OOOPS!

Numerous studies have focused on the contamination level of flexible endoscopes.  Results showed contamination levels range from 5 log10 to 10 logs10 of bioburden (Table 1).  Colonoscopes had the highest contamination levels while gastroscopes were somewhat less.  Bronchoscopes were not included in these studies.  The importance of this becomes evident when we understand that the work Alfa et al. (1999) did in identifying the amount of bioburden that is removed with cleaning.  She and her team demonstrated that cleaning can be reduced by five to tenfold.  This includes precleaning and manual or automated cleaning.  Once cleaning has occurred there may still be remaining viable microorganisms however, high level disinfection must be able to kill at a minimum 5 logs10 before they can be cleared by the Food and Drug Administration.  Between these three steps you should be able to prepare a safe flexible endoscope for the next patient use.

Table 1. Bioburden levels for contaminated endoscopes

A value of zero for bacteria represents the absolute after cleaning
B experimentally contaminated scopes
C bioburden in sucti on channels
D bioburden on device surfaces

Rutala, W., & Weber, D. J. (2004) Reprocessing endoscopes: United States perspective, 56(S2), S27-S39.

Drying is Step 8 in the Endoscope Reprocessing Procedure.  It can be done manually or it can be done using automation in the automated endoscope reprocessor.

Manual Drying

After the scope has been cleaned, inspected, and high level disinfected it is rinsed and an alcohol purge is pushed through each of the channels with low pressure instrument grade forced air and then it is dried externally using a low lint or lint free cloth.  Next, low-pressure instrument grade air is used to push air through the channels.  Do not use syringe air as it is not strong enough or contamination free enough to dry the channel.

Automated Drying

The AER cycle is programmed for an alcohol purge after final rinsing and hepa-filtered air is then forced through all the channels using the validated hookups recommended for the AER and the scope manufacturer.  Some AERs will not be able to do this step for the forward water jet or auxiliary water channel, so it will need to be done manually.  Since the scope touches the surface of the basin in the AER you will need to use a low lint or lint free cloth to dry the external surface of the scope before transport, use, or storage.

Several studies have been completed identify drying to be just as important as the cleaning of a flexible endoscope.  Most research showed scopes could be contaminated exogenously or externally through improper handling, not wearing clean personal protective equipment, environmental contamination, mishandling of the scope or, transport contamination.  Rejchrt et al. (2004) and Brock et al. (2015) discovered microbial growth over periods of time if the scope was not dried sufficiently and handled correctly.  Alfa and Sitter (1991) showed little microbial growth occurred if ten minutes of low pressure forced air drying was used vs the normal two-minute cycle that is used in most automated endoscope reprocessors.  While cleaning removes contamination, drying prevents microbial growth.  Pajkos et al. (2013) showed if scopes are not completely dry then biofilm forms making it even more difficult to reprocess a scope and make it patient ready and safe for use.  Ofstead (2016) recently published a study showing residual moisture found in channels of scopes that were patient ready and had been dried thoroughly before being stored.  Even though the scope had been hung vertically there were still moisture droplets identified using a bore scope and taking digital pictures to record the moisture.  We may need to rethink how we dry flexible endoscopes.  There are different methods for drying scopes.

All society guidelines recommend using low pressure forced air for drying channels of the endoscope.  There is a difference between medical grade air and instrument grade air.  Medical grade air is for patient use only.  It is not plumbed unless it is for patient use in patient care units.  Medical grade air may not be used for medical devices as regulatory agencies mandate there can be no possibility for error or contamination from other sources when using it for patients. Medical grade air may be used if specific backflow valves are in place or the system is completely separate from patient lines.

Instrument grade air or air under pressure, may be in a tank or have facility hose connectivity, provides a low pressure flow so as not to damage instruments, and has been used extensively in Sterile Processing Departments.  Syringes used to force air through the channels are not strong enough to force the residual fluid through the channels.  All society recommendations agree with not using syringes for channel drying.

