Dr. Petersen is Professor of Medicine in the Division of Gastroenterology and Hepatology at the Mayo Clinic in Rochester, Minnesota
Post endoscopy infections have been a clinical problem for several decades. The introduction of standardized reprocessing, including washing, high level disinfection (HLD), and drying steps markedly reduced this problem at the turn of the last century. Subsequent outbreaks of viral hepatitis and other easily inactivated agents occurred after identified lapses in reprocessing. More recently, clusters of infection by multi-drug resistant organisms (MDRO) following endoscopic retrograde cholangiography (ERCP) have challenged our understanding of the safety of GI endoscopy. The complexity of current endoscopes, the multitude of required steps for manual cleaning, and our renewed awareness of the persistence of viable organisms within adherent biofilm despite appropriate reprocessing, all implicate both endoscope design and human factors in many of the outbreaks.
Current reprocessing results are undoubtedly far more consistent than in the past, as a result of increased emphasis on staff training and oversight, simplified instructions for use (IFU’s), timely and optimal washing, inspection, drying after HLD and surveillance testing. Never-the-less, reprocessing success is still subject to individual performance on a per-procedure basis and near perfection cannot be anticipated without major evolution of instrument design and/or reprocessing technologies. As new endoscopes and reprocessing technologies come forward, they will generate numerous questions about safety, efficacy, cost and performance characteristics and likely future iterations.
Fully or Partially Singe-Use Duodenoscopes (Table 1a, b)
Currently available new duodenoscope designs intended to address the risk of microbial transmission include sterile single-use instruments from Boston Scientific (BSC) and AMBU corporations and updated reusable instruments from Fujinon, Olympus, and Pentax with single use protective caps that, upon removal, expose the high-risk elevator region to enhance access for cleaning and HLD processing1. The Pentax version includes a single use disposable elevator. Other fully and partially single-use instruments are anticipated from both legacy manufacturers and new startups. Studies employing the BSC Exalt duodenoscope and the AMBU aScope Duodeno duodenoscope have demonstrated safe and effective function in all prospective multicenter series2,3,4,5. While guaranteed sterility is a feature of both instruments, it is unknown to what degree this will reduce post ERCP cholangitis, as many clinicians believe post procedure infections result primarily from endogenous translocation and incomplete drainage of obstructed sectors, rather than by transfer of exogenous organisms between patients. Many of the historical MDRO outbreaks attributed to contaminated duodenoscopes presented after many weeks and in different organs from the initial exposure, unlike clinically common infections seen early after ERCP.
An additional benefit of the single use instruments is their contribution to efficiency when working in high volume, fast paced environments that cannot be supported by available for Pentax, and has received research support from Boston Scientific and Ambu Inc. reprocessing staff, or when procedures are performed in atypical locations or during off hours from usual practice, such as the operating room, emergency room, or the intensive care units on nights and weekends. Efficiencies based on pace and volume have been reported for diagnostic cystoscopy and bronchoscopy suites.
The ability to iterate designs in realtime of short production runs to incorporate alternations or enhancements for specific purposes is an attractive aspect of single use devices and endoscopes. Indeed, each of the commercially available instruments has already undergone several design changes during parallel study and commercialization. Additional designs will likely incorporate elements preferential to specific needs of patients and endoscopists.
Both single-use instruments are currently available for clinical/commercial use in the United States, with list prices well above the nominal per-use cost of legacy reusable instruments, but well within the range of many single use devices, including self-expanding metal-stents. Markov modeling proposes cost: benefit ratios favoring single use duodenoscopes when infection transmission rates exceed 1%, but the results are highly subject to assumptions about transmission, infection, and causation6. Costs for the single use instruments is currently moderated by specific time-limited CMS passthrough codes for use of new technology in Medicare patients. The codes are employed to enable expanded experience for three years, after which reimbursement hopefully will become standardized among commercial and federal payors. The existing passthrough codes for the two instruments are not synchronous, raising concerns about confusion in the marketplace when the BSC Exalt code expires several months before that for the AMBU a Scope Duodeno instrument. Requests for Congress and CMS to synchronize their timelines have been submitted.
Both the fully single-use and reusable instruments with single use caps have received increased citation in the FDA’s open access database of complications during use7. This non-curated database does not identify or assign causation, and reporting is highly variable and likely more common for new devices with limited clinical experience.
Numerous persisting questions about each of the endoscope designs warrant large scale registries or collaborative data sharing to answer. Undoubtedly physician preferences, institutional decisions about risk and costs, and the tenor of the larger marketplace for medical devices will influence the proportional market share of each of the instruments now available.
I expect a mixed field of both reusable and single use instruments in most larger institutions, with focus toward one or the other largely in those centers with smaller volumes and already higher costs per procedure.
Likely and potential new cleaning and reprocessing technologies (Table 1c)
Multiple new reprocessing technologies have also been described and most remain in development for use during washing and/or high-level disinfection or sterilization phases. Several incremental enhancements in brushing and cleaning technologies have been reported, but none are expected to provide generational improvements. Most anticipated are several novel washing solutions with altered solid and gaseous constituents that facilitate turbulence, abrasiveness and cleaning efficacy, including efficacy for clearance of otherwise intractable biofilms. Patents and developmental work have been impressive, but none have reached commercialization at this time. Another new technology based upon prolonged passive flow of novel solutions has published impressive results and gained FDA clearance for an overnight service, returning your instruments or equivalent leased/loaned instruments following HLD or HLD + ETO sterilization on a contracted per procedure basis. Broad availability and large-scale results have not yet been achieved, however.
New or enhanced sterilization technologies have been on the horizon for several years, but so far, the only moderately employed alternative is use of ethylene oxide, which can now be delivered in a tabletop cabinet with relatively rapid 12-hour turnaround for single instruments. Other novel technologies are still under development but suggest that sufficient delivery to long narrow lumens may prove feasible in coming iterations.11
Table 1: Questions and Future Prospects for New Technology
A. Single-Use Duendoscopes
- Will they reduce clinically important post-procedure infections?
- Should they be reserved for use in select hi-risk patient groups or clinical scenarios?
- Will early reports of injury be mitigated by experience, guidance, and/or newer
iterations? - Will they prove cost-effective for widespread use in routine clinical practice?
- Will their contribution to efficiency enhance their cost-effectiveness in some
practices? - Will availability of multiple iterations for variable patient characteristics or clinical needs prove financially tenable for manufacturers?
- When experience is gained, will disposal and recycling of single use components prove beneficial or a liability in the era of accelerating climate change.
B. Reusable Duodenoscopes with Single-Use parts
- Will removable caps enable clinically significant reductions in post reprocessing culture results showing persistent contamination?
- Will improved post HLD culture results translate to reduced risk of transmission and clinical infections?
- Will reports of injury be mitigated by experience, guidance, and/or newer iterations?
- Will further iterations enable commercial incorporation of enhanced designs to accommodate needs of the endoscopist, patient, or department?
- Will cost effectiveness or disposal considerations prove advantageous to the legacy instruments?
C. Reprocessing Technologies
- Will new washing solutions and automated delivery technologies yield reliable clearance of residual soil, most bacteria, and biofilm?
- Will “inaccessible” biofilm remain a challenge despite enhanced endoscope design and washing technologies?
- Will combinations of automated washing and HLD, with or without new sterilization technologies achieve sterilization or acceptably low thresholds of residual micro-organisms?
Disclosures
Dr. Petersen has served on a review panel and advisory committee for Olympus, a consultant for Pentax, and has received research support from Boston Scientific and Ambu Inc.