Bronchoscopist's perception of the quality of the single-use fiberoptic bronchoscope (Ambu aScope4 ™) in conventional bronchoscopies. A multicenter study in 21 Spanish pulmonology services.

Conclusions: The aScope4 ™ scored well for ease of use, imaging, and aspiration. We found a learning curve with excellent scores from the 9th procedure. Bronchoscopists highlighted its portability, immediacy of use and the possibility of taking and storing images.


Background:
Fiberoptic bronchoscopy is a widely used procedure in most hospitals around the world, especially for the diagnosis of infectious, inflammatory and tumor lung diseases. It is estimated that 92,000 bronchoscopies are performed annually in Spain, with a tendency to growth. Unfortunately, bronchoscopy can spread infections by spreading an infection in the same patient, by cross-infection between patients, or by infecting the personnel involved in the procedure. (1) The effects of cross infection can be severe for the patient and the health system and include complications of the infection and its consequences in terms of laboratory tests, medications, hospital stay, disability, and direct and indirect costs. For this reason, it is necessary to take extreme care and precautions in the decontamination and cleaning of equipment. (2) Despite complex and advanced endoscope cleaning and disinfection systems, disinfection is often inadequate (3)(4)(5) , with the consequent risk of cross infection. (5)(6)(7) A disposable bronchoscope could decrease the risk of cross infection and increase accessibility to bronchoscopy in centers of less complexity or with limited resources and has been recommended by most respiratory societies for bronchoscopies during the SARS-COv-2 pandemic. (8)(9)(10)(11) Patients on mechanical ventilation, (12) immunosuppressed or with infectious contagious diseases are those with the highest risk for cross infections and where these devices may have a more relevant role. These bronchoscopes are also desirable for procedures with a high risk of damage the bronchoscope (e.g. bronchoscopy by orotracheal tube), to reduce repair costs. (13) The utility of single-use bronchoscopes has been extensively studied in anesthesiology, where they have been compared with reusable bronchoscopes in terms of ease of use (14).
In the field of pulmonology, there are not publications listing the perception of pulmonologists when using these bronchoscopes for conventional diagnostic and therapeutic techniques.
This study seeks to evaluate the perception of the bronchoscopist about the quality of the Ambu® aScope ™ 4 bronchoscope and the existence of a learning curve during the performance of conventional bronchoscopies of low complexity in the usual practice in pulmonology services of university hospitals of third level of care.

Methods: Design
A prospective, observational, multicenter, cross-sectional study was conducted of an approved disposable bronchoscope (Ambu® aScope4 ™) with European certification (CEA) and used according to the product data sheet.
The study was carried out between February and August 2018, in tertiary care university hospitals with experience in performing bronchoscopies. The study was approved by the ethics committees of each institution and all the participants signed the informed consent both for their participation in the study and for the bronchoscopy.
The inclusion criteria were patients over 18 years with indication for the performance of a diagnostic bronchoscopy and that the procedure be approved by signing the informed consent. Exclusion criteria were bronchoscopies that required flexible interventional bronchoscopies or in which highly complex equipment was to be used. 300 subjects were recruited prospectively and consecutively in 21 Spanish pulmonology services.
Bronchoscopists had an experience of more than 500 bronchoscopies. The bronchoscopies were only diagnostic bronchoscopies with bronchial aspiration and bronchoalveolar lavage (BAL) and therapeutic bronchoscopies that involved the aspiration of secretions or hematic remains.
The bronchial aspirate (BAS) consisted of collecting the secretions found during the examination by means of simple aspiration or by using instillations of small volumes of physiological serum (5-10 cc) to favor the collection or try to carry away cellularity or microbiota. of the airway.
BAL was performed by interlocking in a segmental or subsegmental bronchus (depending on the bronchial anatomy), three 50-cc aliquots of 0.9% saline were instilled and successively aspirated and processed for study. It was assumed that the first aliquot would collect a sample from the bronchial area, while the last volume instilled would carry distal airway and alveolar contents.
In the cases included in the study, the bronchoscopy was performed by two observers, the main operator who operated the bronchoscope and a collaborator who analyzed the exploration during its development. A video of each bronchoscopy was recorded and saved in the memory of the Ambu® aView ™ device for later visualizations. The videos were labeled according to the order number and date of the examination, without the patient data being included. All procedures were anonymous in storage and confidentiality and privacy regulations were respected.
A search of the literature was carried out on questionnaires that measured the quality of the fiberoptic bronchoscopes for the performance of diagnostic bronchoscopies and none was found, so a new questionnaire was constructed on the Bronchoscope Quality Questionnaire (BQQ) by means of an expert consensus to establish the relevant items and domains to evaluate in the quality of the bronchoscope. A pilot test was carried out to adjust the questions and the psychometric measures of the final instrument were evaluated.
The BQQ was assessed independently and masked by the two bronchoscopists after the bronchoscopy at two different times. Both questionnaires were archived and after a period of 1-15 days from the bronchoscopy, one of the two bronchoscopists viewed the video of the bronchoscopy, and completed the questionnaire again.

