Role of single-use flexible bronchoscopes

Introduction

The development of the first reusable flexible bronchoscope (RFB) in 1967 by Dr. Ikeda was a ground-breaking achievement (1). This invention facilitated a myriad diagnostic and therapeutic procedures to be performed to treat diseases of the airway and lung parenchyma. After decades of use, limitations of RFB have been identified, including the potential for cross-contamination, cost effectiveness and resource utilization (2-4). Unlike RFB, single-use flexible bronchoscopes (SUFB) come pre-sterilized and are intended for a single patient, eliminating the risk of cross-contamination and infection that can arise from inadequate reprocessing of RFB. Although SUFB may appear to incur higher cumulative costs over time, they are typically more cost effective when considering expenses associated with scope reprocessing, scope maintenance and treatment of iatrogenic infections. In addition, in times of staff shortage, the time spent on maintaining these scopes can be saved and used elsewhere. SUFB have been available for more than a decade, with the first product, the Ambu aScope (AMBU, Copenhagen, Denmark), introduced in 2009. More recently, SUFB garnered attention from professional pulmonary societies during the coronavirus disease 2019 (COVID-19) pandemic given the risk of viral transmission with RFB (5).

Despite its use in the intensive care unit or in the peri-operative setting by anesthesia, SUFB has not gained widespread acceptance within the bronchoscopy suite. Barriers to adoption in the bronchoscopy suite may be due in part to the lack of comparative studies demonstrating the equivalent performance of SUFB to RFB in advanced bronchoscopic procedures. In this review, we will summarize the current literature to discuss the advantages and disadvantages of using SUFBs and its implications in advanced procedures.

Infection control

Minimizing the risk of infection transmission and cross-contamination are important considerations when discussing SUFB and RFB. Since SUFB are delivered in a sterile manner, the risk of transmission and contamination due to its single-use nature is minimized. In contrast, RFB require appropriate cleaning, disinfection, leak testing, and drying that place it at risk for contamination, even when performed correctly. Organisms that are commonly identified in transmission of infections by bronchoscopy include M. tuberculosis, atypical mycobacteria, and Pseudomonas species (6). Despite well-controlled disinfection procedures, endogenous infections associated with bronchoscopy persist (7). Transmission can occur from previous patients or contaminated reprocessing equipment like RFB and their accessories. Strict endoscope disinfection procedures are crucial to prevent exogenous infections (8,9). Reprocessing RFB involves a multistep procedure, including manual cleaning, high-level disinfection (HLD) using automated endoscope reprocessors (AER), or sterilization with ethylene oxide (EO) or hydrogen peroxide (H₂O₂) plasma. Inadequate reprocessing, contaminated AER or malfunctioning RFB have been associated with infectious outbreaks following flexible bronchoscopy (10,11).

In a multi-centered prospective study, Ofstead and colleagues reported residual proteins and infectious pathogens on fully reprocessed RFB that were ready for patient use despite complete adherence to HLD and reprocessing procedures (12). A recent systematic review by Travis et al. reported an estimated total cross-contamination rate of 8.69% for RFB that included a standardized threshold based on a well-established endoscopy surveillance-testing guideline (3). These data indicate that RFB cross-contamination rates remain high even though continuous improvements in reprocessing techniques and guidelines have occurred with more stringent reprocessing and sterilization requirements.

Reprocessing aims to stop the transmission of exogenous infection to the patient. However, flexible bronchoscopes, which are characterized by complex structures with narrow internal channels, are prone to heavy contamination during use. Cleaning and disinfecting these instruments can pose a significant challenge due to their intricate design (8,13). The narrow lumens of flexible bronchoscopes, cleaned without direct visualization, make it difficult to disinfect small scratches, facilitating bacterial adhesion and potential biofilm formation (14,15). Biofilms are characterized by microbial cells attached to surfaces and enclosed in a matrix of exopolymeric substances, are resistant to disinfectants and antibiotics, making them challenging to remove (16). The persistence of these biofilms can lead to reprocessing failures and outbreaks of bronchoscopic-related infections (14,15,17,18). Nevertheless, the major recommendations from the various guidelines (19-21) regarding the appropriate reprocessing of RFB are the same. Sterilization can be done, but the chemicals used, either EO or H₂O₂, are expensive and interfere with the mechanical properties of flexible bronchoscopes (20,21). In contrast, SUFB do not require any reprocessing after use, thus eliminating the need for further resources and personnel for reprocessing.

