BASIC FUNDAMENTALS OF MICROBIOLOGY, STERILIZATION, DISINFECTION, AND ASEPTIC TECHNIQUE

Contents

BASIC FUNDAMENTALS OF MICROBIOLOGY, STERILIZATION,DISINFECTION, AND ASEPTIC TECHNIQUE CONTENTS Page SECTION A - Microbiology. 1 SECTION B - Sterilization. 2 SECTION C - Processing Supplies for 6 Sterilization SECTION D - Disinfection. 8 SECTIONE - Aseptic Te chnique. 11

Section B - Sterilization (c, d)

under-pressure sterilization. The efficiency of the steam sterilizer is improved by pumping the air from the chamber and creating a nearly perfect vacuum before introducing steam into the chamber. This procedure allows fast and more positive steam penetration of the entire sterilizer load. The cycles of this sterilizer are relatively short due to the fact that the system removes air from the chamber with a vacuum pump and operates at temperatures of 272° F to 276° F. The sterilizing time required is ,shorter because of prevacuum and higher tempera-ture. The drying time is shorter because of vacuum drying. c. The High-Speed, Pressure-Instrument Sterilizer (Flash Sterilizer). This sterilizer is designed to sterilize surgical instruments. Moist heat, produced by steam under pressure, is the sterilizing agent. Unwrapped instruments which have been dropped or have been omitted from the instrument setup can be sterilized in 3 minutes in a perforated tray. For instruments in a lightly covered or padded tray, the sterilizing time is 10 minutes. Wrapped instruments require IS minuves for sterilization as extra time is required for the steam to penetrate the fabric and for drying the wrapped packages. However, some flash sterilizers are not equipped with a vacuum dryer. Obviously, wrapped instruments cannot be sterilized in sterilizers which have no drying phase capability. If doubt exists, check the manufacturer's instructions. d. Instrument Washer-Sterilizer. An instrument washer-sterilizer is a pressure vessel which automatically washes, sterilizes, and dries surgical instru-ments. An agitated detergent bath, which is heated by steam jets, performs the washing. Residual heat in the instruments dries any moisture which remains after the steam is exhausted. The sterilizing cycle of this sterilizer will sterilize clean, unwrapped instruments in 3 minutes. Instruments with other mate-rials, such as suture or rubber tubing, can be sterilized in 10 minutes. This sterilizer is not suitable for sterilizing wrapped instruments as it has no drying capability.

Section C - Processing Supplies for Sterilisation (a, b,)

a. Information on the label should include the name of the article and the initials of the person preparing the package. Standard nomenclature and abbreviations should be used. b. Date the packages as they are removed from the sterilizer. (Undated packages are not considered sterile.) The date used is the date when the sterility of the item is no longer assured; that is, the date when the package must be returned for reprocess-ing. SECTION D_DISINFECTION 21. Definition. Disinfection is a process which destroys or inhibits the growth of microorganisms, but which cannot be relied upon to produce sterility. Disinfection must be clearly differentiated from sterilization since disinfection may or may not destroy microorganisms, but sterilization completely destroys them. 22. Purpose of Disinfection. Disinfection is used when sterilization is not feasible. Ideally, all material that is used in the care of patients should be sterilized. However, the construction of many mate. rials and the procedures available to sterilize by thermal methods make this impossible. In addition, chemical agents capable of producing sterilization are too toxic for use on human body surfaces. 23. Methods of Disinfection. Disinfection may be

SECTION D - DISINFECTION (a, b, 21, 22, 23)

accomplished by chemical agents (germicides) or by physical means (boiling): a. Although some chemical agents are capable of causing sterilization under specific conditions, the use of chemicals normally results only in disinfection. b. Boiling is the least desirable method of disinfection and should be used only in an emergency or when no other suitable disinfecting agent is availa ble. Boiling is not used for disinfection in hospitals. 24. Antisepsis. Antisepsis is the process of using a mild disinfectant to render the skin and mucous membrane as free of microorganisms as possible. In this case, the relatively weak disinfectant is- called an antiseptic. Antisepsis does not produce sterility as most disinfectants capable of destroying microorganisms would also destroy the tissue. (Alcohol is an exception as it is antiseptic and germicidal in the same concentration.) 25. Classifications of Articles for Disinfection. Articles to be disinfected are divided into two general categories: (1) housekeeping. and (2) instruments. Instruments are further subdivided into critical and noncritical categories. a. Housekeeping disinfection, as the name im-plies, is disinfection of floors, walls, furniture, and large equipment items. b. Instrument disinfection is divided into critical and noncritical categories according to the risk of infection involved: (I) Critical instruments are those used to work beneath body surface areas. This also includes other instruments or items which may be attached to the basic instrument. Instruments classified as "critical" must be sterilized prior to use. (2) Noncritical instruments are those which do not penetrate body surface areas, so sterilization, while desirable, is not essential. 26. Basic Principles of Chemical Disinfection. Certain basic principles form the basis for all procedures involved in chemical disinfection: a. The type and resistance of microorganisms determine the effectiveness of a chemical agent. b. Disinfectants vary in their level of effectiveness according to the chemical agent and the manner in which it is used. c. Other factors to consider: (1) The solution must be of sufficient strength to be lethal to the microorganisms for which it is intended.

