In my opinion, the answer to this question may be given as follows: In the first place, we know that the primary effect of the compressed air upon the organism must be to force the blood from the surface of the body toward the interior, and especially into the cerebro-spinal canal. Or, to express it more succinctly, the blood will be forced in the direction of the least resistance, that is, into the soft organs inclosed by bony walls, which latter completely shut out the element of counter-pressure. Now, when the blood stream is freighted with a soluble chemical of some sort—let us say, for the present, with alcohol—this medicated blood will exert its greatest chemical effect where the tension—the pressure—is greatest, that is, in the cerebro-spinal canal. The reason for this is found in the fact that endosmosis is most pronounced where the blood pressure is greatest. This explanation of why the effects of alcohol are enhanced by exposing the individual who has taken it to the effects of a condensed atmosphere will, I believe, appeal to the physiological conceptions of most medical men. It was the above course of reasoning which, at this stage of the argument, led me to the idea that, just as the effects of stimulating substances are enhanced by exposing the subject to the influence of compressed air, so, inversely, sedatives and analgesics, when brought in solution into the blood stream, either hypodermically or by the stomach, might be greatly enhanced in effect by causing the subject to remain, while under their influence, in a condensed atmosphere.
When I came to investigate the validity of these predictions, as I did shortly after the introduction of antipyrin, phenacetin, and the other members of the same group of compounds, I found my predictions verified, and, indeed, exceeded. To summarize the whole matter, I ascertained that not only could therapeutic effects be obtained from much smaller doses by exposing the subject to the influence of a condensed atmosphere, but, what was of equal interest, I found that the analgesic influence of the remedies was much more permanent, was prolonged, in short, by this mode of administration. When we consider how great must be the nutritive changes in the nervous system, and especially in the cerebro-spinal axis, consequent upon increasing the blood pressure in this way, I hardly think that these things should be matters of astonishment.
CONCERNING THE PRACTICAL APPLICATION OF THE FOREGOING FACTS.—Truths like the foregoing possess, however, much more than a theoretical interest, and we should be greatly lacking in perspicuity did we not seek to derive from them something further than a foundation for mere speculation. Indeed, the whole tenor of these facts is opposed to such a course, for, view them as we may, the thought inevitably arises that here are things which contain the germ of some practical acquisition. This, at least, is the impression which they engendered in my own mind—an impression which, being unable to rid myself of, I have allowed to fructify. Nor has regret followed this tenacity of purpose, since, by the combination of the three principles previously enunciated, I have been able to devise a procedure which, in my hands, has yielded flattering results in the treatment of a wide range of nervous affections, and notably so in melancholia, chorea, insomnia, neurasthenia, and painful conditions of various kinds.
RECAPITULATION OF ARGUMENT.—The method in question consists, then, in the combination of the three facts already elucidated. To recapitulate, they are:
1. That the effects of remedies upon the cerebro-spinal axis may be enhanced by the sequestration of the blood contained in one or more extremities, previous to the administration of the medicament. This is only another way of saying that the quantity of a remedy required to produce a given physiological effect may be reduced by any expedient which suspends, or sequestrates, the blood in one or more extremities. As has been previously said, however, care should be exercised to avoid dangerous exsanguination of the trunk, and consequently of the respiratory and cardiac centers contained in the medulla. This may be done by compressing the central portion of both artery and vein; but I shall presently indicate a better way of accomplishing the same thing.
2. The duration of the effect of a remedy upon the cerebro-spinal axis is in the inverse ratio of its volatility. For this reason the anæsthetic effects of ether disappear shortly after removal of the inhaler, whereas solutions of antipyrin, phenacetin, morphine, and other salts possessing an affinity for nervous tissue exert much more permanent effects upon the cerebro-spinal system.
It is evident, therefore, that the administration of remedies designed to exert an influence upon the central nervous system in the form of gases must be far inferior to the exhibition of potent solutions hypodermically or by the mouth.
3. The pharmaco-dynamic potency of stimulants, sedatives, analgesics, and probably of all remedies possessing a chemical affinity for nervous matter, is enhanced by exhibiting them (the remedies) in solution, or at least in soluble form while the subject remains in a condensed atmosphere.
And, as a corollary to this, it may be stated that this increase—this enhancement of therapeutic effect—is, within physiological limits, in the ratio of the atmospheric condensation. By physiological limits we mean simply that there is a degree of atmospheric condensation beyond which we cannot go without jeopardizing the well-being of the subject.
(To be continued.)