Bougies are made of various materials, but for ordinary purposes the gum-elastic is the best. They are about 7 inches in length with a slightly bulbous point.
In the adult the length of the Eustachian tube is approximately 1½ inches, of which 1 inch forms the cartilaginous and ½ inch the osseous portion. The narrowest part of its lumen is known as the isthmus, and is situated at the junction of its cartilaginous and bony portion. On passing the bougie through the catheter into the Eustachian tube, it is essential to know how far its point is projecting beyond the point of the catheter. For this purpose the bougie may be marked at its outer extremity. Five inches from the point of the bougie, that is, the same length as the catheter, is a black band a centimetre in length; a centimetre farther up is another black band; and again after an intervening space of a centimetre is a third black band (Fig. 214).
Fig. 214. Author’s Graduated Eustachian Bougie.
Technique. The catheter is introduced in the ordinary way, and its position within the entrance of the Eustachian orifice is verified by means of inflation. It is kept fixed with the left hand, and the bougie is pushed into the catheter until the beginning of the first mark on the former just reaches the outer extremity of the latter; the tip of the bougie will now be flush with the point of the catheter. If there be no pain and no resistance, the bougie is very gently pushed on until the beginning of its second black band just enters the catheter. Its point will now project 2 centimetres within the Eustachian tube; that is, to about the region of the isthmus. If the bougie has been successfully introduced into the Eustachian tube, the patient generally states that the instrument is felt within the ear itself. No force should be used for fear of making a false passage, and with gentle manipulation it is very rare for actual pain to occur. On reaching the isthmus resistance may be met with, but by the exercise of slight pressure the bougie can usually be made to pass through it; if there be much resistance the bougie should be withdrawn and a finer one substituted. After passing through the isthmus, the bougie may be pushed in another centimetre, but no further, in case it may actually enter and injure the contents of the tympanic cavity.
After the tip of the bougie has passed through the isthmus the surgeon will hear its movements through the auscultation tube as a rub or crackling sound. It is left in position for five or ten minutes and then withdrawn. The ear should then be gently inflated, when the air entry into the tympanic cavity will probably be found to be much more free.
As the passage of the bougie causes a certain amount of reaction, it should not be passed oftener than once a week. Although no force should ever be employed, the largest possible bougie should be passed at each successive sitting until complete dilatation has been obtained.
Difficulties. 1. If the catheter be not in position, the bougie may pass behind the tip of the Eustachian orifice and enter Rosenmüller’s fossa. This can usually be felt by the patient as a pricking sensation in the throat, and may produce retching and coughing.
2. A stricture of the Eustachian tube may be so great as to prevent entrance of the bougie.
Dangers. (a) Surgical emphysema. If the mucous membrane be lacerated by the bougie, air may be forced into the subcutaneous tissues on inflation, after its withdrawal. In some cases the surgical emphysema is so considerable as to involve the side of the neck and face, and indeed has been known to necessitate the performance of laryngotomy.