Comparison of the effects of high frequency oscillation and controlled mechanical ventilation on hyaline membrane formation in a rabbit model of the neonatal respiratory distress syndrome.

Saline lavage of the lungs of eight anaesthetized New Zealand White rabbits was performed to produce a surfactant-depletion model of the neonatal respiratory distress syndrome. A characteristic change in the shape of the pressure-volume curve occurred, with the appearance of an inflection point on the inspiratory limb. The animals were treated with high frequency oscillation (HFO) at 15 Hz and the results compared with those of a previously studied group of eight similar rabbits treated with controlled mechanical ventilation (CMV) with end-expiratory pressure equal to the pressure at the inflection point, but with the same mean airway pressure of 15 mm Hg. The animals treated with HFO had significantly higher arterial oxygen tensions and end-expiratory lung volumes than those treated with CMV, but there was no significant difference between hyaline membrane scores. Although there was no significant difference in mean survival times, five of the HFO treated animals showed reversion of the shape of their pressure-volume curves towards the prelavage configuration, suggesting a recovery of surfactant function.