A Continuing Education Study Guide

presented by

Sterilization Story

LiquidChemical

The

#003S t u d y G u i d e

Notes

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Nurses:■ To receive 1.2 Contact Hours for completing this Study Guide,

and

Central Service Technicians:■ To receive 1.5 Contact Hours approved by the NICHSPDP for completing this

Study Guide

■ To receive 1.5 Contact Hours approved by the IAHCSMM for completing this Study Guide

You Must:1. Read the complete Study Guide.

2. Complete the Review Questions and compare your responses with the answers provided. If some areas are unclear, review that section of the Study Guide that is indicated in parenthesis next to the correct answer on the answer sheet.

3. Next, you must:

■ Complete the CE Registration/Evaluation Form (found in this booklet).

■ Send the completed CE Registration/Evaluation Form and a $10.00 check or money order payable to STERIS Corporation to:

STERIS Corporation Education Department Secretary 5960 Heisley Road Mentor, OH 44060-1834

*You may copy the blank CE Registration Evaluation Form in this Study Guide so that everyone needing a Certificate of Completion for Contact Hours may apply for them.

4. A Certificate of Completion will be sent to you.

Accreditation/Contact Hours1. This educational activity is worth 1.2 Contact Hours of learning (60 minutes)

provided by STERIS Corporation. STERIS Corporation (OH-202) is an approved provider of continuing education by the Ohio Nurses Association, an accredited approver by the American Nurses Credentialing Center’s Commission on Accreditation (OBN-001-91). STERIS Corporation is a provider approved by the California Board of Registered Nursing, Provider Number CEP 11681.

2. The NICHSPDP has approved 1.5 Contact Hours for the successful completion of Study Guide material.

3. The IAHCSMM has approved 1.5 Contact Hours for the successful completion of each Study Guide.

4. Approval for Contact Hours expires: July 2006.

The Liquid Chemical Sterilization StoryStudy Guide #003

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Description of Study Guide TopicMore heat senstive devices are being developed today for use in surgery or during endoscopic procedures. A sterilization method using a liquid chemical as the sterilizing agent has become increasingly popular during the past decade for the sterilization of heat sensitive devices. Healthcare professionals must understand this low temperature sterilization system, including the indications for use, mechanism of action, efficacy, process monitoring method, and safety issues.

Overall Purpose of the Study GuideTo describe the history of using a liquid chemical sterilant, mechanisms of germicidal action of peracetic acid, indications for use of liquid chemical sterilants, device preparation, sterilization process, process monitoring, and environmental safety.

ObjectivesUpon completion of this study guide program, the participant should be able to:

1. Describe the history and action of peracetic acid.

2. Describe the indications for using a liquid chemical sterilant.

3. Discuss the sterilization method using a liquid chemical, including device preparation, sterilization process, validation, and safety measures.

Intended AudienceThis study guide is a self-study program intended for use by perioperative nurses, surgical technologists, endoscopy suite nurses, central service staff members, infection prevention nurses, and other healthcare professionals.

IntroductionThe demand for less invasive surgical procedures continues to change the nature of surgery today. The rate of conversion from traditional surgical operations to less invasive techniques is expected to continually increase. 1 This increase in minimally invasive techniques for operative and diagnostic procedures has led to the development of more sophisticated medical devices that are complex and heat sensitive. Reprocessing these devices has presented many challenges for the healthcare worker including the risk of pathogenic transmission and scheduling problems related to inadequate inventory. The infection prevention concerns revolve around the ability to effectively process these heat sensitive instruments with an adequate biocidal effect. Surgery and endoscopy scheduling concerns focus on the speed of the reprocessing method chosen so an extensive instrument inventory is not required.

Notes

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Selection of an appropriate reprocessing system for heat sensitive devices depends on:

■ Resistance of microorganisms to the microbiocidal process

■ Intended use of the device (i.e., endoscopic procedures that only contact intact mucous membranes, open surgical procedures that invade the vascular system or other sterile body cavity)

■ Design of the device (hard-to-reach areas or obstructions within the device that could interfere with exposure to the reprocessing process)

■ Compatibility of the device design and materials with the reprocessing process

■ Length of the reprocessing cycle

■ Ease of use

■ Safety measures

■ Monitoring methods

■ Healthcare worker hazards

■ Cost

The primary form of sterilization over the years has been steam, generally used for stainless steel instruments. Steam sterilization is not an option for heat sensitive devices due to the high temperatures needed for sterilization to occur. Today some rigid endoscopes have been designed to withstand steam sterilization.

Ethylene oxide (ETO) has been used for years to sterilize heat sensitive devices. The problem with this method has been the prolonged length of time needed to complete the sterilization and aeration process. Another concern has been the need for an increased inventory of instruments to compensate for the time needed for adequate reprocessing using ETO.

