized and significant biochemical pathways may be impaired.

Various steps need to be followed while preparing sterilization under low temperature liquid chemical sterile processing system:
 It is important to conduct devices’ meticulous pre-cleaning as they posses very complicated small connected lumens. Sterliant will not be able to have surface contact if the devices are not properly cleaned.
in order to prevent leaks from entering into scope and damaging the process, leak test should be carried out with a lumen and any flexible endoscope. Specific guidelines concerning leak testing and cleaning have been provided by SGNA (Society of Gastroenterology Nurses and Associates). Furthermore, particular recommendations are also provided by the manufacturers of medical devices.
 Then the selection of suitable container/tray should be undertaken, followed with the identification of lumens and attached connectors in devices. Manufacturers provide manuals, diagrams, and specific instructions regarding each connector.
A sealed single use cup is used for providing sterilant concentrate as no dilution or pre-mixing is required. In the cycle’s end, empty container is discarded in normal trash receptacles.
Steam sterilizer is quite similar to the processors monitor of today’s era in terms of quality assurance. In the cycle’s end, a printout is taken so that one can ascertain what sterilization parameters were present in the process. The cycle is canceled if any parameter is not met. Diagnostic cycle must be carried at least once in every 24 hours. The sterile water filter membrane’s integrity, pneumatic and electrical systems, and machine’s mechanics are checked during this cycle. This cycle is exclusive of sterilant.
Sterilization’s method has certain weaknesses too, like the process has to undergo a temperature of 55-degree Centigrade, fitted in a suitable tray, and immersible devices must be used. Such kind of temperature setting is better regarded as “low-temperature sterilization” as at a particular dilated concentration, the peracetic acid’s sporicidal activity is maintained.

Ethylene Oxide Sterilization
Since 1950s, ethylene oxide (EO) is utilized as sterilant in the healthcare industry. It is chiefly an odorless, flammable, and colorless gas. Amidst the most generally utilized industrial chemical it is ranked at eighteenth number; furthermore, a quantity which exceeds eight billion ton is produced on annual basis for manufacturing detergent, polyester, plastic, and anti-freeze. Only one percent of the produced quantity is utilized in the healthcare industry for sterilizing moisture and heat sensitive paraphernalia.


Discovered in 1859 and originally utilized as a sterilizer for agricultural and industrial purposes, Ethylene oxide was recognized as a gaseous sterilant by the U.S. Army in the 1940s due to its disinfectant features discovered earlier in the 1920s. By the 1950s, EO had started being used as a sterilant for instruments that were heat-sensitive and facilitated the augmented progression of heat-sensitive curative devices.




Due to the combustible nature of 100% EO, in the 1960s other more secure and fire-resistant EO combinations were created, and later adopted by the medical industry by the 1970s to disinfect heat-sensitive elements.




Occupational Safety and Health Administration (OSHA) set admissible exposure standards and ongoing supervision conditions for work zones as well as employees, when employee health and welfare concerns associated with EO usage came into light in the 1980s. Other issues, particularly those relating to the weakening of the ozone layer due to the existence of CFCs in EO gas combinations and the destruction of the environment, resulted in the Montreal Protocol agreement relating to the discontinuation of the service of EO/CFC mixtures which was successfully finished by 2000.




The process by which the sterilization of ethylene oxide occurs is called alkylation. This chemical process involves the infiltration of the infectious cells by the EO and then the oxidization of the nuclear material, which affects the cell’s capacity to function and process routinely.




The use of EO in the form of a sterilant can be beneficial in a number of ways. The decontamination of elements that can not be otherwise sterilized using heat sterilization takes place using EO. Because of the small size of the EO molecule, the filtration and penetration in every-day items as well as intricate instruments is very prompt. Lately, advancements in technology have made EO decontamination cheaper and more secure. The drawbacks nonetheless, remain substantial.




Due to the detrimental effects of EO on patients as well as employees, an extensive ventilation process is carried out to rid the load of EO. Also, the EO decontamination process is more time consuming than any other. The safety and environmental requirements ensure that the disinfectants meet particular standards in terms of aeration, exhaust and supervision. The combustibility of EO is another limitation, although, the introduction of the one-off 100% EO cartridge has addressed this issue.


