ACIDOSIS 73 



we have allowed, chiefly on the basis of data yielded by C0 2 absorption 

 curves of whole blood. 



. , (Alkali deficit, or. The blood condition repre- 

 Area 6. Compensated! ^^ , - .. 

 [C0 2 deficit 



sented by Area 6 is that commonly observed in the acidoses of metabolic 

 diseases, in diabetes, nephritis, infant marasmus. Until recently it has 

 been the only form of naturally occurring acidosis observed clinically, ex- 

 cept in the premortal state. Since the pH is normal, the alkali neutralized 

 by the invading acids is solely that of the bicarbonate (see page 63) 

 and the fall in blood bicarbonate is an exact measure of the acid that 

 enters the blood. For the reason that this condition at the time represented 

 all clinically observed acidoses, Van Slyke and Cullen in 1917 defined 

 lowered blood bicarbonate as characteristic of acidosis. The definition 

 is adequate for compensated alkali deficit, but it is not sufficient to cover 

 the conditions since observed which are represented by Areas 7, 8, and 

 9, and which are likewise caused by acid retention, and by Areas 2 and 3, 

 in which the bicarbonate is reduced without acid retention. 



As the result of accelerated production of acids (diabetes) or retarded 

 elimination (presumably the case in nephritis) the alkali reserve of the 

 entire body is diminished, that of the blood falling parallel with that of 

 the other body fluids. In experimental acid intoxication Goto(c) (1918) 

 has found that the potassium phosphate of the tissues and the CaCO 3 

 of the bones are also reduced. 



In the evident attempt to maintain a normal H 2 CO 3 : BHC0 3 ratio 

 and blood pH, ventilation becomes deeper, and the II 2 CO:5 is reduced in 

 proportion to the BHCO^. Presumably there is during the acid invasion 

 a slight increase in hydrogen ion. concentration, causing the blood condi- 

 tion to shift toward the border of Areas 6 and 9. The respiratory center 

 is, however, at once stimulated, and CO 2 is driven off so that the condition 

 remains in Area 6. 



The path above delineated is not the only one by which Area 6 is 

 reached. A compensated fall of blood alkali may also occur when the 

 primary cause is not acid retention, but excessive respiratory loss of CO 2 . 

 In this case the fall in blood bicarbonate is a compensatory process which 

 tends to prevent the blood reaction from becoming abnormally alkaline. 

 One respiratory stimulant which has, we believe, been satisfactorily 

 demonstrated to have such an effect is oxygen want. Y. Henderson (1920) 

 has shown from data obtained by Fitzgerald, and by Douglas, Haldane, 

 Henderson, and Schneider on their Pike's Peak expedition that the CO 2 

 of the alveolar air is lowered at high altitudes, and varies in direct pro- 

 portion to the barometric pressure. This is also shown by the data of 

 Hasselbalch and Lindhard (1915). Since the rate of CO 2 production is 

 not lowered (Hasselbalch and Lindhard), it is evident that the minute 

 volume of air breathed is increased, an effect which is also noted 



