CH. XXVII.] DIABETIC COMA 405 



" If from any cause, such as cerebral haemorrhage or circulatory 

 failure, the circulation through the respiratory centre is interfered 

 with, or if the absorption of oxygen is interfered with by such causes 

 as diminished barometric pressure or pathological conditions in 

 the lungs, the occurrence of periodic or Cheyne-Stokes breathing 

 becomes easily intelligible." (Haldane and Douglas). 



Pathological Cheyne-Stokes respiration may be removed by 

 administration either of oxygen or of carbonic acid. 



Pembrey and Pitts have also taken tracings of the same condition 

 in the hibernating dormouse, hedgehog, marmot, and bat. In some 

 cases the respiration has the typical Cheyne-Stokes character, with a 

 gradual waxing and waning. In other cases periods of respiratory 

 activity alternate with periods of apnoea, but all the respiratory 

 efforts are about equal in force. This is known as Biot's respiration, 



FIG. 311. Biot's respiration in hibernating dormouse. The line marked T gives time in seconds. 

 Line 1 gives the tracing of a respiratory group which occurred once every SO seconds, the tempera- 

 ture of the animal being 11 C. On warming the animal to 13 C. the respiratory groups became 

 more frequent (line 2). On warming the animal still further it awakened, and breathing, at first 

 accompanied by shivering, became continuous. (Pembrey and Pitts.) 



and is illustrated by the accompanying illustration taken from a 

 hibernating dormouse. 



Diabetic Coma. 



In the preceding chapter conditions have been considered which 

 depend upon the stimulus given to the respiratory centre by the con- 

 dition of the gases in the blood. Carbonic acid is, however, not 

 the only body capable of affecting the respiratory centre; lactic 

 acid, as we have just seen, will stimulate it, and probably all other 

 acids in solution will do the same. If, therefore, other acid radicals 

 are thrown into the blood, the respiration will increase till the 

 amount of carbonic acid in the blood is proportionally decreased. 

 It is the total concentration of such radicals, or rather of the 

 hydrogen ions which they carry in their wake, that remains a 

 constant factor. In diabetic coma other acids (e.g., hydroxybutyric) 

 make their appearance, and the respiration is exaggerated till only 

 a small amount of carbonic acid remains. 



