The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

EVALUATION OF A BI-DIRECTIONAL MDI ACTUATOR FOR INLINE VENTILATOR DRUG DELIVERY.

J.L. Rau. Ph.D., RRT, C.L. Dunlevy, Ed.D., RRT. Cardiopulmonary Care Sciences, Ga State University, Atlanta, GA.

Introduction: Reservoir (spacer) devices are usually used with metered dose inhaler (MDI) aerosol drug administration to improve drug delivery to intubated, ventilated subjects. Purpose: The purpose of this study is to evaluate MDI aerosol drug delivery of albuterol (Proventil^{TM}) through an endotracheal tube (ETT) using a novel bi-directional actuator (Thayer/Allegiance MiniSpacer) in comparison with four other MDI actuator/reservoir devices. The MiniSpacer is a tee-type adaptor inserted in the inspiratory tubing. Methods: The MiniSpacer was compared to the DHD ACE, the Allegiance MediSpacer, the Monaghan AeroVent, and the Hudson Tee for MDI administration of albuterol, using a lung model. All devices were placed as instructed by manufacturer in the inspiratory limb of a disposable, humidified ventilatory circuit. The MiniSpacer was positioned 22 cm above the patient wye. The patient wye and a right angle adaptor were connected to an 8.0 mm ID ETT a dual chambered test lung. Ventilation was provided by an MA-1 with VT = 800 mls, rate = 10/min, and inspiratory flow = 60 L/min. Twelve MDI actuations were used to measure drug dose, which was collected at the end of the ETT on a Baxter two-way bacterial filter. The filter was washed with a 0.2 M HCl solvent buffered with phosphate, and drug amount analyzed using a Beckman DU 640 spectrophotometer at 276 nm. A total of 6 samples of each brand were tested. Results: Drug delivery at the end of the ETT is expressed as percent of the dose measured from the MDI.

Hudson T* MiniSpacer^{?} Aero Vent^{?} MediSpacer^{?} ACE^{?}

Mean 12.0%(0.4) 17.2%(0.5) 17.7%(1.0) 31.8%(0.7) 30.0%

(SE) (0.8)

Range 11.3-13.5% 15.2-18.3% 15.2-22.1% 29.5-34.5% 28.5-

34.0%

Both Kruskal-Wallis and oneway ANOVA gave a significant difference across all brands (p < 0.005). Follow-up comparisons using Scheffe showed a significant difference (p < 0.05) between brands with different superscripts (*, ?, ?). Conclusion: The new bidirectional MDI adaptor was superior to the unidirectional Hudson T adaptor in dose delivery through an ETT, and equivalent to the large-reservoir AeroVent. The tee-type adaptor does not perform as well as the large reservoir MediSpacer or ACE. Clinical differences remain to be determined.

OF-97-111

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