title: Effects of ultrasonically nebulized distilled water on respiratory resistance and breathing pattern in normals and asthmatics.
abstract: The purpose of this study was to analyze changes in respiratory resistance (Rrs) and breathing pattern in normal and asthmatic subjects after exposure to ultrasonically nebulized distilled water (UNDW). After measurement of baseline Rrs and breathing pattern, ten normals inhaled UNDW for 30, 60, 120, 240 and 480 s administered at 15 min intervals. After the 480 s exposure, subjects inhaled two puffs of metaproterenol. Rrs was measured immediately before and after each exposure to UNDW and after metaproterenol while breathing pattern was continuously monitored. Ten asthmatics were exposed to UNDW and metaproterenol in a similar time sequence, but the durations of exposure to UNDW were 15, 30, 60, 120 and 240 s. Mean (+/- SD) and frequency histograms of minute ventilation (VE), tidal volume (VT), frequency, inspiratory time, fractional inspiratory time, mean inspiratory flow (VT/TI) and end-expiratory level at baseline were compared to values after each exposure to UNDW and after metaproterenol. All subjects experienced laryngeal irritation or cough during the exposure. In normals, there were no changes in Rrs or any of the components of breathing pattern. In asthmatics, 15 and 30 s exposures produced no changes in Rrs or breathing pattern. With subsequent longer exposures, mean Rrs showed a stepwise significant increase, along with parallel increases of VT/TI and end-expiratory level. VE increased after 60 and 120 s exposure, but reached a plateau after 240 s exposure despite continued increase in Rrs.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000328:Adult; D000336:Aerosols; D000403:Airway Resistance; D001249:Asthma / Q000503:physiopathology*; D001985:Bronchial Provocation Tests / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008688:Methacholine Compounds; D012119:Respiration; D014465:Ultrasonics; D014867:Water
chemical_list: D000336:Aerosols; D008688:Methacholine Compounds; D014867:Water