The desire for a more rapid reprocessing time for heat sensitive devices led to the expanded use of high-level disinfection since the time involved was much less than with ETO processing. While high-level disinfection may kill most microorganisms, bacterial spores will not be eliminated without extended exposure times. High-level disinfection chemicals can cause skin, mucous membrane, eye, respiratory, ingestion, and chronic exposure hazards. The controversy surrounding the length of time to soak an instrument in the disinfection solution along with the appropriate solution temperature present challenges to the healthcare professional.

An example of the types of problems that can occur when high-level disinfection is attempted was reported in 1995. This report cited that a 55 year old French man and his 54 year old wife in France both contracted Hepatitis C, probably from a colonoscope that was inadequately disinfected. One week before the March 16, 1995 colonoscopies were performed, these patients had normal serum alanine amino-transferase levels but approximately eight months later, liver biopsies revealed chronic hepatitis. Only three colonoscopies were performed on March 16, with the first procedure conducted on a 42 year old woman who was HCV-positive. The second and third procedures were performed on the wife and husband, respectively. Nucleotide sequence testing noted that all three patients were infected with the same isolate of hepatitis. Since the same colonoscope was used for all three procedures, researchers concluded that the

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endoscope used for the procedures was not reprocessed adequately according to recommendations for high level disinfection.2

Today healthcare professionals realize the value of sterilizing devices. A sterilization system using a liquid chemical sterilant has become very popular for those devices which previously underwent high-level disinfection. Sterilization provides a higher standard of care and margin of safety not found with high-level disinfection methods.

The selection of a disinfection or sterilization method is based on the intended use of a device. AORN (Association of periOperative Registered Nurses) and CDC (Center for Disease Control and Prevention) have developed recommendations based on Dr. E. H. Spaulding’s classification of medical devices. Dr. Spaulding divided items used for patient care into three categories based on the degree of risk of infection.

These three categories are: 3

■ Critical devices

■ Semi-critical devices

■ Non-critical devices

Critical devices are instruments or objects introduced directly into the bloodstream or into other normally sterile areas of the body. Examples are surgical instruments, cardiac catheters, and needles. Critical devices should be subjected to a sterilization procedure before each use. It is the responcibility of the device manufacturer to recommend the method of sterilization.

Semi-critical devices come in contact with non-intact skin or mucous membranes, where risk of infection is less than with critical devices. Some examples of semi-critical devices are non-invasive endoscopes, endotracheal tubes, anesthesia breathing circuits, and cystoscopes. Although these items come in contact with intact mucous membranes, they do not ordinarily penetrate body surfaces. Sterilization of many of these items, although desirable, is not absolutely essential. Semi-critical devices should receive a minimum of high-level disinfection. A high-level disinfection method should be expected to destroy vegetative (growing) microorganisms, most fungal spores, tubercle bacilli, small or non-lipid viruses, and medium sized or lipid viruses.

Non-critical devices come in contact with intact skin. Such devices include bedpans, blood pressure cuffs, crutches, bed boards, and a variety of other medical accessories. Since the infection risk is low, these devices only require intermediate level disinfection, low level disinfection, or cleaning.

To determine the level of bioburden on instruments and other devices, objectives for reduction of microorganisms in terms of sterilization, disinfection, and decontamination must be defined.

■ Sterilization - the complete destruction of all microbial life by physical or Sterilization - the complete destruction of all microbial life by physical or Sterilizationchemical procedures. (Steam under pressure, dry heat, ethylene oxide gas, liquid chemical sterilization using a peracetic acid based solution)

■ Disinfection - kills or eliminates nearly all pathogenic microorganisms on Disinfection - kills or eliminates nearly all pathogenic microorganisms on Disinfectioninanimate surfaces but not necessarily bacterial spores, therefore, does not provide sterilization. There are three categories of disinfection: High-level disinfection, intermediate level disinfection, and low level disinfection. Glutaraldehyde is often used for high-level disinfection.

CE REGISTRATION / EVALUATION FORMStudy Guide #003: The Liquid Chemical Sterilization Story

CE Expiration Date: July 2006

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To receive continuing education credit, please record your answers on the CE Registration/Evaluation form which is the following page and mail it to STERIS.

Rate on a scale of: 1=low 5=high1. To what extent was Objective 1 met? Describe the history and action of peracetic acid.

2. To what extent was Objective 2 met? Describe the indications for using a liquid chemical sterilant.

3. To what extent was Objective 3 met? Discuss the peracetic acid sterilization method using liquid chemical, including device preparation, sterilization process, validation, and safety measures. 4. The overall purpose of this educational activity was to describe the history of peracetic acid, mechanisms of germicidal action, indications for use, device preparation, sterilization process, process monitoring, and environmental safety. To what extent did the objectives relate to the overall purpose?

5. To what extent is this learning method effective? 6. To what extent were your personal learning objectives met?

7. To what extent will this information be useful in your practice setting?

8. How much time was required to read the content, take the test, compare your answers, and complete the registration/evaluation form?

