Terbutaline aerosol from a metered dose inhaler via a 750 ml spacer

The effect on large and small airways of a pressurized terbutaline aerosol delivered via a 750 ml spacer, or via an ordinary actuator, was investigated in a double-blind study of 15 patients with reversible obstructive airflow disease. There was significant bronchodilatation with both devices as measured byRaw, FEV_1.0, PEFR, MEF₇₅, MEF₅₀, and MEF₂₅.Raw showed, a significant difference in favour of the 750 ml spacer. Measurement of Closing Volume (CV) revealed a significant decrease with the spacer, but with the ordinary actuator there was a slight increase in CV; the difference between the devices was significant. The quotient Closing Volume/Vital Capacity (CV/VC%) was significantly decreased with the 750 ml spacer but not with the ordinary actuator. The decrease in volume of isoflow (Viso \(\dot V\) ) was more pronounced with the spacer but not significantly so. The results suggest that use of a 750 ml spacer may promote more extensive peripheral deposition of the drug in the bronchial tract.