Researchers have been studying the importance of drying to help improve patient safety.  Alfa, Degagne and Olson (1999) look at initial loading of bioburden in all types of scopes, colonoscope, gastroscopes and bronchoscopes.  Their research showed bioburden loading to be between 5 and 10 logs contamination.  They also discovered cleaning could reduce levels of protein, endotoxin and sodium ion between five and tenfold of the bioburden, while carbohydrates were below detectable levels.   Viable bioburden was reduced 3-5 logs.  Pineau, Villard and Marchetti (2008) found scopes stored in drying/storage cabinets were lower than those not using drying cabinets and decreased even more after extended drying/storage time.  This is very important as high-level disinfectants can kill up to 5 logs of bacterial bioburden.  So, if cleaning can remove the majority of bacterial bioburden and high level disinfectants kill most of the remaining bacterial burden, the scope is then safe to be used on the next patient.  Drying provides an environment that can prevent and eliminate any remaining viable microorganisms from reproducing. 

Scopes can become contaminated from various sources.  Bacteria from the air and water, hand contact, and in micro cracks and corners of the endoscope which can be left behind even when following IFUs for flexible endoscope reprocessing before storage.  Microbial growth normally requires a moist environment to reproduce.  When water is present and the conditions are right microbial growth can occur with bacteria having the ability to reproduce every 20-30 minutes.  Another major concern is constant moisture can facilitate biofilm formation where it can grow and cover or shelter viable organisms protecting them from destruction during cleaning and high-level disinfection.

Many factors contribute to bacterial growth in flexible endoscopes.  Until recently several professional nursing societies recommended specific “hang time” or storage times for flexible scopes if they had been reprocessed completely.  Currently only The Society of Gastrointestinal Nurses and Associates recommends a STORAGE TIME of 7 days if the scope manufacturer’s instructions for use have been followed meticulously during reprocessing.

Schmelzer and Daniels, (2016) researched literature to determine if there was sufficient evidence to warrant a recommendation for storage time.  Their findings allowed them to recommend 7 days for storage if the flexible endoscope has been meticulously reprocessed following the manufacturer’s instructions for use. (See Table 2.)  The Association of Perioperative Registered Nurses and The Association for the Advancement of Medical Instrumentation no longer specify a time frame for storage before a scope must be reprocessed. Both organizations recommend a multidisciplinary group within the healthcare facility review evidence-based research and come to a consensus on how long the storage time should be for flexible endoscopes before they must be reprocessed.  Whatever the time frame selected it should be incorporated into the facility’s policy and procedure.

The professional society guidelines that are normally used in endoscope reprocessing and drying are listed in Table 2.  SGNA suggests alcohol purge followed by low pressure forced air drying, external wipe down of the scope.  AORN suggest an alcohol purge should be used with manual drying and may be used with automated reprocessors.  The reason for not necessarily using an alcohol purge when using an AER is that you are not handling the scope and all channels receive the same amount of forced air and it can be set to a specific time of drying.  AAMI suggests an alcohol purge followed by low pressure forced air.

Pineau, Villard, Duc & Marchetti (2008) showed that when using a drying cabinet residual microbial counts could be decreased and there was no evidence of microbial growth.  At the same time, vertical hanging of scopes in a conventional cabinet showed a stable microbial level or increased microbial level during storage.  Since microbial reproduction can occur every 20 minutes.

Foxcroft, Hautefeuille, Marchetti, Pineau and Laugier (2013) showed that protected storage environments help control microbial growth.  They also discovered that drying cabinets produced less environmental contamination within the drying storage cabinet compared to the environment in the conventional storage cabinet.  These cabinets were dedicated for endoscope drying and storage. 

Table 2. Endoscope Drying and Storage Recommendations

Another important part of maintaining and protecting flexible endoscopes are the cabinets where they are stored. All society guideline recommendations suggest a protected storage area for patient ready endoscopes. This can be cabinets or a room with limited access. AORN and AAMI do not recommend scopes be stored in a procedure room.
There is sufficient research now for people to better understand how to choose a storage time. Table 3 provides examples of researchers that looked at endoscope storage and what they found.

