Basics of Steam Sterilization

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					     Sterilization Technology

      Basics of Steam Sterilization
      — TO FLASH OR NOT TO FLASH?                                                          by Carol Petro, RN, BSN, CRCST

                 terilization is the complete destruction of all     in the operating room immediately. This is when flash steam
                 microbial life by physical or chemical proce-       sterilizers come into play. Virtually all operating rooms have
                 dures. There are several methods of sterilization   flash sterilizers available adjacent to the operating room suites.
     available today, but steam sterilization continues to be the    These sterilizers provide for the sterilization of instruments
     preferred method to destroy microorganisms. The process         that have been dropped on the floor or contaminated during
     is non-toxic, safe, sporicidal and relatively inexpensive.      the surgical procedure. In addition, these flash sterilizers can
     Further, it rapidly heats and penetrates all fabrics. Other     be used to sterilize instruments that were not anticipated and
     sterilization methods are only used when the item being         subsequently not prepared in advance.
     sterilized cannot withstand the heat and/or moisture of
     steam sterilization.                                            Types of Steam Sterilizers
           The sterile processing department prepares instrument          There are four basic types of steam sterilizers: gravity air
     trays for surgical procedures by assuring that they are         displacement, dynamic air removal, washer-sterilizer and
     decontaminated, inspected, assembled, wrapped and               flash sterilizer.
     sterilized prior to patient use. However, there may be times     Gravity air displacement sterilizers use gravity to remove
     when the instruments are not yet sterile and are needed              air from their chambers. Steam introduced into the chamber
                                                                          creates a layer above the air, which increases until the air is
                                                                          pushed down through a drain at the bottom of the unit. After
                                                                          air is removed, steam temperature and pressure builds, and
                                                                          exposure time begins when the sterilization temperature is
                                                                          reached. Gravity sterilizers are used to sterilize surgical
                                                                          instrumentation, liquids and linen.

                                                                      Dynamic air removal sterilizers (also called prevacuum
                                                                       or “prevac” steam sterilizers) were created to overcome a
                                                                       problem that can occur when using saturated steam in
                                                                       gravity cycles: air can be trapped in the chamber, and cool
                                                                       air pockets may form and hinder sterilization. PreVac steril-
                                                                       izers use a pump to remove air from the chamber before
                                                                       steam is introduced. Dynamic air removal units are, there-
                                                                       fore, more efficient than gravity air displacement sterilizers
                                                                       since air is pumped out before steam enters the chamber,
                                                                       and the steam can immediately penetrate packages. A
                                                                       Bowie Dick test should be used daily with these sterilizers
                                                                       to determine if there is residual air in the chamber, which
                                                                       can prevent steam from reaching all surfaces of the items.

                                                                      Washer-sterilizers are usually located in areas next or
                                                                       close to operating room suites. These combination units
                                                                       wash and sterilize instruments; however, gross contamina-
                                                                       tion must be removed and rinsed from instruments before
                                                                       they are processed. These units use a mechanical cycle to
     Flash sterilizers are located close to operating room suites
                                                                       wash and rinse away debris before the sterilization cycle
     so dropped instruments can be sterilized quickly.                 begins. While this processing does not provide terminal

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                                                                                         Sterilization Technology

