Anesthesia

anesthesia. Loss of sensation.

Effect of General Anesthesia. Local or regional anesthesia is obviously the method of choice in all cases in which it is applicable. Not only is it desirable in the minor surgical operations and the more important ones upon patients suffering with a cardiac or nephritic derangement, where a general anesthetic is positively contraindicated, but in every instance where it is at all possible, the dangers and annoyances of general anesthesia should be avoided, and the regional or local anesthesia should be employed.

Among the advantages, aside from the number of assistants required and the discomfort immediately following the administration of a general anesthesia, are the absence of remote ill effects of the invasion throughout the entire system of a noxious chemical substance and its direct deleterious effects on many large organs such as the lungs, heart, kidneys, and liver, and the assurance, when a proper drug, dosage, and technic are employed, that death cannot be ascribed to the anesthetic.

Of remote ills of general anesthesia no estimate can be made, but that they are legion and of great severity is established. Deaths from general anesthetics in persons apparently able to bear them well, are extremely numerous. It has been estimated that one in fifteen thousand succumbs from ether anesthesia and this number would probably swell greatly were it possible to obtain the exact figures. Even this minimum of danger does not exist in local anesthesia.

An accurate knowledge of the neural anatomy of a particular region enables the operator to anesthetize large areas and to operate with entire freedom from the necessity of observing the appearance and conduct of his patients, many of whom, notably the alcoholic ones, behave badly, become cyanotic and breathe intermittently when under the effects of inhalation anesthetics. The absorption into the body of the substances employed by inhalation may also exert a baneful influence by reducing the powers of resistance upon an economy already lowered by disease, and also by retarding convalescence.

Advantages of Local Anesthesia. In minor or trivial affairs the elimination of pain is not to be considered lightly, for every patient, even the strongest, will appreciate anything which will expedite a cure and at the same time will relieve him of suffering. Rather than lose time from their work or suffer the nausea and dangers of general anesthesia, these patients often bear for years conditions which could easily be cured by operations under local anesthesia. In this class one must first think of hemorrhoids; of cysts; of fatty tumors; of foreign bodies in the hands and feet; of verruca and of ingrown nails. These conditions would be promptly relieved were the element of pain in surgical interference not to enter as a factor.

With a perfect technic, local anesthesia can also be employed with entire satisfaction for certain major operations, where the subject is suitable. Thus, herniotomies are performed with entire success, especially those cases complicated by strangulation in which the dangers arising from fecal vomiting and inspiration pneumonia, are greatly decreased by omitting the general anesthesia.

In many of the more severe conditions not to be classified as minor surgery, the surgeon may consider the comfort of the patient and his own convenience and employ local in preference to general anesthesia, even tho the patients may be of the most robust type.

In this group may be mentioned benign tumors at any visible part of the body, hernias, many scrotal and anal diseases and some conditions peculiar to the extremities, such as varicose veins. These conditions lend themselves kindly to local insensitization.

In certain emergencies where an operation must be performed immediately, such as tracheotomy, thoracentesis and strangulated hernia, local insensibility is imperative. In these operations local anesthesia is also more desirable because of the ill effects of vomiting, which are thus eliminated.

Weakness of the patient enters also as a demand for the exhibition of a local anesthesia in such operations as resection of a rib for empyema, in which instance the action of the heart or lungs is embarrassed. Other operations performed under local anesthesia for the same reason (weakness of the patient) are the exploratory operation for a probable inoperable cancer and the palliative operations such as gastrostomy, enterostomy and colostomy.

Some Valid Objections to the Use of Local Anesthesia

There are, however, valid objections to the general application of local anesthesia and the cases for its use should be selected with care. It does not produce relaxation nor does it give the surgeon perfect control over his patient. These are considerations which must be taken into account, especially in operating on patients of highly nervous temperaments. Though the patient may be convinced that he will suffer no pain, the mental attitude toward the local anesthesia, together with fear, may operate so strongly as to constitute a shock to the nervous system so great that a general anesthetic should be used and the local method abandoned, even were it apparently indicated.

Again, the injection of anesthetic drugs in cicatrical and inflamed tissues is quite difficult of accomplishment and because of the peculiarity of these tissues, diffusion throughout a given area is imperfect, hence insensibility is not complete.

The extravagant claims of enthusiastic advocates of this method of anesthesia have retarded its progress. Thus, in the hands of the competent operator it was given but a perfunctory trial to be discarded as impossible. At the present time, however, local anesthesia bids fair to become the method of choice, other things being equal, for many major operations not yet thus performed. Recent investigations alone these lines have developed methods of its application whereby it is possible to render insensible large areas of the integument, and regional anesthesia is performed by anesthetizing nerves proximal to the seat of operation, thus rendering amputations feasible.

