. 176 EXPKRIMBINT XXX. back of the tambour and placing the block against the opposite side of the neck. Then test the working of the outfit by pinching the side tube. With each heart beat there should be an excursion of the lever of at least 5 mm. Adjust posi- tion of tambour on neck, and pressure of spring to give the largest pulsation, Fig. 36. Tambour and ^"h^n bring Writing point very lightly neck spring used to study agaiust drum. Start drum at 5 mm. the human carotid pulse. , , . , , , . , A, spring; B, baii-and- per sccoud, close Side branch with socket joint, on back of • ^• j j j
. 176 EXPKRIMBINT XXX. back of the tambour and placing the block against the opposite side of the neck. Then test the working of the outfit by pinching the side tube. With each heart beat there should be an excursion of the lever of at least 5 mm. Adjust posi- tion of tambour on neck, and pressure of spring to give the largest pulsation, Fig. 36. Tambour and ^"h^n bring Writing point very lightly neck spring used to study agaiust drum. Start drum at 5 mm. the human carotid pulse. , , . , , , . , A, spring; B, baii-and- per sccoud, close Side branch with socket joint, on back of • ^• j j r it, open tambour; c, block, spmig clip and rccord the curve of the pulse. Unless the friction of writing point upon drum is made as slight as possible, small waves of the pulse curve will be obscured. Mark on the curves to indicate the primary wave and the dicrotic notch. Usually the lever is thrown too high, and as it falls depresses the rubber membrane and records a notch which might be mistaken for the dicrotic notch. The second notch is gen- erally the dicrotic, and is followed by a wave larger than that which would be given by the recoil of the membrane. This is the dicrotic wave. Do pre-dicrotic or post-dicrotic waves occur in the record? Take records with four widely different speeds of drum, and observe the effect on the form of the curve. a. The Pulse Rate. Mount a time signal to write below the pulse curve, con- nect it with the clock circuit, start drum at 5 mm. per sec- ond, and record the curves of time and pulse. Draw per- pendiculars at intervals of ten seconds cutting the pulse curve, and determine the rate of the pulse per minute. b. Duration of Systole and Diastole. Mount a fork in place of the time signal; see that lever is horizontal z^'heii the side tube is open; and record curves of pulse and fork with the fastest speed of drum given by clockwork. Then, without moving drum, remove clip from side tube, and record a base line for the pulse
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphysiology, bookyear1
