The effect of helium on nasal resistance and nasal flows.

Nasal inspiratory resistance and maximal inspiratory nasal flow were measured in 10 normal subjects while they breathed air and while they breathed a mix’ture of 80% helium and 20% O2. After the less dense helium-O2 mixture, there was a nonsignificant increase in K1 (15 ± 93%), a 56 ±20% decrease in K2(p< 0.001), and a 48 ±20% increase in maximal inspiratory nasal flow (p< 0.001). This is consistent with the accepted concept that K represents resistance to laminar flow and K2, resistance to nonlaminar flow (turbulent flow and/or flow due to convective acceleration), and that nonlaminar air flow predominates in the nose.