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Am J Respir Crit Care Med. 2001 Jan;163(1):109-14.

Improvement in aerosol delivery with helium-oxygen mixtures during mechanical ventilation.

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Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Affairs Hospital, and Loyola University of Chicago Stritch School of Medicine, Hines, Illinois, USA.


In mechanically ventilated patients with airway obstruction, helium-oxygen (He-O2) mixtures reduce airway resistance and improve ventilation, but their influence on aerosol delivery is unknown. Accordingly, we determined the effect of various He-O2 mixtures on albuterol delivery from metered-dose inhalers (MDIs) and jet nebulizers in an in vitro model of mechanical ventilation. Albuterol delivery from a MDI was increased when the ventilator circuit contained 80% helium and 20% oxygen (He-O2 80/20) versus O2: 46.7 +/- 3.3 versus 30.2 +/- 1.3 (SE)% of the nominal dose (p < 0.001)-the difference was mainly due to decreased drug deposition in the spacer chamber, mean 39.2% and 55.2%, respectively (p < 0.001). Nebulizer efficiency at a flow rate of 6 L/min was five times lower with He-O2 80/20 than O2, and the amount of nebulized drug was inversely correlated with gas density (r = 0.94, p < 0.0001). When the nebulizer was operated with O2, greater albuterol delivery was achieved when the ventilator circuit contained He-O2 rather than O2. In summary, He-O2 mixtures in the circuit increased aerosol delivery for both MDIs and nebulizers in the mechanically ventilated model by as much as 50%. In conclusion, at appropriate flow rates and concentrations, He-O2 in the ventilator circuit may improve aerosol delivery in mechanically ventilated patients with severe airway obstruction.

[Indexed for MEDLINE]

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