In Healthy Subjects Nasal Nitric Oxide Does Not Correlate with Olfactory Sensitivity, Trigeminal Sensitivity, and Nasal Airflow

Objective: The aim of the study was to determine the relationship between nasal nitric oxide (nNO) and olfactory sensitivity, trigeminal sensitivity and nasal airflow in healthy subjects. Study design: This is a correlational study. Setting: This study was carried out in a tertiary referral centre. Participants: Forty healthy participants were recruited. Main outcome measures: nNO was measured using a chemiluminescence analyser (Niox Vero® , Circassia AB, Uppsala, Sweden), olfactory sensitivity was determined using phenyl ethyl alcohol odour thresholds using the 'Sniffin' Sticks', trigeminal sensitivity was assessed with carbon dioxide delivered by an automated device, and nasal airflow was measured using the peak nasal inspiratory flow (PNIF). Results: The median nNO was 518 ppb (IQR =333) in the right nostril, and it was 567 ppb (IQR = 314) in the left nostril. The median odour threshold was 7.1 (IQR = 4.4), the median CO2 threshold was 919 ms (IQR = 1297) and the mean PNIF was 108 L/min (SEM = 4.9). nNO did not correlate significantly with odour threshold, CO2 threshold or PNIF (Spearman's |ρ| .18). Conclusion: In healthy subjects, nNO does not appear to be associated with olfactory sensitivity, trigeminal sensitivity and PNIF.