Sometimes, however, the obstruction is purely mechanical. It may be due to compression of the trachea by a shoulder brace. In aged individuals, after removing the tooth plate, progressively increasing cyanosis may be due to _valve-action of the lips_. Expiration is unhindered, but inspiration becomes impossible on account of collapse of the lips and cheeks. The difficulty is overcome by turning the head to one side and placing a spindle of gauze in the dependent angle of the mouth to keep the lips apart.
There are other cases in which the base of the tongue drops back into the oropharynx, and hinders breathing. There is a peculiar, noisy, “fluttering” respiration which indicates this condition. The jaw-grip, that is, pushing the jaw forward, is often insufficient. Most of us have been taught to use the wedge, mouth-gag and tongue forceps at once in such an emergency, but it is certainly desirable to escape this maneuver whenever possible. A naso-pharyngeal catheter, or breathing tube of soft rubber, passed through the nostril into the pharynx sometimes instantly relieves the obstruction.
The breathing tube is a soft rubber tube 5/16” in calibre and 7¼” in length. The end is smooth and beveled and has an opening, there being a second opening on the side, about a quarter of an inch distant. To introduce it, the tip of the nose is lifted and the rounded end of the catheter directed into the larger nostril perpendicularly to the face. The use of a little white vaseline obviates friction and unnecessary traumatism. The tube is pushed gently back into the pharynx behind the receded base of the tongue until the respiratory air streams freely through it. Very rarely, it is necessary to pull the tongue forward until the tube is in position. At times it is of advantage to support the angle of the jaw lightly, in order to get the full benefit of the tube breathing. Oxygen, it is true, improves the color when the tongue has receded and there is partial asphyxia, but no one will argue that it _eliminates the cause of the obstruction_, viz., that the base of the tongue has dropped back into the pharynx and occludes the way to the air passages.
Sometimes, when the recession of the tongue is slight, supporting the angle of the jaw helps, because the base of the tongue is carried forward with it. Frequently, this is insufficient. The tongue may be drawn forward by means of forceps or suture, but this method is crude and necessitates also the use of a wedge and mouth gag. The same accessories are imperative, when an attempt is made to introduce a breathing tube _through the mouth_ into the pharynx. It is for these reasons that the nasal route is preferred. The method outlined is uncomplicated—its efficacy is often striking. It seems to be the simplest solution of the problem to re-establish the respiratory air channel, which has been occluded by the recession of the tongue.