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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    figure maximum inspirations and expirations were made, show¬ ing that the “Mittelage” is much higher than under normal con¬ ditions. At B the weights were removed as quickly as possible, and at c, d, e, and /, maximum inspirations and expirations were again made to contrast the “Mittelage” under normal conditions with that obtained when breathing under pressure (a and 6). At C the weights were reapplied, but, as they consisted of five lead weights, an appreciable time was occupied in putting them on the spirometer, thus producing a less sudden increase in in- trapulmonary pressure than that obtained by turning the tap, as was done at A. The large drop in the spirometer at A, C, E, and G, and the corresponding rise at B, D, F and H are due only in small part to the change in the “Mittelage;” the greater part is caused by the compression (expansion) of the air to a smaller (larger) volume both in the apparatus and in the lungs by the addition (removal) of the weights on the spirometer. Figure II shows another tracing for the same subject as in Figure I. Here again, we see no inspiratory inhibition. There is, however, in this curve an irregular pause of very short dura¬ tion (about three seconds), beginning in complete inspiration. This pause, excepting for its irregularity, resembles those obtained by Christiansen and Haldane on distending the lungs. The notches on both the spirometer and pneumograph curves indi¬ cate that rhythmic expiratory movements were being made but were proving abortive: This fact can be explained on the ground that the usual stim¬ uli coming from the respiratory centre to the muscles of respira¬ tion were not sufficiently powerful to cause those muscles to completely contract against the increased load (pressure). After a few seconds the respirations again became practically normal, as by this time the respiratory centre was sending out stimuli of sufficient strength to cause the respiratory muscles to perform the increased work thrown upon them. In experiments follow¬ ing each other closely the delay before normal respiration was resumed markedly decreased, and, in fact, usually entirely dis¬ appeared, as is shown in the latter part of Figure II, where the distension effect was repeated without causing apnoea.