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.
384/664 page 364
![' The use of potash to absorb carbon dioxide must be absolutely rejected,' he stated, ' at least in experiments with chloroform, which it rapidly breaks down. It was through failing to take this fact into account that certain investigators have been altogether misled as to the lethal proportion of chloroform in air.' Bert contrasted the swift and tranquil anaesthesia obtained by administering ' a mixture corresponding to about the middle of the zone maniable ' with ' the results of ordinary methods of anaesthesia, using a compress, sponge, etc' By these latter methods, he pointed out, according to the saturation of the compress and its proximity to the nose and mouth, the patient might breathe an anaesthetic-air mixture which was less than the anaesthetic dose, within the zone maniable or equal to and even greater than the lethal dose. ' The zone maniable ', Bert continued, ' is, in fact, singularly narrow, and a few additional drops of liquid may change the inspired mixture from an active to a lethal dose. This is particularly true of chloroform : 8 grams vaporized in 100 litres of air will not put a dog to sleep, 20 grams kills him. The margin is 12 grams. Ether, which has the same proportionate strength (the lethal dose being double the anaesthetic dose), nevertheless offers far less danger because there is a margin of almost 40 grams between the active and the lethal dose. Herein, incontestably, lies the reason for the relative harmlessness of which ether has given proof in surgical practice. ' When one reads accounts of longish operations, one notices that the surgeons do not omit to draw attention to the quantity of chloroform which they used, that is to say, poured on to the compress, but they do not mention the chloroform lost from the outside [of the compress] nor consider it otherwise than as having entered the patient's lungs. Such information is value- less. I can make a dog breathe an extraordinary quantity of chloroform without producing any anaesthesia, so long as I take care that its proportion in the mixture does not exceed 5 or 6 parts. Inversely, by using a mixture containing 30 parts of chloroform, a very trifling amount is sufficient to kill the animal stone dead. In other words, chloroform does not act according to the quantity inhaled but according to the pro- portion in which it is present in the inspired air. . . . For in both volatile and gaseous anaesthetics, particularly nitrous oxide,](https://iiif.wellcomecollection.org/image/b20457200_0388.jp2/full/800%2C/0/default.jpg)