_____ hrs. _____mins.

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■ Decontamination - disinfecting process that renders contaminated items Decontamination - disinfecting process that renders contaminated items Decontamination safe to handle with reasonable care. It is the first process employed to protect employees from risk of infection when items are returned to Central Service for reprocessing.

Policies within healthcare facilities should specify whether only cleaning (decontaminating), or disinfecting or sterilizing a device is needed to decrease the risk for infection. Decisions about reprocessing should be based on the intended use of an item and not on the diagnosis of the patient on which the device will be used.

If an endoscope is contacting only skin and mucous membranes, high-level disinfection may be adequate. If the endoscope is used for a biopsy or another procedure that accesses the vascular system, then sterilization should be used. When a sterilized heat sensitive endoscope or instrument is required, then liquid chemical sterilization may be the method of choice.

Issues concerning the choice between disinfecting a device or sterilizing a device are continually being addressed by professional organizations including:

■ AAMI - The Association for the Advancement of Medical Instrumentation is a professional organization of engineers, biomedical technicians, physicians, nurses, hospital administrators, consultants, and manufacturers of medical devices. Their goal is to improve the quality of medical care through the application, development, and management of healthcare technology. AAMI publishes technology analyses and reviews, medical device standards, technical information reports, and recommended practices.

■ AORN - The Association of periOperative Registered Nurses is a voluntary organization of professional registered nurses concerned with perioperative nursing care. AORN’s goal is to improve the standards of perioperative nursing care by enhancing the knowledge base and skills of personnel and foster leadership qualities in its members. The AORN Standards, Recommended Practices, and GuidelinesAORN Standards, Recommended Practices, and Guidelines are often referenced for policy development and standards of care.

■ APIC - The Association for Professionals in Infection Control and Epidemiology is a multidisciplinary, non-profit, international organization committed to influencing, supporting, and improving the quality of healthcare through the practice and management of infection control and the application of epidemiology in all healthcare settings. APIC publishes position papers and the APIC Recommended Practices and Guidelines.

■ SGNA - The Society of Gastroenterology Nurses and Associates is a non-profit SGNA - The Society of Gastroenterology Nurses and Associates is a non-profit SGNAprofessional organization of nurses, physicians, assistants, technicians, and industry representatives. SGNA’s goal is to deliver optimal healthcare during GI diagnostic and therapeutic procedures. SGNA publishes a guide for Standards of Practice.

Some of the issues that these groups have discussed include:

■ Inadequate inventory of instruments may cause a facility to select high-level disinfection rather than ETO in an effort to maximize productivity.

■ The minimal acceptable reprocessing method of semi-critical devices is high-level disinfection; some facilities have not been able to provide more than the minimum level of acceptable care.

■ The routine use of high-level disinfection interspersed with sterilization when the time is adequate or the patient is particularly sick.■ The intent of Standard Precautions for Bloodborne Pathogens is that all patients and all devices are treated as if contaminated with a bloodborne and other diseases.■ The clearance from the Food & Drug Administration (FDA) of 2% glutaraldehyde for high-level disinfection requires an exposure time of 45 minutes at 25° C. This immer- sion time and elevated temperature are difficult to achieve in practice, so some facilities are using glutaraldehyde “off-label.”

All of these controversies have added fuel to the debate of whether to disinfect or to sterilize. In the search for the most practical method of reprocessing that will produce effective biocidal activity in a short time period, liquid chemical sterilization continues to gain acceptance and popularity.

Historical Perspective of Peracetic AcidScientists have been working with peracetic acid (PA) since the turn of the century. Freer and Novy reported on the germicidal properties of PA in the early 1900's but PA was not widely used due to expensive manufacturing costs.4 The use of PA increased in the early 1950's when a commercial process became available to economically produce 90% hydrogen peroxide which is an ingredient necessary in the manufacturing process of PA.

The food and beverage industry started to find applications for PA due to its antimicrobial properties and the absence of toxic residues. PA is now commonly used in dairies, wineries, soft drink plants, canneries, railroad tankers, and meat and poultry processing plants.5 The food industry values PA’s nonrinse feature in high dilutions as an advantage in time and money since the breakdown products of PA do not affect taste, toxicity, or odor.

Liquid chemical sterilization with peracetic acid in healthcareIn the medical industry, PA has been effective in the sterilization of rooms, equipment, hemodialyzers, and medical, surgical, and dental instruments.6 PA has gained great recognition and respect for reprocessing heat sensitive medical devices since the 1980's.A liquid chemical sterile processing system allows healthcare workers to safely sterilize immersible surgical and diagnostic instruments between patient procedures near the site of patient care in approximately thirty minutes. Sterilization of devices, as compared to high-level disinfection, reduces concerns regarding cross contamination and worker safety issues.

