File:A text-book of physiology - for medical students and physicians (1916) (14767182631).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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th a small movement, gradually increase * Benedict and Cathcart, Muscular Work, etc., Carnegie Institution ofWashington, 1913. INFLUENCE OF VARIOUS CONDITIONS ON RESPIRATION. 711 to a maximum, and then fall off gradually to the point of completecessation (see Fig. 282). Great variations, however, are shown inthe character and number of the respirations during the so-calleddyspneic phase. From observations made by means of thesphygmomanometer Eyster* has shown that in this conditionthere are also rhythmic waves of blood-pressure (Traube-Heringwaves), and according to the relation of these pressure waves tothe groups of respirations the Cheyne-Stokes cases fall into twogroups. In one group the dyspneic phase coincides with a fallof blood-pressure and a slowing of the pulse-rate. In the othergroup the reverse relations hold, the blood-pressure and pulse-rateboth rising during the dyspneic phase and falling during the apnea.This latter group consists of cases in which there is evidence of
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Fig. 282.—Record showing typical Cheyne-Stokes respiration (from a case of aortic andmitral insufficiency with arteriosclerosis). The time record gives seconds. increased intracranial tension. Under experimental conditionsthe author was able to show on dogs that an artificial increase inintracranial tension calls forth Cheyne-Stokes respirations, wheneverit happens that rhythmic changes in blood-pressure are producedof such a character that the blood-pressure rises and falls alternatelyabove and below the line of intracranial pressure. It is probable,therefore, that in the clinical cases associated with a rise of intra-cranial pressure the blood-pressure likewise rises and falls aboveand below intracranial tension, and that the alternating periodsof apnea and dyspnea are due to this fact in this class of cases.When the blood-pressure falls below intracranial pressure thereis a condition of deep anemia of the medulla sufficient to suspendthe activity of the respiratory center. The fo

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