TO 



DONALD D. VAN SLYKE 



Compensation for the excessive bicarbonate is accomplished by a 

 Slowing of the respiration until sufficient CO 2 is held back to restore the 

 BHCO 3 : H 2 CO 3 ratio, and therefore the pH, to normal. The condition 

 then shifts to that represented by Area 4. Presumably alkali excretion 

 and inhibited ammonia formation continue until the bicarbonate also is 

 reduced to normal, and the condition shifts back to the normal represented 

 by Area 5. 



Maximum tolerated pH range 



Average available 

 alkali normally 

 In buffers other 

 than BHC0 3 



Average available 

 alkali normally 

 in BHC0 3 



pH7.8 7.7 7.0 7.5 7.4 



Fig. 3. Normal and abnormal variations of the bicarbonate and pH values in 

 arterial and venous human whole blood. (The arterial conditions are indicated by 

 the solid lines and curves, venous by the dashed lines and curves.) BHCO 3 and pH 

 values are represented with rectangular coordinates, and the diagram, as compared 

 with Figure 2, is simplified by omitting H 2 C0 3 and CO 2 tension values. BHCO 3 values 

 are expressed in terms of millimolecular concentration ( 1 millimolecular BHCO S = 

 2.24 volumes per cent of bicarbonate CO 2 ). 



For a given individual it appears that the normal pH range is relatively narrow, 

 perhaps not over 0.02, and the BHC0 3 range similarly narrow (Parsons, 1917; Peters 

 and Barr, 1921); so that abnormalities in a given subject can be determined more 

 accurately by comparison with his individual norm than by comparison with the 

 entire Area 5, which covers normal individuals as a class. 



Area 5 is approximately that covered by the nomogram of L. J. Henderson (1921, 

 p. 414). 



Although it appears certain that uncompensated alkali excess causes 

 tetany, it is not certain that all tetany results from over-alkalinity in the 

 blood. In the tetany caused by parathyroidectomy the results of McCann, 

 and of MacCallum and his coworkers are at variance as to whether alkalosis 

 exists or not. 



Areas 2 and 3. Uncompensated C0 2 Deficit. The condition has been 

 caused in men by hyperpnea either voluntary (Collip and Backus(&), 

 1920; Davies, Haldane, and Kennaway, 1920; Grant and Goldman, 1920; 

 Milroy, 1914), or induced by breathing air with a diminished oxygen con- 

 tent, such as is encountered at high altitudes (Haggard and Henderson(rf), 

 1920; Haldane, Kellas, and Kennaway, 1919). 



