Pulmonary gas transport time: larynx to alveolus.

The transport time of gas from the larynx to pulmonary alveolar capillary blood was directly measured by injecting a bolus of carbon monoxide into the inspired airstream of dogs and photoelectrically monitoring the formation of carboxyhemoglobin in the capillaries on the surface of the lung. The rapidity of transit (0.3 second) implies that gas transport during inspiration is facilitated by an interaction between bulk flow and diffusion.