By Kerry Dolan
Endoscope reprocessing is usually focused on achieving a sufficient and effective cleaning and disinfection process. However, recent studies have emerged highlighting the current pitfalls with endoscope drying and storage methods—showing worrying results. The endoscope drying process should be just as vital a component in reprocessing as cleaning and disinfection, but the current guidelines for endoscope drying are inconsistent and confusing for decontamination staff, and methods can vary widely between facilities.
Drying is a critical step in infection prevention, as any residual moisture left inside the endoscope channels can encourage biofilm formation. Endoscopes are saturated after reprocessing, and if there is any remaining moisture within the scope or the internal channels, this can lead to microbial growth.
Any imperfection in the endoscope cleaning process—inadequate cleaning and disinfection, insufficient drying, or inadequate storage—could result in post-endoscopic infections for the patient. However, the risk can be significantly reduced by any process used to dry the endoscope channels and by controlling storage conditions.
The significance of endoscope drying was identified in 1982, in a study by Gerding et al.[1] which showed that 31% of stored endoscopes were contaminated with bacteria. The study led to the introduction of forced-air drying to endoscope storage, which reduced the contamination rate to 5%. This, and several other studies that have followed, have all shown the importance of endoscope drying to manage microorganism escalation during storage.
Manual vs. Automated Drying
Flexible endoscopes can be dried in two ways: by manually drying the endoscope with lint-free cloths, and the channels with filtered, pressurized air for an extended period, after high-level disinfection and before storing in a conventional endoscope storage cabinet; or by placing the reprocessed endoscopes into a designated drying cabinet.[2] Standard storage cabinets are not automated and do not provide direct airflow through the endoscope’s internal channels. Dedicated drying cabinets supply medical-grade compressed airflow through the endoscope channels and over external surfaces. Studies have shown that this process can vary across healthcare facilities and are always dependent on the human factor.[3]
Manual drying supported by medical compressed air is the straightforward method adopted by many facilities. A study in 2018 by Thaker[4] demonstrated that endoscope channels can be dried sufficiently using medical compressed air. Guidelines in the U.S. recommend a 10-minute drying cycle,[5] however, this is highly dependent on the human factor, which becomes particularly impractical when healthcare staff are under strict time restraints.
Automated drying cabinets are designed to dry the entire scope, the channels, and the outside[6] using a continuous flow of pressurized, filtered air through the scope channels. This ensures a standardized and validated drying and storage process in a closed environment. Drying can take between 90 minutes and several hours, depending on the type of endoscope. The efficiency of these cabinets has been demonstrated in several clinical and non-clinical studies.[7],[8],[9]
The latest technology has seen the birth of new drying-cabinet options, which have built-in artificial intelligence and safety aspects to ensure traceability and scope security, along with the more traditional channel drying features.
However, the endoscope-drying process is yet to be standardized in healthcare settings, meaning that while some facilities may acquire a designated drying and storage area with automated drying cabinets, other hospitals may only have provision for a standard storage cabinet available to them.
The guidelines in the UK, Europe, and the United States all facilitate endoscope drying, however, recommendations can differ between institutions. The use of alcohol flush is advocated by some for its antimicrobial activity and to promote drying, whereas other organizations do not endorse alcohol flushes due to concerns that the fixative effects of alcohol could encourage pathogens to be retained within endoscopes.[10],[11],[12],[13]
The manufacturer’s instruction manuals can also be vague, with some stating simply to “dry the channels” without providing specific details about which type of air, how to apply it, and the exact time required for sufficient drying.
Evidence is Key to Drying Time
In a study by Ofstead et al. in 2018, the drying methods of three different hospitals were evaluated. In Hospital A, endoscopes were reprocessed, and then placed directly into a cabinet to drip-dry. The technician would manually apply the air purge using a syringe. It was observed that the scopes were not hanging in a fully vertical position.