Statistic analysis
The qualitative variables were described with absolute and relative frequencies, the quantitative ones by means and standard or median deviations, and interquartile range (25th percentile to 75th percentile) depending on their distribution. The internal consistency of the questionnaire was measured with the Cronbach's alpha coefficient. To unify the item scores and to be able to compare them, the standardized scores were calculated using the following equation: score obtained on the item ________________________________ x100 maximum possible score on the item In this way, the standardized score was left with a range from 0 (worst possible score) to 100 (best possible score).
To assess the bronchoscopies quality related to the number of procedures performed with the aScope4 and the existence of learning curves, we used the binary CUSUM analysis method. We describe the details of this method in the supplemental appendix, which we summarize below. We consider an acceptable failure rate( 0 )10% (90% of the scores in the evaluated aspect ≥80 / 100) and an unacceptable failure rate of 20% ( 1 ) (less than 80% of the scores in the evaluated aspect ≥80 / 100); we defined a type I error (probability of falsely qualifying the bronchoscope as inadequate, designated as α) of 0.1 and a type II error (probability of falsely qualifying the bronchoscope as excellent, designated as β) of 0.1 (15)(16)(17). We plotted the CUSUM graph by plotting the index number of each case (bronchoscopy) on the x-axis versus the cumulative sum score after that case on the yaxis. Consecutive failures drive the CUSUM curve upward while consecutive successes drive the CUSUM curve downward.
The CUSUM chart includes horizontal lines called decision limits (h 1 y h 0 ), which are the limits of an acceptable or unacceptable error rate. When the CUSUM curve crosses a decision boundary from above, it is inferred that the failure rates were within the predetermined acceptable rate of 10% (excellent performance); when the CUSUM curve crosses a decision limit from below, it is inferred that failure rates have reached the unacceptable failure rate of 20% (inadequate performance); If the CUSUM curve is stable between two decision limits, stable performance is inferred within good levels. Therefore, good performance is assumed when the CUSUM curve slopes downward or remains stable, but when the curve slopes upward it indicates a lower than acceptable success rate. Decision limits (h1 and h0) were calculated based on the risk of type I errors (α) and II (β). In our case, as = = 0,1; 0 = 10% and 1 = 20%; therefore h 0 = h 1 = 2,71. For Assuming a confidence of 95%, a margin of error of 6% and an average proportion of 50% for the qualitative variables (more demanding scenario in terms of sample size), a sample size of 267 bronchoscopies was deemed necessary for the study, to compensate possible losses it was decided to increase to 300 bronchoscopies.

Results
A total of 300 bronchoscopies were performed, 15 procedures were made by each  figure S2). The duration of the bronchoscopy had a median of 9.1 minutes (IQR: 6.0-13.0) ( Table 1). The reliability of the questionnaire measured by Cronbach's alpha was 0.88.
The average in user-friendliness, image and aspiration quality was 4 out of a maximum score of 5 (standardized score: 80/100; for a maximum score of 100 and a minimum of 0).
The average standardized score for ease of use, image quality, and aspiration was 80/100 (Table 2 and Figure 1). In 6% of the cases it was necessary to change the aScope 4, the most frequent reasons were limitation to reach the goals of the procedure and damage to the bronchoscope. 54.4% considered that the aScope had lower image quality than reusable video endoscopes. In more than 90% of the cases, all the pulmonary segments could be reached and all the planned techniques could be performed, for a general satisfaction with the team of 86.4% and a recommendation for its use in similar cases in 86.4% of the cases. times ( Table 3).
The analysis by the CUSUM Analysis graphical method to detect if there was a learning curve in the use of the Ambu® aScope4 ™ showed the following learning points (point in which the scores exceeded 80/100 in more 80% of bronchoscopies): ease of passing the fiberoptic bronchoscope to the trachea (intubation) in the 3rd procedure, ease of maneuvering during the bronchoscopy in the 4th procedure, and image quality during the bronchoscopy in the 9th procedure ( Figure 2) . Before these learning points the average scores for these aspects were between 70/100 and 80/100. The assembly of the equipment and the quality of aspiration of the bronchoscope obtained standardized scores higher than 80/100 from the first procedure.
The most outstanding characteristics of the bronchoscope were its portability and immediacy to start the procedure in 99.3% ( effectively than with the aspiration probe at blind.

