ALKALESCENCE, ACIDITY, ANESTHESIA—A THEORY OF ANESTHESIA[*]
[*] Paper delivered before the Virginia Medical Association,
Washington, D. C., October 29, 1914.
Alkalis and bases compose the greater part of the food of man and animals, the blood in both man and animals under normal conditions being slightly alkaline or rather potentially alkaline; that is, although in circulating blood the concentration of the OH-ions— upon which the degree of alkalinity depends—is but little more than in distilled water, yet blood has the power of neutralizing a considerable amount of acid (Starling, Wells). At the time of death, whatever its cause, the concentration of H-ions in the blood increases,— the concentration of H-ions being a measure of acidity,—that is, the potential or actual alkalinity decreases and the blood becomes actually neutral or acid.
To determine what conditions tend to diminish the normal alkalinity of the blood, many observations were made for me in my laboratory by Dr. M. L. Menten to determine by electric measurements the H-ion concentration of the blood under certain pathologic and physiologic conditions.
As a result of these researches we are able to state that the H-ion concentration of the blood—its acidity—is increased by excessive muscular activity; excessive emotional excitation; surgical shock; in the late stages of infection; by asphyxia; by strychnin convulsions; by inhalation anesthetics; after excision of the pancreas, and in the late stages of life after excision of the liver and excision of the adrenals. Morphin and decapitation cause no change in the H-ion concentration. Ether, nitrous oxid, and alcohol produce an increased acidity of the blood which is proportional to the depth of anesthesia.
Many of the cases studied were near death, as would be expected, since it is well known that a certain degree of acidity is incompatible with life.
Since alkalis and bases preponderate in ingested food; since alkalinity of the blood is diminished by bodily activity; and since at the point of death the blood is always acid, we may infer that some mechanism or mechanisms of the body were evolved for the purpose of changing bases into acids that thus energy might be liberated.
These observations lead naturally to the question, May not acidity of itself be the actual final cause of death? We believe that it may be so from the facts that—(1) The intravenous injection of certain acids causes death quickly, but that convulsions do not occur, since the voluntary muscles lose their power of contraction; and (2) the intravenous injection of acids causes extensive histologic changes in the brain, the adrenals, and the liver which resemble the changes invariably caused by activation of the kinetic system (Figs. 74 and 75). In view of these facts may we not find that anesthesia and many instances of unconsciousness are merely phenomena of acidity?
As has been stated already, we have found that the H-ion concentration of the blood—its acidity—is increased by alcohol, by ether, and by nitrous oxid. In addition our tests have shown that under ether the increase of the H-ion concentration—acidity—is more gradual than under nitrous oxid, an observation which accords well with the fact that nitrous oxid more quickly induces anesthesia than does ether.
Further striking testimony in favor of the hypothesis that the production of acidity by inhalation anesthetics is the method by which anesthesia itself is produced is found in the fact that although lethal doses of acid cause muscular paralysis, yet this paralysis may be mitigated by adrenalin—which is alkaline. This observation may explain in part the remarkable success of the method of resuscitation devised by me, in which animals "killed" by anesthetics and asphyxia are revived by the use of adrenalin.