Re-evaluating the nasal cycle by long-term rhinoflowmetry: most individuals demonstrate a “mixed” nasal cycle

Background: The nasal cycle seems to be more complex than a strictly alternating swelling of the nasal mucosa. Long-term rhinoflowmetry (LRFM) allows continuous investigation of changes in nasal airflow over 24 hours (24h). We evaluated the various types of nasal cycle with LRFM over 24 hours and investigated the influence of age and gender. Methods: LRFM was continuously performed over 24h in 55 rhinologically healthy subjects (36 female, 19 male). The LRFM flow curves were examined for phases of the “classical”, “in-concert”, “one-sided” and “no-cycle” cycle types. Subjects were divided into 4 age subgroups (19-29; 30-49; 50-69; >70 years). Correlations of age and gender with the individual cycle forms were analyzed. Results: 85.5% of the subjects presented a “mixed” nasal cycle within 24h. The “classical” nasal cycle was seen most often (92.7% vs. “in-concert”; 56.4% vs. “one-sided”; 18.2% vs. “no-cycle”; 5.5%). Older age groups significantly more often presented the "no-cycle" type. A tendency was seen towards a mixed nasal cycle with increasing age. The mixed nasal cycle was significantly more often seen in the female subjects. Conclusions: LRFM is an easy-to-use measurement tool. The “mixed” nasal cycle predominates. However, all 4 different cycle types can be detected, alternating over 24h in each subject. Moreover, the cycle type varies with age.