December 1, 2000

ELIMINATING FLUID INVASION.. ...IN FLEXIBLE ENDOSCOPES There is an increased demand on CPD to process more with limited budget relief.

There is an increased demand on CPD to process more with
limited budget relief.

By Les Faucher and Lynne A. Thomas, BSN, RN, CGRN

When dealing withendoscopes, facilities want to reduce overall operating costs while having enough scopeson hand in good working order for safe patient care. In today's environment of employeecross-training, competency validation of routine endoscope reprocessing has also becomemore important.

Some of the most expensive and lengthy repairs performed on flexible endoscopes are dueto fluid invasion. Most fluid invasion into flexible endoscopes is preventable; however,even when it's not preventable, the damage can be minimized. The guidelines for care,handling, and reprocessing included in manufacturers' operation and service manuals areoften insufficiently detailed for providing the end user with necessary information forpreventing fluid invasion. Subsequent to this article are examples ofcompetency-validation grids for routine compliance of endoscope reprocessing by bothfrequent and infrequent endoscopic clinicians.

Instrument Design

The flexible endoscope design that we recognize today has been in existence since thelate 1960s. Though the shape has changed little, many improvements have been implementedover the years, including improved imaging technology, superior handling for thephysician, and smaller insertion tubes. Video chips, quickly replacing glass fibers asimage capturing devices, provide better imaging and documentation capabilities. Newermaterials are providing increased range of mobility for the user. Smaller components allowsmaller insertion tube diameters for greater patient comfort.

One of the most significant changes made over the years has been the introduction ofcompletely immersible scopes in the mid 1980s. These instruments can be soaked completelyin appropriate solutions long enough to be classified as high-level disinfected. Prior tothis innovation, endoscope control body and light guide connector sections were not sealedeffectively enough to prevent fluid or moisture from seeping in and causing severe damage.As a result, the instruments were often just wiped down with a topical solution betweenpatients. Sometimes the insertion tubes were soaked during reprocessing but forinconsistent lengths of time. In addition, the scopes could not be pressure tested forpossible leaks in internal channels or the bending section.

Several key changes resulted in the fluid-resistant endoscope we use today. Theinsertion tube and bending section had always been sealed using a combination of epoxyseals and o-ring seals. Today the entire scope is assembled in any section where two partsof the scope form a seam. Epoxies or other hard sealants are often used when parts arethreaded together. The combination of the epoxy and o-ring seals provides awater-resistant shell to the endoscope. This shell allows long immersion times in cleaningand disinfecting solutions, and it allows for pressure testing the entire scope for leaks.Today, all endoscope manufacturers use similar techniques to make their scopeswater-resistant.

These water-resistant scopes can also be pressure tested for leaks, since they areairtight and because the main components of the endoscope are hollow inside to allow roomfor the delicate internal components. (The main components include the bending section,insertion tube, control body, light guide tube, and light guide connector. The internalcomponents include the video chip and wiring assemblies, light guide fiber bundle, anglewires, biopsy/suction channels, and air/water channels.)

It is the general hollowness of the endoscope that allows pressure testing to beeffective. Pressure entering one section of the scope will travel throughout the entirecavity of the scope. Once pressurized, the flexible scope can then be observed for leaksin the water-resistant shell. This hollowness, however, also means that fluid entering onearea will travel throughout the entire scope. So, fluid entering the light guideconnector, for instance, may result in damage to many parts of the scope.

Portals for Fluid Entry

Fluid invasion can occur any time that a flexible endoscope is immersed in water,cleaning solution, disinfectant, or other fluid when the scope's water-resistant shell iscompromised. Following are common points of fluid invasion on the scope and possiblecauses for the water-resistant shell to fail:

Bending sheath: The bending sheath is the soft rubber-like material that coversthe bending section of the scope. It is thin and very flexible to maintain completemobility of the bending section. This sheath is very susceptible to cuts, holes, or tearsfrom any sharp object. Damage to this area may occur at any point during the daily lifecycle of the scope, including storage and transportation.

Insertion tube: The insertion tube cover is comprised of layers of rubber-likematerial with a urethane outer surface. The insertion tube cover is more cut- andpuncture-resistant than the bending rubber but can be damaged in similar ways. Leaks willoccur if the insertion tube cover is cut or punctured by sharp objects or biting.

Control body: The control body components are mostly solid plastic and metalparts. These parts are difficult to damage without severe impact; however, the o-ringseals (where the different parts join together) are much more delicate. Even slight impactto the control body may cause the seals to misalign, causing a leak. This can happen evenif the impact was not severe enough to cause a dent or other indication of damage. Themisaligned o-ring will allow fluid to pass directly into the control body cavity. A commoncause of control-body impact is poor handling in the cleaning sinks. Small or difficult toaccess storage areas often lead to control-body impact damage as well.

Any fluid entering the internal cavities of an endoscope may do severe or evenirreparable damage to its components. The corrosive nature of the fluid will determine therate at which the damage is done. Highly acidic or highly alkaline solutions will corrodemore quickly than water, but any fluid will do serious damage over time.

Leak Testing

Flexible endoscopes are subject to severe damage from fluid invasion, but endoscopemanufacturers have provided a means for inspecting scopes for leaks. Pressure testing orleak testing can allow a user to find potential leaks prior to immersing the scope influid. When performed effectively and at the correct point in each reprocessing cycle,leak testing can eliminate all but the most extreme circumstances for fluid invasion.Through leak testing, problem areas are located before they cause scope damage orcross-contamination of patients.

A leak test may be performed manually (using a hand-held bulb and gauge) ormechanically (using an automated pressure delivery system) and with or without fluidimmersion. Regardless of the method chosen, the general process is the same.

Staff must carefully follow a scope manufacturer's recommended steps for the type ofleak test chosen. Eliminating steps or performing some steps out of sequence may cause afalse reading and failure to detect a leak. The leak test should be performed after everyprocedure prior to immersing the endoscope in fluid. A leak may occur at almost any pointin the daily life cycle of the scope, and this proactive approach to leak testing can helpprevent expensive fluid invasion repairs. More importantly, it ensures the integrity ofthe scope, thereby eliminating potential adverse patient outcomes such ascross-contamination of chemicals or proteinaceous materials from antecedent procedures.

Lynne A. Thomas, BSN, RN, CGRN, is Integrated Medical System's Endoscopy ClinicalSpecialist. Thomas is a nurse with 14 years of clinical endoscopy management practice. Shehas been active in the delivery of education for endoscopy nurses through regional andnational SGNA initiatives, chairing the SGNA's Education Committee and speaking at manyregional and national meetings. Lynne is the president-elect for the Certifying Board ofGastroenterology Nurses and Associates.

Les Faucher is IMS's Endoscopy Technical Specialist responsible for technicalaspects of customer service. He has 15 years of experience in the flexible endoscoperepair--eight of which were as a technical coordinator for Olympus, where he wasresponsible for warranty decisions, training of technicians, and customer education. Heserves as a repair facility manager for IMS.