Experimental physiology / by Sir Edward Sharpey-Schafer.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1934
Catalogue details

Licence: In copyright

Credit: Experimental physiology / by Sir Edward Sharpey-Schafer. Source: Wellcome Collection.

    126/184 (page 114)
    It is not always easy to determine the exact point at which the pulse ceases to be felt. The difficulty is lessened by listening with a stethoscope over the brachial artery at the elbow. As the pressure is raised over the upper arm the pulse beats become heard as distinct taps in the artery at the elbow, but when the pressure is sufficient to occlude the brachial the taps cease. On letting out air and thus diminishing pressure in the armlet the taps reappear. The point at which they again become distinct indicates the systolic pressure in the artery, and is always a little higher than that obtained by palpation of the radial. As the pressure is further lowered the sounds become louder, assume a blowing character ; suddenly the loud blowing sounds become much fainter. This point gives the measure of diastolic pressure. The interpolation between the pump and the manometer of a bag which can be squeezed or allowed to relax by a simple screw adjustment in the manner recommended by Oliver enables the observation to be repeated at will, without the necessity of again pumping air in or letting air out of the apparatus. To recapitulate : Diastolic 'pressure may be determined by (1) inspection of oscillation in manometer (lowest point where oscillations are maximum) ; (2) auscultation of brachial artery (where “ blowing ” sounds disappear on deflation). Systolic pressure may be determined by (1) palpation of radial artery (mean of the readings (a) where the radial pulse disappears on inflation and (b) where it reappears on deflation); (2) auscultation of brachial artery (point where sound disappears on inflation). Determine the diastolic and systolic pressures by the above methods, noting the results.