High-dose MDI salbutamol treatment of asthma in the ED.

Beta-adrenergics have long been under special scrutiny because of their potential for cardiotoxicity. To assess the safety of high doses of salbutamol delivered by metered dose inhaler (MDI) with spacer in the emergency department (ED) setting, 11 patients (mean age 33 +/- 12.2 years) with severe acute asthma were studied. All patients were treated with 400 micrograms of salbutamol at 10-minute intervals for 3 hours (1,200 micrograms each 30 minutes or 7,200 micrograms at 180 minutes. There were dose-related significant increases in forced expiratory volume in the first second (FEV1) and peak expiratory flow (PEF) (P < .01), with a net mean increase of 90.4% and 80.1%, respectively. A significant (P < .01) reduction of heart rate was observed with treatment. At the end of protocol, reductions ranged from 7 beats/min to 35 beats/min (mean decrease 10.6 +/- 10.5 beats/min). There was no prolongation in the QTc interval. Mean baseline serum potassium was 4.23 +/- 0.53 mmol/L and decreased nonsignificantly after treatment to 3.99 +/- 0.62 mmol/L. Only 4 patients showed net decreases. There were no significant changes in oxygen saturation and plasma glucose. The mean end-treatment salbutamol level was 10.0 +/- 1.67 ng/mL. These data support the notion that treatment of acute asthma patients in the ED with 2.4 mg salbutamol per hour delivered by MDI and spacer produce satisfactory bronchodilation, low serum concentration, and minimal extrapulmonary effects.