Tracheobronchial casts

Tracheobroncial casts are endogenous foreign bodies resulting from the accumulation and drying of exudates and secretions. It is rather difficult to obtain the true incidence of these casts due to their extreme rarity and the paucity of data. They attract attention by causing asphyxia. Diphtheria was the indication for tracheostomy in 47.7% of cases. Theoretically, the chances of their formation are greater in summer than in the rainy or winter seasons. A temperature of 37 C and a relative humidity of 100% are ideal to preserve the ciliary activity of the tracheobronchial tree and keep the secretions fluid. Under no circumstances can it be kept at that level artificially or by the upper respiratory tract. Formation of casts bears no relation to the duration of wearing the tracheostomy tube. No one factor seems to be the cause. It may be caused by diphtheritic tracheobronchitis in a manner similar to that reported for casts following diphtheritic esophagitis. The probable explanation is that one predisposes to the other and all the factors together play a role in cast formation. Fatality as complication of tracheostomy is due to an obstructive atelectasis which can be completely relieved by bronchoscopy. The results in 111 tracheostomies are given.