The principles and practice of modern surgery

To Oliver Wendell Holmes we owe the term anesthesia, as generally employed and made to mean insensibility to pain, no matter how produced. A more strict definition would limit the term to conditions comprising not only insensibility to pain but loss of consciousness. For mere loss of sensation we should, strictly speaking, use the word analgesia. This is a distinction with a difference. Thus I have on rare occasions seen a patient under chloroform absolutely oblivious to pain but perfectly conscious, and chatting intelligently throughout the operation. This is a rare phenomenon, but has been noted by various observers. So after intraspinal cocaine injections we secure complete analgesia of the lower portion of the body, but not complete anesthesia, the former being what we are most anxious to produce.

The discovery of anesthesia is essentially to America’s credit. Long, of Georgia, had produced anesthesia by ether as early as 1842; Jackson, of Boston, also claims credit for the discovery; but to Morton, a dentist of Boston, is undoubtedly due the honor of having introduced it for surgical purposes. The first public demonstration of its properties was made by Morton and Warren, October 16, 1846, in the Massachusetts General Hospital. Chloroform seems to have been exploited independently by Guthrie, of Sackett’s Harbor, N. Y., and Simpson, of Edinburgh, in 1847. It is a curious historical fact that the patient to whom Simpson meant first to administer chloroform in his clinic did not receive it because of some failure to have it on hand; she took ether instead and died, presumably of the anesthetic. Had she died under the influence of chloroform it would have been a serious setback to any general appreciation of its merits. Nitrous oxide is also an anesthetic for which America may take the credit. These are the three drugs in common use today, although there are others which are coming into general favor.

It can be stated as an axiom that when a surgeon tries to abolish human sensibility, or pass an instrument through the human skin, he introduces elements of danger which can never be certainly and completely controlled—that is to say, the administration of an anesthetic is never to be undertaken as a trifling matter, but should be entered upon as carefully for a minor procedure as for a dangerous and prolonged operation.

Anesthetics are sources of danger, not only for the moment while they are in use, but because of the disturbances which may follow in their train. These drugs should never be administered carelessly nor thoughtlessly, nor by inexperienced individuals, but entrusted to the wisest and the most discreet. More is expected of the anesthetizer than that he shall barely keep the patient alive; he should be so expert as to keep the patient safely on the side of complete anesthesia and muscle relaxation. Nor should he be willing to yield to the importunities of an impatient operator who may be continually appealing to him to crowd the anesthetic. When thus given, and by an expert, such postanesthetic distress as nausea, vomiting, coughing, etc., may be avoided. So generally are these facts now realized and appreciated, that in many of the large hospitals a regular anesthetizer is employed, whose sole duty it is to administer the anesthetic for the attending surgeons. The management of an anesthetic has much to do with the allied subjects of the preparation of the patient, the management of shock or reduced blood pressure, and the status lymphaticus, which have already been considered.

Fatal accidents from anesthetics are the appalling ones which have generally occurred in cases where it has been assumed that the patient is in good condition, and where neither preliminary examination nor preparation has been made. In the presence of unmistakable cardiac disease, or of great arterial tension, the surgeon may, by foreseeing the possibility of trouble, do much to prevent it; but when an apparently healthy individual is placed upon the operating table without attention to these matters it may happen that his heart will stop as suddenly and unexpectedly as though it had been transfixed. In other words, the accidents of anesthesia usually occur when least expected; on the other hand, accidents will be few and far between when all cases are handled as though promising to be severe ones.

The odor of most anesthetics is so distasteful to patients that they inhale at first with difficulty and with signs of irritation. Much of this can be guarded against by spraying the nasopharynx with a 1 or 2 per cent. solution of cocaine. This expedient will make anesthesia much easier for them. The mouth should be examined; all false teeth or foreign bodies, such as pins, chewing-gum, etc., should be removed. Unpleasant burning of the sensitive mucosa of the nose and lips may be avoided by anointing these parts with cold cream. Attention should be given to the avoidance of irritation of the eyes or the careless escape of an anesthetic into the conjunctival sac; with a struggling patient, or a careless administrator, this may easily happen.