SECTION D - DISINFECTION (27, a-f, 28, a)

(2) The entire surface of the item to be disinfected must be exposed to the disinfectant. (3) The exposure period must be accurately timed as time is important for bactericidal effect. 21. Factors Influencing the Effectiveness of Chemical Disinfection. Several factors influence the effectiveness and efficiency with which a chemical will destroy microorganisms. These factors must be considered when selecting the chemical agent and procedure to be used for disinfecting specific items. a. All items must be absolutely clean and dry. If the item is not clean. the disinfectant cannot contact the surface and any moisture present will dilute the concentration of the chemical. b. The number of microorganisms present also affect the performance of a disinfectant. The more microorganisms present, the longer it will take for the germicide to destroy them. This further stresses the necessity for cleaning prior to disinfecting. c. The type of microorganisms to be dealt with are an important consideration. Most chemical disinfectants can destroy vegetative bacterial forms fairly easily; however. resistant forms. some vi-ruses, and bacterial spores are more difficult to control. d. The concentration of a chemical agent will determine its effectiveness as a disinfectant. A good germicide, in its use-concentration. should rapidly kill the microorganisms for which it is intended. The germicidal action of some chemical agents can be increased by increasing the concentration of the chemical. e. Any organic substance such as blood, feces, or tissue will diminish the activity of the chemical. This is an additional reason why everything must be cleaned prior to disinfection. f. The temperature of the solution will also influence the rate of disinfection. The rate will increase with an increase in temperature and decrease with a decrease in temperature. 28. Procedure for Disinfection. Chemical agents used for disinfection are primarily in liquid form and the articles to be disinfected should be disassem-bled, if possible. a. The first step must be a thorough cleaning and drying of the items to be disinfected. (1) Use cleaning agents selected for the type of material to be cleaned. (2) Change the cleaning solution frequently. The kind and amount of soil will affect the length of time a cleaning agent will remain active.

SECTION D - DISINFECTION (3-6, 29, a-d)

(3) Apply friction to remove soil and use brushes to clean tubular instruments. (4) After cleaning, rinse thoroughly in tap water and follow with a distilled water rinse. (5) Heat dry items which are not heat sensitive. Place them in the steam sterilizer chamber with the steam off and the door open. (6) Air-dry heat sensitive items by exposing them to room air. b. Submerge the clean, dry item in the proper disinfecting solution. Start timing as soon as the item is submerged and remove it from the solution when the specified time has elapsed. 29. Properties of Frequently Used Chemical Disinfectants. The chemical selected to disinfect a specific item should be the best one available for the purpose. It must also be safe to handle and nondestructive to the materials on which it is being used. Table I gives recommendations for chemical disinfection and sterilization. a. The alcohols. ethyl and isopropyl, in use-concentrations of 70 percent to 90 percent are useful as antiseptics. They are rapidly cidal to vegetative bacteria and the tubercle bacillus. but precautions must be taken as they are volatile and flammable. They will also dry and irritate the skin. The disinfecting time vanes according to the material to be disinfected and the type of organisms present b. Formalin is the aqueous solution of formaldehyde gas. Twenty percent formalin is 8 percent formaldehyde. When diluted with alcohol. its action against the tubercle bacillus is increased. It is sporacidal if the exposure time is at least 12 hours. Formalin should be used at room temperature and loses its effectiveness below 65° F. The solution is irritating to the skin, and the fumes are irritating to the eyes and mucous membrane. Bard Parker solution is a combination of 8 percent formaldehyde and 70 percent alcohol. c. Glutaraldehyde in a 2 percent aqueous solution (Cidex) is recommended for disinfection of cystoscopes and other lensed instruments. It will destroy tubercle bacillus within a few minutes and spores in 10 hours. The solution is toxic, but the fumes are less irritating than those of formalin. d. Iodine in the correct concentration is high in germicidal effect and low in tissue toxicity. How-ever, iodine is a staining agent so it is often mixed with a detergent to reduce the staining caused by the iodine. These iodine-detergent combinations are called iodophors. Wescodyne, Hi-sine. Ioclide, Be-tadine, and Povidone are examples of iodophors. Iodophors with 100 ppm of available iodine are effective in destroying vegetative bacteria, and in higher concentrations, 500 ppm, they are effective

