The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

SECONDARY FLOW OF AIR AND HELIOX THROUGH A CLOSED DILUTION NEBULIZER IMPROVES BRONCHODILATOR DELIVERY

James B. Fink, MS, RRT, RCP, John D. Calebaugh, RRT, RCP, and Rajiv Dhand, MD, Hines VA Hospital and Loyola Stritch School of Medicine, Hines, IL.

Background: Large volume nebulizers have been used to deliver continuous bronchodilator therapy to treat refractory acute airway obstruction. He:O_{2} has been advocated in these patients to reduce airway resistance and improve aerosol delivery, but has been shown to reduce aerosol output and efficiency when used to operate pneumatic nebulizers as a primary gas source. We wanted to determine the effects of both air and He:O_{2} on bronchodilator delivery when used as a secondary gas in a closed dilution nebulizer.

Methods: A prototype closed dilution nebulizer (Hope, B&B Medical) was used to nebulize a solution of 30 mg of albuterol sulfate with normal saline to a fill volume of 50 mL. The nebulizer was operated with oxygen at 13 L/min as the primary gas flow, with a seconary flow of air and 70:30 He:O_{2} at 22 L/min, and with no secondary flow (n=3). The standing cloud method was employed with aerosol collected on a filter attached to a mouthpiece, distal to 6 feet of standard aerosol tubing. Aerosol was sampled for 2 minute intervals. Albuterol deposition was determined with spectrophotometry (276 nm), and expressed as µgstandard error. ANOVA was performed with p < 0.05 considered significant.

Results: Delivery of albuterol with oxygen as the primary gas drivign the nebulizer, with no secondary flow was 189.9±6.5µg. The addition of air as a secondary gas flow increased aerosol delivery (333.6±7.2µg; p < 0.0004), while use of 70:30 He:O_{2} as secondary flow resulted in even greater delivery (430.4±17.07; p < 0.005).

Conclusion: While using oxygen as a primary gas source, an auxillary flow of 22 L/min of both air and He:O_{2} significantly increased aerosol delivery. In contrast to use as a primary gas, He:O_{2} introduced as a secondary gas improved the efficiency of the nebulizer delivery system.

Funded by a grant from B&B Medical Technologies, Inc.

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

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