A new approach to acid-base metabolism.

E VEBYO}TB KNOWS the distinction between the two kinds of disturbances in the acid-base metabolism: the respiratory, and the nonrespiratory-. Moreover, everyone agrees that the respiratory disturbances ought to be characterized by the CO2 tension of the arterial blood, as this tension is supposed to correspond with that of the alveolar air. When trying to characterize the nonrespiratory disturbances however, we are faced with difficulties. The purpose must be to cheose a value that reflects the nonrespiratory disturbances only, and which is completely uninfluenced by the changes in the acidbase content of the blood caused by hyperand hypoventilation. Various kinds of bicarbonate values have been, and still are being used for this. Most commonly used are total CO2 of plasma, the COs-combining power of plasma, and what we call the standard bicarbonate of plasma. The latter value is defined as the bicarbonate of true plasma, separated from the blood with the hemoglobin completely oxygenated, at a pCO2 of 40 mm. Hg and at 38#{176}. These three values vary in a blood sample when the pCOs and the oxygen saturation are varied. An experiment illustrating this is conducted as follows. A sample of venous blood is drawn into an Ehrlenmeyer flask, well mixed, and distributed among six tubes. In the three tubes (No. 1-3, Fig. 1) the hemoglobin is oxygenated, and in three (No. 4-6), reduced. The blood is equilibrated with C02, so that the pCO2 will be 20, 40, and 80 mm., respectively, in one tube each of the oxygenated and of the reduced blood (Fig. 1).