Application of multivariate autoregressive modeling for the nasal cycle

In this study, the author proposed the handy system for the measurement of the nasal cycle with high accuracy, which is hardly influenced by environmental changes including room temperature changes and imposes a small burden to the head and small restrictions to body movements and respiration. In this system, small lightweight propellers are rotated independently by nasal expiration through right and left nasal cavities, the pulse sequences generated by light-beam interruption are counted by a light detector. Using this device, two experiments were carried out: firstly to measure quantitatively the phenomenon of the inversion of the dominant side of nasal respiratory capacity and secondly to observe the influences of the circadian rhythm on the nasal cycle for a long period of time. As the result of multivariate autoregressive analysis using two variables, the following features were found to exist probably: either nasal side changes with a stronger rhythm, and the right and left nasal respiratory capacities change certainly in an antagonistic manner, but the change on either nasal side tends to precede when the total respiratory capacity changes.