ELIMINATING FLUID INVASION..
...IN FLEXIBLE ENDOSCOPES
There is an increased demand on CPD to process more with
limited budget relief.
By Les Faucher and Lynne A. Thomas, BSN, RN, CGRN
Some of the most expensive and lengthy repairs performed on flexible endoscopes are due to 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 are often insufficiently detailed for providing the end user with necessary information for preventing fluid invasion. Subsequent to this article are examples of competency-validation grids for routine compliance of endoscope reprocessing by both frequent and infrequent endoscopic clinicians.
The flexible endoscope design that we recognize today has been in existence since the late 1960s. Though the shape has changed little, many improvements have been implemented over the years, including improved imaging technology, superior handling for the physician, and smaller insertion tubes. Video chips, quickly replacing glass fibers as image capturing devices, provide better imaging and documentation capabilities. Newer materials are providing increased range of mobility for the user. Smaller components allow smaller insertion tube diameters for greater patient comfort.
One of the most significant changes made over the years has been the introduction of completely immersible scopes in the mid 1980s. These instruments can be soaked completely in appropriate solutions long enough to be classified as high-level disinfected. Prior to this innovation, endoscope control body and light guide connector sections were not sealed effectively 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 between patients. Sometimes the insertion tubes were soaked during reprocessing but for inconsistent lengths of time. In addition, the scopes could not be pressure tested for possible leaks in internal channels or the bending section.
Several key changes resulted in the fluid-resistant endoscope we use today. The insertion tube and bending section had always been sealed using a combination of epoxy seals and o-ring seals. Today the entire scope is assembled in any section where two parts of the scope form a seam. Epoxies or other hard sealants are often used when parts are threaded together. The combination of the epoxy and o-ring seals provides a water-resistant shell to the endoscope. This shell allows long immersion times in cleaning and disinfecting solutions, and it allows for pressure testing the entire scope for leaks. Today, all endoscope manufacturers use similar techniques to make their scopes water-resistant.
These water-resistant scopes can also be pressure tested for leaks, since they are airtight and because the main components of the endoscope are hollow inside to allow room for the delicate internal components. (The main components include the bending section, insertion tube, control body, light guide tube, and light guide connector. The internal components include the video chip and wiring assemblies, light guide fiber bundle, angle wires, biopsy/suction channels, and air/water channels.)
It is the general hollowness of the endoscope that allows pressure testing to be effective. Pressure entering one section of the scope will travel throughout the entire cavity of the scope. Once pressurized, the flexible scope can then be observed for leaks in the water-resistant shell. This hollowness, however, also means that fluid entering one area will travel throughout the entire scope. So, fluid entering the light guide connector, 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 is compromised. Following are common points of fluid invasion on the scope and possible causes for the water-resistant shell to fail:
Bending sheath: The bending sheath is the soft rubber-like material that covers the bending section of the scope. It is thin and very flexible to maintain complete mobility of the bending section. This sheath is very susceptible to cuts, holes, or tears from any sharp object. Damage to this area may occur at any point during the daily life cycle of the scope, including storage and transportation.
Insertion tube: The insertion tube cover is comprised of layers of rubber-like material with a urethane outer surface. The insertion tube cover is more cut- and puncture-resistant than the bending rubber but can be damaged in similar ways. Leaks will occur 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 metal parts. These parts are difficult to damage without severe impact; however, the o-ring seals (where the different parts join together) are much more delicate. Even slight impact to the control body may cause the seals to misalign, causing a leak. This can happen even if the impact was not severe enough to cause a dent or other indication of damage. The misaligned o-ring will allow fluid to pass directly into the control body cavity. A common cause of control-body impact is poor handling in the cleaning sinks. Small or difficult to access storage areas often lead to control-body impact damage as well.
Any fluid entering the internal cavities of an endoscope may do severe or even irreparable damage to its components. The corrosive nature of the fluid will determine the rate at which the damage is done. Highly acidic or highly alkaline solutions will corrode more quickly than water, but any fluid will do serious damage over time.
Flexible endoscopes are subject to severe damage from fluid invasion, but endoscope manufacturers have provided a means for inspecting scopes for leaks. Pressure testing or leak testing can allow a user to find potential leaks prior to immersing the scope in fluid. 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 or cross-contamination of patients.
A leak test may be performed manually (using a hand-held bulb and gauge) or mechanically (using an automated pressure delivery system) and with or without fluid immersion. Regardless of the method chosen, the general process is the same.
Staff must carefully follow a scope manufacturer's recommended steps for the type of leak test chosen. Eliminating steps or performing some steps out of sequence may cause a false reading and failure to detect a leak. The leak test should be performed after every procedure prior to immersing the endoscope in fluid. A leak may occur at almost any point in the daily life cycle of the scope, and this proactive approach to leak testing can help prevent expensive fluid invasion repairs. More importantly, it ensures the integrity of the scope, thereby eliminating potential adverse patient outcomes such as cross-contamination of chemicals or proteinaceous materials from antecedent procedures.
Lynne A. Thomas, BSN, RN, CGRN, is Integrated Medical System's Endoscopy Clinical Specialist. Thomas is a nurse with 14 years of clinical endoscopy management practice. She has been active in the delivery of education for endoscopy nurses through regional and national SGNA initiatives, chairing the SGNA's Education Committee and speaking at many regional and national meetings. Lynne is the president-elect for the Certifying Board of Gastroenterology Nurses and Associates.
Les Faucher is IMS's Endoscopy Technical Specialist responsible for technical aspects of customer service. He has 15 years of experience in the flexible endoscope repair--eight of which were as a technical coordinator for Olympus, where he was responsible for warranty decisions, training of technicians, and customer education. He serves as a repair facility manager for IMS.