Studies in blood-pressure : physiological and clinical . iew is untenable, and that thesounds are produced by vibration of the walls ofthe artery compressed by the armlet; not much,if at all, by changes in the distal portion of thevessel. I endorse this conclusion, and I regard thepronounced character of the throb over the arteryat the bend of the elbow as due to the augmentedconduction by current, and not as indicating theplace of its origin. 1 In 1910 (see Quart. Journ. of Exp. Physiol., vol. iv, p. 46) I up-held the view then current; but since that date I have been led byobservation to dis
Studies in blood-pressure : physiological and clinical . iew is untenable, and that thesounds are produced by vibration of the walls ofthe artery compressed by the armlet; not much,if at all, by changes in the distal portion of thevessel. I endorse this conclusion, and I regard thepronounced character of the throb over the arteryat the bend of the elbow as due to the augmentedconduction by current, and not as indicating theplace of its origin. 1 In 1910 (see Quart. Journ. of Exp. Physiol., vol. iv, p. 46) I up-held the view then current; but since that date I have been led byobservation to discard it. READING THE ARTERIAL PRESSURE 95 The Phases of Throb.—When the armlet-pres-sure is raised or lowered, a regular succession ofvariations of the quality of throb is compression, these phases are not so apparent orso loud as on decompression. The release throb isgenerally sharp and clear, resembling the sounds ofa foetal heart; then this quality of clear and sharpdefinition gives place to a muffled quality or mur- Release Pressure. Rising Pressure Fig. 5. By kind permission of the Editor of The Practitioner. murishness, or a distinct murmur, which is suc-ceeded by a loud and clear note or thud withoutmurmur ; and finally, the throb suddenly becomesquite dull and distant, before it Puttingaside the reappearance and the final disappearanceof the throb, decompression furnishes four succes-sive stages of variation in the quality of the sound,in the following order, characterised by (1) sharp- 1 Ettinger, Wiener Klin. Wochenschr., 1907, vol. xx, p. 992. 96 STUDIES IN BLOOD-PRESSURE ness, (2) murmurishness, (3) loudness, and (4) dull-ness (see Fig. 5). Of these phases, the murmurishone is the least constant, being frequently absentor so short as to be easily missed. Several observershave assigned some clinical significance to thelength of each phase, which varies considerably indifferent cases. But I think that such an influenceis of doubtful value, e
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