Section C - Processing Supplies for Sterilisation (14, 15, a-h, 16)

14. Introduction. Specific items which are processed and sterilized in the surgical suite will be determined by local policies, the surgical specialties available, and the extent to which disposable products are used. These items will usually include, but are not limited to, instruments and. instrument sets, utensils, linens, and fluids. 15. Cleaning, Sorting, and Inspecting. Instru-ments, utensils, and similar items must be thoroughly cleaned prior to being processed for steriliza-tion. All foreign materal must be removed in order for the sterilizing agent to come in direct contact with the surfaces of the object to be sterilized. For linens the "cleaning" is done by laundering and is accomplished through linen supply. Following thorough cleaning and drying, all items must be sorted, inspected, and tested. Like items should be placed together. a. Inspect all metal items for signs of rust, cracks. chips, bent areas, or missing pieces. b. Check jointed instruments to assure free movement, full closure, and locking of ratchets and to assure that the teeth or serrations meet properly. c. Check sharp or pointed instruments for sharp edges or points and, if applicable. proper closure of cutting edges. d. Spinal needles and others requiring a stylet should be sorted according to type, gauge, and length. The needle and its corresponding stylet should be straight, sharp, and free from hooks and burts. e. Sort suture needles according to type and size and inspect them for burrs, hooks, dullness or distortion from normal shape. f. Endoscopy instruments should be checked for scratches or other defects that may appear on the metal. Inspect both the outside and inside of the cannula. Check to assure that the lens cover is not cracked or cloudy and that the bulbs are working. The connectors should be tight and there should be no breaks in the wire insulation. g. Linen should be inspected for tears, holes, thin or frayed areas, ripped seams, missing ties or belts, stains or other defects. h. Local policy should be followed regarding repair, replacement, or disposal of items which are not serviceable in their present condition. 16. Packaging for Sterilization. Most items must be packaged before they are sterilized so that they

SECTION E - ASEPTIC TECHNIQUE (31, a-k, 32)

31. Principles of Aseptic Technique. All personnel must be familiar with and observe the following general principles of aseptic technique: a. An article is either sterile or nonsterile. IF THERE IS ANY DOUBT, CONSIDER IT NONSTERILE. b. Touch only the outside of the wrapper or cover when opening a container with ungloved hands. C. Always open sterile packages and packs away from the body. d. Do not reach across sterile items unless you are gowned and gloved. e. Always handle sterile articles with a sterile instrument or sterile gloves. f. Once an article is removed from a sterile container, do not retum it to that container. g. Always put sterile articles on a dry surface. h. Do not place sterile articles on the floor. i. The principles of aseptic technique should be applied when creating and maintaining a sterile field. j. Cleanliness of the entire work area is basic to sterility. Certain areas of articles are considered unsterile. Tables are sterile only at table level or on their flat working surfaces. Outer rims of the lids of containers, the edges of wrappers, and the rims of flasks are never considered sterile. k. Once a sterile field has been created, it must be kept sterile until the operation or procedure is finished. Sterile surfaces must touch only a sterile surface. Moisture may contaminate a sterile field; for example, solution basins may spill and soak through covers or drapes. Adhere to all of the principles of aseptic technique. Avoid questionable circumstances. if there is any doubt, consider the item or action as unsterile. 32. Importance of Maintaining Aseptic Technique. Operating room personnel must be acutely aware of the necessity of maintaining aseptic technique throughout all operative procedures. The patient is the loser when aseptic technique is broken. A sterile article does not change appearance if it is touched by an unsterile article, such as a sleeve or hand. However, the item has been contaminated and is capable of transmitting infection. It is always better to replace a contaminated article or setup a new sterile field than to risk causing an infection in the patient.

