Mary Ann Drosnock: The Importance of Drying Flexible Endoscopes

The complete drying of flexible endoscopes has been shown to reduce the risk of microbial recontamination in processed devices. My hope is that facilities will implement the highest quality process for drying available to their facility to help protect patients from the potential issues associated with wet storage and microbial proliferation in endoscopes.

If moisture is retained in the channel of the endoscope and these endoscopes are stored wet while exposed to the environment, there is a possibility of recontamination of the device by the environment and replication of any bacteria that survived disinfection. If poor rinse water quality is used for the final rinse after high-level disinfection (HLD), then this can exacerbate the issue.

Recently, endoscope instructions for use (IFUs), published studies, national standards, and professional society guidelines have updated their guidance to require complete drying, both internally and externally prior to storage. Previously, it was assumed that an alcohol flush and air purge in an automated endoscope reprocessor (AER) or an alcohol flush and syringe air flush for manual reprocessing were enough to produce a dry endoscope. We now know that this is not true and have seen that further forced air drying is necessary to achieve a dry scope.

The standard ANSI/AAMI ST91 states that, for flexible endoscopes, “all channels should be purged with filtered medical grade air at the correct psi (outlined in the manufacturer’s written IFU for that specific scope),” and, “before storage, the channel of the high-level disinfected endoscope should be dry to help prevent bacterial growth and the formation of biofilm.”

Even back in 2008, the CDC HICPAC guideline stated that an endoscope rinsed with tap or filtered water should be followed by an alcohol rinse and forced air drying because forced air drying markedly reduces bacterial contamination of stored endoscopes. Note that use of medical grade air has been challenged as the incorrect terminology for the air quality that should be used for flushing scopes and AORN states in their guidelines that it should be instrument quality air.

Multiple recent published studies have found that endoscopes are not being dried adequately after HLD prior to storage. But, how does a facility implement processes that will result in dry scopes? It is a challenge that until recently was difficult to impossible.

Previously, facilities did not have the ability to inspect internal channels of endoscopes to verify that their drying process was working, nor could they test to see if a scope was dry. Now that industry is aware that endoscopes are not being dried adequately (even when following the IFU of the endoscope manufacturer and/or AER manufacturer) many more options are available to dry the scopes.

Those options include flushing with instrument-quality air through compressed air lines connected to the scope for a period of time demonstrated to result in dry channels, flushing with a drying pump validated for that process, or placing the scope into an active drying cabinet where the forced air is connected directly to the channels. Drying practices can be assessed by checking with commercially available dryness tests or by directly inspecting with a borescope.

With all of that in mind, do you know how your facility is drying flexible endoscopes after processing prior to storage? How is this process being checked? It is a worthwhile endeavor to look at internal practices and make sure that they are adequate based on the current standards and evidence-based practices. Think of these questions when evaluating your facility’s processes:

  • Are we doing anything for drying after HLD (i.e. purging with forced air) prior to storage? If so, what quality of air is being used for drying? Is that type of air of adequate quality knowing these scopes are high-level disinfected?
  • Is there moisture, oil, or other contaminants in this air that could be blown into the processed scope?
  • Are we drying the scope with single-use, non-linting clothes externally and drying any openings of the scope before storage in accordance with the endoscope IFU? Keep in mind that some IFUs state to use sterile non-linting wipes for drying.
  • Are we drying other areas of concern on the endoscope, such as the seals around the control knobs and elevator recesses?
  • Are we testing to make sure that our current process results in a dry scope, such as using a commercially available dryness test or inspecting with a borescope periodically?
  • Do we have HEPA-filtered air circulating around the scopes in the cabinet? Or, are we using a drying cabinet?
  • Are we appropriately drying accessory items, such as valves (especially the rubber seals and recesses on the cleaning adapters and buttons) before storage?

An evaluation of these questions will help to assess current drying practices in your facility and to correct inadequate practices.

Keep in mind that ANSI/AAMI ST91, which is the national standard for processing flexible and semi-rigid endoscopes, is currently under revision. The revised standard is expected to include much more information and guidance on the drying process and its importance.

Mary Ann Drosnock is senior manager of clinical education at Healthmark Industries in Fraser, MI, and co-chair of AAMI ST/WG 84, the working group responsible for endoscope processing. This working group is currently revising ST91, the national standard for processing flexible and semi-rigid endoscopes in healthcare facilities.

2 thoughts on “Mary Ann Drosnock: The Importance of Drying Flexible Endoscopes

  1. Some of our Technowipe clients are saying that they are drying scopes with our low lint wipes after precleaning and prior to Reprocessing to help avoid chemical dilution from wet scopes in the Reprocessing cycle. It is also important to consider to store the low lint wipes from environmental contaminants when not in use. Most wipes once opened cannot be resealed, and the balance of wipes in the package should be discarded. We took this problem into consideration when we developed our products.

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