PULMONARY ARTERIAL CIRCULATION TIME, PULMONARY ARTERIAL BLOOD VOLUME, AND THE RATIO OF GAS TO TISSUE VOLUME IN THE LUNGS OF DOGS*

Open Access
Publisher Website
Google Scholar
Abstract
A method is described for measuring the circulation time and the volume of blood in the non-exchanging portion of the pulmonary arterial tree. This is based on the injection of ether in alcohol into the pulmonary artery of a dog enclosed in a body plethysmograph, and detecting the arrival of ether at the site of gas exchange from the rise in plethysmograph pressure caused by the entry of ether gas into the alveoli. Cardiac output measurements permitted the calculation of pulmonary arterial and of total pulmonary blood volume; from the volume of ether gas appearing in the plethysmograph pressure record and the partition coefficient of ether between air and water, it was possible to calculate the gas to tissue ratio and hence density of the lung. In 12 dogs, the pulmonary artery circulation time averaged 1.1 seconds, and the lung density 0.23 g/ml. In 5 dogs, the pulmonary arterial blood volume was 51 ml, the total pulmonary blood volume was 190 ml, and the cardiac output was 2750 ml/minute. The method makes possible the determination of pulmonary arterial distensibility, and provides a means of calculating pulmonary blood flow per unit alveolar volume. The injection of ether also permits the measurement of arrival of other injected substances such as lactic acid within the vessels of gas exchange, in order to study the rate of dissociation of CO2 from the blood.