The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

IN VITRO AND META-COMPARISON OF MEDICATION DELIVERY OF LARGE VOLUME MEDICATION NEBULIZERS ON OXYGEN AND HELIOX.

M. McPeck1


Background: Continuous aerosolized drug delivery by large volume medication nebulizers (LVMNs) has typically been characterized by gravimetric or volumetric measurements of aerosol generation rate (AGR), which measures total nebulizer liquid output in mL/hr. However, because AGR can not differentiate between liquid output in the particulate phase (aerosol) vs the vapor phase (evaporation) [Chest 1997;111:1361-65] it does not correlate to actual aerosol delivery (Inhaled Mass, IM) as the Stony Brook group previously determined [Chest 1997;111:1200-05]. STUDY QUESTIONS: What is the actual aerosol delivery (IM) of the Healthline Medicator Möbius (MM) continuous aerosol delivery device, and how does it compare to the previous study of the original Vortran HEART nebulizer (HN) or current studies of other LVMNs powered by O2 and heliox (HeO2)?

Methods: I performed duplicate in vitro tests of new Airlife™ “Misty Finity™” (MF), DHD “Flo-Mist™” (FM), and Healthline MM LVMNs, under nearly identical conditions as the 1997 study. MF and FM were filled with 200 mL and MM was filled with 80 mL of radiolabeled (99mTc) 0.9% NaCl solution. A piston ventilator created a sinusoidal breathing pattern (f 20 BPM; VT 500 mL; I:E 1:1) to draw aerosol during inspiration into a cotton ball filter inserted into the mouth of head model from the 1997 study. MF was studied with a typical ported aerosol mask as the patient interface while FM was studied with both a ported aerosol mask and a valved non-rebreathing mask/bag assembly. Masks were “hot glued” to the face of the head model to prevent shifting and leakage during the study. Radioactivity collected on the cotton ball filters was measured at 15 min intervals for 30 mins and the results expressed as % of the total radioactivity in the nebulizer fill and extrapolated to 60 mins to derive the IM in %/hr.

Results:
Inhaled Mass (%/hr) for the different LVMNs and masks is shown graphically.

Conclusion:
The MM, when compared against the previous study of the HN and the present study of the MF and FM, renders the greatest percentage of drug delivery on both O2 and HeO2, a fact that can be effectively used to safely dose the patient without wasting medication.


Drug Delivery Rate of LVMNs
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