"On the physiology of asphyxia and on the anaesthetic action of pure nitrogen" by George Johnson, 1891
I have elsewhere stated that the phenomena which result from the inhalation of nitrous oxide as an anaesthetic by human beings are strictly analogous with those observed during the early stages of asphyxia. While some writers maintain that the anaesthetic action of nitrous oxide is due to its preventing access of free oxygen to the system, others believe that it has a "specific anaesthetic action." It occurred to me that some light might be thrown upon this subject by the administration of pure nitrogen. Accordingly I obtained from the Scotch and Irish Oxygen Company of Glasgow a cylinder containing 100 cubic feet of compressed nitrogen, in which the proportion of oxygen present was only 0.5 per cent. by volume, with 0.3 per cent. of CO₂. As a preliminary trial, Mr. F. W. Braine was good enough to administer this gas in five instances to members of the staff of King's College, who volunteered to submit to the experiments. The result was in each case the production of complete anaesthesia and of general phenomena precisely similar to those observed from the inhalation of nitrous oxide. Encouraged by these results, Mr. Braine felt justified in administering the gas to patients at the Dental Hospital for anaesthetic purposes. Nine patients took the gas. In every case the result was the production of complete anaesthesia, with general phenomena precisely similar to those observed during nitrous oxide inhalation. The pulse was first full and throbbing, then feeble. In the advanced stage the respiration was deep and rapid, and there was lividity of the surface; the pupils were dilated, and there was more or less jactitation of the limbs. The only difference, in the opinion of some of those present, being that the anaesthesia was less rapidly produced, and somewhat less durable, than that from nitrous oxide, though in each case the tooth was extracted without pain.
On a subsequent occasion the same gas was administered by Dr. Frederic Hewitt at the Dental Hospital. As before, nine patients took the gas. The maximum period required to produce anaesthesia was 70 seconds, the minimum 50 seconds, and the mean time 58.3 seconds. In one case two teeth were extracted without pain. In one case only was pain experienced, and in that case, the tooth having been broken up and not extracted, the patient said she felt a "smashing up." Having on several occasions witnessed the administration by Dr. Hewitt of nitrous oxide mixed with 10 per cent. by volume of oxygen, with the result of producing anaesthesia without lividity or jactitation, I determined to try a mixture of nitrogen with a small proportion of oxygen. I therefore obtained from the company above mentioned a cylinder containing forty cubic feet of nitrogen mixed with 3 per cent. by volume of oxygen, and a second cylinder equally charged with a mixture of nitrogen with 5 per cent. by volume of oxygen. These gases were administered by Dr. Hewitt to patients at the Dental Hospital with the following results: - In the case of the 3 per cent. gas, which was given to five patients, the time required to produce anaesthesia varied from 60 to 75 seconds, the average time being 67.5 seconds. In each case the tooth was extracted without pain, the duration of anaesthesia being somewhat longer than with pure nitrogen. In each case there was lividity, dilatation of pupils, and more or less jactitation. On the same day Dr. Hewitt gave nitrogen with 5 per cent. oxygen to four patients. With this mixture the time required for the production of anaesthesia ranged from 75 to 95 seconds, the average being 87.5 seconds. In each case there was complete anaesthesia, during which one patient had three molars extracted, and although she said she "felt the two last," the sensation appears to have been that of a pull, and not of acute pain. In all of these four cases there was slight lividity before the face-piece was removed, but in only one case was there slight jactitation of the limbs. The other three patients were perfectly quiescent.
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