BODY TISSUES AND FLUIDS 457 



aged 32 per cent and in one case reached 68 per cent, the venous un- 

 saturation exceeding 85 per cent. 



The oxygen content of the arterial blood in anemia and heart disease 

 has been studied by Harrop, who likewise made a careful study of the 

 blood gases (oxygen and carbon dioxid) in both. the arterial and venous 

 blood of fifteen normal subjects, his figures for oxygen agreeing closely 

 with those of Stadie. With severe anemia the saturation of the arterial 

 blood did not differ from the normal. Low absolute values were found 

 for the oxygen content of the venous blood, but the normal oxygen consump- 

 tion was maintained. No deviations from the normal were found in 

 arterial and venous blood from cardiac patients without arrhythmias, well 

 compensated, and at rest in bed. With cardiac cases showing varying 

 degrees of decompensation the arterial unsaturation is frequently ab- 

 normally low (sometimes exceeding 15 per cent), although not so low as 

 that found in pneumonia. It is apparent that in many circulatory diseases 

 during decompensation, particularly when there are physical signs of 

 pulmonary congestion, there is a disturbance of the pulmonary exchange, 

 as indicated by the lowering of the percentage saturation of the arterial 

 blood with oxygen. 



Carbon Dioxid. Recent studies on the carbon dioxid of the blood have 

 been devoted largely to the utilization of this determination as a means of 

 ascertaining the carbon dioxid capacity of the blood. This determination, 

 as Van Slyke and Cullen have pointed out, furnishes a most excellent 

 method of ascertaining the degree of an acidosis, since the bicarbonate of 

 the blood represents the excess of base which is left after all non-volatile 

 acids have been neutralized and in this sense constitutes the alkaline re- 

 serve of the body. Before entering into a discussion of this phase of the 

 subject, however, it may be well to consider the actual content of carbon 

 dioxid in normal human blood. 



Harrop(fr) has presented some interesting figures for the oxygen and 

 carbon dioxid content (according to the Van Slyke method) of both arterial 

 and venous blood upon individuals with normal heart and lung findings. 

 A few of these are given in the table on page 458. 



As will be noted the CO 2 content of arterial blood in the first 

 six cases tabulated averages about 50 volumes per cent, while that of the 

 venous blood is 4 volumes per cent higher. After 15 minutes of brisk 

 exercise Harrop found the CO 2 content of both arterial and venous blood 

 reduced, with a considerable increase in the venous-arterial whole blood 

 difference. The oxygen consumption waa, however, only slightly in- 

 creased. 



Smith, Means and Woodwell, employing the Henderson apparatus, 

 found the CO 2 content of eight normal whole bloods to average 50.4 vol- 

 umes per cent, while the venous blood showed 58.7 volumes per cent, a 

 difference of 8.3, which is considerably greater than that recorded below. 



