On the sounds of respiration and of the voice / [Peyton Blakiston].

  • Peyton Blakiston
Date:
[1839]
Catalogue details

Licence: Public Domain Mark

Credit: On the sounds of respiration and of the voice / [Peyton Blakiston]. Source: Wellcome Collection.

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    very indifferent conductor of sound, deadens and weakens the respiratory sounds in their passage from the tubes to the ear of the auscultator. I stated that the sound during expiration was less intense in this region than that during inspiration. This arises from the additional force given to the latter sound by the vesicular respiration of the intervening portion of lung just men¬ tioned, the sound of which is chiefly confined to the time of inspiration. When at length the ear is placed on the remaining portions of the chest, it is no longer approximated to the sides of the bronchial tubes, but to their vesicular extremities. These are so numerous (being not only spread over the periphery of the chest, but also forming the greater part of its internal substance) that only a very minute portion of the air of respiration can reach them at any one spot, and hence very little noise can be produced in them by friction ; while the sound gene¬ rated in the larger tubes, although con¬ fined from total divergence in the air, is amazingly weakened and softened by the extent of surface over which it is thus spread. The sounds previously heard at the sides of the bronchial tubes are here effectually prevented from reaching the ear by the great interven¬ ing mass of spongy lung. All these causes combining to weaken the re¬ spiratory sound, the maximum intensity of which in the trachea can only be heard when the ear is brought into contact with its side, it would not be surprising were no sound detected during respiration at the surface of the chest. Another force, however, is in action. As the wind bears upon it sounds which from their great distance would be otherwise inaudible, so does the current of air during inspiration carry up to the ear those sounds which are engendered in its passage, while that during expira¬ tion acts in a contrary direction : hence th e sound of inspiration is distinctly heard at the surface of the chest, while that of expiration is barely perceptible. I shall now endeavour to ascertain where the sound of vesicular respiration is produced. Sound must be generated in every part of the trachea and its divisions during respiration, but it does not follow that every portion of it should he sufficiently intense to reach the ear of the auscultator at the surface of the chest. I cannot deny that a fraction of that which is heard in vesicular respira¬ tion may be produced by the friction of air against the interior of the vesicles, or by that of one vesicle against another, or by that of the pulmonary on the costal pleura, because a slight sound is heard at the commencement of expira¬ tion when the force of is at its maximum ; but I contend that the principal part of it is not thus produced ; otherwise, taking place immediately under the ear, and therefore unaffected by the direction of the current of air, it would be heard as distinctly during expiration as inspiration; nor on the other hand can it be principally formed in the mouth and fauces, otherwise it w'ould be much strengthened by sterto¬ rous breathing, which is not found to be th e case. The sonorous waves formed in these parts, in passing through tubes, the calibre of which rapidly diminishes, and the direction of which is constantly changing, would seem to be in a great measure broken and destroyed before they reach the vesicles. We seem, then, to have arrived, par la voie d?exclusion, at the bronchial tubes, as the parts in which the sound heard in vesicular re¬ spiration is principally generated ; and this conclusion derives some confirma¬ tion from the fact that sibilous and sonorous rales, which are undoubtedly formed in these tubes, modify, and in some cases, totally mask the sounds of vesicular respiration. When in certain diseases a portion of the lung becomes converted into a solid mass, vesicular respiration is replaced over the spot where that portion is in contact w ith the walls of the thorax, by bronchial respiration, as it has here been defined, coarse, with prolonged expira¬ tion. In endeavouring to account for this alteration, Laennee remarks*, “ Les raisons de la respiration bronchique me paraissent assez faciles & donner. En effet, lorsque la compression on l’en- gorgement du tissu pulmonaire empeche la penetration de Pair dans les vesicles, la respiration bronchique est la seule qui ait lieu and Andral writesf, “ EUe nous parait depend re de ce que Pair ne peut pas penetrer au-dela des gros tuyaux bronchiques.” Thus both writers agree in considering the bron¬ chial tubes, which lead to the solidified lung, as the seat of the bronchial respira- * Yol. i. p. 56 ; 3d Edition. Paris, t Yol. i. p. 432 ; 3d Edition. Bruxelles.