Anaesthesia

Anaesthesia (Greek a, privative aisthesis, sensation) is a condition of insensibility to pain. It may be either local or general. A simple example of local anaesthesia is afforded by incised wounds involving nerve-trunks. Thus, if the nerves of the fore-arm be divided all sensation is lost in the parts which they supply. The operation of dividing nerves is sometimes resorted to in cases of persistent neuralgia, in order to sever the connection between the diseased portion of the nerve and the brain. Certain drugs, too, act as local anaesthetics. Cocaine, which has been introduced of late years, has been tried in dentistry, and has found an extensive application in eye surgery. The patient's eye, after being properly prepared by dropping a solution of the drug upon it, becomes quite insensitive; foreign bodies may be removed from the cornea, nay, even cutting operations may be performed without causing any pain. Again, ether spray is sometimes employed in producing local anaesthesia. In the condition of general anaesthesia a state of insensibility to all external impressions is produced. It is in conferring this boon upon mankind by the discovery of the anaesthetic properties of chloroform and ether that the medical art has achieved its greatest triumph Surgical operations are now performed without causing pain to the patient, and, moreover, they can be methodically conducted, there being no need for the hurry which was so desirable when every touch of the knife meant agony to the sufferer. Various means of producing anaesthesia were practised by the ancients. The Chinese employed a kind of hemp, the Greeks and Romans mandragora. These "drowsy syrups of the East," however, are only interesting from an historical point of view, the introduction of satisfactory anaesthetics being only accomplished in the present century. In 1800 nitrous oxide gas was inhaled by Sir Humphry Davy, who recommended its use, and it is now largely employed by dentists. In 1846 Dr. Morton, of Boston, employed sulphuric ether, and in 1847 Sir J. Simpson discovered chloroform, and these two drugs still hold the field against all competitors. Ether is, perhaps, the safer of the two, as chloroform depresses the heart's action, still the latter is better suited for certain cases; children and old people in particular bear it well, and ether, as it irritates the respiratory passages, is unsuitable in those who are the subjects of bronchitis. Moreover the danger attendant on the administration of anaesthetics in competent hands is exceedingly small. Very occasionally a death occurs while a patient is under their influence, but in most of these exceptional cases it is open to doubt whether it is the anaesthetic which is at fault. When operations are undertaken as a forlorn hope in desperate cases, it is unfair to attribute their want of success to the use of chloroform. In recent years the anaesthesia of the hypnotic state has been much talked of, and it is claimed by some that hypnotism will be used in the future in surgical practice. But few people, however, can be rendered anaesthetic by this means, and in them the remedy would seem to be more productive of harm than benefit.