The histopathology of the upper airway in the neonate following mechanical ventilation

Laryngotracheobronchial lesions were carefully documented in 26 neonatal autopsies and were classified into two main types. Type I lesions were focal desquamative or ulcerative, asynchronous, and variable in severity involving areas exposed to contact with endotracheal tube or suction catheter. These lesions are most likely due to trauma of artificial ventilation. Type II lesions were diffuse, necrotizing, more synchronous and uniform in severity involving tissues distal to the endotracheal tube and extending to second or third generation bronchi. The early or mild type II lesions consisted of coagulative necrosis of epithelial cells and mucosal oedema. The late or severe type II lesions showed features similar to those of necrotizing tracheobronchitis described by Metley et al. All the cases with type II lesions had been ventilated with 100 per cent oxygen continuously for at least 3 h during life. The use of pure oxygen may be an important factor leading to necrotizing tracheobronchitis.