Our study showed the BB to be safe and effective in all kinds of thoracic surgery patients, achieving in most cases a degree of pulmonary collapse that allowed correct visualization and exposure, without ventilation interfering with the procedure.

Performance of any kind of thoracic surgery requires selective one-lung ventilation with an effective pulmonary collapse that allows a surgical exposure conducive to a simple, safe and effective procedure. Although the use of BBs has been described and accepted and is widely practised worldwide, many anesthesiologists are still reluctant to use them in their general practice, with DLTs remaining the gold standard [10,11,12,13]. Despite the publication of contradictory results has resulted in a lack of consensus on which device to use, a general perception seems to exist among anesthesiologists and thoracic surgeons that BBs are associated with a poor pulmonary collapse, and that they should only be used in cases in which lung isolation may present greater complexity, such as in patients with difficult airways, pediatric patients, or those requiring mechanical ventilation [2, 3, 12, 14, 15]. Even if it is true that some authors have reported more successful collapses with DLTs [3, 12], other studies have demonstrated similar collapse rates for the two devices [16], with BBs being associated with lower airway complication rates [3, 17, 18].

Given that the medical team’s experience and personal preference are two of the most crucial factors for deciding which device to employ, BBs are very scarcely used in general clinical practice [10]. In the last reported survey by the European Society of Anaesthesiologists (ESA), only 1.9% of respondents claimed that they used BBs as their preferred device, and only 71.9% reported to have access to them in their hospitals, which means that nearly one-third of anesthesiologists have limited experience of the use of the device [17]. More recently, Italian anesthesiologists were surveyed about their preferences for airway management in thoracic surgeries during the SARS-CoV-2 pandemic. Only 22% of them favored BBs, while 53% preferred DLTs [19]. Although BBs do not require an overly long learning curve, it is essential for professionals to train long enough to become familiar with their use. Thanks to its design characteristics, the Uniblocker device could make it easier for beginner anesthesiologists to master the technique [11, 18].

Only four of our patients presented with poor pulmonary collapse, requiring a switch to a different device for successful completion of the procedure. The rate of poor collapses in our series was 3%, far lower than that reported in the literature for the different BBs available on the market, which ranges between 9.6 and 60% [2, 3, 7, 20]. Although the scale employed in this study to assess pulmonary collapse is subjective, its use is standard in the literature and the assessments of the anesthesiologists in this study, at least in the case of poor collapses, were fully aligned with those of thoracic surgeons.

A significantly higher proportion of excellent pulmonary collapse rates corresponded to patients operated in the lateral position, who also experienced a lower proportion of poor pulmonary collapses. Although some thoracic surgeons prefer to place their patients in the lateral position to optimize the delivery of anesthesia and prevent the risk of cross-contamination, patient positioning should ideally be guided by the type of procedure, the condition suffered by the patient, the patient’s anatomy, and the anesthesiologist’s and surgeon’s clinical judgement. Also, the proportion of patients with excellent collapses was significantly higher in cases where the device was inserted in the left bronchus. This might be due to the right isolation being more challenging due to potential early emergence of the right upper lobe, as well as specific patient anatomical characteristics.

On the other hand, our analysis found that the proportion of patients achieving excellent pulmonary collapse was significantly higher, and that the proportion of poor pulmonary collapses was lower, in video-assisted procedures, which means that the overall efficacy of BBs appeared to be higher in VATS procedures than in open surgeries. In view of the increasing adoption of minimally-invasive procedures, it is crucial to use instruments capable of simplifying the surgeon’s job, particularly in surgeries like the ones discussed here, where three-dimensional visualization may be a challenge [3, 16, 21]. Given the technical difficulties inherent in VATS and the significant degree of pulmonary collapse required by the technique, several authors have confirmed the usefulness of BBs for such procedures [14].

As regards safety, one of the most critical aspects about using BBs is the correct positioning of the device, BB malpositioning potentially leading to intraoperative complications. In the face of this, the reported BB malpositioning rate ranges between 7 and 33% [3, 12, 14, 20, 22]. Such malpositionings often result from multiple failed attempts at proper placement of the device by inexperienced practitioners [14, 18, 22]. The authors of this study were already in the habit of using the Uniblocker device as part of their routine practice, which may have been the reason why repositionings were not required in most cases and only two patients ended up with a malpositioned device and an ensuing poor pulmonary collapse. In addition, the device’s safety was demonstrated by the low complications rate recorded, without any severe events such as injury to the tracheobronchial tree being recorded.

Although BBs are not being used as widely as they could, some authors claim their adoption seems to have increased in the last few years [2, 23]. However, the rates of anesthesiologists without experience in using them appear to have maintained their trend from the previous decade, with approximately 25% in Southern Europe and 19% in Western Europe, as reported in surveys conducted among professionals in the field [17, 24, 25]. In this study, BBs were used for all kinds of thoracic procedures with good results in terms of safety and efficacy and without any statistically significant differences being identified between the different degrees of pulmonary collapse achieved and demographic or clinical variables, which suggests that BBs may be used for all kinds of patients.

The main limitation of this study lies in the fact that it analyzes a retrospective series, which means that variables like the length of time required to insert the BB were not considered as such information is not routinely recorded in our hospital. It could also be considered a limitation that the anesthesiologists who participated in the study had at least two years of experience using the device. However, the authors consider this to be a reliable indicator of the BB’s performance as they have all surpassed its learning curve, thereby minimizing user-intrinsic effects in practice with the device. Even so, to the best of our knowledge, this study reports on one of the largest patient series in the literature on BBs, which is mainly focused on their comparison with DLTs.