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8. After a 12 minute exposure to the sterilizing use dilution, how many sterile rinse cycles are performed? A. 6 B. 2 C. 3 D. 4

9. The total cycle time of the liquid chemical sterile processor is approximately: A. 12 minutes B. 30 minutes C. 45 minutes D. 60 minutes

10. After starting the processor, a buffered protection solution is first created, followed by the introduction of 35% peracetic acid making a use dilution with a PA concentration of 0.2% and an acid pH of approximately 3. A. True B. False

Answers to Review Questions & Section Sources:

1. A (Peracetic Acid)2. C (Sterilant using Peracetic Acid as the Biocide) & (Advantages of Liquid Chemical Sterilization Process) 3. D (Process Monitoring)4. B (Introduction)5. A (Advantages of Liquid Chemical Sterilization Process)6. B (Sterilant using Peracetic Acid as the Biocide)7. C (Sterilant using Peracetic Acid as the Biocide)8. D (Sterilant using Peracetic Acid as the Biocide)9. B (Sterilant using Peracetic Acid as the Biocide)10. B (Sterilant using Peracetic Acid as the Biocide)

1. Peracetic acid is a highly biocidal oxidizer that sterilizes even in the presence of high levels of organic soil. A. True B. False

2. The byproducts of peracetic acid sterilization are: A. Acetic acid, water, nitrogen B. Water, oxygen C. Oxygen, water, acetic acid D. Hydrogen peroxide, water, oxygen

3. The process parameters found on the sterilization printout are: A. Exposure time, temperature, volume B. Temperature, cycle time, volume of water C. Concentration, rinse cycle numbers, temperature D. Exposure time, temperature, concentration

4. An endoscope is a semi-critical device even if it enters the vascular system. A. True B. False

5. Peracetic acid breaks apart protein bonds while glutaraldehyde binds protein together. A. True B. False

6. During sterilization using a PA based sterilant, the use dilution consists of: A. 35% peracetic acid, water B. 0.2% peracetic acid, buffers water C. 20% peracetic acid, buffers oxygen, water D. Vinegar, water, oxygen

7. Placement considerations for device processing in trays and containers includes which of the following criteria: A. Fits, immersible, temperature, sterilizes B. Functioning, intact, time, sterility C. Fits, immersible, temperature, surface contact with sterilant D. Flexible, immersible, tough, surface contact with sterilant

Quest ionsR eview

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Peracetic AcidPA is a highly biocidal oxidizer that sterilizes even in the presence of organic soil. In several studies that compare germicides, PA was found to be the most active against bacterial spores. In one test involving 23 agents, the antimicrobial activity of PA was the most efficacious against Bacillus thermoacidurans spores, including chlorine Bacillus thermoacidurans spores, including chlorine Bacillus thermoaciduranscontaining compounds. 7 When compared to a variety of disinfectant/sterilants, PA was the most effective against a wide range of bacteria, mycobacteria, viruses, yeasts and fungi. 8 Studies also show PA is more efficacious than hydrogen peroxide, formaldehyde, and glutaraldehyde. 9Additional advantages of PA are its rapid action, ability to remain 9Additional advantages of PA are its rapid action, ability to remain 9

effective at low temperatures, efficacy in the presence of organic material, and environmentally friendly byproducts.

Possible mechanisms of germicidal actionThe actual killing mechanism of PA is not well understood. PA may destroy cell membranes by disrupting sulfur and sulfhydryl bonds. PA inactivates a catalase which breaks down hydrogen peroxide and may oxidize enzymes that support biochemical transportation across cell membranes, thus causing the cell wall to rupture. PA is known to be a protein denaturant. 10

Peracetic acid and water result when acetic acid and hydrogen peroxide are combined:

CH3COOH + H2O2 CH3COOOH +H2O

Acetic Acid + Hydrogen Peroxide Peracetic Acid + Water

PA is acetic acid with an extra oxygen atom in this equilibrium equation. The extra oxygen atom of PA is very reactive and it reacts with most cellular components to cause cell death. The ability of PA to inactivate many different critical cellular systems allows it to have broad spectrum antimicrobial activities. As with many other sterilizing agents, defining the exact mechanism by which PA kills spores and microorganisms is difficult since the mechanism may vary with each type of cell (ie., vegetative cells, spores, mycobacterium).

Liquid Chemical Sterilization System

Sterilizing unit A liquid chemical sterile processing system consisting of a tabletop microprocessor controlled unit, a single use cup of PA-based sterilant, and multiple device trays and containers was introduced and patented in the late 1980’s. The processor is automated and creates, monitors, and maintains the conditions and functions necessary for sterilization. The criteria for sterilization are:

■ Proper sterilant use dilution concentration ■ Processing temperature (50 to 56 degrees centigrade)■ Exposure time to the sterilant (12 minutes)

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■ Constant fluid circulation during sterilization and rinse cycles■ Sterile filtration of incoming tap water by a verifiable sterile filtration membrane■ Four sterile water rinses

The processor has push button operation and an internal self-diagnostic and monitoring system that produces a printed strip to confirm if all sterilization parameters have been met during each cycle. If for any reason the conditions are not met, the cycle

will cancel.

