Further remarks on the cause and prevention of death from chloroform / by John Snow.

  • Snow, John, 1813-1858.
Date:
[1856]
Catalogue details

Licence: Public Domain Mark

Credit: Further remarks on the cause and prevention of death from chloroform / by John Snow. 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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    water into the coronary arteries, as well as by giving it by in- halation. In some experiments on frogs, which go on absorb- ing vapour by the skin, after the respiratory movements have ceased, I was able also to ascertain the amount of chloroform which suffices to paralyse the heart, and I found it to be one- eighteenth part as much as the serum of the blood is capable of dissolving; whilst about one part in twenty-two of what the blood will dissolve has the effect of arresting the action of the muscles of respiration. I pointed out also what I consider to be of the utmost im- portance in relation to the accidents from chloroform—viz., that this agent has the effect of arresting the action of the heart, by its direct influence, in animals of warm blood, when they breathe air containing not less than eight or ten per cent, of the vapour. I had ascertained the circumstance in nume- rous experiments in which the stethoscope was applied to the chest of the animals whilst they were inhaling the chloroform, and also in two experiments, in which I was assisted by Mr. Peter Marshall where, the animals being kept alive by artificial respiration after the heart was exposed, the chloroform was administered by a tube inserted in the trachea, and its instant effect on the heart could be seen. The reason why the chloroform is thus able to act directly on the heart, under certain circumstances, is as follows:—When the vapour is breathed till such an effect is produced on the brain and nerves of respiration, that the action of the respiratory muscles is suspended, there is still vapour in the lungs, which has been inhaled during the last inspirations, and this continues to be absorbed into the blood which is passing through the lungs at the moment, increasing the quantity of chloroform which the blood already contains. Whether this additional quantity of chloroform, which is absorbed into the blood during the first few seconds after the breathing has ceased, shall be sufficient to remove the remaining sensibility of the cardiac nerves, and so paralyse the heart, depends on the quantity of vapour in the air last taken into the lungs. I find that when this quantit