Q: Due to its laminar flow, Heliox is more effective (Select one) 

 A) in the small airways 
 B) in the large airways


Answer: B

Heliox, though has a similar viscosity to air but a significantly lower density. In the small airways, resistance is proportional to gas viscosity so Heliox has lesser impact. Moreover, in smaller airways flow is laminar anyway. 

In the large airways, Heliox's low density produces a higher laminar flow in comparison to turbulent flow of air. Laminar flow generates less resistance. Also, in the large airways where flow is turbulent, resistance is proportional to density, so heliox has a significant clinical impact.