The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

RESPIRABLE DOSE OUTPUT COMPARISON OF FOUR MDI SPACERS

Scott A. Foss BS, Joseph N. Lix BA, David T. Sladek CRTT, Jean W. Keppel PhD, Thayer Medical Corporation, Tucson AZ; Paul D. McGowen RRT, Columbia El Dorado Hospital and Thayer Medical Corporation, Tucson AZ

Background: This laboratory study compares the performance of four hand-held MDI spacers: the Airlife^{TM} Hand Held MediSpacer(R), the Aerosol Cloud Enhancer (ACE(R)), the OptiHaler(R), and the AeroChamber(R). Dose output and particle sizes were measured for three drugs: Ventolin(R), Alupent(R), and Intal(R). A cascade impactor (analogous to patient's lung) measured particle sizes and dose output at a constant air flow rate, while a breathing machine simultaneously regulated the flow of aerosol medication through a USP standard throat model (analogous to patient's throat). In all tests the MDI drug canister was actuated at the start of inspiration. Five different devices of each brand were tested with each drug. Method: Output of the spacer goes to the throat model, which feeds into a tee. One branch of the tee feeds into the cascade impactor, with constant flow rate 28 L/min maintained by a vacuum pump; the other branch attaches to a wye that has a breathing machine on one branch and a pressurized air source on the other. The air source is adjusted so that the net flow through the throat model = 0 before the breathing machine is turned on. Flow from air source to vacuum pump bypasses the throat, so flow through the throat is regulated entirely by the cyclic air flow of the breathing machine. Results: Two-tailed t-tests with unequal variances were done; any differences between the averages were considered statistically significant if p < 0.05.

(1) µg of drug per dose in respirable range (1-5 µm) reaching the cascade impactor:

Drug MediSpacer ACE OptiHaler AeroChamber

Ventolin 36 ± 3(StdDev) 26 ± 6 15 ± 4 24 ± 2

Statistically equivalent: ACE/AeroChamber

(Others statistically different.)

Alupent 103 ± 15 29 ± 3 38 ± 11 90 ± 30

Statistically equivalent: ACE/OptiHaler; and

MediSpacer/AeroChamber.

Intal 339 ± 72 137 ± 82 84 ± 25 218 ± 58

Statistically equivalent: ACE/OptiHaler; and ACE/AeroChamber.

(2) µg of drug per dose deposited in throat model: The various drug/device combinations were statistically equivalent except for some differences with Intal:

Drug MediSpacer ACE OptiHaler AeroChamber

Ventolin 0.8 ± 0.1 0.8 ± 0.2 0.8 ± 0.4 1.4 ± 0.6

Alupent 5 ± 3 3 ± 1 2.0 ± 0.4 12 ± 9

Intal 32 ± 14 11 ± 3 9 ± 3 19 ± 7

Conclusions: As is considered desirable, all four devices prevented large quantities of drug from being deposited in the throat model. With respect to respirable dose, the MediSpacer and the AeroChamber always outperformed the OptiHaler, and in 8 out of 9 cases the MediSpacer outperformed the other three devices. Possible reasons are: (a) The volume of the OptiHaler is approximately half that of the other three, so more drug may impact the sides of the OptiHaler directly. (b) Unlike the AeroChamber and the ACE, the MediSpacer has its one-way valves placed outside of the air pathway, so none of the drug impacts a valve during inhalation.

OF-97-047

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 1997 Abstracts » RESPIRABLE DOSE OUTPUT COMPARISON OF FOUR MDI SPACERS