Circumstances which would justify the administration of an anesthetic without the consent of the patient, or the friends or parents, occur but rarely; still in an emergency case, with a patient incompetent to decide for himself, the surgeon must assume the responsibility, in which in all probability the law will sustain him.

The anesthetizer should always be accompanied by an assistant; preferably in the case of a female patient, by a female nurse, who may not only be of assistance to him at the time, but an actual protection should the patient experience any erotic delusions during or after her period of anesthesia. This applies equally well to dentists giving nitrous oxide for the extraction of teeth, or physicians attending cases of accident, convulsions, and the like.

The anesthetics in general use are ether and chloroform. If statistics alone are appealed to it can be easily shown that ether is the safer of the two by a large ratio. But the recovery of consciousness by no means indicates the conclusion of the period of danger. The harm which chloroform does is largely done promptly, whereas the unpleasant effect of ether lasts through a much greater period, and the statistics which give ether an advantage are in many respects fallacious. Chloroform is doubtless the stronger and the more subtle agent of the two, and in careless hands would, in all probability, become the more dangerous. But no anesthetic should be given carelessly, and no one should give it who cannot give it properly. There may be emergency cases, especially in the rural districts, in which the surgeon may have to act in the capacity of anesthetizer and operator as well, and where he may have to transfer the inhaler to some lay assistant who knows nothing of the action of these drugs. If this happen it would be safer to use ether.

When administered by a thoroughly competent person chloroform is the safer anesthetic of the two, and is usually to be preferred. So largely does the personal equation figure in this consideration that it seems unnecessary to reproduce here statistical tables in regard to its efficiency.

ETHER.

The writer’s intention is to confine his views on anesthesia to the practical application of certain drugs whose chemistry, materia medica, and ordinary therapeutic properties are appropriately treated of in other works.

Ether anesthesia has by some been considered to be simply one form of carbon dioxide poisoning; that it may be all of this, in certain cases, may be granted; but it is certainly something more, as is shown, among other things, by the peculiar odor which persists in the breath of the patient for hours or even for days after its use. Various ways of administering it have been recommended. Some give it well diluted with air, and some give it as strong as a patient can possibly bear it, and from the outset. Some keep mixing air with the vapor, while others have devised inhalers, by which the same ether-ladened air is breathed over and over again. These latter produce a certain degree of the carbon dioxide poisoning above alluded to, and are not ideal even if effective.

Even when well diluted with air the vapor of ether causes irritation of the air passages, in both the nose and throat, and leads quickly to a sensation at first of oppression and then almost of suffocation, which is trying to the self-control of intelligent patients and disturbing to those having little or none. An inhaler saturated with ether should not be pressed tightly over the patient’s face, as it is likely to produce struggling to such an extent that weakened bloodvessels may give way and by their rupture produce serious disturbance.

The first momentary period of irritation having subsided, there will likely follow a few deep inspirations, and then perhaps a fixation and immobility of the chest, so that for half a minute or a minute it would seem as though the patient had forgotten to breathe (Hare). But deep respiration is quickly reëstablished, or may be stimulated by slapping the chest, by a few movements at artificial respiration, or at least by compressing the thorax. Then follows the period of “primary anesthesia,” so called, or a period of excitement, during which the patient may rave or become quite disturbed, and in a manner sometimes quite at variance with his ordinary temperament. As this period subsides the state of complete anesthesia begins, and when muscular relaxation is complete, or even before, the surgeon may commence his work. The respiration under complete anesthesia is usually deeper and sometimes more rapid than in health, while as the muscles become more relaxed a positively stertorous breathing is noted, along with an increase in flow of saliva, due to the irritation of the ether vapor. As anesthesia passes into complete narcosis, and this into asphyxia, the color of the surface, especially of the face, changes to a cyanotic hue, the skin becomes moist and clammy, and the pulse, which had been accelerated, fails. The blood also becomes exceedingly dark from lack of oxygen. Under these circumstances the heart may continue to beat feebly for a short time after respiration has ceased. As Hare puts it: “In producing its effects ether first attacks the perceptive and intellectual cerebral centres, next the sensory side of the spinal cord, next the motor side of the cord, then the medulla, and with this last depression death ensues.”

Ether is more pungent and less agreeable to breathe than chloroform, but the chief advantage usually connected with its use is its supposed factor of safety.