Section A - Microbiology (5) Section B - Sterilization (6,7,a b)

5. Bacterial Cultures. Bacterial cells are collected by swabbing a suspect area, using Rodac plates or collecting air samples on culture plates. Sterile, moist swabs must be used if an area is to be swabbed. The cells are then transferred to a tube of culture media or streaked on a culture plate. The tubes or plates are then incubated until the cells reproduce and form colonies which are visible to the naked eye. At this point, they also exhibit clues to the bacteriologist as to their identity. These clues are usually in the form of color, size, and shape. It is from these colonies that the bacteriologist takes samples and sets up slides that finally make microscopic identification possible. SECTION B- STERILIZATION 6. Introduction. Since the basis for the living process in microorganisms is protein in nature, conditions that adversely affect protein will destroy these cells. Heat, chemical agents, and radiation applied in the proper manner will kill or inhibit the growth of microorganisms. The mechanisms responsible for the destruction of microorganisms are the coagulation of the protoplasmic mass or the chemical alteration of the structure of the cell. THE PROCESS WHICH DESTROYS ALL MICRO. ORGANISMS IS CALLED STERILIZATION. 7. Methods of Sterilization. Operating room personnel should be thoroughly familiar with the var-lous methods of sterilization. Not only should they know how to operate the sterilizing equipment, but they should also be able to select the one most effective in a given situation. a. Steam under pressure is the most common form of sterilization used in the surgical suite. Microorganisms are destroyed by heat. However, moist heat kills bacteria faster and at a lower temperature than does dry heat. Moisture is provided by steam, and the pressure is used to assure that the steam will attain and maintain the temperature needed for sterilization. In order for the steam under pressure to produce sterlity there must be direct steam contact with the item to be sterilized. Anhydrous oils, greases, and powders cannot be sterilized by steam under pressure as the steam cannot penetrate these materials. Otherwise, any item which is not heat or moisture sensitive can be sterilized in a steam-under-pressure sterilizer. b. Dry heat (hot-air) is another method of utilizing heat for sterilization. The theory is that heat is absorbed from the surface of the substance which is being sterilized. As explained above, dry heat sterilization requires higher temperature and longer exposure time than moist heat. Hot-air sterilizers

Section A - Microbiology (3, 4)

Escherichia coli, whose normal habitat is inside the intestine, will produce peritonitis if it ruptures through the intestinal wall. The body defenses, such as white blood cells and certain elements of plasma, fight against the invasion of foreign substances, including microorganisms, and as long as the body remains healthy, many organisms are powerless against these defenses. Once the defenses are broken down as the result of an open wound or because of a generally lowered resistance following surgery, the stage may be set for the entrance and growth of pathogenic organisms, as well as those that would ordinarily never cause any harm. 3. Spore-Forming Bacteria. Certain bacteria (Ba-cillus, for example) are capable of protecting themselves against adverse conditions by the formation of spores. Spores are round granules, which are dry and thick-walled. These granules seem to contain protoplasm in a dehydrated form. Protoplasm is the essential form of matter in which life is manifested. Bacterial spores are the most resistant form of microbial life, and they are far more capable of resisting external destructive agents and of withstanding exposure to temperature extremes than are vegetative cells. Once formed within the bacterial cell, the spore remains dormant until proper growth conditions cause it to germinate into a vegetative cell. Since this dormant period may last for years, viable spores are disseminated so widely in nature that we must assume they are present. in most situations involving disinfection and sterilization in medical facilities. 4. Environmental Temperature. The lowest temperature at which a cell will grow is the "minimum temperature, while the highest temperature at which it will grow is the "maximum temperature." "Optimum temperature" is the temperature best suited for a particular organism. The "thermal death point is that temperature which, in time, will kill all organisms present. Cells will grow and reproduce if an adequate temperature and other needs (oxygen, food, moisture, and pH) are met. ALTERING THE ENVIRONMENTAL CONDITIONS MAY DESTROY OR INHIBIT BACTERIAL GROWTH. THIS FORMS THE BASIS OF ALL SURGICAL ASEPSIS.

Section A - Microbiology (1., 2 a b)

SECTION A-MICROBIOLOGY 1. Introduction. The activities so often associated with operating room scenes have a very definite purpose. It took a long time for man to understand the cause of infection and to develop methods for preventing it. The science which evolved about the subject is called "microbiology." Microbiology is the study of living things which are of microscopic size. These microorganisms include bacteria, vi-ruses, fungi (molds and yeasts), and animal parasites (worms and protozoa). A knowledge of the basic principles of microbiology is necessary for a clear understanding of the environmental activities carried out in the operating suite. 2. Identification and Classification of Microorga-nisms. Microorganisms are minute, living structures that are categorized as plants, animals, or viruses. Bacteria are one-celled plants which differ from animal cells. The plant cell has a cell wall made of cellulose in addition to a cell membrane. However, many aspects of plant cells are similar to those of animal cells. These similarities include the facts that both plant and animal cells contain a nucleus and cytoplasm, and both have certain oxygen, tempera-ture, moisture, nutritional, and pH (acid-base) re-quirements. a. A few organisms, because of their oxygen requirements, are of special concern to operating room personnel. The oxygen requirement is important because some organisms (aerobes) must have free oxygen to survive. On the other hand, anaer-obes, such as those causing tetanus and gas gan-grene, can only reproduce in the absence of free oxygen. Anaerobic organisms require special consideration in surgery where deep wounds offer an ideal environment for them to grow and to excrete disease-producing toxins. b. Not all microorganisms are pathogenic (dis-ease-producing). There are microbes on the skin, in the mouth and nose, in the air, and on practically every object we touch. Most of these never produce disease, and many of them have useful functions in the body, as well as in the world at large. In addition, there are certain organisms which will produce disease only after they are introduced, into a particular type of environment. For example,

