INFLUENCE OF PRESSURE ON FORM OF PULSE-CURVE. 151 



Pulsus Paradoxus. Under pathological conditions, especially when there is 

 union of the heart or its large vessels with the surrounding parts, the pulse dur- 

 ing inspiration may be extremely small and changed, or may even be absent. This 

 condition has been called pulsus paradoxus (Griesinger, Kussmaul). 



It depends upon a diminution of the arterial lumen during the inspiratory move- 

 ment. Even in health, it is possible by a change of the inspiratory movement to 

 produce the p. paradoxus (Riegel, Sommerbrodt). 



75. Influence of Pressure upon the Form of the 

 Pulse-Curve. . . 



It is most important to know the actual pressure which is applied to an artery 

 while a sphygmogram is being taken. The changes affect the form of the curve as 

 well as the relation of the individual parts thereof. In Fig. 66, a, 6, c, d, e, are 

 radial curves ; a was taken with minimal pressure, b with 100, c 200, d 250, and e 

 450 grammes pressure, while A, B, C, D, show the relations as to the time of 

 occurrence of the individual phenomena where the weight was successively 

 increased. The study of these curves yields the following results: (1) When the 

 weight is small, the dicrotic wave is relatively less ; the whole curve is high. (2) 

 With a moderate weight (100 - 200 grammes) the dicrotic wave is best marked, the 

 whole curve is somewhat lower. (3) On increasing the weight, the size of the 



C 220 D 240 



Fig. 66. 

 Various forms of curves (radial) obtained by gradually increasing the pressure. 



