_Treatment of Compression Stenoses of the Trachea_.--If the thymus be at fault, rapid amelioration of symptoms follows roentgenray or radium therapy. Tracheotomy and the insertion of the long cane-shaped cannula (Fig. 104) past the compressed area is required in the cases caused by conditions less amenable to treatment than thymic enlargement. Permanent cure depends upon the removability of the compressive mass. Should the bronchi be so compressed by a benign condition as to prevent escape of secretions from the subjacent air passages, bronchial intubation tubes may be inserted, and, if necessary, worn constantly. They should be removed weekly for cleansing and oftener if obstructed. _Influenzal Laryngotracheobronchitis_.--Influenzal infection, not always by the same organism, sweeps over the population, attacking the air passages in a violent and quite characteristic way. Bronchoscopy shows the influenzal infection to be characterized by intense reddening and swelling of the mucosa. In some cases the swelling is so great as to necessitate tracheotomy, or intubation of the larynx; and if the edema involve the bronchi, occlusion may be fatal. Hemorrhagic spots and superficial erosions are commonly seen, and a thick, tenacious exudate, difficult of expectoration, lies in patches in the trachea. Infants may asphyxiate from accumulation of this secretion which they are unable to expel. The differential diagnosis from diphtheria is sometimes difficult. The absence of true membrane and the failure to find diphtheria bacilli in smears taken from the trachea are of aid but are not infallible. In doubtful cases, the administration of diphtheria antitoxin is a wise precaution pending the establishment of a definite diagnosis. The pseudomembrane sometimes present in influenzal tracheobronchitis is thinner and less pulpy than that of the earlier stages of diphtheria. The casts of the later stages do not occur in influenzal tracheobronchitis (Bibliography I, p. 480). _Edematous Tracheobronchitis_.--This is chiefly observed in children. The most frequently encountered form is the epidemic disease to which the name "Influenza" has been given (q.v. supra). The only noticeable difference between the epidemic and the sporadic cases is in the more general susceptibility to the infective agent, which gives the influenzal form an appearance of being more virulently infective. Possibly the sporadic form is simply the attack of children not immunized by a previous attack during an epidemic.