456 



VICTOR C. MYERS 



in an anemic patient, with an oxygen capacity of 6.7 volumes per cent the 

 venous oxygen unsaturation >was 5.2 volumes per cent, indicating that 

 the tissues extract from the blood all the oxygen they need with apparently 

 equal readiness, regardless of whether the extraction leaves a great oxygen 

 reserve in the blood as in polycythemia, or practically no reserve as in 

 anemia. 



Considerable additional information may also be obtained when 

 the study of the oxygen content of the arterial blood is included. Such 

 studies have been conducted on normal and certain pathological conditions 

 by Stadie and by Harrop(&), the arterial blood being obtained from the 

 radial artery. Observations obtained by Stadie for the arterial and venous 

 oxygen, and total oxygen capacity of five normal resting men are given 

 in the table below. As will be noted the arterial unsaturation amounts to 



about 5 per cent while the venous unsaturation slightly exceeds 25 per 

 cent. Similar studies were made on a series of pneumonia cases (chiefly 

 post influenza), a high arterial unsaturation being observed in the fatal 

 cases. A definite relation was found to exist between the degree of cyanosis 

 and the per cent of arterial unsaturation. With increasing cyanosis the 

 arterial unsaturation becomes greater. The venous saturation varies sim- 

 ilarly. Obviously the cyanosis of pnevimonia patients is due to the incom- 

 plete saturation of venous blood with oxygen in the lungs. The range 

 of arterial and venous unsaturation encountered in fatal and nonfatal 

 cases of pneumonia is well illustrated in the table below, taken from 

 Stadie. As will be noted the arterial uu saturation of the fatal cases aver- 