A single element which has entered as a factor in retarding the progress of local anesthesia in general surgery, is that of regarding the operation as one fitted to the method rather than to the patient under consideration. It is obvious that this is a fallacy and the main issue in deciding between general and local anesthesia is: what will the patient best tolerate? In coming to a decision in the matter one should make a general survey and weigh first the general health of the patient; whether he be in perfect systemic condition or undermined by disease, whether the shock will be greater from one method than the other, and whether the part of the body to be operated on is one which will lend itself better to one method than to the other.

These elements are being and will continue to be considered as preliminary to operative procedure and in consequence, general anesthesia will cease to be given in a routine way.

Physiologic Effects

Nerve Pressure; Anemia. That motor and sensory paralysis followed pressure upon a nerve has been well known for many years, and this has been utilized in the effort to produce anesthesia, artifically by applying a rubber tube or bandage around a finger or extremity, with the hope that “ligation anesthesia” would follow the arrest of circulation. This, however, has been unsuccessful as all that was thus accomplished was a slight sensation of numbness with no arrest of the sense of pain. This method could only be successfully carried out, were the nerves themselves subjected to sufficient pressure to injure them. Return to normal sensibility and motor function could not be expected for months.

Cold. The addition of common salt to ice hastens its liquefaction and consequently renders the mixture more cold. This knowledge has been applied in a method of producing anesthesia of limited areas of the skin. A gauze bag of the correct shape and size is filled with salt and ice mixed, and applied to the area to be anesthetized.

This method was used as far back as 1848, by Arnott, but was soon improved upon by Richet and others who used ether or rhigolene sprayed on the part to be anesthetized. It was found that extremely low temperatures could be obtained in this way, especially if a current of air were blown across the field of operation to hasten evaporation, and that a good local insensibility could be brought about if the circulation of warm blood could be either stopped or retarded with an Esmarch bandage or tourniquet. The method of obtaining local anesthesia through the agency of cold was found to be best accomplished by ethyl chloride and this substance is used in preference to any of the others previously mentioned, at the present time. Some years ago Dr. Martin W. Ware of New York experimented with both ethyl chloride and ethyl bromide and he found that the former was more serviceable in producing local anesthesia.

The Sensibility of Various Tissues. Karl G. Lennander, of Upsala, Sweden, shortly before his death, completed a chapter on local anesthesia for Keen's “Surgery” in which is set forth an elaborate account of the sensibility to heat, cold, pressure, and pain of the various nerve terminals throughout the body. In this great work he has given the world the results of many experiments on living tissues, experiments investigating the degree and kind of the tissues sensibilities; thus it is learned that “all internal organs receiving their nerve supply only from the sympathethic nerve and from the vagus, below the branching-off of the recurrent nerve, have no sensation, and that the abdominal and pelvic viscera are devoid of nerves to convey the sense of pain, heat, cold, or pressure.”

From the same authority we are taught that the parietal peritoneum is highly sensitive but that the visceral covering is devoid of all sensibility, enabling the operator much freedom of manipulation within the abdominal cavity.

In a work of this limited size the sensibility of the various tissues cannot be fully treated but it should be borne in mind that the integument and the subcutaneous tissue, fat and muscles as well as the tendons, their sheaths, the muscles and periosteum and perichondrium covering the bones and cartilages throughout the body, are all highly sensitive to pain. It is also equally true that the bone substance, the bone marrow, and the cartilages are devoid of any of the four modalities of sensation. Articular surfaces covered with cartilage have no sensation, neither have the fibrocartilages any sensation.

History. From Corning we learn that the ancient Assyrians alleviated and even entirely prevented the pain incident to circumcision by compressing the veins in the neck. Unconsciousness was probably induced in this way together with pressure on the carotids.

In India, centuries ago, the effects of opium and of Indian hemp were known and employed, and the ancient Egyptians were also conversant with the soporific effects of many drugs. We learn, from the same authority, much which he gathered from literature about the history of local anesthesia, and it is from Corning's well-known book on local anesthesia that most of this history is quoted.

In Peru, the Spanish conquerors learned that the coca loaf was held in high esteem by the natives, inasmuch as they observed that it was chewed by the high priests and nobility only, the vulgar being denied this privilege except as a reward of great merit or of distinguished valor. The leaf was regarded with awe and superstition and was supposed to possess supernatural powers. After the fall of the Incas, the Spanish not only permitted but encouraged the general use of the leaf in order to obtain more work from the natives, a result which the drug seemed to effect. It was also a source of great revenue to them and was sold at exorbitant profit to the natives who became enslaved to its effects but were able to endure great hardship while under its influence.

Chemists throughout the world, recognizing the potent action of the coca leaf, were soon engaged in the effort of extracting its active principle.

