Identifier: americanjournroen07ameruoft (find matches)
Title: The American journal of roentgenology, radium therapy and nuclear medicine
Year: 1906 (1900s)
Authors: American Radium Society American Roentgen Ray Society
Subjects: Radiotherapy X-rays
Publisher: Springfield, Ill. C.C. Thomas
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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ns in the transversediameter of the heart during the rebreath-ing test averaged less than those caused byforced inspiration and expiration, yet theymay occasionally be even greater. Thereason for this is that the rebreathing testproduces forced breathing in certain avia-tors. In the early stages there is frequentlyirregular breathing due to excitement, butduring the latter half of the run the respira-tion is normally very much deepened. Itseems possible that this deepening resultsfrom an increase at both ends of the respira-tory movement. Expiration as well as inspir-ation is exaggerated. This would seem to beshown in many of the respiratory kymo-graph tracings, where the expiratory curveoccasionally goes below the average level ofthe expiratory excursion (Fig. 8). The samechanges in the respiratory movement occurin the low pressure chamber or during anascent to a high altitude as in the rebreath-ing test. There is an increase in the volumeof air breathed per minute, and this increase
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14. KXAMlLF.S SHCI\\IX(; Two 1\I(ISM<)S ()\ ()M II.AIK III I )kmonstratk Displacement of ihe Heaki During Deep Breathing. easily lead to a serious mistake in diagnosis. Out of a series of plates of 89 men, thelargest difference between the transverse75 cm. distance. The average variation was1.37 cm. One heart showed no change in thetransverse diameter—a case of valvulardisease measuring 17.5 cm. at 2 metredistance. During the course of the rebreathing testsof the same 89 aviators, the greatest varia-tion in the transverse diameter in any one in the minute volume results from deepbreathing much more than from anaccelerated rate. Practically we found it extremely difficult,or even impossible in many cases, to time ourexposures with any desired phase of respira-tion. Watching the kymograph drum onefrequently would snap the switch at whatone thought was the height of inspiration,and the next pulse beat would set off theexposure; but the subject would go on The Aviators Heart 75 KALEV

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