[FIG. 72.—A simple manikin. The weight of the small vise serves to steady the rubber tubing. By the use of tubing of the size of the invaded bronchus and a duplicate of the foreign body, any mechanical problem can he simulated for solution or for practice, study of all possible presentations, etc.]
Practice on the Dog.—Having mastered the technic of introduction on the cadaver and trained the eye and fingers by practice work on the rubber tube, experience should be had in the living lower air and food passages with their pulsatory, respiratory, bechic and deglutitory movements, and ever-present secretions. It is not only inhuman but impossible to obtain this experience on children. Fortunately the dog offers a most ready subject and need in no way be harmed nor pained by this invaluable and life-saving practice. A small dog the size of a terrier (say 6 to 10 pounds in weight) should be chosen and anesthetized by the hypodermic injection of morphin sulphate in dosage of approximately one-sixth of a grain per pound of body weight, given about 45 minutes before the time of practice. Dogs stand large doses of morphin without apparent ill effect, so that repeated injection may be given in smaller dosage until the desired degree of relaxation results. The first effect is vomiting which gives an empty stomach for esophagoscopy and gastroscopy. Vomiting is soon followed by relaxation and stupor. The dog is normal and hungry in a few hours. Dosage must be governed in the clog as in the human being by the susceptibility to the drug and by the temperament of the animal. Other forms of anesthesia have been tried in my teaching, and none has proven so safe and satisfactory. Phonation may be prevented during esophagoscopy by preventing approximation of the cords, through inserting a silk-woven cathether in the trachea. The larynx and trachea may be painted with cocain solution if it is found necessary for bronchoscopy. A very comfortable and safe mouth gag is shown in Fig. 73. Great gentleness should be exercised, and no force should be used, for none is required in endoscopic work; and the endoscopist will lose much of the value of his dog practice if he fails to regard the dog as a child. He should remember he is not learning how to do endoscopy on the dog; but learning on the dog how safely to do bronchoscopy on a human being. The degree of resistance during introduction can be gauged and the color of the mucosa studied, while that interesting phenomenon, the dilatation and lengthening of the bronchi during inspiration and their contraction and shortening during expiration, is readily observed and always forms subject for thought in its possible connection with pathological conditions. Foreign body problems are now to be solved under these living conditions, and it is my feeling that no one should attempt the removal of a foreign body from the bronchus of a child until he has removed at least 100 foreign bodies from the dog without harming the animal. Dogs have the faculty of easily ridding their air-passages of foreign objects, so that one need not be alarmed if a foreign body is lost during practice removal. It is to be remembered that dogs swallow very large objects with apparent ease. The dog's esophagus is relatively much larger than that of human beings. Therefore a small dog (of six to eight pounds' weight) must be used for esophagoscopic practice, if practice is to be had with objects of the size usually encountered in human beings. The bronchi of a dog of this weight will be about the size of those of a child.
[FIG. 73.—Author's mouth gag for use on the dog. The thumb-nut serves to prevent an uncomfortable degree of expansion of the gag. A bandage may be wound around the dog's jaws to prevent undue spread of the jaws.]
Endoscopy on the Human Being.—Dog work offers but little practice in laryngoscopy. Because of the slight angle at which the dog's head joins his spine, the larynx is in a direct line with the open mouth; hence little displacement of the anterior cervical tissues is necessary. Moreover the interior of the larynx of the dog is quite different from that of the human larynx. The technic of laryngoscopy in the human subject is best perfected by a routine direct examination of the larynx of anesthetized patients after such an operation as, for instance, tonsillectomy, to see that the larynx and laryngopharynx are free of clots. To perform a bronchoscopy or esophagoscopy under these conditions would be reprehensible; but direct laryngoscopy for the seeking and removal of clots serves a useful purpose as a preventative of pulmonary abscess and similar complications.* Diagnosis of laryngeal conditions in young children is possible only by direct laryngoscopy and is neglected in almost all of the cases. No anesthesia, general or local, is required. Much clinical material is neglected. All cases of dyspnea or dysphagia should be studied endoscopically if the cause of the condition cannot be definitely found and treated by other means. Invaluable practice in esophagoscopy is found in the treatment of strictures of the esophagus by weekly or biweekly esophagoscopic bouginage.
* Dr. William Frederick Moore, of the Bronchoscopic Clinic, has recently collected statistics of 202 cases of post-tonsillectomic pulmonary abscess that point strongly to aspiration of infected clots and other infective materials as the most frequent etiologic mechanism (Moore, W. F., Pulmonary Abscess. Journ. Am. Med. Assn., April 29, 1922, Vol. 78, pp. 1279-1281).
In acquiring skill as an endoscopist the following paraphrased aphorisms afford food for thought.
APHORISMS
Educate your eye and your fingers.
Be sure you are right, but not too sure.
Follow your judgment, never your impulse.
Cry over spilled milk enough to memorize how you spilled it.
Let your mistakes worry you enough to prevent repetition.
Let your left hand know what your right hand does and how
to do it.
Nature helps, but she is no more interested in the survival of your
patient than in the survival of the attacking pathogenic bacteria.
[126] CHAPTER XII—FOREIGN BODIES IN THE AIR AND FOOD PASSAGES
The air and food passages may be invaded by any foreign substance of solid, liquid or gaseous nature, from the animal, vegetable, or mineral kingdoms. Its origin may be from within the body (blood, pus, secretion, broncholiths, sequestra, worms); introduced from without by way of the natural passages (aspirated or swallowed objects); or it may enter by penetration (bullet, dart, drainage tube from the neck).