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 aScope4™ 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.
New bronchoscopes have recently been introduced that offer advantages over existing ones. The quality assessment of these bronchoscopes should be done in the most objective way possible, to validate their functionality. The measurement of the bronchoscopist's perception using standardized questionnaires that include the most relevant domains is a key element for the validation of these devices. In the absence of a questionnaire with these characteristics, we designed one by a panel of expert bronchoscopists, which included questions related to the route of entry, ease of assembly of the equipment, ease of operation, image quality and aspiration, robustness of the equipment to maintain full functionality and to allow the planned sampling, in addition to the degree of general satisfaction.
The evaluation of the psychometric properties of the BQQ showed a very good internal consistency as measured by Cronbach's alpha, with a value of 0.88 . It is noteworthy that the Cronbach's alpha coefficient can have values between 0 and 1, 0 indicates absence of consistency and 1 total consistency. Values between 0.8 and 0.9 are considered very good, values less than 0.7 are considered low and values greater than 0.94 are considered indicative of redundancy in the questions. The participation of a panel of experts in the construction of the questionnaire and the values obtained in Cronbach's alpha gave us the necessary support in aspects related to the validity of appearance, content and construct to apply the questionnaire in our study.
A single-use disposable bronchoscope has significant advantages related to reducing the risk of cross infection, ease of compliance with cleaning and disinfection regulations during non-working hours, and reducing costs related to trauma repairs during use or reprocessing of the equipment. Studies on the effectiveness of reprocessing techniques have shown failures that can occur even when current regulations are followed [4, 5]. This makes single-use bronchoscopes preferable for patients at increased risk of infection, such as immunocompromised patients, or those at risk of spreading infections by resistant or virulent germs (e.g., hepatitis B and C, HIV, multi-resistant bacteria and tuberculosis, among other). Particularly, during the current COVID-19 pandemic most respiratory societies have recommended disposable bronchoscopes to decrease transmission of the SARS-CoV-2 to other patients and to the health care providers [8,9,10,11]. However, these advantages would be of little value if the bronchoscope did not fulfill its functions with quality.
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 sheaths, also designed to reduce the risk of cross infection, had some difficulties in these aspects , 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 sheaths . 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 this study 54.4% of physicians found the quality of images worse than those from reusable videobronchoscopes. Thus, reusable videobronchoscopes remain the cornerstone in interventional pulmonology units.
In a study done with a previous version of aScope4, aScope2 , 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 having such functionality are often not used, and therefore the exploration is only visualized by the bronchoscopist who performs it. The aScope 4 indications are very varied, such as emergency situations, COVID infections, mycobacteria or multi-resistant germs, immunosuppressed patients, ICU admissions, etc. 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 orotracheal tubes 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. Finally, one of the factors to take into account in the future is the possible ecological impact of this device since it is necessary to dispose of it after use and because it is made of plastic materials.