In 1859, after many had tried and failed, cocaine was evolved from crude extractives. Authorities differ as to whether it was Mann or Neimann, a pupil of Woehler, who first presented cocaine to the chemical world; however, fifteen added years elapsed before practical use for it was found. In 1862, Professor Schraff discovered that the tip of the tongue was rendered numb, and insensible when a little of the cocaine alkaloid was applied to it and that it remained so for a considerable length of time. Significant though this experiment was, the action of cocaine on the nerve-filaments was not recognized and the matter was not followed up until Dr. Karl Koller, of Vienna, began his experiments which resulted in a universal awakening to the use of a substance which, though known, had been allowed to remain unnoticed for ages.

Its anesthetic effect upon the eye was demonstrated by Koller at the Opthalmologic Congress at Heidelberg in 1884. Dr. H. D. Noyes was first to direct the attention of the American practitioners to Koller's results in the use of the drug. Its introduction was one of the greatest triumphs of modern surgery. It makes possible the discard of the systemic anesthetics in all minor surgical operations and also in many operations of considerable magnitude.

In the laboratory of Professor Stricker, Koller experimented on the eyes of a number of animals and thus reports his findings:

“A few drops of a watery solution of muriate of cocaine dropped on the cornea of a guinea pig, rabbit, or dog, or instilled into the conjunctival sac in the ordinary way, caused, for a short time, a winking of the eyelids, evidently in consequence of a slight irritation. After one-half to one minute the animal again opens its eyes which gradually assume a staring look. If now the cornea is touched with a pin head (in which experiment we have carefully avoided touching the eyelashes), the lids are not closed by reflex and the eyeball does not move, the head is not thrown back as usual, the animal remains perfectly quiet, and, on application of a stronger irritation we can convince ourselves of the complete anesthesia of the cornea. In this way I have scratched and transfixed the cornea of the animals used for experiment with needles, and have excited them with electric currents so strong as to cause pain in my fingers, and to become quite intolerable to the tongue. I have cauterized the cornea with the nitrate of silver stick until it became milky white; during all of this the animal did not move. The last experiment convinced me that the anesthesia involved the whole thickness of the cornea and did not affect the surface only. But if I incised the cornea, the animals manifested intense pain, when the aqueous humor escaped and the iris prolapsed. I have been unable hitherto to decide, by experiments on animals, whether or not the iris could be anesthetized by dropping the solution into the corneal wound, or by prolonged instillations into the conjunctival sac; for experiments to test the sensibility of non-narcotized animals are very complicated and difficult and do not yield unambiguous results. The last question which I subjected to experimentation on animals, viz., whether or not the inflamed cornea could be anesthetized by cocaine, was answered in the affirmative. The cornea in which I had incited a foreign-body-keratitis, became as insensible as a healthy one.

“Complete anesthesia of the cornea from the use of a two per cent. solution lasts ten minutes on an average. After such successful experiments on animals I did not hesitate to use cocaine also to the human eye, trying it first on myself and on some of my friends, and then on a great number of other persons, obtaining, without exception, the result of a perfect anesthesia of the cornea and conjunctiva.”

Soon after Dr. Koller's report appeared, cocaine was used for a great many operations upon the eye, and its application to mucous membranes in general was soon taken up by practitioners everywhere.

Rectal, vaginal, otologic, rhinologic, oral and urethral anesthesia were soon found to be easy of accomplishment and many operations in these fields were performed under cocainization. The hypodermic injection of cocaine was experimented with and reported upon in 1884 by Drs. N. J. Hepburn, R. J. Hall, and Halsted.

General Principles and Essentials

The first essential to the successful production of local anesthesia is a proper equipment and one that is in good working order. Not only is it necessary to employ the best drug to this end but also to use a syringe having perfect mechanical construction and one not injured by boiling; as also needles of the length, lumen and shape suitable for the surface to be injected.

The old leather pocket syringes, on account of their not bearing water at high temperature without deterioration, should not be employed; this applies also to that variety of glass barreled metal-mounted syringe in which the glass is screwed into the metal end pieces.

The best syringes are those made of all metal or of all glass, the latter being preferred because one may see the contents and express out the air before injecting. Syringes of this type, because of the accurate fitting piston, must be thoroughly dried out after use, as the piston may stick fast within the barrel. All-glass or all-metal syringes must be selected with care as they are often imperfect, the calibre of the barrel being unequal in different parts of its length causing the piston to fit tightly in some parts, and thus to work with difficulty; and in other parts fitting loosely, allowing the fluid to escape backwards.

Syringes are also made in various sizes and shapes to meet certain requirements. For the edematization of large areas of loose tissue, where a considerable amount of a weak solution is intended, the use of a large barreled syringe will be found to save time and the annoyance of refilling.

For such work a five or ten c.c. syringe would be the most useful. The ordinary hypodermic syringe is about of two c.c. capacity (thirty drops), and serves the purposes of every-day work. It does very well for the amount of an anesthetic solution employed in opening an abscess or in the removal of a small cyst or lipoma or papilloma.

