pulse-rate-variation

The text notes how pain affects the mare's pulse rate, increasing it beyond normal healthy levels.

1 chapter across 1 book

Pandaemonium: The Coming of the Machine as Seen by Contemporary Observers 1660-1886 (1985)Humphrey Jennings

1. In December I caused a mare to be tied down alive on her back; she was fourteen hands high, and about fourteen years of age, had a Fistula on her Withers, was neither very lean, nor yet lusty: Having laid open the left crural Artery about three inches from her belly, I inserted into it a brass Pipe, whose bore was one sixth of an inch in diameter; and to that, by means of another brass Pipe which was fitly adapted to it, I fixed a glass Tube, of nearly the same diameter, which was nine feet in Length: Then untying the Ligature on the Artery, the blood rose in the Tube eight feet three inches perpendicular above the level of the left Ventricle of the heart: But it did not attain to its full height at once; it rushed up about half way in an instant, and afterwards gradually at each Pulse twelve, eight, six, four, two, and sometimes one inch: When it was at its full height, it would rise and fall at and after each Pulse two, three, or four inches; and sometimes it would fall twelve or fourteen inches, and have there for the same Vibrations up and down at and after each Pulse, as it had, when it was at its full height; to which it would rise again, after forty or fifty Pulses.

The chapter describes a detailed physiological experiment conducted on a mare to observe the dynamics of blood flow and pulse. By inserting brass and glass tubes into the mare's left crural artery, the observer measures the height and fluctuations of the blood column in response to the heart's pulses, noting variations due to the mare's pain and comparing the pulse rate to that of a healthy horse and human. The experiment concludes with a comparison of blood jet height when exposed to open air versus confined in a tube.