Seasonal change in maximal expiratory flow-volume pattern in patients with Japanese cedar pollenosis.

Fifteen patients with Japanese cedar pollenosis were examined for lower airway function. Flow-volume patterns obtained from flow-volume and volume-time curves during the pollen season (March) and outside of the pollen season (June) were evaluated. In a previous report we classified maximal expiratory flow-volume (MEFV) curves in five patterns from A to E. In the present study, the patterns did not vary between the two periods except in one patient. Eleven patients out of 15 showed type E patterns, in which the flow-volume curve was concave along its entire course. In most of the patients with severe or moderate symptoms of allergic rhinitis only during the pollen season, the curve shifted to the right, but the parameters of the curves did not increase significantly outside of season. These findings suggest that patients with Japanese cedar pollenosis suffer from continuous latent peripheral airway obstruction. Extremely slight changes in the flow rate were detected by comparing the curves obtained during the two periods.