A barrel, large in diameter, requires more pressure on the piston in its operation unless the needle employed is also correspondingly large. For this reason, if the tissue in which the solution is to be injected is not loose or cellular, it will be found better to use a syringe in which the barrel is long and narrow. Such is the shape of the syringe intended for the injection of the gums, the peridental membrane, and also for the periosteum, cartilage or bony cellular structure. A long instrument is also required for use in the large cavities of the body such as the mouth, the vagina, or the rectum. In these localities, an extension fitting is often required to lengthen the instrument sufficiently to reach the desired part. It is also possible to attain this end by using a long needle; this, however, sacrifices rigidity.

For accomplishing the best results, the needles must also be selected for the work at hand. For the initial puncture in sensitive or inflamed tissue, it is proper to use a needle of the finest lumen so as to cause the least possible amount of pain. The ordinary needle, which comes with the usual hypodermic outfit, is about the proper length for the ordinary work already mentioned, but could be improved upon for anesthesia by being made a little finer in calibre. This length (three-quarters of an inch) will be frequently found insufficient to reach the deeper tissues and in the removal of a more or less rounded growth, a longer needle must be selected at the start. Curved or angular ones are only needed in dentistry, where strength is also a consideration. Strength is afforded in those of short length by means of a reinforcement at the hub. Needles so augmented may also be of use in operations upon bone or dense structures in general; the curve, however, is not essential.

The surgeon should be fully conversant with the details of the operation which he is about to perform. His work should be definitely in his mind, for in operations under local anesthesia, there is no justification for a change of procedure after the beginning of the work. Account should be taken of the nature of the tissues to be anesthetized, for it is known that cicatricial tissues and inflammatory areas do not lend themselves to the action of these drugs. In a cicatrix, the diffusibility of the solution is impeded, and in an inflammatory or necrotic tissue, the changes in the quantity and quality of the fluids present, alter the action of the anesthetic.

In considering the personal element of the patient one meets a difficulty which is by no means minor, and full explanation for the selection of the local anesthetic with many assurances of the painlessness of the operation are frequently necessary. This is especially true with one of highly emotional temperament, and, to allay fear in such a patient is not always easy.

Whatever may be said regarding the mental state of the patient who is to receive an anesthetic, whether general or local, the surgeon must remember that to be calm does not always lie within the control of his subject, and it will be found that a hypodermic injection of morphine (gr. one-eighth to one-quarter) an hour before the start of the anesthetic, will often render possible the use of the injection method in a patient with whom it would otherwise have been impossible. Morphine injections, as suggested, are of advantage in patients on whom a major operation is contemplated; they loosen the musculature and diminish the sensations of parts not anesthetized.

The deliberate and confident manner and word of the surgeon go a long way in guiding the feelings of his patient, and a worried or apprehensive surgeon makes for a doubtful and sensitive patient, ready to cry out at the first prick of the needle. Therefore it is a part of good general technic for the surgeon to deport himself in a way conducive to cheerfulness, and conversation must be guided along these lines.

There are many who will writhe and groan at sensations (which they will admit later were not painful) incident to local anesthesia, such as the grating vibrations of instrumentation. Such a patient is not well fitted for the method and it is for the discerning surgeon to recognize such in advance, that he may operate under the most favorable circumstances.

Preparation of the Patient. Proper evacuation of the bowels and a stomach free of undigested parts of a previous meal, are desirable. The subject of an anesthetic should not be purged or starved as these are weakening processes and also disturb the tranquility so essential to a perfect anesthesia. The skin should be prepared so as to accomplish surgical cleanliness without irritating it so as to retard healing. It was once thought that soap, water, alcohol, ether and bichloride were absolutely necessary to this end. It has, however, been found that iodin, applied in the ten per cent. tincture to the site of incision, fulfills every requirement. Where shaving is necessary, it should be done first. In operations about the anus and scrotum, iodin is contraindicated because of its irritating properties; it is painful in these parts and dermatitis is frequently the result of its use.

Instruments. The instruments should be prepared and ready before the anesthetic is given, regardless of the form of anesthesia employed. The surgeon's hands should be rendered aseptic, no matter how trivial the procedure before him, and every precaution should be taken to guard against infection, which is always possible in any surgical procedure however insignificant.

Technic. Various methods of accomplishing the insensitization of a part may be employed. Thus, if the skin alone is to be incised, it alone will require injection and by careful insertion of the end of the needle it may be kept just under the epidermis, thus injecting the anesthetic endermatically in and about the papillae of the papillary layer.

Endermic Method. This method is an end-organ anesthesia, and the solutions employed are strong and act because of their drug content. It is not in any sense a pressure anesthesia. The skin should be picked up and pinched hard for the better insertion of the needle directly into the skin substance. It is therefore endermic and the skin is seen to become blanched as the needle advances delivering its solution on the way. But little of the fluid is pressed out as the needle advances. When the syringe is empty or the needle has advanced to the limit of its length, refill and insert just inside of the last blanched spot and proceed in a line until the end of the contemplated line of incision is reached.

