A controlled clinical comparison of four different surfactant preparations in surfactant-deficient preterm lambs.

Four pulmonary surfactant preparations (natural sheep surfactant, Exosurf, Infasurf, and Survanta) were compared with no treatment in 29 newborn lambs at 126 +/- 1 days gestation. Fetuses were delivered by Cesarean section under general anesthesia and treated with either the manufacturer's recommended dose of a commercial surfactant, 100 mg phospholipid/kg of natural sheep surfactant, or no surfactant (control group). Lambs were mechanically ventilated with 100% oxygen until moribund from respiratory failure or until killed at 24 h after delivery. Lambs surviving to 12 h received surfactant retreatment (of the same type) if hypoxemic. All lambs were surfactant deficient at birth, having less than 0.1 mg/ml of phospholipid measured in the lung liquid. All control lambs developed early respiratory failure and died within 8 h after delivery. Survival was significantly prolonged by natural surfactant (p less than 0.02), Infasurf (p less than 0.0001), and Survanta (p less than 0.02). Natural surfactant, Infasurf, and Survanta significantly improved arterial oxygenation and ventilatory compliance compared with no treatment. These effects lasted as long as 24 h in lambs given Infasurf, but no more than 6 h in lambs given natural surfactant or Survanta. After death, static pressure-volume lung mechanics were significantly better for lambs given natural sheep surfactant, Infasurf, or Survanta. Lambs given Exosurf were no different than control lambs in any variable measured. Thus, in 126-day gestation surfactant-deficient newborn lambs, natural sheep surfactant, Infasurf, and Survanta, but not Exosurf, Improve oxygenation, lung mechanics, and survival.