The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

AEROSOL CHARACTERIZATION OF A NEW NEBULIZER FOR HELIOX SOURCE GAS

N. Tiffin1, R. Vohra2, L. Weinstein2, S. Nowak2


Objective:
Nebulizers designed for use with oxygen or air require high flows of heliox to create aerosol in the respirable range. This aerosol is not well characterized for standard nebulizers and the high flow of heliox is costly. The objective of this study was to characterize the performance of a new nebulizer designed for use with Heliox (80/20) gas and compare it to an industry standard nebulizers.

Method: Using a Malvern Spraytec laser diffractor we measured the aerosol particle size (VMD), total output rate (TOR), respiratory fraction (RF) and calculated the respiratory drug delivery rate (RDDR = TOR x RF). Heliox flows of 7, 9 and 15 L/min were used and normal saline was nebulized. We performed 3 trials with each flow.

Results: Table One shows the characterization for each nebulizer. Respiratory drug delivery rate (RDDR) is the product of total output rate (TOR) and respiratory fraction (RF).

Conclusions: Small changes in heliox flowrate can inordinately alter the aerosol characteristics. The Pronto Heliox disposable nebulizer provides excellent nebulization performance using a flow of 9 lpm of heliox source gas (80/20) similar to an industry standard breath enhanced reusable nebulizers at flow rates of 15 lpm. The Pronto Heliox has the potential to save heliox gas and provide the clinician with an alternative to other nebulizers which have not been designed for heliox and which have not been characterized with alternative gas sources.

Figure One: Aerosol Characteristics of Nebulizers using Heliox as Source Gas
  GasFlowrate (L/min) VMD (um) RF .1-5 (%) TOR (ml/min) RDDR (ml/min)
Pronto Heliox Heliox 7 5.8 46.9 .257 .120
Pronto Heliox Heliox 9 2.4 71.4 .342 .244
LC Plus Heliox 15 3.6 61.9 .478 .295
8900 Heliox 7 6.7 40.2 .202 .081

VMD = volume mean diameter particle size; RF = respiratory fraction (.1 - 5.0); TOR = total output rate of nebulizer; RDDR = RF X RF (respirable drug delivered to the patient over time)


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