Pressing out too much of the solution at one time causes a burning sensation and should therefore be avoided as the only pain should be that of the initial prick of the needle. Care, however, should be taken to inject just sufficient of the solution to penetrate beyond the zone of operation laterally, to insure sufficient space for the insertion of sutures into anesthetized tissues. Only a small quantity of fluid is necessary in this procedure as it comes in direct contact with nerve terminals. By touching the injected line with the needle in several places along its length and inquiring of the patient if it is felt, we may make sure of the completeness of the anesthesia before making the incision which should begin and end inside the anesthetized area.

Subdermic Method. An appreciable area of skin and subcutaneous tissue may be incised by anesthetizing as previously described, together with depositing the fluid well under the skin, thus affecting many terminal nerve branches before they reach their final distribution in the skin, and widening the anesthetized area considerably.

This method is applicable to such work as the removal of small growths, and the deep incision of a carbuncle. Beneath the skin in the loose connective tissue the fluid is deposited and causes anesthesia by acting upon the nerves just before their emergence into the skin. The two methods may be combined. It is not possible to inject directly into thin skin or mucous membrane and it is therefore employed in such operations as circumcision, where the nerve terminals must be anesthetized by the diffusion of the anesthetic from its position under the skin. A little time should be allowed before beginning the operation to permit of the diffusion of the drug. This applies also to such operations as that for ingrown toe-nail where the deeper tissues down to the root of the matrix are involved.

Edemitization Method. This is the method of Schleich and it is to him that the credit must be given for a procedure which has done more to encourage the use of local anesthetics in operative surgery than any other. He employed weak solutions of cocaine and other local anesthetics in great volumes of water in order to gain the combined action of both drug and of pressure. The method is described under the heading of “Cocaine.” It was designed to obtain anesthesia with cocaine with the elimination of the toxic effects of the latter.

There are decided disadvantages to the filling up of the tissues with fluid; healing is delayed; relations are distorted and coaptation of the edges is difficult. This is probably the method of selection where an indefinite amount of manipulation is expected and where the length and depth of the incision may need to be augmented. A large quantity of a very weak solution is employed and the tissues in all directions are injected until visibly distended.

Nerve Blocking Method. By injecting a small quantity of a fairly strong anesthetic solution either directly into a nerve or beneath its sheath, the entire area supplied by it will be anesthetized. This method of nerve blocking may be spoken of as endoneural  when the injection is made directly into the nerve trunk, and perineural  when made into its sheath or immediately outside of the nerve. The injection of fluid around nerves too small to inject directly is also spoken of as perineural nerve blocking. (Hertzler).

Drugs Employed

The essential qualities of a good local anesthetic are:

1. Reliability in producing anesthesia.

2. Constitutional and local harmlessness.

3. Non-irritating qualities.

4. Ability to be rendered aseptic by boiling.

No one local anesthetic can be exclusively relied upon to fulfill all of these requirements at all times. Each one has its advocates and from the large number offered, it is possible to select several which, while not being perfect, are preferable to cocaine in that they obviate the disagreeable train of symptoms peculiar to that drug.

By local anesthetics are understood certain chemical compounds, weak solutions of which, when brought in contact with sensory nerves paralyze them without lastingly injuring them. This effect is dependent upon the presence in these agents of certain atom groups which Ehrlich named anesthiferous. It is possible that just these atom groups enter into certain chemical combinations with the nerve substance and that the nerve thus remains paralyzed until the newly formed compounds are split up and the poison is washed away by the circulating blood.

Cocaine is the original type of a local anesthetic. Einhorn has made possible its synthetic production and has also opened the field for a great number of experiments of scientific and practical importance leading to the discovery of new local anesthetics obtained by exchanging the non-anesthiferous atom groups of cocaine for other groups different for each of the various new agents; thus eucaine, orthoform, anesthesine, alypin, and others have been obtained.

Cocaine  occurs as a white, crystalline powder, readily soluble in water and in alcohol. It is an alkaloid which effects all living protoplasm. It first excites, then paralyzes. In greater concentrations it paralyzes immediately. Its effect is very ephemeral, producing no lasting harm to the cocainized protoplasm. Its effect is most readily understood by assuming that cocaine poisons the protoplasm by entering with it into combinations which are easily broken up. The products of decomposition, among which cocaine cannot be recovered, are slightly or not at all poisonous and are carried away by the circulation.

Effect on the Mucous Membrane. The external application of cocaine in solutions of varying strengths has been of great service since its introduction by Roller in 1884, and many operations on the eye and on its coverings are now greatly facilitated, by reason of its use. Small quantities only are required, hence there is little fear of its toxicity. Its anesthetic qualities by contact are also made use of in operations in and about the nose and throat. Here comparatively mild solutions are used liberally but care must be exercised against its noxious effects; it is usually employed in freshly prepared solutions which are held to be less toxic. Where extensive areas of mucous membranes are to be anesthetized, as in the rectum or urethra or bladder, one of the less toxic drugs is preferable.