SECTION D - DISINFECTION (e -f) Section E Aseptic Technique

against the tubercle bacillus. Iodophors are frequently used as antiseptics because they rapidly degerm the skin and are relatively nontoxic. For some procedures, it is advantageous to use an iodine-alcohol disinfectant. A I- to 2-percent iodine in 70 percent alcohol is a good antiseptic. and 2 percent iodine in 70 percent to 90 percent alcohol may be used to disinfect thermometers. Iodine solutions are corrosive and 0.2 percent sodium nitnte should be present in the solution to prevent corrosion. e. Phenol (carbolic acid is a solution of phenol and phenol derivatives (Creosols). Phenol, as such, is rarely used as a disinfectant. However, many compounds are derived from phenol. Staphene, O. syl, and San Pheno are examples of one percent aqueous phenolic solutions and Vesphine, Tergisyl, and Di-Crobe are two percent phenolic solutions. In the proper concentration these solutions are effective against vegetative bacteria and tubercle bacillus, but they are not effective against spores. These agents in a two percent solution are the agent of choice when dealing with fecal contamination (E. coli). Phenolic compounds are stable and remain active after mild heating or prolonged drying. A dry surface previously treated with a phenolic com-pound, which becomes moist again will become bactericidal. Phenolic compounds irritate the skin and are corrosive. 0.5 percent sodium bicarbonate should be present in phenolic compounds to lessen corrosion. f. Some of the synthetic cationic detergents containing quaternary ammonium compounds have some germicidal activity. The "quats," in the proper concentrations, are effective in destroying vegetative bacteria but the length of exposure time required limits its usefulness. They are ineffective against the tubercle bacillus and spores and do not inactivate viruses. The "quats" are bland in nature. The "quats" are not good antiseptics as they are inactivated by soaps and detergents. Fabric will absorb the "quats" from a solution and rapidly dilute the concentrations. Zephiran 1:750 is the most commonly used quaternary ammonium disinfectant. SECTION E - ASEPTIC TECHNIQUE 30. Introduction. Aseptic technique is performance characterized by precautions for. constant exclusion of microorganisms. To perform an aseptic procedure means to take the precautions and follow the practices and safeguards which are necessary to create an aseptic condition. A protective barrier is created by wearing gowns, masks, and gloves Handwashing, disinfection, and sterilization are all methods of excluding or controlling microorganisms.

Section B - Sterilization (c, d, 8, a, b)

are impractical for operating room use; therefore, they are seldom available in surgical suites. c. Gas sterilization is essentially sterilization with a chemical agent. Ethylene oxide, and other gases, are believed to interfere with the chemical make-up of microorganisms, thus rendering them incapable of biological activities. Ethylene oxide gas is used to sterilize heat-labile and moisture-sensitive materials. In addition to the time and temperature factors, gas concentration and controlled moisture also are important in ethylene oxide sterilization. Barriers to gas permeation or diffusion can create problems in attaining sterility. d. Sterilization by radiation, while not used in hospitals, is commonly used by manufacturers to sterilize many of the prepackaged, presterilized articles used in the operating room. 8. Steam Under Pressure Sterilizers. These sterilizers are designed to hold items for sterilization and to allow steam under pressure to contact or penetrate these items. Figure I illustrates the basic design of a steam under pressure sterilizer. There are several types of steam stenlizers and those most widely used are discussed below. a. The Downward Displacement Steam Sterilizer. After the door is closed, steam is admitted through the inlet. Since air is heavier than steam, gravity draws the air downward and outward as steam enters the chamber. This process is rapid when the sterilizer is empty, but when it is filled, air may be trapped in and around the packages causing cool aur pockets which prevent the steam from contacting all portions of the contents. Once the steam has displaced the air, the outlet is closed by a heat-sensitive valve activated by the heated steam. After time is allowed for steam to penetrate to the center of linen packs, a specified time is required for stenlization. A thermometer recording. system indicates and records the same temperature as that of the thermometer located at the discharge line. It records the length of each exposure cycle over a 24. hour period. The recording chart should be checked at frequent intervals to assure that the correct time. and temperatures are being reached and maintained. An automatic timer gives a light or sound signal at the completion of the sterilization cycle. The steam is then exhausted from the chamber and the mate. rial is dried before being removed from the sterilizer. b. The Prevacuum, High-Temperature Steam Sterilizer. This sterilizer was designed to provide a faster and more reliable method of sterilization than provided by the downward displacement steam sterilizer. Air trapped inside the sterilizing chamber is one of the greatest dangers encountered in' steam-

