(From Greek a, privative, and aisthesis, feeling).
A term in medicine, and the allied sciences, signifying a state of insensibility to external impressions, consequent upon disease, or induced artificially by the employment of certain substances known as anæsthetics, or by hypnotic suggestion. In diseases of the central nervous system, anæsthesia is a common symptom. Usually it is limited in extent, involving a definite area of the skin surface. Its limits can be traced by the distribution of certain nerves. In functional diseases of the nervous system, usually spoken of as hysterical or neurotic, there may be what is called amputation anæsthesia, that is, loss of feeling abruptly limited by a line such as would be followed in an amputation, but not according to the distribution of nerves to the part. In both functional and organic nervous diseases anæsthesia may occur in conjunction with hyperæsthesia and paræsthesia in other parts of the body. Complete anæsthesia occurs in persons suffering from catalepsy, or, occasionally, in those who are in a trance. Artificial anæsthesia by the use of drugs or the inhalation of vapours only came into general use during the last half of the nineteenth century, but there is abundant evidence to show that its practice is very ancient. Homer mentions nepenthe, "an antidote to grief and rage inducing oblivion to all ills". Herodotus relates that the Scythians inhaled a kind of hemp to produce insensibility. Dioscorides alludes to the employment of mandragora to produce anæsthesia when patients are cut or burnt. Pliny refers to the effect of the odour of mandragora as causing sleep if it was taken "before cuttings and puncturings lest they be felt". Lucian speaks of mandragora as used before the application of the cautery. Galen has a short allusion to its power to paralyze sense and motion. Isidorus is quoted as saying: "A wine of the bark of the root is given to those about to undergo operation that being asleep they may feel no pain."
The first mention of anæsthesia, in comparatively modern times, is connected with the name of Ugone da Lucca, who was born a little after the middle of the twelfth century. He had discovered a soporific which, on being inhaled, put patients to sleep so that they were insensible to pain during the operations performed by him. The drug he employed is also known to have been mandragora. There are mentions of anæsthetics in the literary works of practically every century since that time. Boccaccio in the fourteenth century, in the story of Dioneus, gives an account of the effects of an anæsthetic mixture which "being drunk would throw a person asleep as long as the doctor judged it necessary". In the fifteenth century William Bullein described a concoction of an herb which "bringeth sleep, and casteth man into a trance, until he shall be cut out of the stone". In the 16th century Shakespeare, as will be remembered from "Romeo and Juliet," refers four times to the anæsthetic plant under the name of mandrake, and twice under the name of mandragora. In the beginning of the seventeenth century Thomas Middleton wrote of "the pities of old surgeons who cast one asleep, then cut the diseased part". Before this Du Bartas described the surgeon as "bringing his patient in a senseless slumber before he put in use his violent engines". Notwithstanding this continuity of tradition, very little was generally known about the use of anæsthetics, and it seems probable that their effects were rather uncertain. About the beginning of the nineteenth century the task of finding a reliable anæsthetic was taken seriously. In 1800 Sir Humphrey Davy described the effects of nitrous oxide, or laughing gas, in allaying pain or toothache. He suggested its employment in surgery. Ether began to attract attention at the end of the eighteenth century. It was used by inhalation in England, for relief of asthma, and by Dr. Warren, of Boston, in the treatment of the later stages of consumption. In 1818, Faraday proved that the inhalation of the vapour of ether produced anæsthetic effects similar to those of nitrous oxide. This fact was also demonstrated by the American physicians, Godman, in 1822; Jackson, in 1833; and Wood and Bache, in 1834. The first practical use of anæsthesia, however, was delayed until December, 1844, when Horace Wells, a dentist, of Hartford; Conn., had a tooth extracted while under the influence of nitrous oxide, or laughing gas. He resolved to make dentistry painless by this means, but was deterred from pursuing the project by an unfortunate failure in experiments in Boston. About two years later Dr. William Morton, also a dentist of Boston, made use of the vapour of ether for anæsthesia in the extraction of teeth. Subsequently he employed it in cases requiring severe surgical operations, with complete success. In about two months the news of his discovery reached England, and before the end of 1846 operations on anæsthetized patients were performed in London. At the beginning of the year 1847, Sir James Y. Simpson, the distinguished surgeon and obstetrician of the University of Edinburgh, employed ether to allay labour-pains. In November, 1847, Simpson announced his discovery that chloroform was as effective an anæsthetic as ether, and lacked many of its inconveniences. Ives, in Connecticut, had used chloroform for difficult breathing in 1832. After Simpson's announcement it came to be used especially in England, and on the Continent, and even in America, as the favourite anæsthetic, though ether continued to be employed here to a considerable degree. A series of investigations, in the last quarter of the nineteenth century, showed that chloroform had a much greater mortality than ether, and now the latter has replaced it almost entirely for anæsthetic purposes. Other substances, such as the chloride of ethyl and bromide of ethyl, have also been employed. Recent years have seen the development of local anæsthesia to replace general anæsthesia for minor operations. It has been demonstrated that even extensive operations can be performed without causing pain, by the injection of cocaine and similar substances in the neighbourhood of the site of the operation, or into the nerves leading to the part. Spinal anæsthesia, which is a form of local anæsthesia, consists in injecting substances into the spinal cord which paralyze all the sensory nerves from the parts below the point of injection. For a time, about the end of the nineteenth century, it was very popular, but it proved to have many inconveniences and some serious results, and was not always reliable. General anæsthesia always involves some risk. Even in the most careful hands deaths occasionally occur. Usually the fatal termination comes at the very beginning of the administration of the anæsthetic, and seems to be at least partly due to shock. It is impossible to foresee such fatalities, and they occur not infrequently in the young and apparently strong and vigorous. It is important, therefore, that clergymen should take due precautions by advising the administration of the sacraments before anæsthesia, even though it may be but for a slight operation. Surgeons should warn patients of the risks, even though they are but slight, since the reassurance from the due performance of Christian duties will usually make the patient more composed, and less subject to the influence of shock.
FOY, Anæsthetics, Ancient and Modern (London, 1889); MORE-MADDEN, Notes an the probable employment of Anæsthetics in ancient times in Ireland; Dublin Journal of Medical Science (December, 1874); BIGELOW, Anæsthesia and other Addresses (Boston, 1894).
JAMES J. WALSH