Strength of Solutions. In the eye, it is customary to employ a 4 per cent. solution. For work in the nose, 2 per cent. is generally considered sufficient. In the latter connection, it is often combined with adrenalin solution in small amounts to mitigate its depressing effects as well as to control bleeding. The latter effect is but transient and is omitted by many as unsatisfactory because of the more profuse subsequent hemorrhage. In this respect cocaine and adrenalin are similar. They both cause constriction of the minute superficial vessels and immediate blanching of the membrane; work in the nose is hence greatly facilitated, the field of operation being clear and enlarged by the shrinkage of the encroaching membrane, but it is incumbent upon the operator to keep his patient under observation at least an hour after the completion of the operation that he may be certain of the degree of hemorrhage after the effects of the drugs have passed away. For the above reason many operators prefer a general anesthetic or one of the local anesthetic drugs which exert no constrictor action so that they may know, ab initio, the exact degree of bleeding.

Whatever drug is used, strong solutions are seldom necessary for application to the mucous membranes but the necessary time for its absorption is a prime requisite. To secure anesthesia of the conjunctiva and cornea, the solution is dropped into the eye at the outer canthus and as it flows off with the tears, it must be replenished three or four times until anesthesia is accomplished. In the nose, a spray over the site of incision or a pledget of cotton saturated with the anesthetic solution and allowed to rest in contact with that locality, will suffice. The flow of mucus from the nasal mucosa is stimulated by the presence of the cotton pledget and it soon becomes entirely coated with a thick mucus which no longer is able to impart to the membrane its anesthetic solution and must therefore be renewed several times before complete insensibility of the part is assured. The topical application of a strong solution on a cotton wound applicator to a limited area or spot is also efficient.

Application by Injection. In order to bring the anesthetic in contact with the nerves, it is necessary, where a skin surface is to be incised, to inject the solution as already described. The technic, previously detailed, applies here, and any of the methods may be employed for the injection of solutions of cocaine, some preferring a single method to the exclusion of all others. The locality to be treated will also influence the operator as to method.

Endermically. The endermic method is the one most generally employed in securing cocaine local anesthesia by injection. The papillary layer of the skin is well infiltrated with a mild solution (one-eighth per cent. to one-half per cent.), frequently with adrenalin 1-1000, in the proportion of 15 to 20 drops to the ounce of the solution. The strongest of the formulas of Schleich may also be used for endermic infiltration.

The skin is injected to a fair degree of tension and a white ridge marks the line of injection which should be sufficiently extensive to permit the manipulation of the cut edges.

Edemitization. Schleich's solutions are here of extreme value because large amounts of solution are necessary to produce the degree of distention required because of the minute quantity of cocaine present, though the added salt and morphine assist considerably.

Nerve Blocking and Perineural Blocking. Here a stronger solution must be employed; 1 per cent., or even stronger, is injected in small quantities, either into the substance of the nerve or under its sheath, as already described.

Strength of Solution. Schleich has worked out a method whereby very weak solutions of cocaine may be used advantageously. His plan is to enhance the action of the drug by the admixture of morphine in minute quantities and of sodium chloride in proper strength. These substances, in themselves, were found to possess anesthetic powers. Large quantities of Schleich's solutions may be injected—even several ounces, without ill effects as they contain so little cocaine. The formulas used by him are:

1.Cocaine hydrochlorate 0.2
 Morphine hydrochlorate 0.02
 Sodium chloride 0.2
 Distilled water 100. 
2.Cocaine hydrochlorate 0.1
 Morphine 0.02
 Sodium chloride 0.2
 Distilled water 100. 
3.Cocaine hydrochlorate 0.01
 Morphine 0.005
 Sodium chloride 0.02
 Distilled water 100. 

It will be seen that the strength of cocaine in the respective solutions is from one-fifth to one-hundredth of a gram.

The solutions used in the early days of cocaine anesthesia were much stronger than were found necessary afterward and it has now become the rule to employ weak solutions and to give them time to penetrate the tissues. The less toxic action of mild solutions, even when like amounts of the drug are employed, makes it incumbent upon the operator to follow this plan and the element of time is so important in the matter of securing a perfect local anesthesia that it is customary to wait fifteen or twenty minutes after the completion of the injection before making the incision. The weakest solution possible is the one of choice in the use of this anesthesia.