In Hospital B, endoscopes were wiped with towels then flushed with alcohol and air purged immediately after reprocessing, however, the towels they used were reused throughout the day before laundering. Endoscopes were then carried by hand and placed in the storage cabinet. It was noted that the cabinet had the facility for HEPA air filtration, but the fans were unplugged.
In Hospital C, scopes were wiped with single-use, lint-free towels, then at a designated drying station endoscopes were given air purge and alcohol flush and connected to pressure-regulated air for 10 minutes based on a study the hospital had conducted.
To obtain results, a borescope was used and test papers to identify any residual moisture in the scopes left to hang for 24 hours. The results showed that using the drip-dry method, 83% of the scopes had residual moisture, but in the facility that dried the scopes for 10 minutes, only 5% of the endoscopes that had residual moisture. The study concluded that 10 minutes of pressure-regulated forced air was most effective for drying endoscopes.[14]
When the droplets in the endoscopes were tested, they showed significant microbial growth, however it is important to note that these results could also be due to insufficient reprocessing methods, use of insoluble products or waterborne pathogens.[15]
A further study by Bakarat et al. inspected moisture residues retained in scopes after manual and automated drying processes. The results showed that no fluid retention was observed after 10 minutes of automated drying. The study evaluated five different scopes and tested manual and automated drying methods for 5 and 10 minutes to obtain these findings.[16]
To establish the efficacy of automated drying of endoscopes in cabinets, in a further study, three different types of endoscopes were evaluated. A colonoscope (Olympus), duodenoscope (Fujinon) and an enteroscope (Pentax) were all artificially contaminated before the testing process and changes were observed to the residual internal contamination level when stored inside and outside of the drying cabinet for 12-, 24-, 48- and 72-hour periods.
When compared, the findings showed that when scopes were stored inside the drying cabinet, microbial contamination levels on the scopes were lower than the number of bacteria initially introduced and could decrease considerably thereafter. [17] For endoscopes stored outside the drying and storage cabinet, microbial numbers were stable or increased.
Safe Storage, but for How Long?
A cabinet that keeps endoscopes secure and avoids contact with contaminated surfaces, but does not dry the scopes, is referred to as a storage cabinet. If an endoscope is not to be used immediately on the next patient, the scope and its components must be dried and stored away from contamination.[18]
Appropriate storage is key to maintaining endoscopes’ functionality. Endoscopes should hang freely in a closed, well-ventilated storage cabinet to avoid damage and facilitate drying. Cabinets should have a HEPA filter and provide safe storage for endoscope accessories.
However, there is insufficient data to provide a maximum duration for the use of appropriately cleaned, reprocessed, dried, and stored flexible endoscopes. According to an article reviewed and approved by the ASGE by Day et al., endoscopy units should evaluate the available literature, perform an assessment as to the benefits and risks around the optimal storage time for endoscopes, and develop a policy and system specific to their facility on endoscope storage time.[19]
According to the same report, they suggest that some users may choose a combination of both cabinet types; this is dependent on their facility. Some hospitals may have controlled environment storage cabinets for daily-use endoscopes, and separate storage cabinets for the endoscopes only in occasional use and where reprocessing before use is cost-effective.[20]
Current recommendations recommend that flexible endoscopes should be stored in closed, ventilated cabinets that have been designed for vertical storage, or those with sufficient height, width, and depth to allow the scopes to hang freely without coiling.[21]
AORN recommends that if a drying cabinet is not available, flexible scopes may be stored in a closed cabinet with the ability for HEPA filtered air that can provide a positive pressure and allow air circulation around the endoscopes.[22] AORN also recommends that flexible endoscopes and endoscope accessories be stored in a manner that minimizes contamination and protects the device or item from damage.
Damage Control
Drying and storage cabinets do not protect the distal end from damage, and care should be taken when placing scopes in the cabinet and on removal, because damage can occur if endoscopes are allowed to come into contact with each other. In addition, the insertion tube and light guide can clash with hard surfaces while in the cabinet,[23] which can damage the delicate optics of the scope.
