6 



Scientific Proceedings (109). 



tion" and consists in the simultaneous determination of the carbon 

 dioxid dissociation curve of the blood at body temperature and 

 the carbon dioxid content of both the arterial and venous blood 

 as they occur in the body. 



This method has been applied in whole or in part to twenty- 

 three subjects, on whom thirty-eight observations have been made. 

 The group studied consisted of three normal persons, seven patients 

 with decompensated cardiac disease, six patients with severe 

 anemia, four with diabetes, two with emphysema, one with poly- 

 cythemia and one with chronic nephritis. Whenever it was 

 found practicable the alveolar carbon dioxid tension was also 

 determined by the Haldane 1 method. 



The normal limits of variation in height of the carbon dioxid 

 dissociation curve at 37. 5 0 C. were found to agree with those 

 established by previous observers. At 42 mm. CCVtension the 

 limits of variation of the carbon dioxid combining power of whole 

 blood are 43 and 56 volumes per cent. The height of the normal 

 resting dissociation curve is as Christiansen, Douglas and Haldane 2 

 previously found, characteristic for each individual. 



In three of the seven patients with cardiac decompensation 

 the dissociation curve lay below the normal limits, indicating a 

 real reduction of the available alkali of the blood. The carbon 

 dioxid capacity of the venous plasma was, however, normal in 

 these cases. The difference between the CCVcapacity of whole 

 blood and that of venous plasma found in these cases may be 

 explained by the fact that the carbon dioxid capacity of the 

 venous plasma as determined by the Van Slyke 3 method is 

 dependent upon the carbon dioxid content of the blood as it 

 exists in the veins. Therefore, in conditions like cardiac decom- 

 pensation, in which there is a retention of carbon dioxid in the 

 venous blood, the carbon dioxid combining capacity of the venous 

 plasma is inapplicable as a measure of the available alkali of the 

 blood. For this reason whole blood should be used or else the 

 whole blood should be equilibrated with a standard CCVair 

 mixture before the plasma is removed. 



1 Haldane and Priestley, Journ. Physiol., 1904-5, xxxii, 225. 



3 Christiansen, Douglas and Haldade, Journ. Physiol., 1914, xliii, 244. 



3 Van Slyke, Journ. Biol. Chem., 1917, xxx, 347. 



