Identifying the more patent nostril before nasotracheal intubation.

We have studied the reliability of two simple pre-induction tests used to select the more patent nostril for nasotracheal intubation by comparing their results with those obtained from fibreoptic examination of the nostrils, in 75 maxillo-facial patients requiring nasotracheal intubation under general anaesthesia, who had no history of nasal obstruction. The tests comprised (1) estimation of the rate of airflow through each nostril during expiration by palpating the passage of air when the contralateral nostril was occluded, and (2) asking for the patient's assessment of airflow through the nostrils, following the administration of a vasoconstrictor. After each test, noses were classified as left or right nostril clearer or nostrils equally clear. After the induction of general anaesthesia, bilateral nasendoscopies were performed and videotape recordings of these were later analysed by an otolaryngologist who had no knowledge of the test results. Intranasal abnormalities were identified and noses were again classified as left or right nostril clearer or nostrils equally clear. There was no significant difference between the overall diagnostic success rates of the two tests (44% and 47%, respectively). In patients with intranasal abnormalities, the numbers of correct diagnoses made by the two tests were not significantly different and were also not significantly different from the number of correct selections made if only the right nostril or only the left nostril had been used for the intubation. In view of the relatively high diagnostic failure rates, anaesthetists should not rely on the two tests investigated when selecting the best nostril for nasotracheal intubation.