The carbon dioxid dissociation curve and the arterial and venous carbon dioxid tension of human blood in health and in disease

Abstract

A method for the direct determination of the carbon dioxid tension of human arterial and venous blood has been applied to a series of normal and pathological subjects. The method is similar to one recently described by Means, Bock and Woodwell 1 for the determination of arterial carbon dioxid tension, but was developed and applied by us independently before the appearance of Means' paper. It is a development of the work of Henderson and Haggard 2 on the “Hemato-Respiratory Function” and consists in the simultaneous determination of the carbon dioxid dissociation curve of the blood at body temperature and the carbon dioxid content of both the arterial and venous blood as they occur in the body.

This method has been applied in whole or in part to twentythree subjects, on whom thirty-eight observations have been made. The group studied consisted of three normal persons, seven patients with decompensated cardiac disease, six patients with severe anemia, four with diabetes, two with emphysema, one with polycythemia and one with chronic nephritis. Whenever it was found practicable the alveolar carbon dioxid tension was also determined by the Haldane¹ method.

The normal limits of variation in height of the carbon dioxid dissociation curve at 37.5° C. were found to agree with those established by previous observers. At 42 mm. CO₂-tension the limits of variation of the carbon dioxid combining power of whole blood are 43 and 56 volumes per cent. The height of the normal resting dissociation curve is as Christiansen, Douglas and Haldane² previously found, characteristic for each individual.

In three of the seven patients with cardiac decompensation the dissociation curve lay below the normal limits, indicating a real reduction of the available alkali of the blood. The carbon dioxid capacity of the venous plasma was, however, normal in these cases.