Table 3. Research for Storage Times

Unfortunately, reprocessing frequently does not occur the way it should.  Ofstead, Yellin, & Langlay discovered through their research that only 1% of scopes were reprocessed following all of the manufacturer’s instructions for use.  57% of the time all channels were not brushed as instructed.  14% and 10% did not flush with alcohol or completed a final wipe down respectively.
As with any process where humans are concerned, errors can and do occur.  Researchers are now studying contributing factors for missed or omitted steps in endoscope reprocessing.  Ofstead’s work is an example of just how many critical touch points can have an error happen.  Here are a few of the errors that have been identified through research and through anecdotal observations.

Table 4 lists sources of contamination that have been studied through testing.  Many of them show contamination from mishandling.  This can be due to not wearing gloves or the scope coming in contact with clothing, contaminated gloves, other scopes or surfaces.

Table 4.  Microorganisms on flexible scopes and potential causes

There are many critical touch points in endoscope reprocessing.  Two of those touch points have been discussed here.  It is important for the person working in endoscopy to maintain an awareness of latest educational offerings, how guidelines change as more studies are completed and to have a situational awareness of the necessity for attention to detail in completing the flexible endoscope reprocessing steps, especially for drying and storage.  Remember, cleaning removes bioburden and microorganisms while drying prevents microbial growth.

Alcohol purge:  70-90% isopropyl alcohol used to expedite drying in reprocessed flexible endoscopes.

Bioburden:  The degree of microbial load; the number of viable organisms contaminating an object.

Biofilm:  A thin layer of microorganisms adhering to the surface of a structure, which may be organic or inorganic, together with the polysaccharides that they secrete.

Borscope:  A device used to inspect the inside of an instrument through a small opening or lumen of the instrument.

Conventional storage cabinet:  Dedicated cabinet

Critical Water:  Water that is extensively treated to remove microorganisms and other materials.

Decontamination:  A toxic substance present in the outer membrane of gram-negative bacteria that is released from the cell when it disintegrates

Disinfection: The process of cleaning something, especially with a chemical, in order to destroy bacteria

Drying cabinet:  A medical device designed for storage of flexible endoscopes that circulates continuous filtered air through each endoscope channel and within the cabinet.

Endotoxin:  A toxic substance present in the outer membrane of gram-negative bacteria that is released from the cell when it disintegrates

Endogenous: Microorganisms that reside inside the body 

Exogenous:  Microorganisms that are in the environment

High concern microorganism:  Organisms often associated with disease, such as gram-negative bacteria (eg, E. coli, K. pneumoniae, Enterobacteriaceae, P. aeruginosa), S. aureus, and Enterococcus. Positive cultures of organisms of high con­cern require corrective action.

High level disinfection:  Processes that kill all microbial pathogens, but not necessarily all bacterial spores.

Infection Control Risk Assessment:  A documented pro­cess to proactively identify and plan safe design elements, including consideration of long-range infection preven­tion; identify and plan for internal and external building areas and sites that will be affected during construction/ renovation; identify potential risk for transmission of air­borne and waterborne biological contaminants during construction and/or renovation and commissioning; and develop infection control risk mitigation recommenda­tions to be considered.

Instrument air:  A medical gas that falls under the gen­eral requirements for medical gases as defined by the NFPA 99: Health Care Facilities Code, is not respired, is compliant with the ANSI/ISA S-7.0.01: Quality Standard for Instrument Air, and is filtered to 0.01 micron, free of liquids and hydrocarbon vapors, and dry to a dew point of -40° F (-40° C).

Log reduction:  A 10-fold reduction in the number of live bacteria. A 1-log reduction would reduce 100 bacteria to 10.

Low concern microorganism:  Organisms less often associ­ated with disease and potentially a result of contamina­tion of cultures during collection, such as coagulase-negative staphylococci. Levels of low-concern organisms can vary depending on the processing procedures in the facility

Microbial growth:  How rapidly microorganisms can reproduce.