Sterilant using Peracetic Acid as the Biocide

Efficacy testingThe FDA requires standard test methods described by the Association of Official Analytical Chemists (AOAC) to determine the efficacy of a sterilizing agent. These tests employ standardized carriers on which the test organism is deposited. The inoculated carrier is exposed to the sterilizing agent under the exact conditions defined for its routine use (i.e. exposure time, concentration, temperature, etc.). The carriers are then placed into growth media and incubated. No growth on a minimum of 720 carriers (with no failures) is required.

Since the chemical sterilants used on medical devices are considered medical devices, they are regulated by the FDA. The FDA recognizes test data by the AOAC but also requires data for the demonstration of killing spore suspensions in hard water and in the presence of heavy organic soil, such as serum protein, and the calculation of reducing the microbial population by 12 logs (12D time).

The PA based sterilant of the system described above was subjected to these rigorous tests and was passed by the FDA. The result of the AOAC testing was that the liquid chemical using PA produces sterility to a degree that meets or exceeds the criteria required for sterility claims. Neither the washing or rinsing action of the sterilizer are responsible for the sterilization of the AOAC carriers. Since the sterilizer provides sterile-filtered rinse water, no recontamination of the sterilized AOAC carriers from the rinses or within the fluid pathways of the sterilizer occurred.

Use dilutionThe active ingredient of the sterilant concentrate is 35% PA. The sterilant container also contains other ingredients (in powdered form) which buffer the sterilant to nearly a neutral pH and contain corrosion inhibitors which protect the devices being sterilized. The sterilant and buffers are sealed in a single use container to ensure safe handling.

When placed in the processor and the cycle commences, a buffered protection solution is created, followed by the introduction of sterilant concentrate making a "use dilution" with a PA concentration of 0.2% and an acid pH of approximately 6.4. This use dilution is biocidal, sporicidal, bactericidal, fungicidal, tuberculocidal, virucidal, and safe for the instruments being sterilized. Single use packaging of the sterilant and the automated creation of the use dilution within the system

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1. Alfa, MJ, DeGagne, P, Olson, N. “Comparison of liquid chemical sterilization with peracetic acid and ethylene oxide sterilization for long narrow lumens,” AJICAJIC, 1998:26: 469-77.

2. AORN, Standards, Recommended Practices, and GuidelinesStandards, Recommended Practices, and Guidelines, 2002, Denver, CO, Association of Operating Room Nurses.

3. Block, SS. “Peroxygen compounds,” in Block SS. ed. Disinfection, sterilizationDisinfection, sterilization and preservationpreservation. 4th ed., 1991, Philadelphia: Lea & Febiger. 167-81.

4. Freer, PC, Novy, FG. “On the formation, decomposition, and germicidal action of benzoylacetyl and diacetyl peroxides,” Am Chem JJ, 1902:27: 161-93.

5. Ibid.

6. Malchesky, P. “Peracetic acid and its application to medical instrument sterilization,” American Society for Artificial Internal Organs JournalAmerican Society for Artificial Internal Organs Journal, 1993: 17: 147-52.

7. Op cit., Block.

8. Op cit., Block.

9. Op cit., Malchesky.

10. “Surgery in transition,” Surgical Services ManagementSurgical Services Management, Vol 4, No 1, January 1998, p. 56.

11. “Two patients likely contracted HCV from colonoscope,” OR ManagerOR Manager, Vol. 13, No 6, September 1997.

12. Tucker, RC, Lestini, BJ, Marchant, RE. “Surface analysis of clinically used expanded PTFE endoscopic tubing treated by the STERIS process,” American Society forAmerican Society for

Artificial Internal Organs JournalArtificial Internal Organs Journal, 1996:42:4: 306-13.

13. Tucker, RC, Lestini, BJ, Marchant, RE. “Surface analysis of clinically used expanded PTFE endoscopic tubing treated by the STERIS process,” American Society forAmerican Society for

Artificial Internal Organs JournalArtificial Internal Organs Journal, 1996:42:4: 306-13.

Re fe rencesSuggested Readings/References/References/References

Critical device Devices that are introduced directly into the bloodstream or into other normally sterile areas of the body must be sterilized (examples - surgical scissors, needles).

D valueDecimal reduction time. The D value expresses the time required to reduce the viable microbial population by 90% or one log. The lower the D value, the faster the rate at which a sterilization process occurs.

D - time required for a one log reduction of viability 12D - time to reduce the microbial population by 12 logs

Disinfection The use of germicidal chemical agents to destroy vegetative forms of potentially infectious organisms.

