Distension of the lungs : its effect on the respiration in man and in normal and vagotomized dogs / by Walter M. Boothby and Frank B. Berry.

  • Boothby, Walter M.
Date:
[1915?]
Catalogue details

Licence: In copyright

Credit: Distension of the lungs : its effect on the respiration in man and in normal and vagotomized dogs / by Walter M. Boothby and Frank B. Berry. Source: Wellcome Collection.

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    mouthpiece was closed near the end of inspiration in such a man¬ ner that the subject’s air-way was entirely closed. This pro¬ cedure is equivalent to clamping the trachea with the lungs dis¬ tended. From the pneumograph curve, it is evident that the inspiratory movement almost instantly stopped, though probably not completely, as shown by the slight notch at a.. The chart level then fell slightly at b but at c there is a sharp inspiratory movement. This inspiration was abortive, as no air could enter the thorax, and immediately a negative pressure was probably produced. The inspiration at c is slightly delayed, but the fol¬ lowing notches d and e are very close to the normal respiratory rhythm. At / the subject makes a more pronounced inspiratory effort, followed by one less marked and then five which are very pronounced. The tap is then opened at g, so that the subject can breathe room air. The notches indicating inspiratory at¬ tempts do not show in all our tracings, though by observing our own reactions we feel sure that they occur. Their absence in some of the experiments may be explained by the fact that the rhythmic stimuli are not strong enough to cause the respiratory muscles to contract sufficiently to produce a change in the shape of the thoracic wall, so that a record would be made by the pneu¬ mograph. Apparently, the absence of the notches is not due to complete cessation of the respiratory stimuli. In the distension experiments on ourselves we did not obtain any indication of the secondary or chemical apnoea, so well shown by Christiansen and Haldane. The failure of such an apnoea to occur in our subjects is, however, to be expected, as in neither of them is the most violent and prolonged forced breath¬ ing followed by apnoea.10 Figure VII is a tracing obtained from a normal dog. The tap is turned at various points in the respiratory cycle, so that the animal first breathed the air of the room, and then the air under pressure in the respiration apparatus. The upper curve is that written by the spirometer and the straight lines are made when the dog is breathing the room air. The lower curve is that ob- 10Boothby: Absence of apnoea after forced breathing. 1912, Jour. Physiol, xlv, 5, 328-337.