DETERMINATION OF CARDIAC OUTPUT IN THE DOG BY THE FICK PROCEDURE

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Abstract
In 11 dogs in barbital anesthesia, blood was drawn from the venae cavae (I), from 2 points in the right auricle (II), or from the right auricle and right ventricle (III), without exposure to air and analyzed for O2 content. The avg. differences were (I) 2.57, (II) 0.86, (III) 1.79 ml./100 ml. There may be a large error in cardiac output as estimated by the Fick procedure if venous blood is drawn from the right auricle. In 12 barbitalized dogs, serial detns. of cardiac output were made. A progressive decrease in cardiac output during the first 3-4 hrs. of anesthesia was seen. There were frequent large discrepancies between outputs calculated from O2 data and from CO2 data. This is apparently from variations in respiratory activity, which were marked.