The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

HELIUM:OXYGEN REDUCES NEBULIZER EFFICIENCY

Rick Kita RRT, J. Cronin RRT, L. Brennan RRT, R.Dhand MD, P.Fahey MD, MJ Tobin MD, J. Fink, RRT. Div of Pulm and Crit Care Med, Loyola Univ Chicago, Stritch School of Medicine, Maywood, IL.

Patients with acute severe airway obstruction commonly require aerosolized bronchodilators for relief. Helium: oxygen (He:O_{2}) mixtures have been employed as an adjunct to decrease airway resistance and to relieve respiratory distress experienced by these patients. However, the effect of He:O_{2} on aerosol delivery to the lower respiratory tract and pneumatic nebulizer performance has not been determined. METHOD: We compared aerosol delivery with a pneumatic nebulizer (HEART) while driven by He:O_{2} of 80:20 and oxygen at a variety of flow rates. For each experiment, we administered albuterol sulfate (40 mg) with 0.9% NaCl (72 ml) for ten minutes, collecting albuterol on filters distal the nebulizer output and distal to an upper airway/lung model (TTL) which simulated spontaneous breathing. Gas flow and volumes were monitored with a pneumotach/microprocessor (VenTrak) and albuterol was measured with spectrophotometry (n=3). Results: Nebulizer output (mean±SD) when operated at a flow of 10L/min was higher with O_{2} (610.9±39µg) than with He:O_{2} 80:20 (443±59µg; p < 0.005), as was delivery to the lung model (95.6±8 µg, 49±22 µg, respectively; p < 0.03). When He:O_{2} 80:20 flow was increased to 23 L/min, nebulizer output (590±2 µg) increased, and delivery to the lung model (289±15 µg) was greater than with O_{2} at 10 L/min (p < 0.0001). In summary, using standard operating conditions, the efficiency and drug delivery with a nebulizer was reduced when it was operated with He:O_{2} instead of O_{2}, however, when the He:O_{2} flow rate was increased by 250%, the delivery of albuterol to the lung model increased by more than two fold. CONCLUSION: He:O_{2} of 80:20 is less efficient than O_{2} in driving a pneumatic nebulizer at standard operating conditions.

Veterans Administration Research Service

OF-97-177

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