The Effects of Heated and Unheated Distilled-Water Aerosols on Expiratory Flowrates in Persons with Normal Pulmonary Function

Abstract

We examined the effects of heated and unheated distilled-water aerosols generated by large-reservoir jet nebulizers on expiratory flowrates in normal subjects at rest. Methods: Thirty subjects were divided into three groups. The control group breathed room air at 25° C and a vapor pressure of 10-13 torr. One experimental group breathed unheated water aerosol at 18-19° C and a vapor pressure of 19-21 torr. The other experimental group breathed heated aerosol at 36° C and a vapor pressure of 47-49 torr. FEV₁, PEFR, and FEF_25-75% were measured at baseline, immediately after the breathing of inspirate, and 10 minutes afterward—and the percentage of change from baseline was noted. Results: There were no significant differences across the three groups in spirometric variables after the subjects breathed the test inspirates. Subjects in all three groups perceived the breathing conditions as comfortable. A low incidence of cough was reported 1 hour after exposure in both the aerosol-breathing groups but not by the controls. Conclusions: Water aerosol from large-reservoir jet nebulizers has no significant effect on expiratory flowrates in normal subjects at resting levels of ventilation. Water aerosols can provoke cough in normal subjects.