Two additional studies further illustrate the importance of dose when comparing different aerosol delivery techniques. Jenkins et al and Mestitz et al performed separate cumulative dose response curves prior to commencing a comparison of MDI delivery of (J-agonist bronchodilators with HHN delivery in outpatients with obstructive airways disease. On separate days, subjects would inhale cumulative doses of bronchodilator by MDI or HHN until the maximum degree of bronchodilation was produced.
There was some variation in the equivalent dose of MDI and HHN among the subjects. Both studies concluded that equivalent doses of MDI and HHN bronchodilator resulted in equivalent bronchodilation and clinical improvement. Although these studies differed from the present study in that different bronchodilators were used, terbutaline and albuterol, and the subjects were stable outpatients, the determination of the equivalent dose of MDI and HHN bronchodilator is necessary before we can conclude one delivery technique is superior to the other. Unfortunately, it is impossible to perform comparable dose-response curves in unstable subjects with acute bronchospasm.