Comparison of flexible bronchoscope guided nasotracheal intubation with videolaryngoscopic nasotracheal intubation after induction of general anesthesia in patients with normal airway: A single-blinded pilot randomised controlled trial

Endotracheal intubation is a crucial step in patients undergoing surgery under general anesthesia. There are many ways to intubate the trachea, the commonest of which include direct laryngoscopy, video laryngoscopy and flexible bronchoscope (FB) guided intubation. Awake FB-guided intubation is the gold standard and preferred way to secure the trachea in cases of anticipated difficult airway. However, FB-guided intubation after general anesthesia is not frequently chosen by anesthesiologists in day-to-day practice although its use is mentioned in unanticipated difficult airway guideline. [1]

 Under general anesthesia, muscle tone is reduced which makes upper airway structures collapse and fall towards the posterior pharyngeal wall. [2-3] This may make the airway potentially difficult for FB-guided intubation after induction of general anesthesia. In a previous study, where FB-guided orotracheal intubation after general anesthesia was evaluated, the aforementioned problem was prevented by applying jaw thrust and lingual traction. [4] Nasotracheal intubation is a commonly performed procedure to secure the airway during surgeries involving the oral cavity. It is usually done by direct or video laryngoscopy which carries the added risk of trauma related to direct instrumentation. Blind introduction of an endotracheal tube through the nostrils can lead to the avulsion of nasal spur/ polyp or mechanical obstruction. Using a FB for nasotracheal intubation helps in the evaluation of the passage prior to the introduction of the endotracheal tube and can avert complications associated with the blind introduction.

 We hypothesize that in an airway not anticipated to be difficult, FB-guided nasotracheal intubation after induction of general anesthesia will be better compared to the videolaryngoscopic intubation in terms of improved success rate, a lesser degree of airway trauma and lesser added instrumentation. FB-guided nasotracheal intubation may also be associated with a lesser surge in blood pressure and heart rate usually associated with laryngoscopy and intubation. Though airway collapse may interfere with the advancement of the bronchoscope, choosing the nasotracheal route might help in better alignment of airway axes leading to a higher success rate of endotracheal intubation.