Cytologic evaluation of pulmonary effluent in neonates with respiratory distress syndrome and bronchopulmonary dysplasia.

Tracheobronchial effluent from 108 infants with respiratory distress syndrome (RDS) was classified cytologically in relationship to the duration of endotracheal intubation and mechanical ventilation with supplemental oxygen. Three cytologic classes emerged: class I (1 to 4 days), associated with exfoliation of cohesive and organized sheets of tracheobronchial cells, class II (4 to 10 days), during which regeneration of tracheobronchial cells was prominent and reactive cells were present, and class III (after 10 days), during which squamous metaplasia, chronic inflammation and regeneration were characteristic. An influx of polymorphonuclear neutrophilic leukocytes and macrophages was typical of classes II and III. In 70% of the cases, the identification of class III changes enabled the diagnosis of bronchopulmonary dysplasia (BPD) to be made earlier than by radiography alone. This classification of tracheobronchial cytology should be of benefit in the identification and treatment of infants with bronchopulmonary dysplasia. It may also offer a more direct means for evaluating new therapy to prevent or modify this disorder.