Comparing performance of flexible bronchoscopy with videolaryngoscopy for awake tracheal intubation

Kamga et al. [1] evaluated the performance of the Airtraq® (Prodol Meditec S.A., Vizcaya, Spain) videolaryngoscope for awake flexible nasal bronchoscopy in patients with an anticipated difficult airway. To differentiate the effect of one factor on the primary outcome in a randomised controlled trial, all other factors must be standardised to avoid potential bias. However, other than the limitations described in the discussion section, we have noted several issues in the methods and results of this study that have not been addressed. First, as a gold standard technique for management of an anticipated difficult airway, adequate airway anaesthesia and sedation are vital for success and patient comfort [2]. In the methods, the authors provide details of airway anaesthesia in the Airtraq group, but not the anaesthetic techniques used for the upper and lower airways in the flexible bronchoscopy group. It would be interesting to know if same methods were used for both groups. Both the nerve blocks and transtracheal injection used in this study are invasive procedures. For patient comfort, we favour the use of only topical local anaesthesia of the airway in combination with a standard or modified 'spray as you go' technique when awake tracheal intubation is performed with either the fibreoptic bronchoscope or videolaryngoscope [3, 4]. Second, for a comparative study of airway devices, equal competence of participants with the studied tools is mandatory [5]. We note that up to 72% of cases were performed by trainees in this study. The experience of an expert was clearly defined, but experience of trainees in these techniques was not provided. The results of this study show that success rate of awake tracheal intubation for trainees under expert supervision was only 69% with the Airtraq and 82% with the bronchoscope, indicating low competence for both tools. It is unclear whether the trainers participating in this study were evenly distributed in both groups. We are concerned that significant between-group differences in the competence of trainees with both studied tools have biased the findings of this small study. Third, it was unclear why two intubation pathways were utilised, that is, nasal with the bronchoscope and oral with the Airtraq. This may further confuse the interpretation of primary and secondary outcomes. Finally, in the design of this non-inferiority randomised controlled trial, both an 8% non-inferiority limit and similar success rates of 99% for both studied tools were hypothesised. The results show that the success rate was 82% (32/39) with the Airtraq and 97% (38/39) with the bronchoscope. An absolute between-group risk difference of 15% exceeds the designed non-inferiority limit (see Fig. 2, Kamga et al. [1]). Most important, all seven videolaryngoscopy failures were successful following conversion to fibreoptic-guided intubation. In these cases, we cannot agree with the authors that the Airtraq is not non-inferior to the fibreoptic bronchoscope in this setting.