Alkalescence, Acidity, Anesthesia - A Theory of Anesthesia : Part 1

Origin and Nature of Emotions
by George W. Crile, M.D.

(Page 8 of 9)

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. 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.

In animals under inhalation anesthesia Williams found that no nerve-current could be detected by the Einthoven string galvanometer, a fact which might be explained by postulating that nerve-currents can flow from the brain to the muscles and glands only when there is a difference of potential. Any variation from the normal alkalinity of the body must change the difference in potential. Since the nerve-currents in animals under anesthesia are not demonstrable by any apparatus at our command, and since anesthesia produces acidity, then we may infer that acidity reduces the difference in potential. As long as there is life, a galvanometer of sufficient delicacy would perforce detect, a nerve-current until the acidity increased to such a point as to reduce the difference in potential to zero - the point of death. If at this point a suitable alkali - adrenalin solution - can be introduced quickly enough, the vital difference in potential may be restored and the life processes will be renewed. Bearing especially on this point is the fact that if adrenalin in sufficient quantities be administered simultaneously with an acid, it will not only prevent the fall in blood-pressure usually caused by the acid, but will also prevent the histologic changes in the brain, adrenals, and liver which are usually caused by the intravenous injection of acids.

This hypothesis regarding the cause of anesthesia and unconsciousness explains and harmonizes many facts. It explains how asphyxia, overwhelming emotion, and excessive muscular exertion, by causing acidity, may produce unconsciousness. It explains the acidosis which results from starvation, from uremia, from diabetes, from Bright's disease, and supplies a reason for the use of intravenous infusions of sodium bicarbonate to overcome the coma of diabetes and uremia. It may explain the quick death from chloroform and nitrous oxid; and may perhaps show why unconsciousness is so commonly the immediate precursor of death.

One of the most noticeable immediate effects of the administration of an inhalation anesthetic is a marked increase in the rapidity and force of the respiration. The respiratory center has evidently been evolved to act with an increase of vigor which is proportional - within certain limits - to the increase in the H-ion concentration, whereas the centers governing the voluntary muscles are inhibited. In this antithetic reaction of the higher cortical centers and the lower centers in the medulla to acidity we find a remarkable adaptation which prevents the animal from killing itself by the further increase in acidity which would be produced by muscular activity.

About the Author

George Washington Crile (1864 - 1943) was a significant American surgeon. Crile is now formally recognized as the first surgeon to have succeeded in a direct blood transfusion. He also contributed to other procedures, such as neck dissection.