Background: The differences in nasal geometry and function between OSA patients and healthy individuals are not known. Our aim was to evaluate the differences in nasal geometry and function using acoustic rhinometry (AR) and peak nasal inspiratory flow (PNIF) between an OSA population and healthy controls. Methodology: The study was designed as a prospective case-control study. Ninety-three OSA patients and 92 controls were enrolled from 2010 to 2015. The minimal cross-sectional area (MCA) and the nasal cavity volume (NCV) in two parts of the nose (MCA0-3/NCV0-3 and MCA3-5.2/NCV3-5.2) and PNIF were measured at baseline and after decongestion. Results: The mean MCA0-3 in the OSA group was 0.49 cm2; compared to 0.55 cm2 in controls. The mean NCV0-3 correspondingly was 2.51 cm3 compared to 2.73 cm3 in controls. PNIF measured 105 litres/minute in the OSA group and 117 litres/minute in the controls. Conclusions: OSA patients have a lower minimum cross-sectional area, nasal cavity volume and peak inspiratory flow compared to controls. Our study supports the view that changes in the nasal cavity may contribute to development of OSA.

Background: The effect of pulmonary pathology on peak nasal inspiratory flow (PNIF) remains largely unknown. We investigated an association between a diagnosis of asthma and of lung function on PNIF when adjusted for possible confounders. Further, we investigated the perception of nasal obstruction in asthmatics compared to healthy controls when adjusted for PNIF. Methodology: Eighty-seven asthmatics and 92 non-asthmatic controls underwent PNIF (categorized into groups of high, medium and low), acoustic rhinometry (AR) and spirometry, and we assessed symptoms of nasal obstruction on visual analogue scales (VAS) in three categories. Results: PNIF was significantly associated with asthma and forced expiratory volume in the first second (FEV1) (% predicted). Other factors associated with PNIF were the degree of nasal obstruction measured both subjectively on a VAS and objectively with AR, age and disease status. Asthma patients were 19 times more likely to be in a higher VAS category compared to non-asth- matic controls independent of PNIF group. Conclusion: Special care has to be taken when interpreting PNIF values in patients with asthma or reduced FEV1 (% predicted). The sensation of nasal obstruction in asthmatics is different from controls despite being in the same PNIF group.