Discussion
Our study provides as novel aspects the evaluation of the bronchoscopist's perception of the quality of the aScope4 ™ disposable bronchoscope through a standardized questionnaire and the measurement of its learning curve. The aScope4TM was very well evaluated in terms of ease of use, imaging and aspiration, obtaining an average score of 80/100 and a high degree of satisfaction in the bronchoscopist. After the 9th procedure, the scores exceeded 80/100 in more than 80% of the bronchoscopies. They highlighted its portability, immediacy to start the procedure and the possibility of storing the images. Given their high sensitivity to detect changes in positive or negative trends, the cumulative checksum graphs (CUSUM) are probably the most appropriate method to evaluate the introduction of new technologies, study learning curves and assess the quality of the results (15)(16)(17)19) This analysis showed that the aScope4 did not require a learning curve in aspects related to equipment assembly and aspiration quality, probably because it works similarly to reusable bronchoscopes. The disposable covers, also designed to reduce the risk of cross infection, had some difficulties in these aspects (20) , the advantage of the single-use bronchoscope may be due to not needing to couple an external sheath with a second working channel. Image quality, ease of tracheal intubation and maneuvering had standardized scores ≥ 80/100 from the 9th procedure, with previous scores between 70/100 and 80/100, these results show a good performance of the aScope4 from the first procedure and excellent performance from the 9th procedure. However, like previous studies on the quality of single-use bronchoscopes (14,21,22) or disposable covers (20) . They did not evaluate the existence of learning curves by methods validated for this purpose, nor did they use standardized questionnaires. Their comparison with our results has these limitations.
In a study done with a previous version of aScope 4, aScope2 (21) , authors observed lower image quality and greater difficulty in maneuverability. In our study, the scores in the domains related to image quality, maneuverability, aspiration, ease of assembly and general satisfaction were good, which is probably due to the technical improvements made in this new version of the device. Our study has as limitations not having included more complex procedures such as taking biopsies or punctures and not having included a control group, so that it does not allow us to establish the usefulness of aScope 4 for such procedures or the superiority or inferiority of aScope 4 versus other video bronchoscopes.
Among the advantages of the aScope 4 they highlighted the fact that it is sterile, that it is for single use, the portability and immediacy to start the procedure, the possibility of taking and storing videos and photos of the procedure. Taking and storing images can be particularly useful when the equipment is used in intensive care units, where fiberoptic bronchoscopes are often not used, and therefore the exploration is only visualized by the bronchoscopist who performs it. This device also constitutes an advantage in the training of specialists because it allows them to visualize the examination or teach the bronchoscopic findings to the members of the medical team and could also reduce the costs related to the damage of such equipment due to the trauma they receive when entering through tubes, orotracheal or non-invasive ventilation masks. In addition, the characteristics of the aScope 4 allow it to be kept permanently at the patient's bedside when there are serious problems with airway obstruction due to abundant secretions, so that they can be aspirated under direct vision in a way that is probably more effective than blindly.

Conclusions
The aScope 4 scored very well in terms of ease of use, image quality, and aspiration. We observed a learning curve with excellent scores from the 9th procedure. They highlighted its portability, immediacy of use and the possibility of taking and storing images.

Abbreviations
Cumulative checksum graphs CUSUM European certification (CEA)

Declarations
• Ethics approval and consent to participate The study was approved by the ethics committees of each institution and all the participants signed the informed consent both for their participation in the study and for the bronchoscopy • Consent for publication Not applicable for that section.
• Availability of data and material To share our data in the follow link: https://docs.google.com/spreadsheets/d/1s3TZklwXO0UX_93PbxN7Oij3OmWGhX7j1Zmh J6IcxME/edit?usp=sharing

• Funding
This study has been designed by the bronchoscopy unit of the Jiménez Díaz Foundation sponsored by Ambu (Copenhagen, Denmark). However, the sponsors did not participate in the analysis and interpretation of the results.

• Competing interests
The authors declare that they have no competing interests. Uribe-Hernandez A: Contributed to writing the entire manuscript, statistical analysis and final approval of the manuscript.

• Acknowledgements
Not applicable for that section.  Average score for ease of use, image quality and aspiration quality 80% Notes: a IQR: interquartile range; b Standardized score: calculated by dividing the score obtained by the maximum possible score and multiplying by 100, the best possible standardized score is 100% and the worst is 0%. 95% CI: 95% confidence interval. Notes: 95% CI: 95% confidence interval. Notes: Intubation: passing the bronchoscope through the vocal folds into the trachea. When the CUSUM curve is directed upward it indicates inadequate performance (less than 80% of procedures were scored with a standardized score 80/100), when the curve stabilizes indicates that between 80% and 90% of the procedures were rated with a standardized score 80/100, when the curve is directed downwards indicates that more than 90% of the procedures were scored with a standardized score 80/100. The assembly of the equipment and the quality of aspiration obtained standardized scores 80/100 from the first procedure. Intubation ease obtained standardized scores 80/100 in more than 80% of cases since the 3rd procedure, the ease of maneuver obtained standardized scores 80/100 in more than 80% of cases since the 4th procedure, the image quality obtained standardized scores 80/100 in more than 80% of cases since the 9th procedure