1788 QUANTITATIVE ASSESSMENT OF VENTILATION INDUCED PULMONARY EPITHELIAL INJURY IN THE NEWBORN PIGLET

To better understand the airway damage that occurs in BPD we performed the following study to establish and quantitate a model of sub-lethal airway injury in a newborn animal. Six piglets less than 2 days old were anaesthetized, intubated, and ventilated with dry pure oxygen for 2 hours with a pressure limited time cycled ventilator. Lungs were fixed by instillation at 50 cmH2O pressure. Four unintubated piglets served as controls (C). Light and electron microscopy demonstrated 2 types of epithelial damage in the ventilated piglets (V). Injury was quantitated in the trachea and first 4 bronchial divisions. Type I damage, presumably from mechanical trauma, consisted of denudation of the epithelium down to the basement membrane and was only seen in the trachea. Type II damage, presumably from dessication, consisted of ciliary damage or disorganization and was seen from the trachea to the 4th bronchial division. Results are % of cross section surface area.We conclude that significant morphologic damage of airway epithelium is induced by 2 hours of ventilation with dry oxygen in the newborn piglet. (Supported by Physicians' Services Incorporated Foundation, Toronto, Ontario).