On the other hand, the accidents which are due to ether are in a large measure those common to the use of any anesthetic agent. Among the most prominent is arrest of respiration, which may be caused either by mucus or some foreign body in the air passages, or by the tongue dropping back in the pharynx, and the impediment to respiration thereby offered. When the cause of the difficulty is ascertained it is usually easily removed. Should great pallor accompany these symptoms, then, it is usually because the heart as well is at fault, and vigorous stimulation of this organ should be promptly instituted.

Another disadvantage pertaining to ether results from the irritation which its vapor produces in the bronchi and lungs, or in the kidneys during its elimination. From the former may result bronchitis, congestion, or even pneumonia; the latter more often of the catarrhal type than of the croupous. As the result of renal irritation there may be temporary albuminuria, or the congestion resulting may assume so serious a type as to produce absolute suppression (anuria), which is practically always fatal. Ether is said to be particularly undesirable in cases of diabetes, because of the resulting acetonuria. Patients have even been known to pass from anesthesia into diabetic coma.

It has been found that complications are more common in males than in females, but more severe in the latter. Vomiting following the use of ether is a frequent and most unpleasant sequel. It is to be prevented by previous lavage, as well as by the same measure at the conclusion of the operation. It will rarely subside when present until the ether vapor has been eliminated. So far as it is possible to suppress it with drugs probably 2 Gm. doses of chloral and one of the bromides, with a little laudanum, given by the rectum in salt solution or a little starch-water, will give the best results.

As already stated, it was formerly held that anesthesia was carbon dioxide poisoning, plus something else which was vaguely described by different authorities; much clearer notions now prevail regarding the mechanism of anesthesia. A few years ago Meyer and Overton concluded that anesthesia is produced by solution of the fatty constituents of the cells by the anesthetic absorbed, this being true at least with chloroform and ether, both of which are solvents of fat. The absorbability of the anesthetic varies with the blood temperature, this varying widely between the cold-blooded and warm-blooded animals. They estimate that 1 part of ether to 400 parts of serum is necessary for complete anesthesia in man, while one part in 4500 to 6000 parts is a sufficient proportion of chloroform. According to these views the dissolved fat is not removed from the cells, and no satisfactory explanation yet accompanies this theory, even assuming its accuracy.

Of no small importance are the experiences of Snel, who found that anesthetics decrease the bactericidal properties both of the blood and of the tissues, but that this power is quickly recovered after the elimination of the anesthetic. He furnishes reason for the theory that the thus lowered resistance of the lungs is an important factor in the production of the pneumonia which occasionally follows operations.

There is a belief that ether is more irritating to the kidneys than chloroform. This, however, does not seem to be justified by evidence, neither is the prejudice against the use of ether during the existence of albuminuria or in the presence of casts. In the presence of a high degree of albuminuria any anesthetic is dangerous, and here ether would be the less desirable of the two. Nevertheless in ordinary mild albuminuria one need not fear to give ether.

About twenty years ago it was suggested that ether anesthesia could be induced by passing its vapor into the colon through an ordinary rectal tube. There are many obvious reasons why it would be of great advantage if anesthesia could be safely practised in this way, not only in operations about the face and head, but because of the avoidance of pulmonary and gastric irritation.

The method was to thoroughly empty the colon and then connect a rectal tube with a receptacle containing ether, which was placed in warm water and the vapor passed into the intestine. It was found that patients could be readily anesthetized in this manner, but unfortunately it was also found that a considerable degree of intestinal irritation was produced.

The writer recalls one case in which this method was practised, which terminated fatally within twenty-four hours after the operation, where the autopsy disclosed a violent degree of acute colitis.[7]

CHLOROFORM.

It is important that pure chloroform should be secured for anesthetic purposes. It should be kept in dark bottles, and in the dark, as it is liable to undergo decomposition in the presence of sunlight. It is less volatile than ether, and mixtures of the two drugs are not stabile, since the ether is likely to evaporate first. In its anesthetic effects it resembles ether, acting first upon the perceptive and last upon the motor centres.

