ANAESTHESIA. In its simplest sense this term means simply absence of feeling and has been handed down to us from a very re spectable Greek antiquity. We cannot get behind this. There may be anesthesia of a part of an organ or of a special sense or of the entire sensorium, but it is all want of feeling, want of sense perception in the part or the whole. The term, like so many of the Greek terms, is basic and inclusive. We moderns are accustomed to say there is a general and a local anesthesia according as the entire sense of feeling is obliterated or only a section of it. There is a general anesthesia in sound sleep, in profound stupor or coma, in surgical shock, in the unconsciousness which comes from the in halation of certain vapors and the influence upon the sensory centres of poisonous drugs, and in the rare conditions called trance and intense mental concentration when mind seems to be carrying on an independent existence apart from matter. The examples of local anaesthesia are innumerable; tie a string around your finger, cutting off its nerve and blood supply, and feeling in the finger disappears; continue this long enough and you can have the finger cut off without knowing it, or the finger may drop off, being dead and no longer a part of the living organism. Interfere with the cir culation of your foot by pressure or con strained position, and you say it is asleep and has no feeling in it ; freeze it and you may cut it or prick it or pinch it without wincing. Inject under the skin solutions of certain drugs or even distilled water and if properly done you may cut the skin and the tissues which are under it and even invade one of the cavities of the body and cut out diseased organs or new growths without excessive pain, perhaps with very little or none as is now being done by skillful surgeons every day. Such is the mar velous control which men have gained by experience and• investigation over the natural operations of physical functions.
How is this brought about? Consciousness is governed by the interaction of the blood and the nervous system. Remove a sufficient quan tity of blood from anybody and consciousness ceases. If you were to look at the brain, the centre of consciousness, of one who had lost this blood, you would find it pale instead of red as it is when the blood is flowing through it ; its blood vessels would be more or less collapsed instead of distended. This is probably what happens during natural sleep. There may be other factors, too, about which there has been much speculation and investigation, but this is the principal one.
When the brain is anaemic or when the blood flowing through it is poisoned by certain drugs there is an arrest of consciousness. This is general anaesthesia; there is no feeling either of pain or pleasure in any portion of the body. The including the mucous membranes lin ing certain cavities of the body, is the principal organ of sensation. We get sensations through the eyes, the nose, the cars, the mouth, but the skin, the organ of touch, is by far the most extensive and there is no portion of it which does not respond more or less actively to the impression of contact with matter in any form, to heat and cold, hard and soft, solid, fluid and gaseous.
We are conscious of this contact by means of the peripheral nerves, the sensory nerves, which are distributed to each infinitesimal por tion of the skin and which converge to trunk nerves going to the spinal cord, by which the impressions are conveyed to the brain and there interpreted. If this line of communication is
cut or otherwise interrupted the impression cannot reach the brain and there is local anaes thesia or want of feeling at that portion of the skin where the contact was made and where under ordinary circumstances there would be consciousness of the contact.
Among the most important applications of general and local anaesthesia has been the aboli tion of painful impressions in the skin by the influence of medicine and surgery. Ancient medicine knew of drugs that would relieve pain, but not many of them. We read of the somniferous poppy, and mandragora and helle bore rubbed into the skin or taken into the stomach, and wine has been celebrated from time immemorial as the unfailing remedy for hurts of mind and body. Ancient surgery was even more deficient than medicine in its means for relieving pain. Those who were compelled to undergo surgical treatment, whether in civil or military life, usually had to bear the pain if they could, and they had the consciousness of pain just as we do. If they could not bear it they succumbed, and that was the frequent accompaniment of surgical operations, far more frequently than now. The abolition of pain in very many of the hurts of life, in the painful neuralgias, in the throes of childbirth, in civil and military surgery is now a relatively simple matter by both general and local anaesthesia.
When the anaesthetizing influence of the in halation of the vapors of ether and choloro form was announced to the world it was the dawn of a new era; it was a gift which can be appreciated only by remembenng the pains of those who were deprived of it. Modifications and variations of these two substances have been devised from time to time, but they have not lac their supremacy and. probably they never will. The unfavorable effect which their use often has upon those whose organs are dis eased, especially the liver, kidneys, lungs and heart, has led to the wide application and em ployment of local anaesthesia in surgical prac tice. The scat of painful sensations resting principally in the skin, it has been found that by infiltrating the skin or injecting into the cellular tissue beneath it suitable solutions of such substances as cocaine, stovain, novocain, etc., sufficient detachment of the peripheral nerves added to the anaesthetizing effect of the drugs upon the nerves will permit of the pain less or nearly painless performance of even very extensive operations, and this is of the greatest advantage to those for whom general anaesthesia would be inadmissible or at least unadvisable. Anesthesia by way of the rectum and the spinal canal are devices of recent years which have had their day and a brief one, too. They have not commended themselves to sur geons generally and it is doubtful if they will ever come into general use. The use of sco palamine and morphine in obstetric practice, which has had a vogue in certain quarters within the past few years, but which is now subsiding, is not properly a method of anmthe sia, but of analgesia or amensia.