EfficacyThe power to produce a desired effect (for example, the sporicidal efficacy of a chemical is the power of that chemical to destroy bacterial spores).

Leak testing The pressurization of a flexible endoscope to determine the integrity of the endoscope’s seals and demonstrate that no damage has occurred to either the external surfaces or to the inner channels during use.

Non-critical device Devices that touch only intact skin (examples - bed pan, blood pressure cuff).

Peracetic acidAn acetic acid with an extra oxygen atom, effective for sterilization.

Semi-critical device Devices that come in contact with intact mucous membranes, a minimum of high-level disinfection is recommended (examples - gastroscope, thermometer).

SporeUnicellular structure which is highly resistant to destruction; a reproductive cell, produced by plants and some protozans.

SterilizationThe use of physical or chemical agents to eliminate all viable microbial forms including bacterial spores.

G lossary :G lossary :

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ensures the optimal concentration of the sterilant with every cycle. The sterilant concentrate is not intended for reuse or for use in a manual open-pan sterilization system.

Placement ConsiderationsThere are several considerations for placing devices in the trays and containers:

■ Device must fit into the tray or container comfortably.■ Device must be immersible.■ Device must withstand temperatures of up to 56° C.■ All surfaces must come in contact with the use dilution.

Precleaning the endoscope takes place wherever the endoscopic procedure is performed. When the scope exits the body, gross debris is wiped off the outside surface while fluid is pulled through the channels. Precleaning should always be done to remove and loosen debris before manual cleaning is performed in the reprocessing room.

Leak testingFlexible endoscopes must then be leak tested prior to thorough cleaning. Leak testing is the pressurization of the flexible endoscope to determine the integrity of the endoscope’s seals and demonstrates that no damage has occurred to either the external surfaces or to the inner channels during handling or use. The basic supplies needed for leak testing are as follows:

■ Leak tester (powered or manual)■ Waterproof cap (for videoscopes)■ ETO cap (for fiberscopes, usually already attached to the leak tester)■ Syringe (optional but if used, a 20cc is preferable)■ Basin of warm water (or a large sink)■ Flexible endoscope

The process involved with leak testing is quite simple but often overlooked. The leak tester should be inspected to ensure that it is working appropriately. The process of leak testing includes the following steps:

1. Remove the endoscope valves.

2. Place the moisture cap on the endoscope.

3. Attach the leak tester to the cap. (Make sure the leak tester is checked to ensure it will provide the proper amount of air flow to pressurize the endoscope. The airflow of a powered leak tester can be checked by depressing the pin located inside the connector cap to ensure air is being emitted through the coiled tube.)

4. Adequately pressurize the endoscope.

5. Place the bending section of the endoscope in water.

6. Angulate the distal tip of the endoscope in all directions while noting if any air bubbles are created. (Since the internal structure of the endoscope is pressurized, any hole or defect will cause the internal pressurized air to escape, thus causing bubbles to form).

7. Completely immerse the endoscope in the water (while maintaining pressurization).

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8. Use the syringe to flush the air out of all of the lumens (so trapped air doesn’t form bubbles that may incorrectly be identified as a leak). (This step may or may not be recommended by the endoscope manufacturer but if used, it helps to fill the channels with water so that any trapped air is forced out.) 9. Wipe standing bubbles from surface of endoscope. If bubbles re-appear, there is a leak. Scope should be sent out for repair if this occurs.10. Angulate the scope in all directions. (There may be leaks around the angulation control from a worn or faulty gasket)11. If no leak is found, remove the pressurized endoscope from the water.12. Deflate the leak tester (but leave it attached to the endoscope for about 2 minutes to allow the air to dissipate).13. Disconnect the leak tester from the endoscope.14. Continue with cleaning process.15. If a leak is noted, the endoscope needs to be returned for repair. Cleaning can be safely accomplished if pressurization is maintained within the endoscope. The decontaminated scope can then be returned for service. Do NOT sterilize the endoscope in a liquid chemical sterilization system.

Cleaning processWhen preparing devices for sterilization, cleaning and preparation procedures for reprocessing devices should be followed as recommended by the device manufacturer and professional organizations (ie., AORN, AAMI, APIC, SGNA, CDC, etc.) Devices must be totally disassembled so that cleaning and removal of all protein material can be accomplished. Debris left on the devices impedes surface contact with steriliant. Cleaning is accomplished by using a recommended enzymatic detergent depending upon type of soil on the device. Brushes to clean lumens and ports should have intact bristles and the size of the brush should be appropriate for the diameter and length of the lumen to be cleaned. Brushes should never be forced through instrument ports or lumens. Continue to brush until the brush is void of debris. Short rounded strokes should be used to clean the exterior of the endoscope.

After the devices are meticulously cleaned, thorough rinsing is critical to remove debris and detergent. The instruments do not need to be dried before placing them in the liquid chemical sterilizing system.

