Does nasal breathing cause frictional trauma in allergic rhinitis?

Frictional stress on the walls of a tube increases with increased air flow and as the diameter of the tube is reduced. High values of frictional stress may occur in the nose during nasal obstruction which could damage the nasal mucosa particularly when the mucosa is inflamed and fragile as in allergic rhinitis. The effect of nasal airflow induced frictional stress on the nasal mucosa was studied in patients with allergic rhinitis.

We studied nasal peak flow rate in eight patients with allergic rhinitis and nasal obstruction comparing the change in peak expiratory flow after they breathed for 30 minutes through an obstructed and a patent nostril. Patients were studied in the right and left lateral decubitus positions to increase and decrease the resistance in the lower and upper nostril respectively and thus minimize any effects of cyclical changes in nasal resistance. Subjects breathed for 30 minutes through the upper patent nostril (schedule 1) and for a further 30 minutes through the lower obstructed nostril (schedule 2). Nasal peak expiratory flow rate was measured in both nostrils separately in both positions after each schedule.

There was a significant reduction in mean (SD) nasal peak flow rate (-12.8 (4.06) L/min) after subjects had breathed for 30 minutes through the obstructed nostril. There was no significant change in nasal peak flow rate after subjects had breathed through the patent nostril, or in the nostril that had no flow for 30 minutes.

These findings are compatible with the hypothesis that frictional stress due to airflow through an obstructed nostril induces trauma and swelling of the nasal mucosa of patients with allergic rhinitis.