Hydrogen Peroxide Sterilization


The health and welfare industry has, in recent times, seen a novel and different sterilization process that uses hydrogen peroxide. In this process, a plasma cloud is created when a hydrogen peroxide mixture is diffused in a vacuum chamber. Important cellular elements are dissolved resulting in the unresponsiveness of microorganisms using this sterilization method. The existence of the energy source leads to the presence of the plasma cloud. The absence of the energy source results in the creation of oxygen and water vapor. This leads to lower need of environmental supervision and zero toxic residues and harmful radiations.


The temperature lies between 40-50°C (104-122 degree Fahrenheit) which makes it compatible with moisture and heat resistant curative instruments. A cassette contains the sterilant chemistry and the sterilization process is around 45-55 minutes long which is reliant on the sterilizer version and make. The sterilizing devices are covered before the initiation of the process and can be stored or utilized instantaneously.


Polypropylene or non-woven wraps, polyethylene foam, Tyvek/Mylar peel bags and synthetic paper are some of the coverings used for a hydrogen peroxide disinfectant. A count sheet is to be sterilized and put outside the set if it is to be used with a devise set.


A hydrogen peroxide process consists of the following five stages:
1) A vacuum is created in the chamber using a vacuum phase and a fall in the pressure as low as one pound/square inch is observed, which continues for 20 minutes.
2) A chemical known as the aqueous hydrogen peroxide is inducted into the vacuum compartment and is turned to gas using vaporization. This leads to an increase in pressure which is caused by the rise in molecules.
3) The dissemination stage diffuses the hydrogen peroxide gas everywhere in the compartment and the sterilant is led to the packs due to the rise in pressure. This exposes the device exteriors to the disinfectant and exterminates the microorganisms.
4) The plasma stage sees the application of the radio frequency energy that divests molecules from the electrons and creates a plasma cloud that is low in temperature. This leads to the loss of high energy by the stimulated composites and they then come together to develop water and oxygen. The vacuum inoculation and dispersion methods are carried out again to ensure that all instruments are completely sterilized.




The aeration stage involves the letting in of air into the compartment and then the exposure to normal environmental pressure in order to access the door. This phase is one minute long.
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A microprocessor is employed to monitor all the key factors to aid this process of low-temperature decontamination and produces a printout when the process ends for documentation purposes. If the key factors do not meet the standards then the process is discontinued and the cause is stated in the printout.


This process also has its drawbacks. Items that are made of paper of cloth like count sheets, peel bags, linen, cotton, etc, can not be employed as device covers or set augmenters. It is a requirement for the item to be entirely dry before the initiation of the process or the result will be termination. Inflexible scopes with lumens have constraints like lumen size less than 400 mm in length and more than 3mm in diameter for acceptance for the hydrogen peroxide decontamination process, while flexible scopes can not be used for this method.
Quality Assurance Monitoring for all Methods
Quality assurance is always in process, and everyone using any cleaning process should work upon the suggested guidelines which are mentioned by Association for advancement of Medical Instrumentation and rule and regulation of their facility. Though the rules of AAMI are not law, yet they are considered and agreed upon rules for sterilization in industry and these may be referred for any law proceedings. It is necessary for all the relevant user for sterilization to be able to read and work upon information presented in quality assurance supervision so that they should match with what it is recommended in AAMI and every other health care related facility’s rules and procedures.

NOTE: their isn’t any rule and standard recommended by AAMI for liquid per acetic acid sterilization or hydrogen peroxide sterilization.

Physical Monitors
The performance of every sterilization method should be supervised. The quality assurance for each step should be judged on the base of physical, chemical and biological checking .physically checking involves gauge ,printouts and bowie dick tests, and the investigative done for SYSTEM1 sterile processing system .these physical observation allows detection of fault of equipment and machinery in early stages, as they observe the cycles while in operation. They assure perfect timing, temperature, pressure and concentration. These measurement are then saved on print out that become a part of proper phase of documentation.

