Pathways through the nose for nasal intubation: a comparison of three endotracheal tubes

In nasotracheal intubation, there are two main pathways in the nostril through which the endotracheal tube may pass. The lower pathway lies along the floor of the nose underneath the inferior turbinate. The upper pathway lies above the inferior turbinate, just below the middle turbinate. The lower pathway may be considered to be the safer route as it is located away from the middle turbinate and cribiform plate.

We conducted a randomized controlled trial comparing the frequency with which preformed, reinforced, and thermosoftened preformed tubes pass through upper and lower pathways. Ninety-two maxillofacial patients requiring nasotracheal intubation as part of their anaesthetic management were studied. Two patients were excluded from the study at endoscopy because of atypical nasal anatomy. After the induction of general anaesthesia, a standardized traditional nasal intubation was performed with a Macintosh laryngoscope, the operators endeavouring to direct the tube along the floor of the nose. Fibreoptic nasendoscopy was then performed by passing the tip of the fibrescope 2-3 cm into the nasal cavity above and below the tube, to identify the pathway taken.

Data were analysed on 30 patients in each group. Five (16.7%) preformed tubes, 17 (56.7%) reinforced tubes, and 6 (20%) thermosoftened preformed tubes passed through the lower pathway. Significantly more reinforced tubes took the preferred pathway (P=0.001). Tubes passing through the upper pathway caused significantly more epistaxis than tubes passing through the lower pathway (P=0.003).

Endotracheal tubes, particularly preformed tubes, frequently take the less favourable pathway during nasotracheal intubation, in spite of specific attempts to avoid this.