AN.KSTHI 



ANAESTHETICS. 



writers. AniMtheaia MB al*> be produced by artificial moans, u in 

 of the nervous y*tem brought oo by what U ceiled animal 

 In thU *tato of the tyatem the anaMthesU u sometimes ao 

 gioal operation* have been performed on person* whilst 

 This wu known previous tu Uio general 



of anawthetic agent* during the (wrfonwuiua of surgical 

 operation* generally. All narcotic medicine* will produce coudit i..n> 

 of maethnen, in which surgical operation* may be performed without 

 pail. During the action of alcohol on the nervous ny>tem in drunken- 

 a***, operations have been performed without the knowledge of the 

 patient. Although theae circumaUnoe* have been generally known, it 

 waa not till about the year 1847 that any attempt was inatle to intro- 

 duce tnaielliiilii agenU a* a meana of alleviating pain during the per- 

 formance of mrgical operation*. About this time, two gentlemen in 

 America, Dra. Morton and Jackson, made experiment* on human being* 

 with the nitrous oxide (laughing gas), and found that a state of inseusi- 

 bility could be produced by its agency, under which operation!) could 

 be performed. The effects of thu gaa ill producing excitement of the 

 nervous system had been made known by the experiments of Sir 

 Humphry Davy, and ita peculiar action waa often exhibited in the 

 lecture-room of the chemist. It waa also known that sulphuric ether 

 produced j"fil* effect* on the human system. The merit however 

 of the application of theae remedies to the production of insensibility 

 during the performance of surgical operation* is due to Dm. Morton 

 and Jackson. Having discovered that ether waa much preferable for 

 this purpose to nitrous oxide, they made known the important fact, 

 that under the influence of this agent an insensibility might be pro- 

 duced under which ]>eraon* might undergo the mogt severe operations 

 without pain, and might be restored from this condition without injury 

 to their health. This announcement was speedily made known, and in 

 the course of a few months the facts were realised in all parts of the 

 world. In London the action of this agent was extensively tried, and 

 realised the most sanguine expectations. The action of ether, and the 

 belt method of administering its vapour, was investigated by Or. John 

 Snow, who, in September 1849, published a work on the ' Inhalation of 

 the Vapour of Ether.' After the success of the first experiments with 

 ether, it waa found that other agents similarly constituted acted in the 

 same way upon the human system. This subject was investigated with 

 great success in Edinburgh, and led to the discovery by Dr. Simpson 

 of that city, that chloroform, a terchloride of formyle, acted more 

 speedily and efficaciously than even ether. From this time chloroform 

 became more generally used, and U now the substance which is 

 generally employed for the production of artificial anaesthesia. After 

 this. Dr. Snow found tliat amyleue was capable of producing the same 

 effects as chloroform. 



Theae agents appear to act entirely through the nervous system, and 

 according to the time employed in their administration will be their 

 effect on the nervous centres. The first part of the nervous system 

 which appears to be affected is the brain, and a kind of intoxication 

 come* on in which the patient is excited, the intellectual powers are 

 deranged, and the person acts as though drunk. This effect in produced 

 much more quickly by the vapours of the above-mentioned substances 

 than by drinking alcohol ; it also passes off much more rapidly. It was 

 to this action more especially that the effects of the nitrous oxide and 

 ether were confined previous to the discovery of their anaesthetic 

 properties. If however the use of the vapour is persevered in, the 

 effect extends from the brain to the cerebellum, and this organ loses 

 the power of regulating the movements of the body. This effect on the 

 body is also produced by the drinking of alcohol. As the vapour con- 

 tinues to act on the system, the next nervous centre affected is the 

 spinal chord, and the functions of sensation and motion more imme- 

 diately under the control of this part of the nervous system, are more 

 or leas affected. It is in this stage that consciousness and the jiowcrs 

 of motion and sensation are entirely lost, and the individual is pro- 

 nounced in a state of anesthesia. In this condition animal life is held in 

 abeyance, and the body is insensible to all external agent*. There is 

 till however a sufficient amount of nervous power left to maintain the 

 functions of organic life. The heart beat*, the lungs perform their 

 functions, and other actions essential to life are carried on. These 

 functions are however under the influence of these antaathetic agent*, 

 and should too large a dose of them be administered, they cease, and 

 death ensues. This is one of the accidents to which the employment of 

 these remedies is exposed, and against which the greatest precaution 

 should be employed. 



Dr. Snow, who lias practically studied the agency of these remedies 

 more extensively than any other writer, divides the action of ether 

 into five stages. " In the Jirtt ileyrre the person experiences various 

 changes of feeling, but still retains a correct consciousness of where he 

 U, and what is occurring around him, and a capacity to direct his 

 voluntary movements. In this stage the patient's feelings are generally 

 agreeable, often highly so. In this stage it is not practicable to perform 

 operations without a certain amount of pain. When, however, persona 

 hire experienced the more intense degree* of the amcuthetic agent 

 they return to this stage, and are free from the pain of an operation 

 whilst their consciousness ha* sufficiently returned to enable them to 

 know what is going on. In the tri-vxd dryrte the mental functions ma\ 

 be exercised and voluntary actions performed, but in a disordered 

 mnnr In this stage person* are often seized with a tendency to 



laugh, sob, or scream. They throw themselves about, their actions 

 are instinctive, and not under the direction of their intelligent 

 thi* stage it is not advisable to perform operation*, and many operator* 

 lot carrying thu action of the anaMthetic further than this stage have 

 regarded it a* useless. The patient may return to this stage from a 

 further one, but it U most desirable that operations -li,.,,i.i not I* per- 

 formed in it. In the third deyrte there is no evidence of any mental 

 :;n. ;:on being exercised, consequently no voluntary motions occur, 

 nut muscular contractions in addition to those concerned in respn 

 may occur. There U aomutimes great rigidity of the munch 

 more frequently this is not present. There is a tendency to nnwn. but 

 not to utter any articulate sound*."" If this degree is well established, 

 in. I if t lie pat i, nt him I .,-.-n detained in it at the same (xiint, by inhaling 