Section B - Sterilization (f, g, 11, a, b, c, d, e, f, 12, a)

arranged on their sides or edges in positions which allow the air to "spill" out. f. Articles which require the same type of sterilization (gas or steam) and the same time and temperature may be sterlized together. g. Fluids must be sterilized separately using slow vacuum to release the steam as high vacuum will pull liquids out of their containers. In vacuum sterilizers. the load is not vacuumed after the exposure time. 11. Errors in Sterilization. Usually errors which cause sterilization failures originate with people. Those errors of primary importance are: a. Failure to observe and understand the regulation of the sterilizer so that saturated steam is maintained at sterilizing temperature. b. Incorrect methods of packaging and wrapping supplies. c. Carelessness in loading the sterilizer, including disregard for the necessity of providing for complete air removal and for free penetration of steam throughout the load. d. Failure to time the exposure period correctly. e. Removing wrapped supplies from the sterilizer while they are wet. f. Equipment which is faulty because it has not been inspected regularly and maintained properly. 12. Sterilization Indicators. There are several ways to keep a constant check on the proper functioning of the sterilizer and to ensure efficient sterilization. Mechanical controls are used to regulate physical conditions in the sterilizer, while the thermal and biological controls test the efficiency within the load that is being processed. a. Mechanical indicators are devices which are used to assist in identifying and preventing malfunctions and operational errors in the sterilizer. (1) Indicating thermometers measure the temperature in the sterilizer discharge line throughout the sterilizing cycle. They indicate the temperature on a dial on the face of the sterilizer. It does not detect cool air pockets at the center of the load or linen packs. (2) Recording thermometers indicate and record the same temperatures that indicating thermometers show. They also record the duration of the exposure time for each sterilizing cycle. If exposure periods are greater or less than prescribed, or if the temperature has not been maintained within proper limits, there is a positive record of the errors, thus providing necessary information upon which to act

Section B - Sterilization (10, a, b, c, d, e)

been sterilized by gamma radiation must not be resterilized with ethylene oxide as it causes a chemical reaction which produces polychlorhydrin. Polychlordydrin causes toxic reactions to body tissues. 10. Loading the Sterilizer. The integrity of sterilization relies to a great extent on the correct loading of the sterilizer. The steam or gas must be allowed to flow in, around, and out of the articles or packages being sterilized. a. Packs must be loosely wrapped and not exceed 12 by 12 by 20 inches and 12 pounds in weight. b. The load should be arranged with the least possible resistance to the free passage of air from all areas of the chamber. c. The sterilizer must not be overloaded or crowded. The passage of steam or gas from the top to the bottom and around the sides of the chamber must not be blocked. d. Place all packages on edge, with large linen packs at the bottom and small packages in an upper layer crosswise to the lower layer, as illustrated in figure 2. e. Utensils (such as pans and basin sets) should be

Section C - Processing Supplies for Sterilisation (d, e, 19, a-b, 20)

d. Box locks on instruments must be open for positive penetration by the sterilizing agent. e. Items should be arranged in the order or se quence in which they will be used as much as possi-ble. 19. Methods of Wrapping. There are several acceptable ways to wrap packages. The wrapper must be large enough to wrap completely around the item that is to be packaged. Linen wrappers should consist of four thicknesses (two double thicknesses). Two basic methods of wrapping packages are by the diagonal method and the straight method. a. The diagonal (butcher wrap or envelope style) is used for small packages. Two wrappers should be used, but if only one wrapper is used, or if the second wrapper is used as part of the inner package, the item will have been wrapped in a double-thickness instead of a four-thickness wrap-per. (I) Place two wrappers of the same size, one on top of the other, on the work table with one comer toward you. Place the item to be wrapped in the center of the wrapper, parallel to the table edge. (2) Fold the nearest comer over the item to be wrapped, then fold the same corner back to the point of the original fold. (3) Fold the left comer over the item that is being wrapped and then fold the right corner over the item. (4) Fold the remaining corner toward you and secure without tucking the corner. b. The straight fold (drug sture or square wrap) is used for basin sets and linen packs when sheets are used instead of a wrapper. (1) Place the item that is to be wrapped in the center of the wrapper and square with its sides. (2) Fold the side toward you over the top of the item that is being wrapped, and then half-fold it back toward you, making a cuff. (3) Repeat step (2) with the other side. (4) Fold the left side over the item that is being wrapped, tucking the ends under the outer fold. (5) Repeat step (4) with the opposite end. (6) Secure the package with indicator tape. A linen pack wrapped by the straight fold method is illustrated in figure • 4. .. 20. Labeling Packages. The contents of packs, packages, sets, and fluids must be identified as the supplies are prepared. Otherwise, it would be impossible to know the contents of each pack or the type of fluid once they are all mixed together for sterilization. In addition, each must be dated when it is removed from the sterilizer.

