SALBUTAMOL TREATMENT OF ACUTE SEVERE ASTHMA IN THE ED - MDI VERSUS HAND-HELD NEBULIZER

The objectives of this study were to compare the efficacy of salbutamo l delivered by either metered-dose inhaler plus spacer (MDI-spacer) or by wet nebulization (NEB), and to determine the relationships between physiologic responses and plasma salbutamol concentrations. Asthmatic patients presenting to the emergency department (ED) with acute sever e asthma (forced expiratory volume in the first second [FEV1] less tha n 50% of predicted) were enrolled in a randomized, double-blind, paral lel-group study. The MDI-spacer group received salbutamol, delivered v ia MDI into a spacer device, in four puffs actuated in rapid successio n at in-minute intervals (2.4 mg/h), The NEB group was treated with ne bulized salbutamol, 1.5 mg, via nebulizer at 15-minute intervals (6 mg /h). Doses were calculated on the basis of the percentage of total dos e that reaches the tower airway with both methods. The protocol involv ed 3 hours of this treatment. Mean peak expiratory flow rate (PEFR) an d FEV1 improved significantly over baseline values for both groups (P = .01). However, there were no significant differences between both gr oups for PEFR and FEV, at any point studied. The examination of the re lationships between cumulative dose of salbutamol and change in FEV1 s howed a significant linear relationship (P = .01) far both methods (MD I r = .97; NEB r = .97). The regression equations showed that for ever y 1 mg of salbutamol by MDI-spacer, 2.5 mg are needed from nebulizatio n to have equal therapeutic response. At the end of treatment, the sal butamol plasma levels were 10.1 +/- 1.6 ng/ml for the MDI-spacer group and 14.4 +/- 2.3 ng/ml far the NEB group (P = .0003). Both groups sho wed a nonsignificant heart rate decrease. A significant group-by time interaction means that differences between groups increased with time (P = .04), Additionally, the NEB group presented a higher incidence of tremor (P = .03) and anxiety (P = .04), reflecting larger systemic ab sorption of salbutamol. These data indicate that when doses used are c alculated on the basis of the percentage of total drug that reaches th e lower airway, there was equivalent bronchodilatation after salbutamo l administered by either MDI-spacer or nebulization in patients with a cute severe asthma. However, nebulizer therapy produced greater side e ffects related to the increase in salbutamol absorption and higher pla sma level. Copyright (C) 1998 by W.B. Saunders Company.