ACIDOSIS 49 



accompanying certain forms of renal disease (chronic interstitial nephri- 

 tis), which raises the question as to whether the retention may not be 

 due to faulty elimination of the bicarbonate rather than to its retention in 

 order that a deficient alkaline reserve may be corrected. It has not been a 

 very simple matter to entirely disprove this possible explanation, and ex- 

 periments of a variety of types have had to be devised in connection with 

 the problem. One of them consists in determining the effect of a second 

 dose of bicarbonate administered to an acidosis patient to whom a suffi- 

 cient amount had previously been given to render the urine just alkaline. 

 It has been found that a few grams now suffice, indicating, apparently, 

 that the alkaline reserve must have been restored to its normal level. 

 Even to this experiment the objection can be raised, however, that the 

 large doses 'were retained because the threshold of the kidney for the ex- 

 cretion of bicarbonate was a very high one, and that the second, smaller 

 administration just sufficed to overstep this threshold. 



Sellards' careful work with this method seems quite clearly to establish 

 its value, however, and for practical purposes it is probably the most prac- 

 ticable test of acidosis at present available in routine clinical work. It 

 has the important advantage, furthermore, of being simple and of requir- 

 ing no elaborate apparatus. 



It may be advantageous in this place to classify the possible causes 

 which might lead to a want of stability in the C H of the blood; that is, 

 to threatened acidosis or alkalosis, not of acidosis in the narrow sense im- 

 plied in Van Slyke's definition, but in the broader sense of any disturb- 

 ance in the acid-base equilibrium. 



In general, a tendency to acidosis might be due to an increase in the 

 numerator or decrease in the denominator of the molecular equation 

 TT .r<(\ -i 



= , or to a proportionate decrease in both. In the latter 



XT T-T 



J\aH(JO 3 20 



case, there would be no actual change in CH, but the alkaline buffer would 

 be depleted so that the change would very readily set in when foreign 

 acids were added. Furthermore, it should be understood that NaHC0 3 

 only stands as a symbol for all substances that might serve as alkaline re- 

 serves, for although this salt is no doubt the most important of these, the 

 alkaline phosphates, of the corpuscles, and the protein of the blood and 

 tissues must also be considered. A tendency to alkalosis which is no 

 doubt extremely rare as a pathologic condition would be due to changes 

 of a reverse character. A theoretic classification of the conditions which 

 might cause these changes is given: 