Section B - Sterilization (e, 9, a, b, c, d, e)

e. Specific Details. Specific details for operating these sterilizers have not been included here as their operation may vary according to the manufacturer. Local operating procedures and manufacturer's instructions should be consulted for operating details. • 9. Ethylene Oxide Gas Sterilization. Sterilization with ethylene oxide gas is used for articles which would be damaged by the heat or moisture in steam-under-pressure sterilizers. Gas sterilization should not be used for any article which can be steam sterilized. a. Ethylene oxide is a colorless gas which acts as a vesicant if it comes in contact with the skin. The vapor may cause eye and nose irritation, and overexposure can lead to nausea, vomiting, and dizziness. It is highly flammable and when mixed with air can be ignited by electric spark, static electricity, open flame, or other heat- or spark-producing conditions. b. To overcome the toxic and flammable properties of ethylene oxide gas, it is mixed with an inert gas, such as carbon dioxide or fluorinated hydrocar-bons. These mixtures are relatively safe when correctly used in properly constructed sterilizers. c. Gas sterilizers look similar to steam sterilizers, but the conditions which produce sterility depend on the concentration of gas and humidity as well as time and temperature. Air is withdrawn from the chamber, and gas is forced in under pressure. The temperature and humidity are then brought to specified levels and held constant for the duration of the sterilizing period. Gas sterilizers must be operated by skilled personnel strictly in accordance with the instructions provided by the manufacturer. d. Residual ethylene oxide and its byproducts, ethylene glycol and ethylene chlorhydrin, are toxic substances which can remain with articles sterilized by ethylene oxide gas. For this reason, adequate aeration time must be allowed following sterilization to reduce these residuals to a safe level. Aeration may be accomplished in a well-ventilated room. However, a faster and more efficient method is to have specially designed aeration cabinets which provide systematic air changes. Aeration time will be influenced by the type of material as well as the bulk and permeability of the items. e. Following the manufacturer's instructions is extremely important in the overall process of ethyl ene oxide sterilization. A copy of the operating instructions should be affixed to each sterilizer and referred to prior to operating the sterilizer and aerating the material. In addition, manufacturer's instructions regarding resterilization of commercially prepared items must be adhered to; for example, articles containing polyvinylchloride which have

Section B - Sterilization (b, 1, 2, c, 1, 2, 3, 4, d)

in correcting discrepancies. The records of the recorder should contain the number of the sterilizer, the time, and the date. Recording thermometers, like indicating thermometers, do not detect cool air pockets. b. Thermal indicators are used to detect conditions inside the sterilizer chamber. They are useful for checking packaging and loading techniques as well as exposure to sterilizing cycles. THERMAL INDICATORS DETECT OPERATOR MISTAKES AND/OR STERILIZER MALFUNC TION BUT THEY DO NOT "PROVE" STERI. LIZATION. The two most widely used types of thermal indicators are: (1) Heat-sensitive tape that has lines or squares that turn dark when the package is exposed to heat and certain conditions of time and temperature are met. This tape is not a check on the sterility of the package. Its primary function is to indicate that the package has been exposed to a sterilizing cycle. (2) A sealed glass tube containing a small tablet which melts when certain conditions of heat and temperature are met and maintained for a specified period of time. These tubes are placed at the center of packages as they are wrapped. If the tablet has not melted when the package is opened, then the package has not been exposed to sterilizing condi-tons. c. The Bowie- Dick test measures the adequacy of residual air removal and the uniformity of steam penetration in the prevacuum, high-temperature ster-ilizer. Commercial test sheets or a piece of fabric with 4 or 5, 8-inch strips of heat-sensitive tape cnisscrossed on the surface, may. be used for the test. The test must be performed daily: (1) Place the test sheet or fabric in the center of a linen pack and process this single pack through the sterilizing cycle. (2) Remove the test sheet or fabric from the pack and examine the markings for color change. If the color change is. uniform (all lines or circles darkened) it suggests that the sterilizer is functioning properly. (3) Irregular color changes suggest the presence of residual air in and faulty operation of the sterilizer. (4) If the prevacuum, high-temperature sterilizer cannot pass the Bowie- Dick test, it should be considered a gravity displacement sterilizer and operated as such. d. Biological indicators are used to check sterilization efficiency. Negative reports from biological controls prove that wrapping techniques are correct and that the sterilizer is working properly for the load that is being tested. Tests should be conducted once a week, but more frequent testing may be

