Humming-induced release of nasal nitric oxide for assessment of sinus obstruction in allergic rhinitis: pilot study

Humming greatly increases nasal nitric oxide (NO) in healthy people by causing a rapid washout of NO from the sinuses. This increase is abolished in patients with complete sinus ostial obstruction.

Allergic rhinitis is a risk factor for development of sinusitis and we wanted to study whether nasal NO measurement during humming could be used to detect sinus abnormalities in this disorder.

Fifty-nine consecutive subjects with mild to moderate allergic rhinitis were studied. Their present nasal symptoms were recorded. Then NO levels were measured by chemiluminescence during quiet single-breath nasal exhalations and humming exhalations at a fixed exhalation flow of 0.2 L s(-1). Based on the NO results the patients were divided into two groups: those with a great increase in nasal NO during humming (humming responders, n = 46) and those without a significant increase (humming nonresponders, n = 13). In 11 of the nonresponders and in 22 of the responders the passage to the osteomeatal complex area was assessed and scored by nasal endoscopy. This was carried out by an oto-rhino-laryngologist unaware of the NO results.

Among the nonresponders nine of 11 patients (80%) had endoscopic signs of bilateral sinus obstruction, compared with one of the 22 (< 5%) humming responders. Baseline nasal symptom score and NO levels during quiet exhalation were not significantly different between the groups

Absence of a nasal NO peak during humming is associated with endoscopic findings suggestive of sinus ostial obstruction in subjects with allergic rhinitis. Measurement of nasal NO during humming may be a simple method to detect sinus abnormalities in these patients.