CHAPTER II. ANESTHESIA.
Anesthesia is a condition of insensibility induced by anesthetic agents.
GENERAL ANESTHESIA is associated with unconsciousness, and is indicated to abolish pain during surgical operations, renal colic, etc.; to con- trol convulsive seizures; to secure muscular relaxation in order to make a diag- nosis, or to carry out such treatment as reduction of a hernia or a dislocated joint; and to abolish volition in order to detect a malingerer. Except for the purpose of saving life, it is contraindicated in profound shock, great exhaustion, and in acute or advanced renal, circulatory, or pulmonary disease. The general anesthetics most frequently employed are, in the order of their safety, nitrous oxid (one death in 300,000), ether (one death in 15,000), ethyl chlorid (one death in 12,000), and chloroform (one death in 3,000).
The choice of a general anesthetic depends principally upon the con- dition of the patient and the character of the operation.
Ether is the best and least dangerous general anesthetic in the hands of one with little experience, likewise in the hands of the specialist in anesthesia when, as is the case in most of the major operations of surgery, the patient is to be completely relaxed, hence, under these circumstances, should always be employed unless there are distinct contraindications. ‘The most impor- tant contraindication to ether is inflammation of some portion of the respiratory
apparatus, owing to its irritating action upon mucous membranes. Of secondary importance, and by no means absolute, are marked arteriosclerosis, because of the danger of vascular rupture from the struggling incident to the etherization; disease of the kidneys (many authors believe chloroform to be more irritating to the kidneys than ether; in these cases nitrous oxid and oxygen or local anesthesia should be employed whenever possible) ; operations about the nose or mouth, in which the anesthetic can be applied intermittently only, and in which chloroform, being more powerful, will better maintain anesthesia (this contraindication ceases to exist if one of the insufflation methods is employed); operations in which the actual cautery may be needed in the region of the mouth, owing to the inflammability of ether, although it may be used in these cases, if the precaution is first taken to remove the anesthetic and fan away the fumes; and operations performed in the presence of an exposed artificial light, although, since ether vapor is heavier than air and descends, the danger in these cases is obviated by placing the light several feet above the level of the patient's head. Ether should not be administered in the presence of fire in an open grate or stove.
Chloroform secures complete muscular relaxation, and it does not distend the veins like ether, hence makes bleeding less annoying; it is also quicker Yn its action, more agreeable to the patient, and more convenient to the anesthetist and operator, especially in operations about the head, face, and neck; but these advantages are overbalanced by its increased danger. Chloroform is no safer in children or during pregnancy than at any other
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16 MANUAL OF SURGERY
time. It is preferable in military surgery, because it economizes space and time, and is generally employed in the tropics, owing to the great volatility of ether. In diseases of the liver and in diabetes chloroform is absolutely contraindicated. In the latter nitrous oxid mixed with oxygen is the safest general anesthetic; ether, however, must be employed if muscular relaxation is mandatory.
Nitrous oxid is by far the safest anesthetic for brief operations (from two to five minutes) in which muscular relaxation is not desired, such as the extraction of a tooth or the incision of an abscess. For longer operations in which muscular relaxation is not important, nitrous oxid combined with oxygen or with atmospheric air is the safest anesthetic. It is particularly indicated in diabetes and nephritis. It is contraindicated when the heart or the arteries are seriously affected, when there is mechanical obstruction of of the air passages, when the patient is under five years of age (owing to the ease with which infants are asphyxiated), and when the anesthetizer is un- skilled. Muscular adults addicted to the excessive use of alcohol and tobacco are bad subjects for nitrous oxid, indeed for any anesthetic. Among the disadvantages attending the administration of nitrous oxid must be mentioned its great expense, the necessity for cumbersome and complicated apparatus, and the marked increase in venous congestion, the last constituting a decided objection in many operations.
Ethyl chlorid is often used as a substitute for nitrous oxid in brief opera- tions and as a preliminary to ether. As it is 25 times more dangerous than nitrous oxid, however, we believe it should never be employed.