The British Chloroform Committee estimate that from 1 to 2 per cent. of chloroform in the inspired air is sufficient for anesthetic purposes, and may be safely used; that 5 per cent. is more than adequate, and that anything stronger than 2.5 per cent. is dangerous.

The effect of chloroform upon the heart is to quicken and then slacken it. The former action is due to a depression of the vagus centre, while subsequent slowing is due partly to vagus stimulation and partly to direct weakening of the heart muscle. While chloroform does not materially affect the excitability either of the vagus or accelerator nerves its main effect is on the strength of the heart action, and is less marked on the auricles than on the ventricles. Ether has a more marked tendency to raise blood pressure than chloroform, while the latter is likely to be more responsible for sudden falls in blood pressure even after its administration has ceased.

The question of the relative dangers of the two drugs has engaged the attention of investigators the world over, and one of the side questions to be discussed is whether chloroform kills by arresting the circulation or the respiration. Chloroform produces a fall in blood pressure (see Chapter XVII) but as long as the blood pressure within the brain, and especially the medulla, is maintained this effect is of secondary importance; but when the respiratory centres lack their natural stimulus, and respiration becomes irregular, then, as it were, the patient “bleeds into his own vessels.” It is under these circumstances that adrenalin produces its most marked and prompt effect.

The first effect of chloroform inhalations is to raise blood pressure, but this is soon followed by lowered tension. The pupils may dilate slightly at first, but usually contract and remain contracted during anesthesia. When they dilate suddenly means should be adopted to avert the danger threatened, as the relaxation of the iris is the first visible relaxation of death. While the pupils react to light there is little danger.[8]

Death from chloroform usually occurs when it is assumed that no accident is likely to happen, as when it is given to an athlete, or to drunkards who are supposed to be secure from any reflex influences. Patients with weak hearts can be conducted safely through a prolonged anesthesia if there be time to prepare them. (See chapter on the Preparation of Patients.)

The after-dangers of chloroform are smaller than those of ether, due in part to the fact that a much smaller amount of the drug suffices; in other words—that it is the stronger.

After anesthesia has been produced and the patient is unconscious it requires but small additional amounts to maintain unconsciousness, as it is necessary to add only as much as may be required to replace what is lost by evaporation and exhalation. It is sometimes advantageous to commence with nitrous oxide gas, for there are fewer unpleasant reflexes, less salivation, and less disturbance of every kind. Shallow breathing may be improved at almost any time with a few drops of ether.

Many anesthetizers have a habit of testing the degree of anesthesia by touching the cornea with their fingers. A piece of sterile gauze will prove equally effective and less irritating.

When the mask upon which chloroform or ether is given is held over the face free salivation will frequently be excited, and the patient will be tempted to swallow as well as inhale. In this way the vapor of the anesthetic is taken into the stomach as well as into the air passages, and when the stomach is empty this comes into direct contact with the gastric mucosa. This may produce not only irritation, but, in extreme cases, gastritis. It has been suggested that to allow the patient to drink a quantity of water at intervals before taking the anesthetic, and especially a half-pint or more immediately before beginning it, will be to permit of absorption and dilution of the anesthetic vapor without their causing this irritation.

The simplest method of administering chloroform is upon an ordinary mask, the covering of which should be thin in order to permit of easy play of air. By this method a patient can always be anesthetized, but with a waste of the anesthetic and with absolute uncertainty as to the proportion of chloroform vapor in the inspired air. A variety of expedients have been suggested in time past, and chloroform inhalers of various patterns are constantly upon the market. The Junker inhaler, introduced some twenty-five years ago, was a great improvement upon its predecessors, but only recently has a really scientific measuring inhaler been placed before the profession. This is the one devised for and introduced by a committee of the British Medical Association, and is the result of the study and ingenuity of Prof. Vernon Harcourt. It has already been stated that more than 2 per cent. of chloroform vapor in the inhaled air is dangerous. The Harcourt apparatus consists of a two-necked bottle, nearly filled with chloroform, into which are dropped two colored glass beads, which serve to indicate when the temperature is between 55° and 59° F. If the temperature be below 55° F., both beads will float; if it be above 50° F. both will sink. If the former, the proportion of chloroform will be below that indicated by the pointer; if the latter, it will be greater. Inasmuch as during inhalation the chloroform is cooled by evaporation, it is necessary to occasionally place the warm hand over the bottle until the blue bead has sunk and the red bead is beginning to sink, indicating that the temperature is again approaching 59° F. A stopcock is so constructed that when the pointer is at one end of the arc the maximum amount of chloroform which may be taken up is 2 per cent.; when the pointer is at the opposite end, the patient breathes only pure air. There are valves which prevent the entrance of expired air into the apparatus, and which show whether the stopcock is working. They also show the character of the respiration. Administration is begun with the pointer at 0.2, and while it may require 2 per cent. of vapor to produce narcosis; i. e., the complete and final stage of anesthesia, it will take scarcely more than 1 per cent. to maintain it. The mouth-piece has an expiratory valve, and the apparatus can be held in any position, but should be kept nearly vertical. The mask is fitted with an air cushion, which can be molded in hot water so as to fit the patient’s face. Buxton, who is the leading authority on anesthetics in London, has abandoned all other apparatus for this. While he is a most skilled expert, he has shown that by means of this apparatus chloroform can be given with almost absolute safety.

