Gaseous Diffusion from Alveoli to Pulmonary Vessels of Considerable Size.

• In studies of gas exchange between the lung and the pulmonary circulation it is generally assumed that the principal exchange takes place at the level of the pulmonary capillaries. The work presented here shows that some gaseous exchange can occur as well between the lung and vessels of macroscopic size. Hydrogen gas when administered to a subject by inhalation can be detected in the pulmonary artery wedge position within two seconds after the inhalation of hydrogen.