With adults no anesthesia, general or local, is given for esophagoscopy. For laryngeal operation and bronchoscopy the following technic is used:
One hour before operation the patient is given hypodermatically a full physiologic dose of morphin sulphate (from 1/4, to 3/8 gr.) guarded with atropin sulphate (gr. 1/150). Care must be taken that the injection be not given into a vein. On the operating table the epiglottis and pharynx are painted with 10 per cent solution of cocain. Two applications are usually sufficient completely to anesthetize the exterior and interior of the larynx by blocking of the superior laryngeal nerve without any endolaryngeal applications. The laryngoscope is now introduced and if found necessary a 20 per cent cocain solution is applied to the interior of the larynx and subglottic region, by means of gauze swabs fastened to the sponge carriers. Here also two applications are quite sufficient to produce complete anesthesia in the larynx. If bronchoscopy is to be done the gauze swab is carried down through the exposed glottis to the carina, thus anesthetizing the tracheal mucosa. If further anesthetization of the bronchial mucosa is required, cocain may be applied in the same manner through the bronchoscope. In all these local applications prolonged contact of the swab is much more efficient than simply painting the surface.
[67] In cases in which cocain is deemed contraindicated morphin alone is used. If given in sufficient dosage cocain can be altogether dispensed with in any case.
It is perhaps safer for the beginner in his early cases of esophagoscopy to have the patient relaxed by an ether anesthesia, provided the patient is not dyspneic to begin with, or made so by faulty position or by pressure of the esophagoscopic tube mouth on the tracheoesophageal "party wall." As proficiency develops, however, he will find anesthesia unnecessary. Local anesthesia is needless for esophagoscopy, and if used at all should be limited to the laryngopharynx and never applied to the esophagus, for the esophagus is without sensation, as anyone may observe in drinking hot liquids.
Direct laryngoscopy in children requires neither local nor general anesthesia, either for diagnosis or for removal of foreign bodies or growths from the larynx. General anesthesia is contraindicated because of the dyspnea apt to be present, and because the struggles of the patient might cause a dislodgment of the laryngeal intruder and aspiration to a lower level. The latter accident is also prone to follow attempts to cocainize the larynx.
Technic for General Anesthesia.—For esophagoscopy and gastroscopy, if general anesthesia is desired, ether may be started by the usual method and continued by dropping upon folded gauze laid over the mouth after the tube is introduced. Endo-tracheal administration of ether is, however, far safer than peroral administration, for it overcomes the danger of respiratory arrest from pressure of the esophagoscope, foreign body, or both, on the trachea. Chloroform should not be used for esophagoscopy or gastroscopy because of its depressant action on the respiratory center.
For bronchoscopy, ether or chloroform may be started in the usual way and continued by insufflating through the branch tube of the bronchoscope by means of the apparatus shown in Fig. 13.
In case of paralysis of the larynx, even if only monolateral, a general anesthetic if needed should be given by intratracheal insufflation. If the apparatus for this is not available the patient should be tracheotomized. Hence, every adult patient should be examined with a throat mirror before general anesthesia for any purpose, and the necessity becomes doubly imperative before goiter operations. A number of fatalities have occurred from neglect of this precaution.
Anesthetizing a tracheotomized patient is free from danger so long as the cannula is kept free from secretion. Ether is dropped on gauze laid over the tracheotomic cannula and the anesthesia watched in the usual manner. If the laryngeal stenosis is not complete, ether-saturated gauze is to be placed over the mouth as well as over the tracheotomy tube.
Endo-tracheal anesthesia is by far the safest way for the administration of ether for any purpose. By means of the silk-woven catheter introduced into the trachea, ether-laden air from an insufflation apparatus is piped down to the lungs continuously, and the strong return-flow prevents blood and secretions from entering the lower air-passages. The catheter should be of a size, relative to that of the glottic chink, to permit a free return-flow. A number 24 French is readily accommodated by the adult larynx and lies well out of the way along the posterior wall of the larynx. Because of the little room occupied by the insufflation catheter this method affords ideal anesthesia for external laryngeal operations. Operations on the nose, accessory sinuses and the pharynx, apt to be attended by considerable bleeding, are rendered free from the danger of aspiration pneumonia by endotracheal anesthesia. It is the safest anesthesia for goiter operations. Endo-tracheal anesthesia has rendered needless the intricate negative pressure chamber formerly required for thoracic surgery, for by proper regulation of the pressure under which the ether ladened air is delivered, a lung may be held in any desired degree of expansion when the pleural cavity is opened. It is indicated in operations of the head, neck, or thorax, in which there is danger of respiratory arrest by centric inhibition or peripheral pressure; in operations in which there is a possibility of excessive bleeding and aspiration of blood or secretions; and in operations where it is desired to keep the anesthetist away from the operating field. Various forms of apparatus for the delivery of the ether-laden vapor are supplied by instrument makers with explicit directions as to their mechanical management.