Some scopes are too long to fit into the cabinet and can be damaged when the distal end hits the floor. Using a distal tip protector that is suitable for use in a drying cabinet can reduce the risk of damage. Several tip protection options are available in the market, but when choosing it is important to consider that a tip protector made of material that can retain moisture, like a sponge, can create an environment favourable for microbial growth.
Distal tip protectors should not cover the opening of the tip and should be single-use, unless otherwise specified in the manufacturer’s written IFU.[24] A preferred choice should allow maximum air flow while in the storage cabinet, such as the ProTech distal tip protector.
Should Drying Cabinets be Mandatory?
Current guidelines do not enforce drying or storage cabinets within healthcare facilities, but they are recommended.[25] Endoscopy units are left to decide their own methods for endoscope drying, which is more often determined by departmental budget and capacity.
Drying and storage cabinets are large pieces of equipment that not only require plenty of space, but also a large chunk of departmental funding. According to an article in the Hospital Times in 2019, the purchase cost of an EN 16442-compliant drying and/or storage cabinet was $25,000–$40,000. In addition, the running and maintenance costs can range from $4,300–$5,000 per cabinet, per year.[26]
Despite evidence indicating that endoscope drying is a fundamental step in the reprocessing cycle, a paper by Thacker et al. identified that of 249 U.S. institutions surveyed concerning duodenoscope processing practices, 52.2% did not use forced-air drying after reprocessing.[27]
With so many regulations applied for reprocessing endoscopes, it seems incorrect that there is not a requisite towards a standardized drying process. If endoscope drying is an essential factor in reprocessing, why isn’t sufficient funding available to ensure that all facilities have identical drying equipment and processes?
Conclusion and Future Development
The use of drying and storage cabinets for endoscopes should be advocated by all healthcare facilities to reduce microbial contamination after reprocessing. Drying cabinets are not designed to improve reprocessing but should be used in conjunction with current reprocessing methods to maintain endoscope cleanliness and viability for the next patient.
However, with the inconsistency of current guidelines between facilities, a serious issue needs to be addressed. Institutions should be looking to create a standardized process for endoscopes to ensure they are subject to the same drying and storage conditions in all healthcare settings to ensure safe, reprocessed, patient-ready endoscopes.
Additionally, an improved testing method for reprocessed scopes should be developed to ensure that endoscopes are not left with residual moisture in the channels. It is the responsibility of all societies to create consistent guidelines to make this aspect of the reprocessing cycle standardized, in order to ensure the safety of patients everywhere.
Kerry Dolan has had a long career in freelance writing and is currently head of marketing for Meditech Endoscopy Ltd., a global product development company. Her marketing expertise focuses on creating innovative marketing strategies, content creation and managing the company website and social media accounts. Dolan has a special interest in creating awareness about the challenges that endoscopy staffers experience, and to provide solutions that combine industry and nursing staff working together for better patient outcomes.
References
[1] Cleaning & disinfection of fiberoptic endoscopes evaluation of glutaraldehyde exposure time and forced air drying. D.N. Gerding et al. Gastroenterology, 1982.
https://www.sciencedirect.com/science/article/pii/S0016508582801972
[2] Hung Out to Dry: The Importance of Endoscope Channel Drying Prior to Storage By Melinda Benedict, MS, CIC, CFER Manager, Infection Control Program Olympus Corporation of the Americas
Melinda Benedict
[3] Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness. Ofstead, C, Heymann, O.L, Quick, M.R, MPH, Eiland, E. RN, MS, Wetzler, H.P. MD, MSPH. American journal of Infection control, Vol 46, issue 6, June 2018, P689-696.
[4] Thaker A M, Kim S et al. Inspection of endoscope instrument channels after reprocessing using a prototype borescope. Gastrointestinal Endoscopy, 2018: 88; 612-619.
