Effect of Gas Density on Resistance to Respiratory Gas Flow in Man

Abstract

By a previously described method (Amer. Jour. Physiol. 152: 106. 1948), the pressure gradient between the alveoli and the mouth was measured at various velocities of flow of respired gas. A lesser pressure gradient is required to produce a given velocity of flow when the subject breathes a mixture of 80% helium-20% oxygen at ground level or air at simulated altitude than he breathes air at ground level. The effect appears to be due largely to a decreased turbulence in the less dense gases.