Aside from the danger and discomfort pertaining to the use of chloroform in apartments lighted or heated with natural gas, there is another similar danger in connection with ordinary city illuminating gas. In the presence of a flame produced by the latter the vapor of chloroform is broken up not only into chlorine and hydrochloric acid, but into a carbon oxychloride, known also as phosgene, which is toxic and produces a sense of suffocation by producing decomposition within the blood. A fatal occurrence of this kind led to experiments on animals by an Italian observer, which showed that the substance produced rapid disintegration of hemoglobin, which fell rapidly to 40 per cent., and that accompanying this there was suppression of urine with convulsions.

Unless chloroform be given by one familiar with its use, it is best given from a dropping bottle. If this be so arranged that it will discharge but one drop at a time, and the anesthetizer so administer it as to allow perhaps one drop to fall each second, the patient will at no time get an overdose, nor will there be struggling or choking. Irregularity of breathing is usually the result of insufficient air, and the mask should be at once removed, so that the patient may take one or two deep inspirations. When the cornea is insensitive the patient will stand almost any manipulation except, perhaps, stretching of the sphincters. When the sphincter can be stretched without provoking any effect except a prolonged inspiration, then the patient is, in all probability, completely relaxed and ready for any procedure. When the breath becomes stertorous the mask should be removed even though the cornea be sensitive. It will quickly lose its sensitiveness again within a few seconds. Proper breathing must be maintained. Free supply of air is important above all other things, and it is better that the surgeon should wait rather than the anesthetizer.

Additional safety in the use of chloroform may be afforded by the simultaneous use of oxygen gas, by which cyanosis is usually avoided and vomiting often prevented. It may be safely used with chloroform, but not with ether. If ozonized air be conducted into anhydrous ether it forms a thick liquid, probably ethyl peroxide, which explodes if heated (Hare). It is a mistake to so manage the administration of chloroform with oxygen that the patient receives no pure air. Oxygen is of great value, but it is not physiologically breathed in its pure state. When the gas is allowed to bubble through a bottle of chloroform, carrying with it the vapor, no idea can be formed as to relative percentages. A better way is to administer the chloroform upon a mask, and the oxygen by a tube from a wash-bottle filled with water and passed into the nostril under the edge of the inhaler (Hare).

Gwathmey has introduced a modification of the well-known standard Junker inhaler, by which oxygen and chloroform, or nitrous oxide and ether, may be given together, or by which any desired combination can be effected. Its special advantage is the same as the Harcourt apparatus, that the percentage of chloroform or ether vapor can be estimated or controlled. So far as the administration of chloroform with oxygen is concerned, Roth has shown that oxygen does not decompose the chloroform, but diminishes the danger of its administration.

Gwathmey refers to the advantage of keeping an open airway by turning the head a little to one side and pressing the jaw well forward; he also advises that when the anesthetic is removed from the face it is well to replace its odor by some other perfume, such as cologne or smelling salts, as it is presumed that the olfactory nerve is responsible for the initial symptoms of nausea and gastric distress.