[5] Day L W, Muthusamy V R, Collins J et al. Multisociety guideline on reprocessing flexible GI endoscopes and accessories. Gastrointestinal Endoscopy, 2021: 93; 11-33.
[6] Endoscope drying and its pitfalls. Kovaleva,J. Journal of Hospital Infection, July 2017. https://pubmed.ncbi.nlm.nih.gov/28729139/
[7] Pineau L, Villard E, Duc D L et al. Endoscope drying/storage cabinet: interest and efficacy. J Hosp Infect. 2008;68:59–65.
[8] Grandval P, Hautefeuille G, Marchetti B et al. Evaluation of a storage cabinet for heat-sensitive endoscopes in a clinical setting. J Hosp Infect. 2013;84:71–76. doi: 10.1016/j.jhin.2013.01.013
[9] Perumpail R B, Marya N B, McGinty B L et al. Endoscope reprocessing: Comparison of drying effectiveness and microbial levels with an automated drying and storage cabinet with forced filtered air and a standard storage cabinet. Am J Infect Control. 2019;47:1083–1089. doi: 10.1016/j.ajic.2019.02.016.
[10] Health Technical Memorandum 01-06: Decontamination of flexible endoscopes. Part C. Operational management. 3.38 (9) Drying.
[11] Reprocessing of flexible endocopes and endoscopic accessories used in gastrointestinal endoscopy: Position statement of the European Society of gastrointestinal Endoscopy (ESGE) and European Society of Gastroenterology Nurses & Associates (ESGENA) Update 2018. (6.7)
[12] ANSI / AAMI ST91:2015
[13] British society of Gastroenterology Guidance on Decontamination of Equipment for Gastrointestinal Endoscopy (10)
[14] Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness. Ofstead C.L, Heymann O.L, Quick M.R, Eiland J.E, Wetzler H.P. AJIC June 2018:46(6):689-696
[15] Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness. Ofstead C.L, Heymann O.L, Quick M.R, Eiland J.E, Wetzler H.P. AJIC June 2018:46(6):689-696
[16] Comparison of automated and manual drying in the elimination of residual endoscope working channel fluid after reprocessing. Monique T Barakat, MD, PhD, Robert J. Huang, MD, and Subhas Banerjee, MD. Published in Gastrointestinal Endoscopy 2019, issue 89.
[17] Endoscope drying / storage cabinet: interest and efficacy. Pineau, L., Villard, E., Duc, D, L., Marchetti, B. Journal of Hospital Infection, Jan 2008. https://pubmed.ncbi.nlm.nih.gov/18055064/
[18] Beilenhoff U, Biering H, Blum R et al. Reprocessing of flexible endoscopes and endoscopic accessories used in gastrointestinal endoscopy: Position Statement of the European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastroenterology Nurses and Associates (ESGENA) – Update 2018. Endoscopy. 2018;50:1205–1234. doi: 10.1055/a-0759-1629.
[19] Multisociety guideline on reprocessing flexible GI endoscopes & accessories. Day et al. Gastrointestinal Endoscopy, November 2020.
[20] Multisociety guideline on reprocessing flexible GI endoscopes & accessories. Day et al. Gastrointestinal Endoscopy, November 2020.
[21]Drying and storing of flexible endoscopes: An area of growing concern. Behm, T. MSN, RN, CIC, Robinson, N. PhD. AAMI, May / june 2020. https://www.aami.org/docs/default-source/bi-t/bit/drying-storing-endoscopes—bit-may-june-2020.pdf
[22] Guideline summary: Processing flexible endoscopes. AORN journal, September 2016, Vol 104, No. 3. (XI)
[23] Which drying cabinet is right for your endoscopes? Dhalin, D. The Inside Tract. https://theinsidetract.sgna.org/Article/ArtMID/385/ArticleID/235/Sponsored-Which-Drying-Cabinet-Is-Right-for-Your-Endoscopes
[24] AAMI ST91 2021, page 68
[25] The British thoracic Society. Du Rand IA, Blaikley J, Booton R, et al. British Thoracic Society guideline for diagnostic flexible bronchoscopy in adults. Thorax 2013;68:i1-i44.