 at intervals, or by inhaling dilute vapour, an operation may usual 

 perl. .imed without producing any other effect than a distortion of the 

 features expressive of pain, and perhajw a slight moaning and an in- 

 creased frequency of respiration , and in some instances a general ri . 

 of the muscular system." There is never any recollection of operations 

 in this degree, even when symptoms of pain have been exhibited. 



In the fourth il-i/rte no movements are seen, except those of respira- 

 tion, and they are incapable of being influenced by external impression*. 

 All the muscles are relaxed, and the limbs hang down, or rest in any 

 position in which they ore supported. The breathing is deep, regular, 

 and automatic, and there is much snoring. In this degree the patient 

 always remains perfectly passive under every kind of operation. It 

 lasts seldom more than two or three minutes after the iuhalai 

 discontinued. The integrity of the functions of respiration and circu- 

 lation is not impaired. The pulse is distinct, and however much 

 deranged in previous stages, is little disturbed in this ; the sensibility 

 of the glottis and pharynx is maintained, and the patiunt swallows 

 without difficulty. In the fifth degree tho movements of respiration 

 and circulation become impaired, and every care should be tak 

 prevent the action of the vapour from arriving at this point, a* death 



ay shortly ensue. 



With regard to the quantity of ether required, and the time necessary, 

 Dr. Snow makes the following remarks : " If a middle-aged man, about 

 the average size, is supplied with air mixed with vapour of ether in the 

 proportion of 45 per cent, vapour to 65 per cent, air, and breathes it 

 easily and without obstruction, he usually consumes about two drachms 

 of ether per minute. It is not all absorbed, for a irt is expired after 

 p*""""E no further than the trachea. At the end of the first minute he 

 is usually in the first degree of etherisation ; of the second minute in 

 the second degree ; of the third minute in the third degree ; and at the 

 end of four minutes, having inhaled an ounce of ether, in the fourth 

 degree. If the inhalation is now discontinued, he commonly remains 

 in this degree of etherisation for one or two minutes, passes gradually 

 back into the third degree, which lasts for three or four minutes, at the 

 end of which time he is in the second degree, which lasts about five 

 minutes, to give place to a feeling of intoxication and exhilaration, 

 which lasts for ten or fifteen minutes, or longer, before it entir.lv 

 subsides." 



The general effects of chloroform resemble closely those of ether. It 

 is, however, a more potent remedy, and produces anaesthesia more 

 rapidly and certainly than ether. Hence it has been employed more 

 generally. This substance was originally discovered by Liebig and 

 Soubeiran in 1881, and its chemical nature waa investigated by 1 1 

 He first pointed out that the liquid which had been called chloric 

 ether, and chloride of carbon, was composed as follows, C. H Cl ... an. I 

 called it chloroform. Liebig subsequently |K>inted out that it 

 terchloride or perchloride of the base formyle. This substance is pre- 

 pared, according to the Pharmacopoeia of the London College of 

 Physicians, as follows: Take of chlorinated lime iv. Hi.; r, 

 spirit Ogg ; water Ox ; chloride of calcium broken into pieces 3j. Put 

 the chlorinated lime first mixed with the water into a retort, and then 

 add the spirit, so that the mixture may fill only a third port of th.- 

 retort. It is then heated in a sand-bath, and as soon on ebullition 

 begins, the heat is withdrawn. The liquid is then distilled 

 receiver. A quart of water is then added to the distilled liquid and 

 well shaken. The heavier port ion which subsides is then separated, 

 ami the chloride of calcium added to it, and frequently shaken i 

 hour. The liquid, which is the chloroform, is again distilled from a 

 glass retort into a glass receiver. It is a transparent colourless liquid, 

 having a specific gravity of 1-48. It boils at 140" Kali., anil the 

 density of ita vapour is 4'2. It lias a fragrant ethereal apple-like 

 odour, and a slightly acid sweet taste. It is soluble in alcohol and 

 ether, but requires 2000 part* of water for its solution, it di- 

 camphor. Indian-rubber, wax, and resins. It is not inflammable. Thi- 

 substanoe is sometimes given internally in doses of from five to ten 

 minim*, and acts as a stimulant sedative antispaamodic and anesthetic. 



Administered in the form of vapour a* an anicsthctic, chlorofoim i 

 much more powerful than ether. This effect seems to arise fp 

 being much more sparingly soluble in the blood than ether. " Tin- 

 quantity of chloroform," says Dr. Snow, " required to induce insensi- 

 bility is less than one-tenth as much by measure as in the case of ether. 

 Viewed in this manner, it i more than ten times a* strong; but to 

 ascertain their comparative \-' I povvi-r. wlun inhaled in a 



similar manner, their volatility reqniic ,- to be taken into account. In 

 order to perceive the relative strength of these two medicines, wo mav 