     sterilization for patient use, it does render the instruments        temperature of steam to kill microorganisms. Microbes die
     safe for handling after the operation.                               when steam under pressure creates changes in cell structure,
                                                                          and when cell protein coagulates (thickens into a mass).
 Flash sterilizers are typically located near operating room                   The first steps in sterilization involve proper cleaning
  suites. They are used to quickly sterilize dropped instruments          (the removal of visible and invisible soil) and decontami-
  using cycles with minimum exposure times and temperatures               nation (the removal or reduction of infectious organisms
  for unwrapped items. Sterilized items must be transferred               or other harmful substances). Failure to adequately
  immediately from the flash sterilizer to the operating room             prepare an item for sterilization hinders the direct steam
  using aseptic technique to minimize recontamination from                contact needed to destroy microorganisms. Operating
  pathogenic organisms. There is considerable risk that flash-            rooms run on a tight schedule, but proper decontamination
  sterilized items can be contaminated during transport to the            of instruments is mandatory. The concern with flash
  point of use. The decision to use a flash sterilizer requires           sterilization is that in order to accommodate the surgeon
  that the benefit of having these instruments is greater than the        and schedule, the operating room staff will be pressured
  risks associated with the process of flash sterilizing and              to eliminate steps, therefore proper decontamination may
  transporting these instruments.                                         not occur between surgical procedures. The Association
                                                                          for the Advancement of Medical Instrumentation (AAMI)
The Basics of the Steam Sterilization Process                             states that flash sterilization should only be considered if
     Steam, by itself, is inadequate to achieve sterilization. Pressure   “work practices ensure proper cleaning, decontamination,
that is greater than the atmosphere is required to increase the           inspection and arrangement of instruments into the

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     Sterilization Technology

     recommended sterilizing trays or other containment                 be sterilized. All instruments should be opened and disassembled to
     devices before sterilization.”1                                    allow the steam to completely contact items during sterilization.
           There are four critical parameters to steam sterilization:   The sterilizer should not be overloaded and items should not be
     steam, temperature, pressure and time. Steam must be of            allowed to contact the sterilizer’s chamber walls.
     high quality and contain no more than 3 percent moisture
     and a relative humidity (the amount of water vapor) of             Monitoring Sterilization Cycles
     97 percent. The temperature depends upon the type of                     Sterility should never be taken for granted. Sterilization cycles
     sterilizer used. Gravity air displacement sterilizers require      should be routinely monitored using mechanical, chemical and
     a temperature of 250°F (121°C). Dynamic air removal,               biological indicators.
     washer sterilizers, and flash sterilizers require a temperature          Mechanical indicators are indicators that come from the
     of 270°-275°F degrees (132°C-134°C). To achieve these              sterilizer itself to indicate how it has functioned. This may include
     temperatures, the pressure must reach 15 pounds per square         thermometers, timers, gauges, recorders and/or other devices that
     inch (psi) for the 250°F (121°C) setting, and 27 psi to            monitor its function. At the end of every cycle, the sterilizer
     sterilize at 270°F.                                                printout tape should be checked for:
           Exposure times depend upon the sterilizer manufac-            Start time and date;
     turer’s recommendations based upon load contents. Flash             Operator’s initials;
     sterilization times usually vary from three minutes to 10           Sterilizer parameters selected (Was the correct cycle and
     minutes. If the load consists of a single instrument                     time selected?);
     comprised of metal (nonporous) and without lumens,                  Sterilizer parameters met (time, pressure, minimum temperature).
     a three minute cycle should be used. If the load includes
     multiple instruments or instruments with lumens, a 10                    Chemical indicators are indicators that verify exposure to
     minute cycle should be used.2                                      a sterilization process by changing color. Chemical indicators or
           The intense heat of flash sterilization can shorten the      integrators can be used in flash sterilizers. They will change color
     life of power equipment (drills and saws) and batteries.           when the exposure or parameters have been met. The chemical
     Frequently, when the flash cycle is complete, batteries            indicators/integrators should be placed in each tray among the
     are not immediately removed from the sterilizer; hence             instruments with every cycle.
     the batteries sit longer in the extreme heat than they                   Biological indicators (BI) monitor the adequacy of the
     should. The condensation that is formed inside the power           sterilization process and the destruction of microorganisms. They
     equipment can increase the chance of corrosion and                 consist of an inoculated carrier (Geobacillus stearothermophilus
     damage to the internal components, therefore an additional         for steam sterilization) that provides a defined resistance to the
     eight minute “drying time” may be added to help dry the            sterilization process in which they will be used. Sterilizer operators
     water droplets that have been created in the device.               should verify that the date on the BI has not expired, and should
           Precautions must be taken when items are loaded into         be placed in the middle of the sterilizer above the drain. AAMI
     the sterilizer to ensure that steam will contact all items to      recommends that a biological test be performed at least weekly,
                                                                        preferably every day that the sterilizer is used. A positive result
                                                                        for growth would indicate that the sterilizer did not function
                                                                        appropriately. The sterilizer must be taken out of service immedi-
                                                                        ately and the instruments must be re-sterilized. In fact, all items that
                                                                        were processed in that sterilizer since the last negative BI are
                                                                        considered non-sterile. This is why documentation of all flash
                                                                        sterilization cycles must be traceable to a patient.