It is important to note that SUFB are not designed to tolerate the same decontamination process as RFB and standard hospital cleaning processes may not be adequate for infection control. A study by McGrath et al. showed that prolonged bedside storage of SUFB after initial use followed by flushing the working channel with saline and external decontamination still resulted in microbiological growth of organisms that can cause pneumonia (22). Thus, SUFB should be treated as single use devices not intended for multiple uses on a single patient.

Workflow and flexibility

Another benefit of SUFBs includes the ability to streamline workflow. Utilizing SUFB in institutions in which bronchoscopy carts and towers are limited allows for parallel as opposed to linear use. This approach can decrease delays between procedures and increase the number of bronchoscopies that can be performed (23), which may lead to improved access to care for patients.

Cost analysis of SUFB vs. RFB

Numerous studies have suggested that SUFB may offer better cost-effectiveness in the intensive care unit and bronchoscopy suite compared to RFB. These studies indicate that usage is linked to fewer instances of cross-contamination and bronchoscopy-related infections, resulting in potential cost savings from reduced infection-related expenses (24,25). One notable advantage of SUFB is their one-time use design, eliminating the need for reprocessing after each procedure, leading to lower cleaning and storage costs compared to RFB (23). It is important to note that the methodology used to calculate the cost differences varied greatly amongst studies.

In a systematic review, the cost of savings associated with use of SUFB compared to RFB was on average 157 United States Dollars (USD) per percutaneous dilatational tracheostomy (PDT) (26). However, RFB repair rates were also higher in PDT procedures compared to other bronchoscopic procedures, so the cost savings of SUFB utilization may vary based on the type of bronchoscopic procedure performed. A meta-analysis looking at the cost effectiveness of SUFB compared to RFB showed that when assuming equal clinical performance, SUFB demonstrated dominance over RFB as each procedure was associated with an incremental saving of 63 USD in American bronchoscopy suites, but the amount of savings was contingent upon individual hospitals’ bronchoscopy suite setup, annual procedure volume, and SUFB cost (4). However, these cost-saving benefits may not be apparent in institutions with high volume bronchoscopic procedures. In a single French hospital performing more than 1,500 bronchoscopic procedures annually, found that using SUFB cost 154 Euro (EUR) more than RFB per procedure (27). The authors noted that the high procedure volume as well as having a centralized and automated washing unit helped reduced cost of RFB (27). Other hospitals may have individual units manually carry out the washing which may add to the cost of RFB. Recent studies have found that the break even point of SUFB and RFB to vary, with one study citing 306 annual procedures per site (28) and another study suggesting 756 procedures per year (4). These estimations allow individual hospitals to assess the cost advantages of RFB or SUFB based on factors such as size and procedure volume (4,28).

Environmental impact of using SUFB vs. RFB

It is a common misconception that SUFB produce more environmental waste than RFB. To determine the environmental impact of SUFB and RFB, life cycle analysis (LCA) needs to be performed (29). LCA involves evaluating how products impact the environment throughout their production, use and end-of-life phases (29). The production stage often has a more significant environmental footprint than other phases, with raw material for complex devices like bronchoscopes sourced globally, manufactured in different locations, and distributed to end-users (29). Transportation emissions vary based on production and destination locations, transportation methods and energy sources (29). A single-centered prospective observational study aimed to quantify the impact on waste mass production, energy consumption and recyclability of bronchoscopic procedures found that single-use instruments generated nearly twofold more recyclable waste than reusable instruments, but the latter constituted a higher portion of waste generated during the reprocessing phase (30).

A comparative study from the University of Southern Denmark assessed various factors including energy consumption, emission of CO₂-equivalent, and consumption of scarce resources for SUFB and RFB (31). The authors demonstrated that RFB had comparable or higher material and energy consumption, including higher emissions of CO₂-equivalents and values of resource consumptions (31). The factors with the greatest contribution to environmental detriment were the cleaning and drying demand of RFB (31). Repeated washing is required if a bronchoscope is unused for 72 hours (31). Though the environmental assessment is complex, further research optimizing the cleaning and drying portion of RFB could improve its significant environmental impact.

