Epithelial Changes in the Trachea of Children

The respiratory tract epithelium from the carina, one bronchus and lower trachea has been studied of 203 children submitted to routine autopsy. In all, 304 sections were microscopically examined. The very young (aged less than 12 months) constituted 74% of the total, which represented the largest of such a group so far investigated for changes in the epithelium. Although only one or sometimes two sections from a limited part of the lower respiratory tract were microscopically examined, four specimens exhibited squamous metaplasia, ten stratification and two demonstrated the coexistence of both these changes in the one section. As far as some previous postulates as regards ætiology are concerned, the exanthemata, smoking and disease of the lungs did not appear to be implicated. On the other hand, disease of the respiratory tract itself or instrumentation (tracheostomy and repeated intubation) were strong presumptive causative factors in 11 of 13 cases in which the epithelial changes under investigation were observed. It is impossible to clearly differentiate between these two major causes, as repeated intubation and often suction was performed in four cases because of the preexistent disease of the respiratory tract. Repeated or prolonged intubation and certainly repeated suction can damage the epithelium, and squamous metaplasia has been shown to be a process in the healing of the epithelium. It would seem that in this series disease of the respiratory tract itself could be the major factor.