SPECTROPHOTOMETRIC DETERMINATION OF BLOOD OXYGEN

Gasometric methods for estimating blood oxygen are time-consuming. This consideration often limits the number of observations which can be made in the course of experiments requiring oxygen determinations. In many cases it is an arteriovenous difference which is particularly desired, as in the measurement of cardiac output by the Fick principle, or the estimation of oxygen consumption by human liver, kidney, or brain. The present paper describes a rapid, simple spectrophotometric method for determination of arteriovenous oxygen differences with an accuracy satisfactory for ordinary needs. The absolute oxygen content can also be estimated, subject to error caused by "inactive" hemoglobin. The method is based upon the principle that two well hemolyzed samples of blood drawn nearly simultaneously from the same individual will have substantially the same total hemoglobin content, "inactive" hemoglobin (1), turbidity, and content of other light-absorbing material; and that, consequently, the difference in optical densities of the two