METABOLISM IN RESPIRATION AND CIRCULATION 547 



he found the arterial oxygen and carbon dioxid to be normal, but in two 

 out of three cases with decompensation (one with congenital heart disease) 

 the oxygen content was slightly below normal. In none of his cases was 

 there any evidence of retention of carbon dioxid. Harrop obtained similar 

 normal results in analyses of the blood gases in compensated heart disease, 

 and found the saturation of the blood abnormally- low in seven out of nine 

 decompensated patients. As compensation was regained and pulmonary 

 symptoms disappeared, the oxygen content of the blood tended to rise. 

 The average normal percentage saturation of the blood was 95.5, and, in 

 only three of the patients did it fall below 85, and the lowest saturation 

 was 81.4. No striking variations from the normal were found in the 

 carbon dioxid, although the decompensated cases frequently had amounts 

 slightly below normal. In diseases of the lungs (tuberculosis, pleural 

 effusion, pneumonia) Hiirter found that the oxygen saturation was normal 

 or slightly decreased and the carbon dioxid was normal. In a large series 

 of observations on cases of pneumonia (lobar pneumonia, postinfluenzal 

 bronchopneumonia), Stadie found that the arterial blood was rarely more 

 than 90 per cent saturated with oxygen while his normal figures were 

 between 85 and 98 per cent. A fall below 85 per cent was usually accom- 

 panied by the development of cyanosis, and no case recovered in whom 

 the arterial saturation fell below 80 per cent. Six to twelve hours before 

 death the arterial oxygen saturation was found as low as 32 per cent. 

 These changes were apparently due to the mechanical effect of exudate 

 and edema in the lungs, and not to the infectious process. The venous 

 oxygen paralleled the arterial closely except in cases with failing circula- 

 tion where it was disproportionately low. Lundsgaard found the oxygen 

 unsaturation of the venous blood (difference between oxygen capacity 

 and venous oxygen content) to be essentially normal in cardiac patients 

 with compensated lesions, whereas it was much increased during periods 

 of decompensation. Scott(a) has made observations on the total carbonate 

 content of the arterial and venous plasma in patients with pulmonary 

 emphysema, and, finds it to be increased. Siebeck(a) likewise, from 

 studies on the "reduced volume" or dead space and "effective middle 

 capacity" or lung volume, concluded that the arterial blood in emphysema 

 is oxygen poor, and carbon dioxid rich, in comparison to that of normal 

 individuals. 



As stated above, values for venous oxygen or carbon dioxid have less 

 significance than those for arterial blood. This is likewise true of values 

 for alveolar air. However, the carbon dioxid tension of the venous blood 

 as shown by Van Slyke and Cullen, and of the alveolar air according to 

 Peabody(c) (/), is of considerable significance in showing the presence of 

 abnormal acid products which in respiratory and circulatory diseases with 

 normal kidney function must be attributed to disturbed metabolism. On 

 this basis, Forges, Leimdorfer and Markovici explained their findings of 



