Sphygmograph

The Sphygmograph or - graf ( altgr. " pulse recorder " ) is a device for permanent recording of pulse frequencies as curves; with him the blood pressure could be measured for the first time without bloodshed.

Operation

For all sphygmograph alternately expanding and contracting artery is a small plate in motion, which in turn acts on a long lever arm. This lever arm writes the movement of the arterial wall on an enlarged scale of a strip of paper, which is rotated by a movement in the uniform motion, and passed in front of the tip of the lever arm. On paper, the pulse movements form into a shape depending on the nature of the investigated pulse variously modified wave line. Knowing the rate at which passes the paper at the lever tip, so you can calculate the duration of a pulse wave; also can be seen on the curve to the gradual ascent and descent of the pulse waves, etc. trace their succession accurately.

History and Development

The first such device was probably by the physiologist Karl Vierordt (1818-1884) developed in 1854. More common was the improved replica of the French Natural History Professor Étienne -Jules Marey in 1860, who later invented the chrono photographic gun. Marey variant drew the curves on soot-covered glass plates. Still constructed in 1891 by Dr. Frey, however, a Sphygmograph after Vierordts principle.

However, the medium term the Sphygmograph could not prevail and was replaced in 1877 by the heart rate monitor forest mountain.

Sphygmophon

A Sphygmophon is a subspecies of sphygmograph. It is a connected with a galvanic battery and phone resilient circuit breaker, the - set to the artery - makes loud audible pulse and its modifications.