The Lumleian lectures on the muscular arterioles : their structure and function in health and in certain morbid states : delivered at the Royal College of Physicians / by George Johnson.

  • George Johnson
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: The Lumleian lectures on the muscular arterioles : their structure and function in health and in certain morbid states : delivered at the Royal College of Physicians / 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.

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    men ovale and the ductus arteriosus being closed, all the blood ha^ to pass through the pulmonary vessels and is thus subjected to their regu- lating and retarding influence. With reference to the exact seat of the impediment which arrests the flow of blood through the lungs, I may remark that the extreme an£emia of the minute tissue of the lungs, when examined immediately after death in cases of acute apnoea, is evidence that the stoppage occurs before the blood has reached the capillaries. If, in accordance with the hypothesis of Alison and Reid, the blood were attracted into the capillaries and retained there, in consequence of its not having undergone the normal chemical changes, the capillaries would be in a state of engorgement, and not in that nearly bloodless state in which they are actually found to be. In the phenomena which attend the inhalation of nitrous oxide gas, when given as an ansesthetic, we have a very interesting confirmation of the results obtained by experiments on animals, and, on the other hand, the records of physiological experiments enable us more com- pletely to understand and interpret the facts of nitrous oxide anaes- thesia. On several occasions, I have availed myself of the opportu- nity afforded me by the courtesy of the authorities at the Dental Hos- pital to watch the phenomena which attend the inhalation of the gas, and I will now briefly describe them. In most cases, during the first few seconds the pulse and the breathing are quickened, as a result probably of emotional excitement. In the next stage, the breathing becomes slow and shallow and the pulse full and firm. Then, after a period which varies in different cases from forty to eighty or ninety seconds, the pulse suddenly becomes almost, or even quite imperceptible, the features become livid, the pupils are widely dilated, there is a state of general muscular rigidity ; in short, all the phenomena of the first stage of an epileptic fit are present. The mouth -piece being removed, the morbid phenomena quickly pass away, the features regain their normal colour, the pulse returns, and for a few seconds has again a full and throbbing character, but quickly regains its normal condition. The explanation of the phenomena appears to be sufficiently obvious. It is admitted on all hands that, at the temperature of the body, the nitrous oxide gives up no oxygen to the blood or the tissues. The gas becoming rapidly diff'used and replacing the oxygen in the lungs and in the blood, black unoxygenised blood passes into the systemic arteries,
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