150 INFLUENCE OF RESPIRATORY MOVEMENTS ON PULSE-CURVE. 



carotid and radial arteries respectively, during Miiller's experiment, 

 in which the dicrotic waves, r, r, indicate the diminished tension in the 

 vessels. In Cj and E 19 taken from the same person during Valsalva's 

 experiment, the opposite condition occurs. 



Fig. 64 



C, curve from the carotid, and R, radial, during Miiller's experiment ; GX and Rj, 

 from the same vessels during Valsalva's experiment. Curves written on a 

 vibrating surface. 



On expiring into a vessel resembling a spirometer (see Respiration), (Waldenburg's 

 respiration apparatus), and filled with compressed air, the same result is obtained as 

 in Valsalva's experiment the blood-pressure falls and the pulse-beats increase; 

 conversely, the inspiration from this apparatus of air under less pressure acts like 

 Miiller's experiment, i.e., it increases the effect of the inspiration, and afterwards 

 increases the blood-pressure, which may either remain increased on continuing the 

 experiment, or may fall (Lenzmann). 



The inspiration of compressed air diminishes the mean blood-pressure (Zuntz), 

 and the after-effect continues for some time. The pulse is more frequent both 

 during and after the experiment. Expiration in rarified air increases the blood- 

 pressure (Zuntz, Lenzmann). The effects which depend upon the action of the 

 nervous system do not occur to the same extent in all cases. Exposure to com- 

 pressed air in a pneumatic cabinet lowers the pulse-curve, the elastic vibrations 

 become indistinct, and the dicrotic wave diminishes and may disappear (v. 

 Vivenot). The heart's beat is slowed and the blood-pressure raised (Bert, 



Fig. 65. 

 Pulsus paratloxus, after Kussmaul E, expiration; J, inspiration. 



Jacobsohn, Lazarus). Exposure to rarified air causes the opposite result, which is a 

 sign of diminished arterial tension. 



