The effect of reconstituted bovine surfactant on pulmonary mechanics in infants with respiratory distress syndrome.

We performed sequential measurements of pulmonary mechanics following instillation of reconstituted bovine surfactant (surfactant TA) in 10 neonates with severe respiratory distress syndrome. The respiratory compliance did not increase significantly until six hours after surfactant administration, while the arterial oxygenation and radiographic appearance improved rapidly after surfactant therapy. Six infants developed clinically significant PDA between 24 hours and 48 hours after surfactant therapy, when the compliance decreased temporarily after initial improvement until the PDA was closed pharmacologically. In six cases airway resistance rose transiently following surfactant treatment, whereas PCO2 fell significantly in all cases by six hours after surfactant administration. We recommend that only inspired oxygen concentration should be adjusted without changing the pressure setting of a respirator for at least three hours after surfactant therapy.