The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

DOSE OUTPUT FROM MDI DISPENSERS IN CLOSED-SUCTION SYSTEMS

Scott Foss BS, David Sladek CRTT, Rebecca English BS, Jean Keppel PhD, Thayer Medical Corporation, Tucson AZ.

Background: Closed-suction circuits are becoming more widely used because of the advantage of not having to break the ventilator circuit for suctioning. The two most frequently used closed-suction systems are the Ballard Trach Care(r) and the Concord Steri-Cath(r). Both have an accompanying metered dose inhaler (MDI) adapter, which is placed on the side of the closed-suction manifold. Laboratory tests in this study show that the MiniSpacer(r) MDI dispenser used with the Allegiance Trach-Eze^{TM} closed-suction system gives a significantly higher dose output than either the Ballard or the Concord.

Method: A ventilator and a humidifier were on the inspiratory limb of the circuit. With the Ballard and Concord systems the patient wye feeds into the closed-suction manifold and the MDI adapter is installed on the facing side of the manifold. With the Allegiance system the MDI adapter goes directly between the wye and the closed-suction manifold. In all cases the manifold feeds into the ET tube, which in this study was followed immediately by a filter. The MDI canister was actuated at the start of inspiration of the ventilator, and we then assayed the total amount of drug/dose collected on the filter. The assay was repeated 10 times for each drug/device combination.

Results: The amount of active ingredient (µg/dose) for each of the three systems is graphed below, for Alupent(r), Maxair^{TM}, and Ventolin(r). Error bars are one standard deviation. On average for the three drugs, the Allegiance system delivered about twice as much as the Concord system and three times as much as the Ballard system. Twotailed t-tests showed that the differences are statistically significant (p < < 0.05).

(See original for figure)

Conclusions: The MiniSpacer differs from the other MDI dispensers in two ways: (1) The nozzle is in the path of the airflow instead of to the side, so the aerosol plume is more readily carried to the end of the ET tube. (2) The dual-spray nozzle delivers higher dose than a single-spray nozzle (Rau JL, Dunlevy CL, Respir Care 1997;42(11):1093).

The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 1998 Abstracts » DOSE OUTPUT FROM MDI DISPENSERS IN CLOSED-SUCTION SYSTEMS