The sterilization processCleaned devices are placed in the appropriate tray or container that is positioned in the processor. The processor is designed to accept these interchangeable trays and containers to hold the many different types of instruments and ensure that these instruments are correctly positioned for processing. Lumened devices, such as endoscopes, are attached to specific trays with special connectors to allow fluid to flow through the internal channels. A chemical indicator is used with each cycle.

A cup containing the 35% peracetic acid solution in the inner cup and the powdered buffers in the outer cup is placed in the processor. A cup cutter in the bottom of the sterilant compartment penetrates through the bottom part of the outer cup to release the buffers during processing.

SummaryThe growth in the number of minimally invasive surgeries coupled with the need for rapid device sterilization has led to an increase in the use of liquid chemical sterilization. Safety, nosocomial infection transmission, cost containment, labor, and time must all be factored when determining an appropriate reprocessing method. Liquid chemical sterilization addresses these issues and provides an innovative and rapid sterilization process in today’s dynamic and challenging healthcare environment.

Release date: July 2004.

This study guide has been planned, produced and approved as a continuing education (CE) activity. This material will be reviewed within 2 years of its release date and re-released, or its designation for CE credit will become invalid.

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■ Safety for the environment -Safe for disposal of use dilution in sanitary sewer -PA is water soluble -Absence of toxic byproducts and residues (acetic acid, water, oxygen) -No special monitoring required■ Process is standardized (Microprocessor)■ Automated controls provide standardization of processing and allow for process and load identification for documentation purposes ■ Diagnostic cycle (to readily note any sterilizer problems)■ Printouts confirm successfully completed cycle or documents reason for canceled cycle■ Rapid sterilization of devices -Short cycle times (approximately 30 minutes) -Quick turn-around time for equipment -Less device inventory required■ No need to dry devices after cleaning■ Cost effective■ User friendly

The advantage of PA’s ability to function in the presence of organic matter is unique. Unlike glutaraldehyde and formaldehyde, with their inherent tissue fixing properties, PA is a protein oxidizer, meaning it breaks apart protein bonds. Research has shown that the length of time needed for sporicidal action with glutaraldehyde is 32 times higher and with formaldehyde is 64 times higher than that for PA against Bacillus anthracis with Bacillus anthracis with Bacillus anthracis4% horse serum at 20 degrees C.11 In studies by various investigators, results note that PA is efficacious in narrow lumens in the presence of serum challenges. 12 Studies done by Tucker et al. demonstrate the ability of PA to remove glutaraldehyde-fixed protein in lumens. 13

Limitations of PA based liquid chemical sterilization processThere are a few limitations that must be noted with the liquid chemical sterilization process.Those include:■ Devices must be totally immersible.■ Devices must be able to withstand a temperature range of 50-56°C. ■ Items are processed prior to intended use (just-in-time use, no shelf life).■ Items must fit comfortably in the sterilization containers and trays. ■ The sterilant must make contact with all surfaces of the device.

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A probe with a spike (the aspirator probe) is inserted into the top of the sterilant cup while the probe tubing is positioned appropriately so that the PA can be aspirated out of the cup during the process. The processor lid is then closed and the system is activated by pushing the start button. When the start button is pushed, the microprocessor takes control. The buffers mix with water to form the chemical protection system. The active ingredient, PA, is brought into solution at the appropriate time.

The sterilant (PA and buffers) is automatically mixed with sterile water, created by filtration within the processor, to form, "use dilution" within the processor chamber. The "use dilution" concentration of the PA is 0.2% with a pH of approximately 6.4. Sterilization takes place between 50 º – 56º C which is safe for most heat sensitive devices.

The "use dilution" comes in contact with all accessible external and internal surfaces of the instruments. Exposure to the use dilution lasts for 12 minutes and is followed by four sterile water rinses to remove any sterilant residues. The end-products of acetic acid (vinegar), water, and oxygen are safely disposed of in the normal sanitary sewer system without environmental concerns.

The entire sterile processing cycle is completed in approximately 30 minutes. The sterilized devices are removed from the system for immediate use. Processing trays are available that incorporate tortuous pathways to protect sterile instruments from contamination during transport.

Process Monitoring The sterilization process is standardized. The same sequence of events happen every time since the unit is computer-controlled. The process monitoring for the sterilization process involves five methods:

■ Operator observation and interaction■ Parametric monitoring■ Chemical monitoring■ Biological monitoring■ Diagnostic cycle

Operator observation and interactionOperator observation and interaction is critical for the appropriate preparation and operation of the sterile processing system. The sterilant container is examined closely before placing it in the sterilizing unit. The appearance of the cup and packaging box should be noted to determine if the container has been compromised, is wet, has turned a bright yellow color, or has a strong vinegar-like odor. The expiration date must be verified so that outdated chemicals are not used. The bottom part of the cup that contains the buffer powders should not be hardened.

