basics of steam sterilization

8/3/2019 Basics of Steam Sterilization

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55January 2009 MANAGING INFECTION CONTROL

Sterilization Technology

temperature of steam to kill microorganisms. Microbes die

when steam under pressure creates changes in cell structure,

and when cell protein coagulates (thickens into a mass).

The first steps in sterilization involve proper cleaning

(the removal of visible and invisible soil) and decontami-

nation (the removal or reduction of infectious organisms

or other harmful substances). Failure to adequately

prepare an item for sterilization hinders the direct steam

contact needed to destroy microorganisms. Operating

rooms run on a tight schedule, but proper decontamination

of instruments is mandatory. The concern with flash

sterilization is that in order to accommodate the surgeon

and schedule, the operating room staff will be pressured

to eliminate steps, therefore proper decontamination may

not occur between surgical procedures. The Association

for the Advancement of Medical Instrumentation (AAMI)

states that flash sterilization should only be considered if

“work practices ensure proper cleaning, decontamination,

inspection and arrangement of instruments into the

sterilization for patient use, it does render the instruments

safe for handling after the operation.

Flash sterilizers are typically located near operating room

suites. They are used to quickly sterilize dropped instruments

using cycles with minimum exposure times and temperatures

for unwrapped items. Sterilized items must be transferred

immediately from the flash sterilizer to the operating room

using aseptic technique to minimize recontamination from

pathogenic organisms. There is considerable risk that flash-

sterilized items can be contaminated during transport to the

point of use. The decision to use a flash sterilizer requires

that the benefit of having these instruments is greater than the

risks associated with the process of flash sterilizing and

transporting these instruments.

The Basics of the Steam Sterilization ProcessSteam, by itself, is inadequate to achieve sterilization. Pressure

that is greater than the atmosphere is required to increase the



56 January 2009MANAGING INFECTION CONTROL


recommended sterilizing trays or other containment

devices before sterilization.”1

There are four critical parameters to steam sterilization:

steam, temperature, pressure and time. Steam must be of

high quality and contain no more than 3 percent moisture

and a relative humidity (the amount of water vapor) of

97 percent. The temperature depends upon the type of sterilizer used. Gravity air displacement sterilizers require

a temperature of 250°F (121°C). Dynamic air removal,

washer sterilizers, and flash sterilizers require a temperature

of 270°-275°F degrees (132°C-134°C). To achieve these

temperatures, the pressure must reach 15 pounds per square

inch (psi) for the 250°F (121°C) setting, and 27 psi to

sterilize at 270°F.

Exposure times depend upon the sterilizer manufac-

turer’s recommendations based upon load contents. Flash

sterilization times usually vary from three minutes to 10

minutes. If the load consists of a single instrument

comprised of metal (nonporous) and without lumens,

a three minute cycle should be used. If the load includesmultiple instruments or instruments with lumens, a 10

minute cycle should be used.2

The intense heat of flash sterilization can shorten the

life of power equipment (drills and saws) and batteries.

Frequently, when the flash cycle is complete, batteries

are not immediately removed from the sterilizer; hence

the batteries sit longer in the extreme heat than they

should. The condensation that is formed inside the power

equipment can increase the chance of corrosion and

damage to the internal components, therefore an additional

eight minute “drying time” may be added to help dry the

water droplets that have been created in the device.

Precautions must be taken when items are loaded intothe sterilizer to ensure that steam will contact all items to

be sterilized. All instruments should be opened and disassembled to

allow the steam to completely contact items during sterilization.

The sterilizer should not be overloaded and items should not be

allowed to contact the sterilizer’s chamber walls.

Monitoring Sterilization Cycles

Sterility should never be taken for granted. Sterilization cyclesshould be routinely monitored using mechanical, chemical and

biological indicators.

Mechanical indicators are indicators that come from the

sterilizer itself to indicate how it has functioned. This may include

thermometers, timers, gauges, recorders and/or other devices that

monitor its function. At the end of every cycle, the sterilizer

printout tape should be checked for:

Start time and date;

Operator’s initials;

Sterilizer parameters selected (Was the correct cycle and

time selected?);

Sterilizer parameters met (time, pressure, minimum temperature).

Chemical indicators are indicators that verify exposure to

a sterilization process by changing color. Chemical indicators or

integrators can be used in flash sterilizers. They will change color

when the exposure or parameters have been met. The chemical

indicators/integrators should be placed in each tray among the

instruments with every cycle.

Biological indicators (BI) monitor the adequacy of the

sterilization process and the destruction of microorganisms. They

consist of an inoculated carrier (Geobacillus stearothermophilus

for steam sterilization) that provides a defined resistance to the

sterilization process in which they will be used. Sterilizer operators

should verify that the date on the BI has not expired, and should

be placed in the middle of the sterilizer above the drain. AAMIrecommends 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.

ConcernsAAMI 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 possibleconsequences 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

severe.”3 In addition, implants should be quarantined until the

results of the BI are known.Printout tape from the sterilizer verifies that parameters

have been met.





