AN IMPROVED METHOD FOR THE DETERMINATION OF CARDIAC OUTPUT IN MAN BY MEANS OF ETHYL IODIDE

Publisher Website
Google Scholar
Abstract
By an improved method of estimation, the distribution coefficient of ethyl iodide between air and blood, in vitro, was found to have an average value of 6.1. By experiments on anesthetized dogs, it was demonstrated that the distribution of ethyl iodide between alveolar air and arterial blood has the same ratio as between air and blood in vitro. A further set of experiments was made to compare the ethyl iodide in alveolar air and arterial blood of human subjects inhaling the same concentrations as used in blood flow determinations. After the subject inhaled ethyl iodide for twelve minutes, 2-5 litres of air having passed through the sampling tube, blood was withdrawn from the radial artery. The concentration of ethyl iodide was analyzed and compared with that estimated from the alveolar sample. It was found that by using the distribution coefficient determined in vitro the ethyl iodide content of arterial blood in man may be determined from a sample of alveolar air. Experiments were then performed on dogs which breathed ethyl iodide; samples of venous blood were withdrawn, and the dogs then rebreathed for several seconds, additional samples of venous blood being taken during the process. Analysis of these samples demonstrated that the ethyl iodide content of mixed venous blood remains constant during rebreathing and can be estimated from that of the rebreathed air. By indirect methods it can be shown that these same principles apply to man. Experiments were then made to estimate the flow through a dog''s lungs perfused at a known rate, by determining the simultaneous concentrations of ethyl iodide in the inspired and expired air and in arterial and venous blood. Based on these experiments, a method of determining the rate of blood flow through the lungs of human subjects was devised and carried out.

This publication has 2 references indexed in Scilit: