Histamine log(dose)-response curves in asthmatics. A comparison between the Wiesbadener Doppelinhalator and the De Vilbiss Model 645 nebulizer.

In 9 asthmatic patients log(dose)-response curves were obtained on 4 successive days with the Wiesbadener Doppelinhalator (WDI) and the De Vilbiss (De V) 645 nebulizer, respectively. log(dose)-response was expressed as a quadratic regression equation. From those equations the dose, causing a fall in response (FEV1) of 10% of the initial value, was obtained and defined as the provocative concentration (PC(10] or sensitivity. Moreover, the reactivity was defined as the slope of the linear regression through the steeper part of the curve. Although we compared the De V and the WDI log(dose)-response curves after correction for the different liquid output, a significantly greater sensitivity was found for the De V nebulizer. As to the reactivity, no significant differences were found. The difference in sensitivity could perhaps be explained by the fact that, as compared with the De V nebulizer, the WDI may cause a larger deposition of aerosol on the throat and the pharynx, due to the much greater linear velocity of its aerosol jet.