The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum].
- Duncum, Barbara M.
- Date:
- 1947
Licence: In copyright
Credit: The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum]. Source: Wellcome Collection.
471/664 page 451
![cause of primary syncope when allowed to take place at certain stages of the inhalation. . . . '. . . In four experiments four cats [enclosed in jars] inhaled 4 per cent, of chloroform for one minute. In one instance the observation was a failure owing to the resistance of the animal, and in another the cardiac rate, which had been 140 before the inhalation, was extremely rapid when the cat was taken out of the jar ; but there was a sudden stoppage in half a minute which lasted for about five seconds, and this was followed by extreme irregularity for a minute and a half, when the cat recovered. There were pauses between individual beats in this case ; some- times after every third beat, whilst the sounds were very weak during this irregular action. ... In the other two experiments the results were similar, rapid but regular action of the heart ending in sudden stoppage and irregularities in about half a minute.' Very similar results were obtained in. further experiments in which cats breathed per cent, of chloroform vapour for from two to eight minutes. ' More or less irregular cardiac action occurred during recovery in all.' ' These results ', Kirk remarked, ' showed that very deep anaesthesia in the cat did not always modify reactionary effects on the heart, but the fact that these stoppages were longer in occurring after deep anaesthesia proved that the latter were not due to absorption of the chloroform and that they could only be accounted for by the vapour reaction. . . . The irregular action commences when the last drop of chloroform has left the blood, but as long as it continues the animal is as passive as if under the influence of a profound dose of the agent.' Dogs submitted to the same experimental conditions ' showed that the dog was liable to similar stoppages of the heart as the cat, and that they were almost invariably associated with spasms of the respiratory and other muscles. They further showed that deep anaesthesia modified or altogether prevented these effects on the heart, and this is a vital part of the inquiry. It was found, moreover, that immediately after the struggling stage and when the animal was quiescent the anaesthesia was nevertheless not deep enough to prevent irregular cardiac action. . . . ' It is maintained that the stoppages and irregularities of the heart, as above described in experiments on cats and dogs, corres- pond with and explain the fall of blood pressure to zero which has been observed by some other experimenters after the admin- istration of chloroform has been discontinued, and also the](https://iiif.wellcomecollection.org/image/b20457200_0475.jp2/full/800%2C/0/default.jpg)
