On the proximate cause of albuminous and dropsy, and on the pathology of the renal blood-vessels in Bright's disease / [Sir George Johnson].

  • Johnson, George, 1818-1896
Date:
1850
Catalogue details

Licence: Public Domain Mark

Credit: On the proximate cause of albuminous and dropsy, and on the pathology of the renal blood-vessels in Bright's disease / [Sir George Johnson]. Source: Wellcome Collection.

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    I have to offer on this subject will, perhaps, be rendered more intelligible by a previous brief reference to one of those lucid and valuable essays bequeathed to us by the late lamented Dr. John Reid.1 The essay to which I allude is that f On the Order of Succession, in which the Vital Actions are arrested in Asphyxia/ The principal facts and argu¬ ments therein contained, and which concern us in our present inquiry, are the following:—when the trachea of an animal has been obstructed, by the insertion of a tube with a closed stop-cock, dark blood is at first transmitted freely through the lungs, and reaches the left side of the heart, by which it is driven through all the textures of the body. As the blood becomes more venous, its circulation through the vessels nf the brain deranges the sensorial functions, and rapidly suspends them, so that the animal becomes unconscious of all external impressions. For about two minutes after the animal has become insensible, and when the blood in an exposed and unobstructed artery is equally dark as that in the accompanying vein, the large arteries become more dis¬ tended and tense than before the stop-cock in the trachea was shut, and when the animal was breathing atmospheric air freely. At the same time, a hsemadynamometer being placed in the artery of one limb, and a similar instrument in the corresponding vein of the other, the former indicates an in¬ crease, and the latter a diminution of pressure, as compared with that observed in the same vessels before the air was excluded from the lungs, this evidently resulting from an impediment to the passage of the venous blood through the systemic capillaries. At the expiration of the time before mentioned, viz. about two minutes, the instrument in the artery indicates a diminution of pressure; the mercury, at first falling very gradually, and at last very rapidly, in con¬ sequence of the blood being arrested in the pulmonary capillaries, ceasing to pass through the lungs, and so stag¬ nating in the right side of the heart and in the veins. Dr. Reid then quotes some observations by Dr. Alison2 1 Physiological, Anatomical, and Pathological Researches, p. 17. 2 Pathology and Practice of Medicine, p. 120.