When the sterilization cycle is completed, the contents

should be removed immediately for use. Items are considered

sterile when necessary conditions have been met during a

sterilization process. The circulating nurse should assure that

all parameters have been met before releasing the load. The scrub

nurse should visually inspect the chemical indicator for color change.

Biological indicators need to be processed and read in a timely manner

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

that all items are allowed to cool before using. To meet theScrub nurses need to verify color change on chemical

indicators.



58 January 2009MANAGING INFECTION CONTROL


not used on the procedure, the documentation must be

completed for that particular cycle. Accountability for each

load must be maintained. Sterilization records are considered

legal documents and, since the length of time they must be

kept varies, each healthcare facility must develop record-

retention policies based upon state and local regulations and

legal considerations.

Sterilizer MaintenanceSterilizer maintenance is important. Sediment screens

should be removed and cleaned daily because clogged strainers

prevent air from being removed from the unit. Chamber

interiors should be cleaned weekly with a mild detergent.

Note: Sterilizers must be allowed to cool for eight hours

before cleaning. Maintenance requirements differ depending

on the model used, and the sterilizer manufacturer’s instruc-

tions should always be followed.

Sediment screens need to be checked daily for

proper maintenance.

Ongoing ConsiderationsTo flash or not to flash, that is the question. According to the

Association for periOperative Registered Nurses (AORN), it

states that flash sterilization should be minimized. It should only

“be used in selected clinical situations and in a controlled

manner.”5 It should not be used as a substitute for not having

enough instrumentation. Scheduling of cases in a manner that

does not require back-to-back usage of the same instrument trays

needs to be addressed. Managers who have budget constraintsoften end up with insufficient instrument inventory. However,

purchasing of additional instruments to maintain the daily

caseload should be a priority. Enforcing policies to have on

time arrivals of vendor pans, brought in the day before surgery,

is critical for providing the best care for the patient.

demands of the surgical procedure, scrub nurses frequently

try to cool the instruments by immersing them in cool

sterile water or wrap in sterile wet towels. Depending on

the item, this cooling process can cause harm to the instru-

ment. For example, if attempting to cool autoclavable

scopes too quickly, it can crack the lenses inside the scope.

Cooling power equipment (drills/saws) quickly can causemore condensation to form on the inside. Most importantly,

the hot instruments can cause injury to the patient and/or

physician. Depending on the thickness of the metal, the

scrub nurse might think it is cool enough to use, but instead

it heats up in the surgeon’s hands or while on the patient.

Some retractors are thick and the heat continues to leech

out during the case. Burns may not be noticed until the

retractor is removed from the incision site. We must

remember that while the patient is under anesthesia and

unable to alert the staff to undesirable conditions, we must

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 fromthe 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.

DocumentationDocumentation 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;

Chemical indicator;

Contents of load (including BI if used);

Patient information;

Reason for flash sterilization;

Initialed printout tape of cycle parameters.

Effective documentation ensures that the sterilization

process is monitored as it occurs, that required cycle param-

eters have been met, and that accountability is established.

At the end of each day, each sterilizer should have complete

documentation for each load. A common problem with

flash sterilization is incomplete documentation. Operatingroom employees are overwhelmed with the other duties and

tasks pertaining to their job and sterilization records take a

low priority. Chemical control cards or integrators are lost;

contents of the load are not documented and/or patient

information not included. Even if the instruments were





Carol Petro, RN, BSN, CRCST,is the clinical educator for

Clarian Health sterile processing

departments at Methodist Hospital,

University Hospital and Riley

Hospital for Children in

Indianapolis. She has worked in

the sterile processing department

for two years and the surgery

department for 25 years. She has a

Bachelor of Science Degree in Nursing from University of

Indianapolis. She received her technical training as a

Certified Registered Central Service Technician (CRCST)

from IAHCSMM in 2006.Previous positions held at Clarian included Oral/

Maxillofacial/Ophthalmology Specialty Coordinator from

1992 to 2001 and Special Projects Coordinator/SurgiNet

Informatics Project Leader from 2001 to 2005. She may

be reached at [email protected].

Alternatives need to be created for the doctor’s specials that arecarried from the operating room of one hospital to another. Can we eval-

uate what is contained in these special instrument sets and provide them

in one of our existing sets, so that they are sterile prior to the procedure?

Operating room personnel must maintain high standards of

sterile technique. Every individual is accountable for their role in

infection control. Work practices need to ensure that proper

cleaning and decontamination is performed and that procedures

are developed and followed in regard to flash sterilization. ✛

References1. ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization and

Sterility Assurance in Health Care Facilities. Arlington, VA.2006, page 2-3.2. International Association of Healthcare Central Service and Materiel

Management. Central Service Technical Manual. Seventh Edition. 2007.Point of Use Processing, chapter 14, page 269.

3. ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization andSterility Assurance in Health Care Facilities. Arlington, VA.2006, page 3.

4. ANSI/AAMI ST79:2006. Comprehensive Guide to Steam Sterilization andSterility Assurance in Health Care Facilities. Arlington, VA.2006, page 2.

5. Association of PeriOperative Registered Nurses (AORN). Standards,Recommended Practices, and Guidelines. Denver, CO. 2007, page 675.

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basics of steam sterilization

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