Pathogenesis of neonatal lung lesions induced by artificial ventilation: evidence against the role of barotrauma.

Premature newborn rabbits, delivered on day 27 of gestation, were ventilated for 10 min with a standardized peak pressure of 35 cm H2O, with or without previous instillation of natural surfactant into the airways. Lung-thorax compliance and stability were significantly enhanced in surfactant-treated fetuses. Although these fetuses were greatly overventilated, their tendency to develop bronchiolar epithelial lesions was significantly reduced in comparison with controls; this was verified by light as well as electron microscopy. Our findings argue against barotrauma as the cause of bronchiolar epithelial lesions during artificial ventilation, and favor the concept that these lesions reflect an abnormal expansion pattern due to surfactant deficiency.