On the physiology of asphyxia and on the anaesthetic action of pure nitrogen / by George Johnson.

  • Johnson, George, 1818-1896.
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: On the physiology of asphyxia and on the anaesthetic action of pure nitrogen / by George Johnson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    17/26
    ( *3 ) In one dog, weighing 19^ lb., 2 oz. of blood gushed from the distended right cavities, while 2J drachms of blood flowed slowly from the comparatively empty and flaccid left side. In a dog half the size of the above, the experiment having been performed by Mr. Martin, the right auricle was found distended, the left empty; the right side of the heart contained 5J drachms of blood, the left a quarter of a drachm.1 The explanation which I have before given of these facts appears to me to be the true one—viz., that during the later stages of asphyxia, when the blood has become entirely deoxidised, the pulmonary arterioles contract and cause the extreme distension of the right cavities, with ancemiaof the pulmonary capillaries and a corresponding defective blood- supply to the left cavities of the heart. [The extreme distension of the right cavities of the heart while the left are flaccid and comparatively empty, the minute tissue of the lungs being pale and bloodless, clearly indicates an impediment to the flow of blood between the right ventricle and the pulmonary capillaries. Such an impediment is explained by the contraction of the pulmonary arterioles—the vaso-constrictors of the lungs. It appears to me that the phenomena of asphyxia afford a more complete proof of the powerful action of the pulmonary vaso- constrictors than can be derived from any kymographic tracing. ] I venture to suggest the following explanation of the increase of blood pressure in the pulmonary veins, which has been observed by Mr. Martin and other experimenters during the successive stages of asphyxia. In the first stage, when, with high systemic arterial tension, the left cavities of the heart are distended (Fig. 1), there must he a backward pressure in the pulmonary veins, extending, perhaps, as far 1 The results of these experiments suffice to prove the error of those physiologists who maintain that the comparative emptiness of the left cavities after death from asphyxia is the result of rigor mortis.