To explore the cause of nasal obstruction and a feeling of nasal obstruction, dry air was administered into the intranasal cavities under various conditions. From changes in intranasalresistance associated with changes in intranasal humidity, involvement of these factors were examined. In addition, the functions of the nasal cavity in elderly group (aged 60 to 79 years) were compared with those in younger group. Moreover, the relation between a feeling of nasal obstruction and dryness of the nasal cavity was also examined.
(1) In the younger group, dryness in the nasal cavity causes reduction in humidity and elevation in resistance of the nasal cavity and decrease in mucociliary movements, inducing subjective feeling of nasal obstruction. It was postulated that increase in friction resistance of the mucosal surface and occurrence of turbulent flow are the possible causative factors.
(2) In the elderly group, it was confirmed that, as compared to younger subjects, intranasal humidity and resistance were decreased. Moreover, it was confirmed that with an increase in intranasal humidity, the resistance decreased. At the same time, symptoms such as a feeling of nasal obstruction were improved.
(3) As the responsible factor for the reduction in intranasal resistance observed in the elderly group, the reduction in frictional resistance and inhibition of turbulent flow were assumed.
(4) In the treatment of nasal obstruction and a feeling of nasal obstruction not associated with unfavorable morphological change of the nasal cavity in elderly group, it is useful to correct dryness of the nasal mucos.
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