Comparison of clinical performance of SUFB vs. RFB

Since 2018, there has been a proliferation of SUFB from different manufacturers. This latest generation of SUFB may be suitable for advanced bronchoscopic or interventional pulmonology procedures. In 2020, Liu et al. compared the performance of H-SteriScope (Vathin Medical Instrument Co. Ltd., Hunan, China) against the current SUFB and RFB based on operators’ perceptions (32). This comparative study was the first of its kind, evaluating multiple aspects of the SUFB, including scope quality, handling, maneuverability, tool interaction, and image quality. The H-SteriScope performed better in all categories compared to previous generation SUFB and appeared to have similar maneuverability as RFB, with operators favoring the single use device (32). More than half of the respondents did feel that RFB provided better image quality than SUFB (32). It is important to note that the majority of current SUFB on the market were not available at the time of this study.

In another single center study, nine physicians were surveyed on their perception of multiple SUFB, including the H-SteriScope Normal (Olympus America, CO, USA), Ambu aScope 4 (AMBU Inc., MD, USA), Verathon GlideScope BFlex (Verathon Inc., WA, USA), compared to the reusable Olympus EVIS EXERA III BF-H190 (Olympus America, CO, USA) (32). Although no SUFB was preferred over this RFB, the H-SteriScope was rated highest among other SUFB in terms of maneuverability into difficult airway segments both with and without a tool in the working channel (33). This finding is of particular interest to interventionalists as this could mean decreased deflection when the target lesion is more distal or apical.

In 2022, the first study highlighting the technical performance of the new SUFB was completed at two US sites with simulated bronchoscopy tasks (34). Fifteen physicians from various specialty backgrounds and levels of training were asked to complete three bronchoscopic tasks (water suction and visualization, “mucus” mass suctioned in 30 seconds and “mucus” plug suction) using each of the three sizes of SUFB from the EXALT Model B (Boston Scientific Coporation, Marlborough, Massachusetts, USA) Ambu aScope4 (AMBUR, Ballerup, Denmark) lines (34). In comparison of scopes with the same outer diameter, the EXALT Model B outperformed Ambu aScope 4 in aspirated mean mass by weight of water and “mucus” (34). Another study comparing the interaction of SUFB with biopsy tools such as forceps and aspiration needles and adjunct tools like dilation balloons, argon plasma coagulation catheters, cryoprobes, bronchial thermoplasty catheters, and endobronchial valve catheters to their RFB counterparts found that the newer generations of SUFB were comparable or even superior to RFB (35). Our institution has used the Ambu aScope 5 to perform some advanced bronchoscopic procedures such as evaluation of endobronchial valve placement, airway stents, bleeding, and airway balloon dilation (see Figure 1).

Figure 1 Endoscopic images using Ambu aScope 5 in patients. (A) Endoscopic view of endobronchial valves; (B) endoscopic view of airway bleeding; (C) endoscopic view of metallic airway stent; (D) endoscopic view of airway through inflated balloon.

These studies have several inherent limitations. First, the evaluation of SUFB were completed on model airways or cadavers. In vivo experience could be divergent. Additionally, while these models simulate bronchoscopy completed under general anesthesia, it did not simulate bronchoscopy in patients who are under light or moderate sedation and may be coughing. Second, most of these studies were non-blinded, completed at single-centers, and involved surveying a small number of respondents, which could lead to sampling bias. Respondents tended to be self-selected individuals and may not be representative of all practicing bronchoscopists. Recently, a prospective, controlled study was published comparing the performance of SUFB in transbronchial biopsies and bronchoalveolar lavage (BAL) and found that SUFB are non-inferior to RFB in these procedures (36). Additional studies are needed to further substantiate these findings.

Conclusions

SUFB offers distinct advantages over RFB. These benefits include portability, immediate availability, reduction in iatrogenic infections, and improved flexion/extension. Despite these advantages, familiarity with RFB has helped maintain its position as the default option for more complex bronchoscopic procedures such as 185 management of hemoptysis, tracheal stenosis, endobronchial obstruction, and staging and diagnosis of lung malignancy. Based on growing evidence and experience, the latest generation of SUFB can be safely and effectively used for advanced bronchoscopic procedures, beyond traditional therapeutic mucous aspiration, bronchoalveolar lavage, and transbronchial biopsy. Further research is required to substantiate this experience.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, AME Medical Journal for the series “Diagnostic & Therapeutic Bronchoscopy”. The article has undergone external peer review.

Peer Review File: Available at https://amj.amegroups.com/article/view/10.21037/amj-23-178/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://amj.amegroups.com/article/view/10.21037/amj-23-178/coif). The series “Diagnostic & Therapeutic Bronchoscopy” was commissioned by the editorial office without any funding or sponsorship. B.S.B. and J.S.K. served as the unpaid Guest Editors of the series. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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