MYOCARDIAL INSUFFICIENCY-Reply

To the Editor:— Dr. Labecki is right. He read the paper more carefully than I or my associates read the proof. The statement on page 509 concerning the direct application of the Fick principle should read, "cardiac output per minute equals the total oxygen consumption divided by the arteriovenous oxygen difference times 100." The only way I can explain it is that I had "A.V." in my manuscript and my secretary interpreted the A.V. incorrectly as auricular-ventricular rather than as it should have been, arteriovenous. I should have caught the error in proofreading. The routine application of the Fick principle in measuring the cardiac output in man has been indirect. However, right heart catheterization permits the direct application in man. There is some preference for determination of the difference between oxygen content rather than carbon dioxide content in the arterial and venous blood samples. The arterial blood is taken from