In some States natural gas is used as fuel, usually in open fireplaces or stoves. When chloroform is administered in a room thus heated, or even lighted by natural gas, formaldehyde gas is the result of a mutual decomposition, and this is exceedingly pungent and irritating, and will soon produce violent coughing in all who are present in the room. It may be impossible to avoid this, but natural gas flames should be extinguished and some other source of illumination should be depended upon when practicable.

A. C. E. MIXTURE.

Under this term are known various mixtures of alcohol, chloroform, and ether, the intent being to counteract the depressing influence of chloroform by alcohol and ether. It may be said of every mixture of anesthetics that it is no less dangerous than its strongest constituent. Thus a mixture of chloroform and ether should be given with as much precaution as pure chloroform.

Mixtures of this kind should be made fresh for each administration, as the most volatile ingredient may evaporate in unknown amount and thus change the proportions. This is true of the mixture even after it is poured upon the inhaler, and the patient will thus be subjected to a chloroform mixture of varying strength.

The administration of ether for a few seconds during chloroform anesthesia will often prove beneficial in regulating or deepening inspiration, but it would be best to have the two drugs separate, and use the ether as it may seem called for, rather than to rely upon any such mixture. Moreover the vapor of alcohol is of itself irritating and undesirable.

ETHYL BROMIDE.

For operations of but short duration ethyl bromide offers some advantages, in that its effects quickly pass away and that there are few unpleasant sequels. Indeed, patients may take it for a few minutes with almost as little disturbance as is produced by nitrous oxide; nevertheless it cannot be regarded as being as free from danger as was originally claimed. Only a pure preparation should be used. When given as ether is usually given, upon a cone or mask, complete anesthesia may often be produced within one minute. It can hardly be relied upon to produce muscular relaxation and it frequently causes great congestion of the face and head, consequently it is not as convenient for short operations on the nasopharynx as its other good qualities might render it. It is not unpleasant to take, and ordinary ether anesthesia may well be begun with it.

METHYLENE BICHLORIDE.

For a number of years this anesthetic agent was in favor, especially in Great Britain, where it was warmly advocated by Spencer Wells. Its odor is agreeable, its action rapid, and recovery from its effects is usually prompt. But it proved to be unsafe, since it was found that the substance commonly used under this name was really chloroform diluted with one-fifth of methyl alcohol, while the genuine methylene bichloride was found by experiment to be a dangerous substance, and its use has been discarded.

ETHYL CHLORIDE.

This, like every other drug used for the purpose, should be used in perfectly pure form. While this can be obtained from manufacturers in this country, there seems to be a tendency to rely upon the imported preparation sold here under the name of Kelene. For certain short operations, such as those upon the eye, nose, and throat, and for children, it has many advantages and appears to be a reasonably safe drug for the purpose. Consciousness is quickly recovered after its use, and the after-effects are slight. It is in general use preparatory to one of the stronger anesthetics, like ether or chloroform, and affords a means of putting patients under the relaxing effect of either of these drugs. It should be administered upon a cone or mask, from which evaporation should not occur too easily, because it is extremely volatile. In the hands of one accustomed to its use, operations of considerable magnitude and duration may be successfully maintained. A special valveless mask has been devised for its use, consisting of a rubber mouth-piece which can be snugly fitted to the face, and a movable tube over which two or three layers of gauze may be stretched, upon which the ethyl chloride is allowed to drop or is ejected from the tube in which it is sold. Sometimes the expired air will freeze upon this gauze. This is of no disadvantage.

Local Use.

—On account of its extreme volatility, chloride of ethyl affords a ready means of producing local anesthesia. It boils at 50° F., and when the tube containing it is held in the hands and its capillary tip is opened it issues in the form of a fine spray, which being directed upon the part to be desensitized first chills and then freezes it. Whether this part be skin or mucous membrane the effect is the same. As soon as the desired area is covered with a thin layer of small frozen crystals, looking like hoar-frost, the surface is anesthetized and the necessary instruments may be used. Blowing on the part to be anesthetized will favor evaporation and shorten the time necessary for the purpose.

