Efficacy of high-flow nasal cannula in improving the view of the glottis during flexible bronchoscopy for tracheal intubation.

Background: Flexible bronchoscopy for tracheal intubation is indicated in patients with difficult airways, but the upper airway is frequently obstructed in sedated or anaesthetised apnoeic patients. This makes it more difficult to locate the glottis through bronchoscopy, and increases the risk of hypoxaemia. Nasal high-flow oxygenation is useful to prevent hypoxaemia during airway management, but no studies have assessed if this method of oxygenation improves the bronchoscopic view of the glottis by preventing upper airway obstruction.

Methods: As a crossover design, we studied 20 anaesthetised apnoeic patients to assess if nasal high-flow oxygenation (60 L min) improves the view of the glottis during attempts at bronchoscopic intubation by widening the pharyngeal space.

Results: The pharyngeal space was wider with nasal high-flow oxygenation than without in 19 of 20 patients (95%; 95% confidence interval [CI]: 85-100%; P<0.0001), and bronchoscopic view of the glottis was better with high-flow oxygenation than without in 17 of 20 patients (85%; 95% CI: 69-100%, P<0.0001). The flexible bronchoscope was easily inserted into the trachea in all patients, and no complications including hypoxaemia were observed.

Conclusions: Nasal high-flow oxygenation facilitates flexible bronchoscopy for tracheal intubation by widening the pharyngeal space and by improving the view of the glottis through the bronchoscope. Therefore, use of nasal high-flow oxygenation is useful in patients with difficult airways in whom flexible bronchoscopy for tracheal intubation is indicated.