[26] Resolving endoscope storage issues and saving money. Hospital Times, 2019.
[27] Thacker A.M, Muthusamy V.R, Sedarat A et al. Duodenoscope Reprocessing Practice patterns in US Endoscopy Centres: A survey study. Gastrointestinal Endoscopy, 2018 – 88(2): 316-22.
Sidebar
What Harm Can a Little Moisture Do?
Why Thorough Drying of Flexible Endoscopes is So Important
By Nancy Chobin, RN, AAS, ACSP, CSPM, CFER
Water is critical for the survival of life on earth. According to Weymiller, “Around 60 percent of our body is made up of water and we can only live three to five days without fluids.” Our bodies use water to flush waste, regulate temperature, digest our food properly and transport nutrients.
Moisture can encourage the growth of certain microorganisms, such as Pseudomonas aeruginosa, a relatively common bacteria found in soil and water, as well as other environmental locations. Of the various strains of Pseudomonas, the one that most often causes infections in humans is Pseudomonas aeruginosa.
Standards and Guidelines
According to the Centers for Disease Control and Prevention, Pseudomonas aeruginosa “can cause infections in the blood, lungs (pneumonia), or other parts of the body after surgery. These bacteria are constantly finding new ways to avoid the effects of the antibiotics used to treat the infections they cause. Antibiotic resistance occurs when the germs no longer respond to the antibiotics designed to kill them. If they develop resistance to several types of antibiotics, these germs can become multidrug-resistant.” The Multisociety Guideline on Reprocessing GI Endoscopes and Accessories states that endoscopes “should undergo drying after the completion of all reprocessing steps as described in the endoscope manufacturers’ IFU.”
The Association for the Advancement of Medical Instrumentation (AAMI) recommends that an endoscope and its components “should be dried after completion of the cleaning and disinfection process. Flexible endoscopes with channels should be dried for a minimum of 10 minutes with pressure-regulated forced instrument air or a minimum of HEPA-filtered air (Ofstead, 2018 [242]; Barakat, 2018 [79]”.
SGNA agrees. “Drying is a critical element in reprocessing. Moisture allows microorganisms to survive and multiply; therefore, all channels and the surface of the endoscope must be thoroughly dried before storage. Outbreaks of Pseudomonas aeruginosa, Acinetobacter spp., carbapenemase-producing K pneumoniae, and other pathogens have been traced to inadequately dried endoscopes (Alfa, 2013; Carbonne et al., 2010; Kovaleva et al., 2013).”
The Association of peri-Operative Registered Nurses (AORN) offers similar guidelines. “Dry the exterior surfaces of the endoscope with a soft, lint-free cloth or sponge. Dry the endoscope channels by purging with instrument air of using a mechanical processor drying system. Dry removeable parts and endoscope accessories.”
A 2018 study looked at endoscope reprocessing at three hospitals. The authors wrote, “Fluid was detected in 22 of 45 (49%) endoscopes. Prevalence of moisture varied significantly by site (5%; 83%; 85%; P < .001). High adenosine triphosphate levels were found in 22% of endoscopes, and microbial growth was detected in 71% of endoscopes. Stenotrophomonas maltophilia, Citrobacter freundii, and Lecanicillium lecanii/Verticillium dahliae were found. Retained fluid was associated with significantly higher adenosine triphosphate (ATP) levels (P < .01). Reprocessing and drying practices conformed with guidelines at 1 site and were substandard at 2 sites. Damaged endoscopes were in use at all sites.” This study demonstrated the magnitude of the problem and why we need to focus on the critical drying part of reprocessing flexible endoscopes.
What Should You Do?