The purposes to which this drug may thus be used are numerous and obvious. For instance, in dentistry it will do much to allay the pain of tooth extraction; in genito-urinary surgery such operations as incision of the prepuce, the cauterization of venereal ulcers, and circumcision may be done with little or no pain. The small operations required in various skin diseases, the incision of small abscesses, the use of caustics wherever they may be needed, may all be made easy under its effect; while in cases of neuralgia, stings, bites, etc., it will often alleviate the symptoms. The skin may also be anesthetized in this way before the introduction of the needle through which antitoxins are injected or hypodermoclysis practised. Before venesection or before exploratory puncture it may also be used.

Somnoform.

—This agent, composed of ethyl bromide 5 parts methyl chloride 35 parts, and ethyl chloride 60 parts, was introduced by Rowland, of Bordeaux, as a convenient means of producing an analgesic condition, i. e., something between complete anesthesia and conscious sensibility. The dose is about 5 Cc., to be sprayed upon a tightly fitting mask. The patient should be told to breathe and swallow as naturally as possible, and the effect is obtained within a few seconds. The agent is so speedy in producing its effects that it is sometimes difficult to tell when the proper degree of unconsciousness has been secured. A patient may be directed to hold up an arm in order that when it drops the surgeon may proceed. There is neither cyanosis nor corneal reflex, and nausea does not usually occur. The essential point of administration is the exclusion of air. Twenty seconds of administration will give from one to two minutes of anesthetic effect, during which various brief operations can be performed. By proper management this period can be lengthened many times.

Petroleum Ether.

—Petroleum ether was introduced by Schleich for the purpose of diluting chloroform. By itself it has a weak anesthetic power, and seems to possess some dangers of its own in the way of depressing the heart’s action and producing convulsions.

OTHER VOLATILE ANESTHETICS.

Schleich was among the first to demonstrate that the retention of an anesthetic within the body depends upon its boiling point. W. Meyer carried Schleich’s views still farther and showed the at least theoretical value of an anesthetic mixture whose boiling point was that of the normal blood temperature. If the evaporating point be much higher than the blood it is volatilized too easily, while if it be lower it reduces body temperature as it evaporates. After considerable experimentation Meyer recommended a mixture by volume of chloroform 3 parts, ether 2 parts, and ethyl chloride 1 part, and introduced this mixture under the name of anesthol. This composition does not seem to have met with great favor as yet, although it has theoretically much to commend it, as it seems slower in action and but little more satisfactory in other respects.

NITROUS OXIDE GAS.

This is by all means the most rapid general anesthetic in use. Patients can be placed under its influence in from twenty-five to sixty seconds. For a long time its employment was confined to dental practice, but it is now in general use by surgeons, as a preliminary to the use of ether or as the sole anesthetic agent. When managed properly patients can be kept for a half-hour or even an hour under its influence. Two disadvantages attend its administration: (1) It is difficult to completely relax the muscles and so maintain them that no difficulties are placed in the operator’s way, e. g., in certain operations upon the abdomen where muscle rigidity delays and makes difficult the operation. (2) The use of nitrous oxide alone so far impairs proper oxygenation of the blood that this fluid becomes dark or almost black and frequently obscures the field of operation. These difficulties, especially the latter, can be overcome by the skilful simultaneous use of oxygen gas, by which the blood is kept well oxygenated, and by which the deep stupor of nitrous oxide poisoning can be made so safe that it can be prolonged to the degree necessary to afford relaxation.

Nitrous oxide anesthesia is thus proved to be something more than mere asphyxia, or it would be completely counteracted by oxygen. Suitable apparatus can now be procured by which both gases can be blended together as desired; considerable experience, however, is necessary for their successful use. It is generally stated that nitrous oxide alone should not be given to persons with fatty hearts or atheromatous vessels. From a brief period of nitrous oxide anesthesia patients usually recover within a few minutes and without after-effects; still, relaxation of the sphincters may occur. After its prolonged use there may be considerable headache and vertigo.

THE CHOICE OF AN ANESTHETIC.

This will depend upon who is to be the anesthetizer as well as upon the actual condition of the patient. If an inexperienced person is to administer the anesthetic, ether is safer than chloroform, though slower. On the other hand, when given by an expert, and after due preparation of the patient, chloroform is ordinarily preferable. The latter is especially indicated in the young and aged, as well as in those who have bronchitis or chronic cough, and those who have advanced renal diseases or atheroma, because it is not likely to produce such high arterial tension.

