Continuous investigation of the nasal cycle over 48 hours.

Background: Previous results on the nasal cycle refer to measurements over up to 24h. The long-term rhinoflowmetry (LRFM) allows continuous observations over a longer period. The aim of the study was to observe the nasal cycle for the first time over 48h under everyday conditions.

Methodology: The LRFM was continuously applied to 30 rhinologically healthy subjects (20 female, 10 male) over 48h. The different types of nasal cycle were classified as follows: "classic", "in concert", "one-sided", "no-cycle" and "mixed". The focus of this study was on the results over the entire 48 hours. The comparison of the two consecutive days was also made.

Results: A nasal cycle could be detected in 100% of the subjects over 48h. With 97%, the mixed type most commonly occurred as a combination of classical and in concert components. In all subjects, classical cycle components could be detected at least once. The no-cycle type was not observed. In the awake state, the mixed type dominated (80%), as a combination of classical and in concert parts. In the sleep state, the classical type was the most common type (97%). The average phase duration was 206 +- 83 minutes.

Conclusions: In the very first continuous 48-hour study on the nasal cycle, 100% of the subjects presented a nasal cycle. The LRFM method is the only one that offers the possibility to perform continuous measurements over a longer period during daily routine. The results of previous single-stage examination methods should thus be questioned.