The preparation for anesthesia, in cases requiring a major opera- tion in which there is no emergency, should extend over two or three days, during which time, in addition to the special preparations for the operation itself, the patient should be carefully examined, particularly for the presence of disease of the heart, blood vessels, lungs, and kidneys. The condition of the nose, throat, and mouth should be known, and in many cases a careful examination of the blood will be required. The bowels should be moved by a laxative, and an enema administered the morning of the operation. The diet should be light and easily digestible. No solid food should be given on the day of operation, although a cup of tea, coffee, or consommé may be given not less than six hours before the time of anesthesia. In the feeble and exhausted purgation should be avoided, and stimulating or nutri- tive enemas may be continued until within a few hours of the operation. Just before operation the patient should pass urine, or, if necessary, be catheterized. If a woman, hair-pins should be removed and the hair braided and done up in a cap or towel. Artificial teeth or other foreign bodies should be removed from the mouth, the lips and nostrils greased, especially if chloroform is to be used, and, to prevent conjunctivitis from chloroform or ether vapor, the eyes covered with gauze moistened with boric acid solu- tion. The patient should be protected from cold, and jewelry of various kinds should be put away in a safe place. In cases of intestinal obstruction the stomach should be washed out previous to the administration of the an- esthetic, in order to prevent sudden death from inundation of the lungs with vomited fecal matter. In minor surgical procedures the period of preparation mentioned above will not be required. In all these cases, however, a com- plete examination should be made. A patient should never be anesthetized without removing the shoes and without making sure that all clothing about the neck, chest, and abdomen is loose; corsets always should be removed.
ANESTHESIA 7
With the possible exception of nitrous oxid, a patient should never be an- esthetized in the sitting posture.
The anesthetist should ascertain whether the patient has previously taken an anesthetic, and whether addicted to the use of alcohol or other drugs. He should know the results of the urinalysis, listen to the heart and lungs, study the pulse, note the color of the skin and mucous membranes, and assure himself that the mouth is free of foreign bodies. His hands should be clean, and in operations on the head and neck they should be sterilized and he should wear a sterile gown and cap. In addition to the anesthetic / and inhaler one should provide himself with a mouth-gag, tongue forceps, | a pair of hemostats with gauze sponges for swabbing out the pharynx, a hypo- dermic syringe with strychnin and atropin, and a tracheotomy tube. It is desirable to have also a solution of boric acid for the eyes in case they be- come irritated, and in some instances oxygen may be needed; an electric bat- tery is very rarely demanded. A third person should always be present to assist, if necessary, in restraining the patient and to act as a witness, as unjust accusations are occasionally made against the anesthetizer, especially by females.
The administration of ether by inhalation is rendered less terrifying to the patient, and, it is said, actually less dangerous, if three or four drops of a 25 per cent. solution of oil of bitter orange peel in alcohol (75 per cent.) is placed on the mask a few minutes before commencing the administration of the ether. It is supposed that oil of orange, by dulling the sense of smell to the irritating fumes of ether, prevents harmful reflex stimulation of the pneumogastric nerve. One of three methods of etherization by inhalation may be employed. In the open method, which is very slow, the ether is inhaled from a folded towel, held over the patient’s nose and mouth in such a way as not to exclude the air. The closed method, in which the air is decidedly restricted, and in which the expiratory products are retained and rebreathed, is quick, and warms, moistens, and economizes the ether, but is more dan- gerous than either of the other meth- ods. Some anesthetists maintain, how- ever, that rebreathing, with all forms of inhalation anesthetics, is physio- logically advantageous. Those who use the closed method find the Clover inhaler satisfactory. It consists of a dome-shaped ether reservoir sur- rounded by a water chamber, which maintains the ether at the proper temperature for evaporation. A fenestrated metal tube runs through the reservoir from a large rubber bag to the face piece. By rotating the reservoir varying quantities of vapor escape into the rubber bag, from which it is breathed backward and forward with the expiratory products; fresh air may be admitted from time to time by raising the face piece. The semi-open method, in which the entrance of air is slightly limited, but in which the expiratory products are not retained, is the one commonly employed. An inhaler may be im- provised by rolling a folded towel or a piece of gauze into the shape of a cone. The Allis inhaler (Fig. 4) consists of a cylindrical metal frame with slits in
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Fic. 4.—Allis’ Inhaler.