Exhaled nasal nitric oxide during humming: potential clinical tool in sinonasal disease?

Figure 1. The paranasal sinus behaves like a Helmholz resonator. The alternating pressure in the nasal cavity forces the air plug in the ostium of the paranasal sinus resonators to vibrate, thus expelling nitric oxide gas from the cavity.
(Figure omitted. See article PDF.)

Figure 2. Representative track of nasal nitric oxide during humming and quiet exhalation. Nasal nitric oxide output during (A) humming and (B) quiet exhalation. Data taken from [11].
(Figure omitted. See article PDF.)

Nasal nitric oxide

Measurement of nitric oxide (NO) in exhaled breath is a noninvasive, simple and safe way of measuring airway inflammatory diseases including asthma. Reference guidelines for practicing healthcare providers, aimed at guiding them to the appropriate use and interpretation of exhaled and nasal NO (nNO) in clinical practice, have recently been published [1].

Differently from exhaled NO, nNO measurements have been proposed for clinical applications in only a few diseases, such as primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) [1]. Indeed, the clinical value of nNO has been the object of intense investigation, particularly in sinonasal disease, during the past 10 years. Arnal et al. showed in 1999 that nNO concentration was inversely correlated with the extent of tomodensitometric alteration of the paranasal sinuses in patients with paranasal sinus inflammatory diseases, including allergic and nonallergic polyposis [2]. The authors concluded that changes in nNO concentration in patients with nasal polyposis appeared to be dependent on both the allergic status and the degree of obstruction of the paranasal sinuses. In another study, Colantonio et al. found that nNO was significantly lower in nasal polyposis than in uncomplicated allergic rhinitis (AR) despite high levels of inducible NO synthase in the latter [3]. They postulated that the prevalent sinus NO contribution to exhaled nNO was lost because of the blockage of the ostiomeatal complex, as well as the failure of NO generated constitutively in the sinuses to reach the nasal airway. Accordingly, nNO provided a valuable noninvasive, objective measure of the response to therapy in patients with chronic rhinosinusitis (CRS) and abnormal CT scan [4]. Moreover, the predictive diagnostic role of a lower nNO value in patients with CRS and polyposis, when compared with patients with CRS without polyposis, was also appreciated [5]. In two different reviews,...