1020 



PHYSIOLOGY 



SYSTOLIC OUTPUT OF THE HEART 



Since the height of the arterial pressure depends on the relation 

 between the amount of blood leaving the arterial system by the 

 capillaries and that entering from the heart, the determination of the 

 heart output becomes of considerable importance. Several methods 

 have been used for this purpose. 



Stolnikow and Pawlow practically cut out the systemic circulation 

 altogether and caused the blood from the left ventricle to traverse 



FIG. 404. Diagram of Stolnikow's instrument. 



an instrument (current measurer, Stromaiche) which recorded auto- 

 matically the amount of blood that went through it in a given time. 



In Fig. 404 I and II are two cylinders containing accurately 

 fitting floats, bearing writing levers on their upper ends. Each of these 

 communicates below with two tubes, A and v, one of which is con- 

 nected to the right carotid artery, while the other is inserted into the 

 superior vena cava. All other branches of the aorta, as well as the 

 inferior vena cava, are ligatured. At the beginning of the experiment 

 cylinder II is filled with defibrinated blood. This blood passes down 

 the tube 2v into the right auricle, and so through the right ventricle 

 and lungs, where it is aerated, into the left auricle and ventricle. As 

 'the heart continues beating, the left ventricle expels its contents into 

 cylinder I, so that the piston in I is rising while that in II is falling. 

 As soon as cylinder II becomes empty the tubes Iv and 2a are released 

 and the tubes la and 2v are clamped. The left ventricle now expels 



