Rhinomanometric reference intervals for normal total nasal airflow resistance

Background: Reference intervals (RIs) or mean values for normal total nasal airflow resistance are essential for the diagnosis of nasal obstruction. Data relating to nasal airflow are not standardised, and valid and reliable RIs do not exist for the time being. This meta-analysis aimed to determine such “standard” 95%-RIs. Methodology: Research of related literature listed in Medline, Embase, Cochrane, and Web of Science databases. Results: Airflow resistance data were gathered from 38 studies using active anterior rhinomanometry at a differential pressure of 150Pa to examine patients under congested and decongested mucosal conditions. In the meta-analysis overall values and RIs for normal total nasal airflow resistance under congested nasal mucosal conditions were calculated for all subjects at 0.25Pa/cm3/s (95%-RI 0.10-0.40Pa/cm3/s), adults regardless of gender at 0.25Pa/cm3/s (95%-RI 0.12-0.38Pa/cm3/s), men at 0.24Pa/cm3/s (95%-RI 0.09-0.39Pa/cm3/s), and women at 0.26Pa/cm3/s (95%-RI 0.08-0.44Pa/cm3/s). Asian, African and Caucasian ethnic groups exhibited rising airflow resistance mean values: 0.23Pa/cm3/s (95%-RI 0.08-0.39Pa/cm3/s), 0.25Pa/cm3/s (95%-RI 0.11-0.38Pa/cm3/s) and 0.26Pa/cm3/s (95%-RI 0.13-0.38Pa/cm3/s), respectively. Lower overall mean values resulted under decongested nasal mucosal conditions. Conclusion: The reference intervals and mean values ascertained in this meta-analysis improve the diagnosis of nasal obstruction and may represent a useful supplement in existing guidelines for the standardisation of rhinomanometric measurements.