ANIESTHESIA (Greek, "lack of sen sation"), a term used to express a loss of sensibility to external impressions, which may involve a part of the whole surface of the body. It may occur nat urally as the result of disease, or may be produced artificially by the administra tion of anaesthetics.
In ancient writers, we read of insensi bility or indifference to pain being ob tained by means of Indian hemp (canna. bis indica), either smoked or taken into the stomach. The Chinese, more than 1,500 years ago, used a preparation of hemp, or ma-ya, to annul pain. The Greeks and Romans used mandragora for a similar purpose (poiein anaisthe sian); and, as late as the 13th century, the vapor from a sponge filled with mandragora, opium, and other sedatives was used. In 1784, Dr. Moore, of Lon don, used compression on the nerves of a limb requiring amputation, but this method was in itself productive of much pain. In 1800, Sir Humphrey Davy, ex perimenting with nitrous oxide or laugh ing-gas, suggested its usefulness as an ansthetic; and in 1828 Dr. Hickman suggested carbonic acid gas. As early as 1795, Dr. Pearson had used the vapor of sulphuric ether for the relief of spas modic affections of the respiration. The fact that sulphuric ether could produce insensibility was shown by the American physicians, Godwin (1822), Mitchell (1832), Jackson (1833), Wood and Bache (1834); but it was first used to prevent the pain of an operation in 1846, by Dr. Morton, a dentist of Boston. The news of his success reached England on Dec.
17, 1846; on the 22d, Mr. Robinson, a dentist, and Dr. Liston, the eminent sur geon, operated on patients rendered in sensible by the inhalation of sulphuric ether. This material was extensively used for a year, when Sir J. Y. Simpson, of Edinburgh, discovered the anesthetic powers of chloroform and introduced the use of it into his special department, midwifery. Since that time, chloroform has been the anaesthetic in general use in Europe, but ether is preferred in the United States. Other substances have been used by inhalation, such as nitrous oxide gas, which is the best and safest anesthetic for operations that last only one or two minutes, as in the extraction of teeth; bichloride of methylene and tetrachloride of carbon have also been employed.
Local anaesthesia, artificially produced, is of great value in minor operations, and in painful affections of limited areas of the body. It depends upon a paralysis of the sensory nerves of the part, and may be induced by the ap plication of cold, or of medical agents. Of medical agents the best is cocaine, prepared from the coca shrub of Peru (erythroxylon coca). Eucaine, thymol, menthol, aconite, belladonna, chloroform (the last three as the well-known A. B.
C. liniment), phenol, chloral, and Indian hemp, have also a local ansthetic action if rubbed on the skin, or applied to abraded surfaces, but most are too irri tating to be of any great value.