Relation of the Plasma and Whole Blood CO 2 in Cancer

Abstract

Van Slyke and Sendroy 1 have worked out a line chart for estimating the factor by which whole blood [CO₂] is multiplied to obtain plasma or serum [CO₂]. This factor is dependent upon the pH, the oxygen capacity and the degree of saturation of the hemoglobin. In the majority of blood analyses presented by these authors, the difference between the observed and calculated value was not over 1 volume per cent. In the values calculated from the data of Peters, Bulger and Eisenman, 2 however, a greater deviation was observed. “The greater variability of these bloods was regarded as due to the fact that they were from a miscellaneous group of hospital patients, many of whom were obviously in very pathological condition.”

In studies on the blood chemistry of a series of hopeless cancer patients we determined the data required to calculate the plasma [CO₂] from the whole blood [CO₂]. The plasma [CO₂] was also determined. We are reporting the results because of the abnormal relationship between whole blood and plasma [CO₂] observed in several instances.

The plasma pH was determined by means of the quinhydrone electrode, by a method (slightly modified) recommended by Cullen. The other data were determined by the Van Slyke-Neil manometric apparatus. We have included analyses of the bloods of several noncancerous individuals. The plasma [CO₂] of this group as calculated from the line chart falls well within the error found by Van Slyke and Sendroy. The greatest deviation between the observed and calculated plasma [CO₂] is 1.2 volumes per cent.

The bloods of 11 hopeless cancer patients were studied. Of these the difference between the observed and calculated plasma [CO₂] was abnormally large in 5 cases.