Developmental Alterations in Pulmonary Function of the Lamb

Pulmonary function was evaluated in 40 lambs ranging in age from 106 to 161 postconceptual days. Preterm lambs were delivered by cesarean section and newborn lambs were delivered vaginally. All animals were mechanically ventilated and had indwelling catheters. Measurements of transpulmonary pressure, airflow, tidal volume and functional residual capacity enabled calculations of lung compliance, specific compliance, lung conductance and specific conductance. Regression analysis indicated that lung compliance, lung conductance and functional residual capacity increased with developmental age; whereas, specific compliance and specific conductance decreased with maturity. These data quantitate the developmental alterations in the pulmonary function of preterm, term and newborn lambs.