Pulmonary Arterial Blood Volume and Tissue Volume in Man and Dog

After the injection of an ethyl ether-alcohol solution above the pulmonic valve, the pulmonary arterial circulation time was determined in conscious man by an established body plethysmographic technique and in anesthetized man by a newly developed pneumotachographic method. In the anesthetized dog, estimates of pulmonary arterial circulation time determined by this new method were compared with those simultaneously determined by the plethysmographic method; agreement was good. The usefulness of applying corrective factors for the right-to-left intrapulmonary shunt and the uptake of ether gas from the alveoli into the blood while the ether gas is being evolved from the initial injection was evaluated from the dog experiments. In five humans with normal pulmonary arterial pressures, pulmonary arterial blood volume estimated by these methods was 172 ± 22 (sd) ml. Estimates of pulmonary tissue volume in both dogs and man were much larger than previously reported values determined from the tritiated water space of the lungs but more in keeping with previously published estimates of the total water content of the lungs determined at postmortem examination.