The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

COMPARISON OF PERFORMANCE OF TWO VALVED HOLDING CHAMBERS (VHCS) AT FLOW RATES APPROPRIATE FOR SIMULATING PEDIATRIC USE

Jolyon P. Mitchell Ph.D, Sara-Lou Bates, Cathy C. Doyle B.Sc, and Mark W. Nagel HB.Sc
Trudell Medical Aerosol Laboratory, London, Canada

VHCs are recommended for use with pressurized metered-dose inhalers (pMDIs), especially with small children whose coordination between pMDI actuation and the onset of inhalation may be poor. We compared the delivery of a bronchodilator (CFC-Ventolin®, GSK, 90 µg/dose albuterol) via two VHCs (AeroChamber Plusª with medium mask, Monaghan Medical Corp., Plattsburgh, NY, (volume = 149 ml)) and OptiChamber® Advantage, Respironics®, Pittsburgh, PA (volume = 218 ml )) (n = 5 devices/group). We measured total emitted dose (TED) and fine particle (< 4.7 mm aerodynamic diameter) dose (FPD) at 4.9 and 12.0 L/min, representing inspiratory flow rates achieved by small children, by means of a low flow Marple-Miller cascade impactor equipped with USP Induction port, following compendial procedures. Each VHC was washed with an ionic detergent, rinsed and drip-dried to minimize the influence of surface electrostatic charge. 5-doses of medication were delivered at 30 s intervals from pre-primed and shaken pMDIs. The induction port and stages of the impactor and the VHC were subsequently assayed for albuterol by HPLC–UV spectrophotometry. Measurements of fine particle dose (FPD – particles < 4.7 mm aerodynamic diameter) and total emitted dose (TED) are summarized in the table. Fine particle fraction (FPF) is the ratio of FPD/TED, expressed as a percentage.

mean ± S.D

 
4.9 L/min
12.0 L/min
AeroChamber Plusª VHC OptiChamber® Advantage VHCs AeroChamber Plusª VHC OptiChamber® Advantage VHCs
TED (mg) 24.3 ± 2.0 18.0 ± 3.6 32.4 ± 6.0 25.5 ± 1.9
FPD (mg) 23.6 ± 1.8 17.8 ± 3.4 31.8 ± 5.9 25.2 ± 1.9
FPF (%) 97.5 ± 1.0 99.1 ± 3.1 98.1 ± 0.4 98.7 ± 0.1

 

As expected, both types of VHC largely eliminated coarse particles, with values of FPF > 96% at either flow rate. However, both TED and FPD from the AeroChamber Plusª VHCs were significantly greater than their equivalent values from the OptiChamber¨ Advantage VHCs (un-paired t-test, p ² 0.41). The larger volume of the OptiChamber¨ Advantage VHCs was not associated with improved delivery, indicating that other considerations such as inhalation valve design as well as internal geometry may be important.

OF-02-017

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