File:A text-book of physiology - for medical students and physicians (1916) (14770312075).jpg

Identifier: textbookofphysio1916howe (find matches)
Title: A text-book of physiology : for medical students and physicians
Year: 1916 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology Medicine
Publisher: Philadelphia and London : W. B. Saunders Company
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

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ion ofthe variations in disease consult Mackenzie, The Study of the Pulse, etc.New York, 1902. 522 CIRCULATION OF BLOOD AND LYMPH. different distances from the heart and the pulse wave as it passes bya given point in each artery may be recorded by some convenientapparatus, such as can be devised in any laboratory. If the wavesare recorded on a rapidly revolving kymographion whose rate ofmovement can be determined, then the difference in time in thearrival of the pulse wave at the two points is easily ascertained.That there is a perceptible difference in time one can easily demon-strate to himself by feeling simultaneously the pulse of the radialand the carotid arteries. If this difference in time is determinedfor two arteries—for instance, the femoral and the tibialis anterior—and the distance between the two points is recorded, we haveevidently the necessary data for obtaining the velocity of thepulse wave in the arteries of that region. A record of this kindis shown in Fig. 211.
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Fig. 211.—To illustrate the method of determining the velocity of the pulse wavein man. Shows record of the pulse at two points on the leg at a known distance apart.The difference in time is given by the verticals dropped from the beginning of these wavesto the time curve. This last is made by the vibrations of a tuning fork giving 50 vibra-tions per second. The difference in this case was equal to 0.07 sec. The results obtained by various authors indicate that the velocityvaries somewhere between 6 and 9 meters per second for adults.The figures published bjr later observers show also that the velocityis somewhat greater in the upper extremities (7.5 m. for carotid-radial estimation) than in the descending aorta (6.5 m. for carotid-femoral estimation).* The average of thirty determinations madein the authors laboratory upon medical students shows that thevelocity in the leg (femoral-anterior tibial) is 6.1 m. when therecords are made upon the same leg, and 7.4 m. when the recordfor

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