Section B - Sterilization (1, 2, 3, e, 13, a, 1, 2, 3, b, c)

necessary under adverse conditions or when sterilizers are old or troublesome. Commercially prepared spore strips using highly resistant spores in known populations are used to check sterilizer efficiency. Spore strips containing B. subtilis are used to check ethylene oxide sterilizers and B. stearothermophilus is the organism of choice to check steam sterilizers: (1) In checking the steam sterilizer, the spore strips are placed in the center of a large linen pack. which is then placed in the front, bottom position of the sterilizer (the position most likely to retain trapped air). (2) In checking the ethylene oxide sterilizer, the spore strips are placed in various areas throughout the load as well as inside of packaged items. (3) Following exposure to the sterilizing cycle, the spore strips are sent to a bacteriology laboratory for determination of results. If a bacteriology laboratory is not available locally, the spore strips may be sent to a commercial laboratory or to the manufacturer of the spore strips. e. If any of the foregoing indicators shows erratic sterilizer operation, trained maintenance personnel should check the sterlizer at once. 13. Steam Sterilizer Maintenance. In order to keep these sterlizers in proper working order, they must be cleaned and inspected regularly. Daily and weekly routines should be established as follows: a. The interior of the chamber and the chamber drain strainer should be cleaned daily. This cleaning should be done in the moming when the sterilizer is cOol: (1) Wash the inside of the chamber, the door. and all trays, carriages, and racks with a mild detergent and rinse well with plain water. Strong abrasives, steel wool, or similar substances must not be used as they can damage surface areas. (2) Remove the chamber drain strainer and use a brush to clean lint and sediment from its pores. If the strainer is not kept clean, the sterilizer cannot be depended upon for sterilization. b. The chamber discharge line and trap should be flushed once a week. Remove the strainer and flush the chamber drain line with a hot solution consisting of I ounce of trisodium phosphate to I quart of water or use a nonphosphate detergent as a flushing agent. Then flush the line with I quart of plain hot water and replace the strainer. c. Qualified maintenance personnel should inspect and maintain the sterilizers regularly to protect them from superheated (unsaturated) steam, incomplete air exhaustion, and other factors resulting from mechanical failure.

Section C - Processing Supplies for Sterilisation (a-e, 17, 18, a-c)

will stay sterile until they are ready for use. (This does not apply to instruments sterilized in open trays and taken directly to the operating room or articles sterilized in liquid germicides.) Several types of packaging materials are available. Paper, plastic. and fabric wrappers are commonly used, and they are not necessarily interchangeable. However, all must meet certain prerequisites: a. The wrapping material must provide protection against contamination in handling after sterilization. b. It must be an effective dust filter and guard against insects and vermin entering when the package is stored. c. The wrapping material must be of known porosity and must be permeable to the sterilizing agent. d. The wrapper must be durable enough to withstand the handling that is necessary from the time an item is wrapped, through sterilization. storage, and use. e. The size, shape, and nature of the item to be packaged must be considered. For example. sharp or pointed items must be packed so that they cannot cut or penetrate the wrapping material. 17. Size and Density of Packages. The size and density of the package to be sterilized have a direct relationship to the time that is required for the sterilization process. Basic exposure times have been established as 30 minutes at 250° F for the gravity displacement sterilizer and 4 minutes at 270° F for the prevacuum high-temperature steri-lizer. In order to assure positive steam penetration and sterilization at these times and temperatures. the dimensions of the largest package should not exceed 12 by 12 by 20 inches and 12 pounds in weight. 18. Arranging Items for Packaging. A standard method of arranging items is necessary in order to assemble a package properly. This is usually done by an indexed file-card system. The file card should describe the use, method of cleaning, contents. wrapping, sterilization, storage and stock level. An example of the suggested entries on the index file card is shown in figure 3. a. Packages should be wrapped loosely and arranged so that the sterilizing agent will circulate freely into the center of the contents. b. Different types of supplies. such as basins and linens, should not be included in the same package for sterilization. c. Impermeable surfaces must be separated by a porous material.