                                                                             AAMI and the Centers for Disease Control and Prevention
                                                                        (CDC) warn against flash sterilizing of implantables. AAMI states
                                                                        that “implantables should not be flash-sterilized. The possible
                                                                        consequences to the patient from placing even a minimally
                                                                        contaminated device in an essentially avascular environment and
                                                                        leaving it there at the conclusion of the procedure are potentially
     Printout tape from the sterilizer verifies that parameters         severe.”3 In addition, implants should be quarantined until the
     have been met.                                                     results of the BI are known.

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      When the sterilization cycle is completed, the contents     all parameters have been met before releasing the load. The scrub
should be removed immediately for use. Items are considered       nurse should visually inspect the chemical indicator for color change.
sterile when necessary conditions have been met during a          Biological indicators need to be processed and read in a timely manner
sterilization process. The circulating nurse should assure that   according to manufacturer’s instructions.
                                                                        Attention should be made to avoid heat injuries when unloading
                                                                  the sterilizer. The instrument(s) must be removed and transported
                                                                  using aseptic technique. Transferring the sterilized item to the sterile
                                                                  field is difficult without contaminating it. The scrub nurse needs to pay
                                                                  attention to how they reach into the sterilizer to remove the contents
                                                                  and not touch the edges of the sterilizer. The circulator should escort
                                                                  the scrub nurse to the flash sterilizer eliminating traffic or opening
                                                                  of doors from the inner core during transportation of the sterile
                                                                  instruments. The risk of contamination increase if “transported
                                                                  through areas where personnel are scrubbing or washing their hands,
                                                                  creating splashing or aerosolization.”4 The work area should be
                                                                  arranged so that it ensures direct delivery of sterilized items to point of
                                                                  use without physical hazards and possible contamination.
                                                                        Another concern of flash sterilization is being able to assure
Scrub nurses need to verify color change on chemical              that all items are allowed to cool before using. To meet the

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     demands of the surgical procedure, scrub nurses frequently       not used on the procedure, the documentation must be
     try to cool the instruments by immersing them in cool            completed for that particular cycle. Accountability for each
     sterile water or wrap in sterile wet towels. Depending on        load must be maintained. Sterilization records are considered
     the item, this cooling process can cause harm to the instru-     legal documents and, since the length of time they must be
     ment. For example, if attempting to cool autoclavable            kept varies, each healthcare facility must develop record-
     scopes too quickly, it can crack the lenses inside the scope.    retention policies based upon state and local regulations and
     Cooling power equipment (drills/saws) quickly can cause          legal considerations.
     more condensation to form on the inside. Most importantly,
     the hot instruments can cause injury to the patient and/or       Sterilizer Maintenance
     physician. Depending on the thickness of the metal, the               Sterilizer maintenance is important. Sediment screens
     scrub nurse might think it is cool enough to use, but instead    should be removed and cleaned daily because clogged strainers
     it heats up in the surgeon’s hands or while on the patient.      prevent air from being removed from the unit. Chamber
     Some retractors are thick and the heat continues to leech        interiors should be cleaned weekly with a mild detergent.
     out during the case. Burns may not be noticed until the          Note: Sterilizers must be allowed to cool for eight hours
     retractor is removed from the incision site. We must             before cleaning. Maintenance requirements differ depending
     remember that while the patient is under anesthesia and          on the model used, and the sterilizer manufacturer’s instruc-
     unable to alert the staff to undesirable conditions, we must     tions should always be followed.
     act as their advocate and prevent these accidents from
     happening. Let’s not forget the danger to the employees
     themselves. When carrying hot and heavy instruments from
     the flash sterilizer, poor body mechanics are frequently
     used in holding the hot items out and away from their body
     to prevent burning. These poor body mechanics lead to the
     straining of the lower back and arms.

