To the Editor:—
Heidegger et al. 1are to be congratulated for a well-performed study that validates the relative safety of their practice. The conclusions from their study, however, can be applied only narrowly. First, as they admit, it was conducted by individuals with extensive previous experience with the technique. Indeed, each had performed more than 200 previous bronchoscopic intubations. Therefore, the study addresses the safety of bronchoscopic-assisted intubation for those needing to maintain, rather than acquire, this skill. It does not serve to document the equivalent safety of this technique with direct laryngoscopy for those with limited previous experience. Second, the study was performed on the very population not requiring flexible bronchoscopic intubation—namely, those with normal airways. The study falls short of documenting the absence of vocal cord sequelae when performed in patients who may require this approach. Third, the authors have compared the vocal cord sequelae resulting from a nasally inserted 6-mm tube with an orally inserted 7- or 8-mm tube. Nasal tubes assume a more vertical passage through the larynx and exert less force on the posteromedial glottis.2Likewise, smaller tubes probably exert less force on the vocal folds and arytenoid cartilages.3Finally, their technique involved the induction of anesthesia absent neuromuscular blockers. The national guidelines referred to,4,5insofar as they address the anticipated difficult airway, recommend the preservation of spontaneous ventilation. This demands much less medication than Heidegger et al. administered and results in a higher probability of coughing and difficulty in advancing the tube. These may increase the probability of vocal cord sequelae.
Skill at intubating with a flexible bronchoscope is essential to the safe practice of anesthesia. It is important that this skill be acquired and maintained in a manner that simultaneously meets our professional needs and protects our patients from harm. Heidegger et al. have demonstrated that their methods achieve those ends for experienced clinicians on patients with normal airways, but their findings cannot be extrapolated to dissimilar practices.
University of Toronto, Toronto General Hospital, Toronto, Ontario, Canada. firstname.lastname@example.org