Chemical Monitors
Chemical observation and testing isn’t depending upon sterilization, it is added to confirm the phase’s efficiency. Chemical pointers are used to identify faults in packaging, loading and sterilizer functions. The chosen chemical indicator must inform the method to be use or used for sterilization. Chemical indicator are not to confirm sterilization, they are to make sure that each of the clause is successful during sterilizing process. Their are two types of indicators, internal indicators and external indicators. external monitors are placed out side of the packaging in mist .EO and hydrogen peroxide plasma sterilization and they permits healthcare staff to distinguish between packages which are exposed to sterling and those which don’t

Internal methods for chemical indication are used for every way of sterilization. they are to place in the packages or containers ,in those areas which are hard to access .these measures are then read and observed when the pack is opened ,these are basically for end user, that the steriliant reached the required part inside the pack.

Chemical integrators are multi factor indicators used internally in each pack or packages contrary to chemical indicator. the integrators reaches all the critical process measures. the integrator ink is relevant to a particular biological tests and assures a confidence of level of performance nearby or matching to somewhat biological indicators; however, chemical integrators are not a substitute to be replaces for biological tests.

Biological Monitors
Every process of sterilization should be observed with biological indicator (BI).the BI has a method of dealing with each bound of sterilization process and judging the ability of cycles to destroy microorganism. As per AAMI policies, a biological indication is useful to use for the identification of parameter of new sterilizer mechanism, to confirm the verification of sterilizer cycle parameter after important improvement and routinely in a fully loaded chamber. For vaporization it should be done weekly if can`t be done daily. a biological indicator should be involved in very pack contain implantable devices and in Ethylene load. AAMI polices also suggest to assure the phases of parameters of new system and to re verify cycles of important improvements. .three simultaneously connected BIs should be done through phases in an empty chamber and should show same non positive results after required incubation periods.
The most resistant bacteria in the sterilization process are the bacterial spores which are used in the biological tests. Although they are not harmful to the humans, but, sterilization process requires complete shed off from all kind of bacteria. For ethylene oxide sterilization, Bacillus atrophaeus (which was known as bacillus subtilis) is used. In order to check the validity of the biological tests, a “control” spore test striped is used; it is exposed to the growth medium and nurtured as well so that the control result shows a positive sign about the presence of spores on the biological test strip. In addition to this, for the test of peracetic acid, steam, and gas plasma sterilization, a spore named Geobacillus Stearothermophilus is used.

Environmental Monitoring

While going through the Ethylene Oxide sterilization process, environmental factors should not be overlooked. Employees’ health factor should be the most important aspect. There are proper guidelines provided by the OSHA which help in protecting the workers from the possible exposure to Ethylene Oxide. As per OSHA, an employee’s passive and direct exposure should be closely monitored with the help of respective monitoring devices which should be installed in the vicinity of Ethylene Oxide sterilizer and on each and every employee.


The Importance of Record Keeping

In order to have epidemiological tracking and continuous monitoring of sterilization cycle to have an insight about its effectiveness, it is very important to keep a valid record of each and every step. Record keeping helps in many ways, such as value addition in the process, benchmarking, and for any troubleshooting at any stage.

There is no such hard and fast guideline about the duration of keeping a sterilization record; therefore, in addition to the procedure’s policy and guidelines, one should follow the prevailing requirements of the respective state and the law as well. The reason being, that, up-to-date records includes precise information about the performance cycle, its documentation and maintenance records.


Conclusion

The gist of the above discussion is that no matter whatever technological advancements take place in future in terms of healthcare facilities, the basic sterilization processes will remain there as most of them share common methods and traits. Advancement of medical devices and instruments would not bring in totally new sterilization concepts, rather, existing behavior will be applied to the new ones as well.
The best practices and professional guidelines available currently can help the personnel of healthcare who are engaged in medical devices’ sterilization and reprocessing as they can study them. In order to learn more about best practices, going through materials and organization mentioned here is highly encouraged.