Ether should never be given near an unprotected flame, and lamps or gas-jets should be held above the level of the operating table, as the vapor of ether is heavier than air and will tend to sink. The disadvantages of chloroform where natural gas is in use have already been mentioned.

Efforts should be made to prevent struggling, as in the violence of this unconscious act an overtaxed heart might yield, or at least undergo dilatation. Chloroform is notably less likely to be followed by nausea and vomiting than ether, and yet nausea cannot always be prevented. There can be no doubt that morphine, alone or with atropine, may be given with advantage to most patients before administration of a general anesthetic. The treatment of postanesthetic nausea has been referred to in the chapter on the Preparation and After-care of Patients. By general consent, chloroform is the anesthetic of choice during labor.

THE DANGERS OF AND ACCIDENTS FROM ANESTHETICS.

The principal dangers from any of the volatile anesthetics come from interference with circulation and with respiration. The heart may give rise to alarm by gradual failure in strength, while the pulse becomes more rapid and irregular, or by sudden and apparently complete cessation of activity. When the pupils suddenly dilate and do not react to light danger is close at hand, if it have not already manifested itself, and then is the time to discontinue the anesthetic and resort to vigorous methods, which may include artificial respiration, but must include attention to the heart. It is customary to use injections of strychnine, which are often too weak or too small to be of service, nothing less than ¹⁄₂₀ Gr., which may be repeated in a few moments, will be of any service. If ¹⁄₁₅₀ to ¹⁄₁₀₀ Gr. of atropine be given with the strychnine it will prove a much more effective stimulus. It is right and proper to administer these drugs in this emergency, but still more reliable measures are at hand.

Sudden stoppage of the heart, being the most disastrous accident during or after anesthesia, has attracted no small amount of attention on the part of experimenters. An active massage of the heart seems to furnish the basis for all the newer methods of treating it, all of which are accompanied by artificial respiration. Some of Crile’s work in this connection was alluded to in the chapter on Blood Pressure and Shock.

Numerous investigators have revived the hearts of experimental animals by massage and saline injections, and Crile has shown the advantage of adding adrenalin to the latter. It is better to begin the efforts while the heart is still feebly beating than to wait until it has ceased. Ordinarily this massage should be made through the intact thorax, but the time is coming when it will be esteemed life-saving either to open the abdomen and massage the heart through the diaphragm, or to open the thorax and do it directly. The former can be done during almost any abdominal operation. The greatest obstacle to success has been the formation of clots in the cardiac cavities. These are formed within a few moments after the heart has ceased to act.

Massage of the heart, coupled with the use of adrenalin, will prove of service.

Approaching cardiac weakness is always indicated by failure of capillary circulation, which may be easily and instantly estimated by making pressure upon the finger-nails. The rapidity with which the blood will return to give them a natural appearance, after such pressure is made, will be the index as to whether or no stimulation is necessary. Tardiness in return of color, or absence, is a better indication of the approach of shock than is coldness of the nose or moisture of the skin. It often precedes acceleration of the pulse.

Respiration may be interfered with by a variety of causes. Not infrequently the tongue is allowed to drop backward into the pharynx as the patient lies upon his back, which, by its pressure, causes the epiglottis to fall backward upon and close the glottis. The indication here is to lift the tongue forward and carry the epiglottis upward so as to restore the air channel. Extension of the head and neck will accomplish much in this direction, as well as holding the lower jaw forward and upward by well-regulated pressure exerted behind the angle and at the same time by upward and forward traction upon the hyoid bone. But when it is necessary in cases of emergency to carry out this maneuver forcibly and extensively, then the tongue should be drawn upward and forward in the direction indicated in Figs. 41 and 42.

Tongue forceps are often resorted to for this purpose, and can be procured in various forms and shapes. To the writer their employment has always seemed far more barbarous than the much simpler expedient of passing a curved needle, armed with silk, through the tongue in either direction, 3 to 5 Cm. back of its tip. The suture thus drawn through is knotted and made into a loop, and may be employed through a long operation to make all the traction that will be required. This really makes the tongue less sore and produces less swelling and after-discomfort than does the use of forceps.