After placing the sterilant cup in the system, the aspirator probe must be properly positioned and the tubing must be inspected for kinks that would prevent aspiration of the PA to form the "use dilution". The presence of the "use dilution", and the constant flow

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of the solution is noted through the window in the system lid. At the end of the cycle, the sterilant cup should be checked to note the complete aspiration of the active ingredient. If fluid is noted in the cup, appropriate disposal methods must be employed according to the manufacturer’s instructions, and the devices must be reprocessed.

Parametric monitoringDuring the sterilization phase of the process, the system continually monitors and verifies the three critical process parameters including: solution concentration (175 or greater), temperature (50-56°C), and exposure times (12 minutes). The sterilizer will cancel the process if the sterilization parameters are not met. The process parameters are checked by the operator at the end of the cycle, and should be printed on the printout paper. Any “fault” messages or cycle cancellations will be documented on the printout paper. The sterile processing printouts provide a positive audit trail and also can be used to record the biological and chemical monitoring results.

Chemical monitoringChemical indicators monitor the presence of the minimum necessary concentration of the active ingredient during the sterilization process. A chemical indicator does not guarantee sterility of the load but merely shows that the active ingredient was present for sterilization to be achieved. The manufacturer recommends that a chemical indicator be included with each sterile processing cycle to verify the presence of the active ingredient. The single use chemical indicator strip is read, recorded, and then discarded.

Biological monitoringBiological monitoring consists of a test challenge compared to a control culture obtained from a live spore strip of Geobacillus stearothermophilusGeobacillus stearothermophilusGeob . The frequency of the testing will be determined by the healthcare facility’s internal policy. A chemical indicator should be run with all biological testing. Only the biological indicators made specifically for this liquid chemical sterilization system should be used. After appropriate incubation, the test challenge is compared with the control and the results are recorded.

Diagnostic cycleThe diagnostic cycle should be run daily when the processor is in operation. The first phase of the diagnostic cycle tests the electrical, mechanical, pneumatic, and hydraulic systems. The second phase verifies the integrity of the sterile filter membrane. A failed diagnostic cycle will lock out any attempts to use the sterilizer until the fault is corrected, and a successful diagnostic cycle is completed. A cup of sterilant is not used when running a diagnostic cycle.

Environmental MonitoringOperation of the sterile processing system requires no special air monitoring or engineering controls. Testing has shown that all ingredients of the PA based sterilant fall well below airborne permissible limits, thus eliminating the need for expensive monitoring equipment.

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Toxicity and residue analysisToxicity evaluation of the sterilant concentrate and use dilution (sterilant concentrate mixed with water) were done to determine the safety risks, if any, associated with human contact. The sterilant concentrate was found to be caustic to skin and eyes, but only moderately toxic if orally ingested. The sterilant concentrate package was designed to prevent operator exposure to the concentrate.

The use dilution underwent acute oral and dermal toxicity testing and ocular irritation testing. The use dilution has a nearly neutral pH of approximately 6.4, is nontoxic by oral or dermal administration, and has no caustic effect to the skin.

The amount of sterilant residue which may remain on medical devices after processing also was studied. After replicate sterilization cycles and exposures to use dilution and the sterile rinses, extracts were taken for study. No evidence was found that the cycles resulted in any cumulative increase in residues and PA could not be detected.

Advantages of Liquid Chemical Sterilization ProcessThe automated liquid chemical sterilization process provides a rapid low temperature alternative to more traditional forms of sterilization. The advantages of this sterilization process are many including:

■ Safety for the operator -No aeration or ventilation required -Single use container (minimizes contact with chemical) -Sealed processor using non-toxic use dilution (The single use sterilant delivery system allows for an accurate measurement of the ingredients and provides for worker and patient safety) -Automatic rinsing at the end of the exposure cycle■ Safety for the patient -Packaging prevents human error factors of over-dilution or contamination -No residue left on instruments or devices -Removes existing buildup of residue on instruments or devices -Sterilant remains active in the presence of organic material -Sterilizes the instruments and devices -PA remains the most active antimicrobial liquid germicide known■ Safety for the devices -Low temperature is safe for most heat sensitive devices -Sterilization chamber is not “pressurized” -No residue on instruments and devices after sterilization -Less damaging than steam for non-heat sensitive devices -Compatible with a wide variety of materials (plastics, rubbers, epoxies) -Variety of interchangeable trays and containers provide a wide range of flexibility to accommodate a broad spectrum of instruments and devices -Variety of quick connects are available (allows for most small lumened endoscopes to be sterilized) -Endorsed by leading device manufacturers

STERIS Corporation ■ 5960 Heisley Road ■ Mentor, OH 44060-1834 ■ USA800-JIT-4-USE (800-548-4873) ■ www.steris.com

Publication ID #M1720EN.2004-07, Rev. E©2002-2006 STERIS Corporation.All rights reserved.