          Documentation of the flash sterilization process should
     be consistent with requirements for sterilizing wrapped
     items. However, flash sterilized items require documentation
     linking the patient. The following information should be
     documented for each flash sterilization cycle:
      Date;
      Sterilizer number and sterilizer load number;
      Sterilizer operator;                                           Sediment screens need to be checked daily for
      Chemical indicator;                                            proper maintenance.
      Contents of load (including BI if used);
      Patient information;
      Reason for flash sterilization;                                Ongoing Considerations
      Initialed printout tape of cycle parameters.                         To flash or not to flash, that is the question. According to the
                                                                      Association for periOperative Registered Nurses (AORN), it
          Effective documentation ensures that the sterilization      states that flash sterilization should be minimized. It should only
     process is monitored as it occurs, that required cycle param-    “be used in selected clinical situations and in a controlled
     eters have been met, and that accountability is established.     manner.”5 It should not be used as a substitute for not having
     At the end of each day, each sterilizer should have complete     enough instrumentation. Scheduling of cases in a manner that
     documentation for each load. A common problem with               does not require back-to-back usage of the same instrument trays
     flash sterilization is incomplete documentation. Operating       needs to be addressed. Managers who have budget constraints
     room employees are overwhelmed with the other duties and         often end up with insufficient instrument inventory. However,
     tasks pertaining to their job and sterilization records take a   purchasing of additional instruments to maintain the daily
     low priority. Chemical control cards or integrators are lost;    caseload should be a priority. Enforcing policies to have on
     contents of the load are not documented and/or patient           time arrivals of vendor pans, brought in the day before surgery,
     information not included. Even if the instruments were           is critical for providing the best care for the patient.

58    MANAGING INFECTION CONTROL                                                                                                January 2009
                                                                                                  Sterilization Technology

                                                                                                     Reader Service No. 40

     Alternatives need to be created for the doctor’s specials that are                                         Carol Petro, RN, BSN, CRCST,
carried from the operating room of one hospital to another. Can we eval-                                   is the clinical educator for
uate what is contained in these special instrument sets and provide them                                   Clarian Health sterile processing
in one of our existing sets, so that they are sterile prior to the procedure?                              departments at Methodist Hospital,
     Operating room personnel must maintain high standards of                                              University Hospital and Riley
sterile technique. Every individual is accountable for their role in                                       Hospital for Children in
infection control. Work practices need to ensure that proper                                               Indianapolis. She has worked in
cleaning and decontamination is performed and that procedures                                              the sterile processing department
are developed and followed in regard to flash sterilization. ✛                                             for two years and the surgery
                                                                                                           department for 25 years. She has a
References                                                                          Bachelor of Science Degree in Nursing from University of
1.   ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization and
     Sterility Assurance in Health Care Facilities. Arlington, VA.2006, page 2-3.   Indianapolis. She received her technical training as a
2.   International Association of Healthcare Central Service and Materiel           Certified Registered Central Service Technician (CRCST)
     Management. Central Service Technical Manual. Seventh Edition. 2007.           from IAHCSMM in 2006.
     Point of Use Processing, chapter 14, page 269.
3.   ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization and                 Previous positions held at Clarian included Oral/
     Sterility Assurance in Health Care Facilities. Arlington, VA.2006, page 3.     Maxillofacial/Ophthalmology Specialty Coordinator from
4.   ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization and            1992 to 2001 and Special Projects Coordinator/SurgiNet
     Sterility Assurance in Health Care Facilities. Arlington, VA.2006, page 2.
5.   Association of PeriOperative Registered Nurses (AORN). Standards,              Informatics Project Leader from 2001 to 2005. She may
     Recommended Practices, and Guidelines. Denver, CO. 2007, page 675.             be reached at

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