The supposed relation between alkalosis and tetany and similar conditions

Abstract

Examination of the work of Wilson, Stearns and Thurlow 1 shows that their conception of an “alkalosis” as one of the consequences of parathyroidectomy rests essentially upon the supposed increases in the oxygen saturation of the blood at definite oxygen tensions. Wilson, Stearns and Thurlow used Barcroft's 2 formula

in which y is the percentage saturation of the blood with oxygen, x is the oxygen tension in millimeters of mercury, and n is a constant to which Barcroft assigned the value 2.5 for human blood. Wilson, Stearns and Thurlow assumed the same value for dog blood although calculations from Barcroft's value for dog blood (Barcroft, page 50) show that, in this case, the value of n was not 2.5, but approximately 2.2. Barcroft worked at 40 mm. CO₂, Wilson, Stearns and Thurlow at 0 mm. CO₂. According to Barcroft, this difference does not affect the value of n in human blood. But calculating from the figures of Wilson, Stearns and Thurlow, which differ considerably from one another, the value of n is found to be not 2.5, nor 2.2, but approximately 1.5. Using this value of n in recalculating the value of K from the data of Wilson, Stearns and Thurlow it is found that this is not regularly greater in the blood of parathyroidectornized dogs than in the blood of normal dogs. The significance of such changes in percentage oxygen saturation as do occur is obscure. Many factors, other than change in reaction or in alkaline reserve may be responsible. Barcroft's figures (Barcroft, page 62) indicate a specific effect of phosphates in increasing the value of K and decreasing that of n. Moreover, any unrecognized decrease in n will increase the apparent value of K.