EFFECTS OF EXOGENOUS SURFACTANT THERAPY ON DYNAMIC COMPLIANCE DURING MECHANICAL BREATHING IN PRETERM INFANTS WITH HYALINE-MEMBRANE DISEASE

In a prospective, randomized, controlled clinical trial, the immediate and the longitudinal effects of exogenous surfactant therapy on pulmonary mechanics were evaluated in extremely premature infants during mechanical respiration. Ninety-four infants weighing between 600 and 1250 gm received either exogenous surfactant or sham (air) therapy in the delivery room and up to three additional doses in the first 48 hours of the life if they were ventilator-dependent, had fractional inspiratory oxygen requirements > 0.30, and radiographic findings consistent with hyaline membrane disease. Each infant underwent pulmonary mechanics assessment (dynamic compliance, total pulmonary resistance, fidal volume) immediately before and 1 hour after each dose, and at 24, 48, and 72 hours and 7 days of age. There were no significant differences in dynamic compliance, total pulmonary resistance, and tidal volume in the surfactant (n=47) and control (n=47) groups before and 1 hour after each dose. However, dynamic compliance was 50% greater in the surfactant group at 24 hours of age (p≤0.009); this difference steadily increased to 94% at 7 days of age (p≤0.009). Oxygenation, assessed by the ratio of alveolar to arterial oxygen pressure, was significantly greater in the surfactant group during the first 72 hours of life; the greatest difference was noted at 24 hours (p≤0.001). Mean airway pressure requirements in the surfactant group were significantly less than in the control group at all times during the first week. We conclude that exogenous surfactant therapy, administered at birth and during the first 48 hours of life in extremely premature infants with hyaline membrane disease, improves dynamic compliance and gas exchange during mechanical breathing. © 1990 The C. V. Mosby Company.