Toxicology. The repeated use of cocaine in the same patient should be avoided on account of the danger of establishing the cocaine habit. The drug should be given with the greatest care, especially in operations about the head, neck, face, and urethra, as several deaths and many alarming cases of syncope, delirium and paralysis or tetanic fixation of the respiratory muscles have followed its use. Because of its marked depressing effect upon vital organs, it should never be given unless the patient is in the recumbent position. The administration of one drop of a one per cent. solution of trinitrin given at the first onset of the constitutional effects and repeated if necessary every five minutes, will entirely prevent any unpleasant effects as it is a true physiologic antidote.

If the surgeon has a case in which he intends to use large amounts of cocaine, it is best to have at hand and ready for use the following agents: a hypodermic and a rectal syringe, a battery, cardiac and respiratory stimulants, oxygen, and a catheter.

If the patient becomes very delirious and is in no way depressed, chloral or hyoscine should be given. In all cases of cocaine poisoning the patient should be catheterized to prevent re-absorption and should then be treated symptomatically.

Strong solutions should never be employed for any purpose except in cases where, by previous experience with the mild ones, it is known that no idiosyncrasy exists.

The central nervous system, and next the sensory and motor nerves, are affected by cocaine. Respiratory paralysis follows the introduction of appreciable amounts of cocaine into the circulation and respiratory depression may follow the introduction of smaller quantities. A given quantity of the drug in great dilution will, under normal conditions, give no toxic symptoms, whereas the use of the same amount in a more concentrated form will give rise to pallor, cyanosis and even syncope and collapse. It is said that a maximum dose of cocaine can never be fixed; this, however, seems of less importance than knowing the minimum dose, for while it is true that many bear it well, this drug so frequently gives rise to toxic symptoms, and the idiosyncrasy for it is so common, that one can never be certain of an exact dosage. Various pharmacopias place the maximum dose at 0.05 grm. (about seven-eights of a grain).

Bearing in mind that a great dilution of a given amount makes for safety, we are astonished to learn that 7 c. c. (about 2 drams), of a 1 per cent. solution introduced into the urethra has caused death. (Czerny).

Hertzler cites numerous instances in which a few drops of a more concentrated solution (2 per cent. to 4 per cent.) have caused death. It is therefore obvious that the use of this drug must be guarded by a technic so perfect that but the smallest quantity of a very weak solution shall be permitted to enter the circulation.

Adjuvants, Substitutes and Safeguards. The numerous disadvantages in the general use of this most efficient but most treacherous local anesthetic have operated so strongly that efforts have constantly been made to find a substance which, when used with it, would correct its toxic effects.

The desirability of employing large quantities of an anesthetic solution so as to enable the operator to infiltrate large areas of tissue has led to the method of preparing very dilute solutions and mixing them with various chemical substances which in themselves would act as mild anesthetics and at the same time increase the diffusibility of the cocaine. With any of these substances, cocaine still remains toxic and the quantity injected must be kept account of when an operation of any extent is being performed even though the solution be never so mild.

A valuable preventive to this absorption is found in the application of a constricting band or tourniquet to impede the return circulation and allow the washing out of much of the drug before the obstruction is removed. It is evident that no method has yet been devised whereby the use of cocaine is rendered safe and it is for this reason that chemists throughout the world have sought to produce either a new anesthetic drug or to evolve a drug synthetically, from cocaine, minus its toxicity. This has been done, but cocaine still has its adherents because of its superior qualities.

Quinine and urea hydrochloride is one of the new substitutes which has found much favor. Among the synthetic derivatives may be mentioned alypin, novocaine, stovaine, betaeucaine, tropacocaine, anesthesin, subcutin and many others. Each of these has its advocates and all of them have some advantage over cocaine; they have disadvantages as well, which, however, in the hands of skilled operators, may be overcome.

Quinine and Urea Hydrochloride. Among the quinine salts and combinations, the above has found most favor. It consists of a molecule of quinine hydrochloride and one of urea. It occurs as a fine crystalline powder and is readily soluble in water, forming an acid solution.

This substance is one of the most recent and best substitutes for cocaine, being capable of a wide range of usefulness and practically devoid of any toxicity. It causes redness on being injected and, in strong solutions, may delay healing considerably, this constituting the main disadvantage to its use. After the use of this anesthetic, primary union is not usual.

In a one per cent. solution, anesthesia is accomplished by any of the methods already described. Weaker solutions require a more perfect technic, and are therefore not generally employed. They, however, are indicated where it is imperative to secure primary union and when for some reason no other local anesthetic is available. The scar formation which almost always follows the use of this anesthetic would indicate that some other drug be employed in operations about the face and neck. This anesthetic is preferred by many because of its safety in large quantities and because of the length of insensibility following the injection of solutions of from 1 per cent. to 2 per cent. strength.

Notwithstanding knowledge of the facts above enumerated as to the difficulty of primary union and the likelihood of scar formation in connection with the use of urea and urea-hydrochloride for purposes of local anesthesia, this drug is still considered a most valuable and useful one for providing local anesthesia for operative purposes.