When there are varying recommendations, it is important to determine which guidelines your facility will follow. Then develop policies and procedures based upon those guidelines and monitor for staff compliance.
Drying can be accomplished manually using either instrument air or HEPA filtered air. Instrument air is defined as “a medical gas that falls under the general requirements for medical gases as defined by the National Fire Protection Association (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 -40º F (-40º C).” Instrument air may be supplied from cylinders, bulk containers and/or medical air compressors.
The definition of a medical air compressor (per NFPA) is a compressor that is designed to exclude oil from the air stream and compression chamber and that does not, under normal operating conditions or any single fault, add toxic or flammable contaminants to the compressed air.
Manual drying can be achieved by blowing instrument air through all endoscope channels for a specified period of time and at the recommended pressure. There are insufficient data regarding the effectiveness of using a 70% to 80% ethyl- or isopropyl-alcohol flush after air drying. If it is facility policy to use an alcohol flush, personnel should follow the endoscope manufacturer’s IFU on the volume of alcohol and method to be used for each endoscope lumen and then remove any remaining alcohol with instrument air (or as otherwise recommended by the endoscope manufacturer). The manufacturer’s written IFU should also be consulted regarding the appropriate air pressure in relation to channel size. Syringes should not be used to dry channels. All removable endoscope parts should also be dried (ANSI.AAMI ST-91).
Proper storage of endoscopes is paramount for maintaining their functionality and ensuring patient safety. Endoscope storage cabinet guidelines should be well-ventilated to prevent moisture buildup and subsequent bacterial growth. Each endoscope should be stored separately to prevent cross-contamination, and thorough drying before storage is essential. Endoscope storage cabinet guidelines with built-in drying systems are preferable. Security measures should be in place to prevent unauthorized access, and regular maintenance and inspections are necessary to ensure cabinets remain in optimal condition. Adhering to these guidelines is crucial for healthcare facilities to safeguard their endoscopes and uphold high standards of patient care.
If the endoscope is not completely dry after 10 minutes (or the time recommended by the endoscope manufacturer), continue to dry the scope. Verification of complete drying can be difficult since there are small channels on the scope. There are various tests on the market to determine dryness, but these tests might not be definitive. Some facilities use a borescope to view the internal channels of the endoscope for cleanliness, damage, and any evidence of moisture. Every effort should be made to ensure the endoscope is completely dry.
A second method of drying is to place the HLD and rinsed endoscope into a drying cabinet. A drying cabinet is not the same as a conventional storage cabinet. Conventional cabinets have HEPA-filtered air that is circulated throughout the cabinet and around the surfaces of the endoscopes. However, drying cabinets differ because they have adapters that provide HEPA-filtered or instrument air not only around the outside of the scopes, but also inside the channels of the scopes. Drying cabinets dry the endoscope, whereas conventional cabinets do not. So if your facility has a drying cabinet, manual drying is not needed (ANSI/AAMI ST-91 (2021).
If your facility does not have drying cabinets, then manual drying is needed. Storage cabinets without HEPA-filtered air should not be used. It is essential that the drying cabinet manufacturer’s IFUs are followed exactly as stated and that staff is trained in the use of the cabinet, especially how to connect the adapters to the endoscope, clean the cabinet, and perform any recommended maintenance.
The endoscope manufacturer’s written IFUs for the recommended procedure for drying their specific models of endoscopes, including the amount of pressure to be used, should be followed at all times. It is important to monitor staff compliance with drying procedures and to ensure that every effort has been made to produce a dry endoscope to prevent recontamination of the scope while in storage.
Nancy Chobin, RN, AAS, ACSP, CSPM, CFER, is the president and CEO of Sterile Processing University, LLC, of Lebanon, New Jersey. Her company was founded in 1996 and provides SPD and GI consultations, competency assessments, design of sterile processing areas (in hospitals, surgery centers and endoscopy processing areas), on-site training, and online training courses for ambulatory surgery, SPD and endoscopy processing personnel.