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Optimal particle size for beta 2 agonist and anticholinergic aerosols in patients with severe airflow obstruction
1Department of Pulmonary Diseases, University Hospital Utrecht, The Netherlands.
Background:
The optimal particle size of a beta 2 agonist or anticholinergic aerosol in patients with severe airflow obstruction is unknown.
Methods:
Seven stable patients with a mean forced expiratory volume in one second (FEV1) of 37.9% of the predicted value inhaled three types of monodisperse salbutamol and ipratropium bromide aerosols with particle sizes of 1.5 microns, 2.8 microns, and 5 microns, respectively, and a placebo aerosol. The volunteers inhaled 20 micrograms salbutamol and 8 micrograms ipratropium bromide, after which lung function changes were determined and analysed with repeated measurements analysis of variance (ANOVA).
Results:
Greater improvements in FEV1, specific airway conductance (sGaw) and maximum expiratory flow at 75%/50% of the forced vital capacity (MEF75/50) were induced by the 2.8 microns aerosol than by the other particle sizes.
Conclusions:
In patients with severe airflow obstruction the particle size of choice for a beta 2 agonist or anticholinergic aerosol should be approximately 3 microns.