Surfactant effect on lung pressure-volume in preterm rabbits

Pressure-volume relationships for the inflation and deflation of surfactant-deficient and surfactant-treated preterm rabbit lungs. The control lungs are from 27-day preterm rabbits. Rabbits with surfactant deficiency have high opening pressure, low maximal volume at a distending pressure of 35 cm H₂O, and the lack of deflation stability at low pressures on deflation (orange squares). In contrast, treatment of 27-day preterm rabbits with a natural surfactant alters the pressure-volume relationships with lower opening pressure, improved maximal volume at a distending pressure of 35 cm H₂O, and deflation stability at low deflating pressures (green circles).