The Science Journal of the American Association for Respiratory Care

2000 OPEN FORUM Abstracts

DRUG DELIVERY OF HYDROFLUOROALKANE-ALBUTEROL SULFATE USING INLINE MDI ACTUATORS IN MECHANICALLY VENTILATED LUNG MODEL

A. M. Al-Bagaawi, B.S., RRT, J. L. Rau, Ph.D., RRT, A. Ari, M.S., CRT, CPFT, R. Restrepo, MD, RRT, V. Deshpande, M.S., RRT, Georgia State University, Atlanta, GA

Previous research has shown that the type of metered dose inhaler (MDI) actuating device can have an effect on drug delivery from an MDI during mechanical ventilation. Purpose: The purpose of the study is to investigate the effect of hydrofluoroalkane (HFA)-formulated albuterol sulfate by MDI (Proventil® HFA) on drug delivery in a mechanically ventilated lung model using various MDI actuating devices.

Methods:
MDI delivery of HFA albuterol sulfate was assessed using a dual spray nonreservoir dispenser, the Airlife? Dual Spray MiniSpacer (MiniSpacer, Allegiance), the Hudson RCI Inline MDI Adaptor (Hudson Inline), and the Airlife? MediSpacer (MediSpacer, Allegiance) in a mechanically ventilated lung model using humidified air. All devices were placed in the inspiratory limb of the ventilator circuit, with the nonreservoir devices 22 cm above the patient wye and the MediSpacer at the patient wye. The patient wye and a right angle adaptor were connected to an 8.0 mm endotracheal tube (ETT). An MA-2 provided ventilation at a rate of 10/min, inspiratory flow of 60 L/min and VT = 800 mL. Twelve MDI actuations were given for each trial and synchronized with the beginning of inspiration. Drug dose was collected at the end of the ETT on a filter and analyzed by spectrophotometer at 276 nm. Five samples of each device were tested.

Results:
Drug delivery at the ETT is expressed as a percent of the dose per puff measured from the MDI.

Hudson Inline MiniSpacer MediSpacer
Mean (SD) 4.5% (0.48) 14.8% (1.96) 19.5% (1.43)

There were significant differences across device types (p < 0.0001) when tested by one-way analysis of variance (ANOVA). A Scheffe post-hoc comparison showed significant differences among each of the three device types (p < 0.05). Conclusion: These data suggest that albuterol sulfate from an HFA MDI is delivered more efficiently through a reservoir chamber (MediSpacer) than nonreservoir devices, and that the dual spray MDI adaptor (MiniSpacer) was superior to the unidirectional Hudson Inline adaptor.

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