Pulmonary mechanics and energetics in preterm infants who had respiratory distress syndrome treated with synthetic surfactant Vinod K. Bhutani, MD,a Soraya Abbasi, MD,a W a l k e r A. Long, MD,b, c a n d J e f f r e y S. Gerdes, MDa From the Divisionof Neonatology, Universityof Pennsylvania,a Philadelphia, Pennsylvania,the Department of Pediatrics,Universityof North Carolina at Chapel Hill,b and the Clinical Research Division,~ Burroughs Wellcome Co., Research Triangle Park, North Carolina Pulmonary mechanics and energetics were determined in 32 neonates with respiratory distress syndrome, who were randomly assigned to receive treatment with an exogenous synthetic surfactant, Exosurf Neonatal, or air p l a c e b o . Pulmonary mechanics were measured before and 2 hours after surfactant (n = 13) or air p l a c e b o (n = 19) treatment, then l o n g i t u d i n a l l y at 24, 48, and 72 hours after treatment, and again at 7, 14, and 28 days of age. There were no significant differences in the values for pulmonary mechanics or energetics 2 hours after the first dose of surfactant. Improvement in pulmonary mechanics was apparent 24 hours after surfactant treatment, when d y n a m i c c o m p l i a n c e was 36% greater than in the p l a c e b o group (p