Novocaine. This drug is one-seventh as toxic as cocaine but is also weaker in action. It does not cause vascular constriction but has a preliminary vasodilator action. Like quinine, it has a decidedly irritating action when injected. It has a decidedly toxic effect when used in stronger solutions than 2 per cent. and causes tonic and clonic spasm. In a 1 per cent. solution it is probably safest and best as an anesthetic and one-half ounce of such a solution may be injected without fear of unpleasant consequences.

Its dose is said to be about seven grains, but this may often be the cause of alarming symptoms, and half of this quantity would perhaps be a safe limit. The duration of anesthesias of fairly strong solutions is about fifteen minutes; the action is more prolonged if used with adrenalin.

Various combinations of drugs besides adrenalin are employed with novocaine. Fischer recommends its use with thymol, but even so, it is not efficient for a longer period than twenty or twenty-five minutes.

Novocaine is frequently used in alcoholic solutions for injection in neuralgic subjects. The commercial tablet of novocaine and adrenalin is convenient for office use.

Alypin. This substance occurs as a crystalline powder, easily soluble in water, alcohol and ether, and makes a neutral solution.

Alypin is in every respect the equal of cocaine though not quite as strong. Schleich has found that its use, in conjunction with minute quantities of cocaine, permitted of a reduction of the entire amount of anesthetics necessary to accomplish insensibility.

In its use on mucous membranes it does not cause any anemia and therefore no secondary bleeding occurs. This is a great advantage also in the examination of mucous membrane lined cavities, such as the eye, nose, throat and urethra, inasmuch as after the application of cocaine, the blanching of the membrane conveys no idea of the real condition of the parts.

Because of the results he obtained, Schleich now recommends the following solutions for infiltration:

1.Cocaine 0.1
 Alypin 0.1
 Sodium chloride 0.2
 Distilled water 100. 
2.Cocaine 0.05
 Alypin 0.05
 Sodium chloride 0.2
 Distilled water 100. 
3.Cocaine 0.01
 Alypin 0.01
 Sodium chloride 0.2
 Distilled water 100. 

For other operative procedures of a minor character, it has been found that one-fourth per cent. to one-eighth per cent. is sufficient. For application to mucous membranes, as in the urethra, nose and throat, 1 per cent. to 2 per cent. has proved effective.

Stovaine. Stovaine is used more for spinal anesthesia than for local purposes; it is said to work well in inflamed tissues.

Several drugs have been used because of their lessened toxicity and many are constantly being tried but to be abandoned because of their inefficiency or irritating qualities. None of them are as efficient as cocaine and the weak solutions of Schleich are about as active as stronger solutions of many of these and are not more toxic.

Among the other cocaine substitutes in general use are betaeucaine, tropacocain, anesthesin, and subcutin.

These all find a special field of usefulness, but for general work, are limited, because of some disadvantages which each and all of them possess.

Individual selection plays an important part in the use of a local anesthetic, and one operator, by practical experience, may obtain results with a given drug, which another fails to achieve.

The essential feature to be remembered by the practising chiropodist is, that the use of any drug employed for anesthetizing purposes, even though but local, should be safeguarded in every way.

Cold. The methods of using ether, rhigolene, or ice and salt, to produce cold, are slow and unsatisfactory. If cold is to be used to produce local anesthesia the most efficient and convenient method of applying it is by means of ethyl chloride. This fluid is very volatile and is best controlled by having it in air-tight tubes. When not in use, a valve covering one end of the tube prevents leakage. When the valve is pressed upon, the orifice of the tube is opened and the heat of the hand forces out a fine stream of the liquid which is directed upon the parts to be frozen. Rapid evaporation causes intense cold. The nozzle should be held about fifteen inches from the area to be acted upon. When the spray strikes the integument, redness almost instantly results but in a few seconds the part becomes hard and white. This condition indicates local insensibility and lasts about two minutes. If the action is slow, it can be much hastened by gently blowing upon the parts to increase the rapidity of evaporation.

The refrigeration method of local anesthesia is of limited usefulness and is recommended only for the opening of felons and abscesses, for removing wens from the scalp and back, and for producing a painless area in which a puncture is to be made. It must be borne in mind that sloughing and ulceration of the skin are liable to follow the use of cold.

Work under this form of anesthesia must be done with rapidity not always consistent with thoroughness, and should therefore be employed only when a single incision or puncture is indicated.

The pain incident to subsequent thawing is severe and, in general, is about as hard to bear as an incision without an anesthetic.

For the purposes of practical podiatry, the chiropodist is advised to use a substitute for cocaine rather than the cocaine itself when local anesthesia is necessary. In the clinics of the School of Chiropody of New York, novocaine, quinine and urea hydrochloride, and alypin are preferred, and no single instance of toxemia has ever been experienced. There have been cases in which the anesthesia did not prove thoroughly effective, but, in the main, these drugs have well answered the purposes of their use.