Acute and Sustained Effects of Lucinactant Versus Poractant-α on Pulmonary Gas Exchange and Mechanics in Premature Lambs With Respiratory Distress Syndrome

BACKGROUND. Animal-derived, protein-containing surfactants seem to be superior to protein-free surfactants. Lucinactant, a synthetic surfactant containing a surfactant protein-B peptide analog, has been shown to be effective in animal models and phase II clinical trials. To date, lucinactant has not been compared with an animal-derived surfactant in a premature animal model. OBJECTIVE. The objective was to compare the acute and sustained effects of lucinactant among premature lambs with respiratory distress syndrome (RDS) with the effects of a natural porcine surfactant (poractant-a). METHODS. After 5 minutes of mechanical ventilation twin premature lambs were assigned randomly to the lucinactant group (30 mg/mL, 5.8 mL/kg) or the poractant-a group (80 mg/mL, 2.2 mL/kg). Heart rate, systemic arterial pressure, arterial pH, blood gas values, and lung mechanics were recorded for 12 hours. RESULTS. Baseline fetal pH values were similar for the 2 groups (pH 7.27). After 5 minutes of mechanical ventilation, severe RDS developed (pH: 80 mm Hg; Pao 2 : <40 mm Hg; dynamic compliance: <0.08 mL/cm H 2 O per kg). After surfactant instillation, similar improvements in gas exchange and lung mechanics were observed for the lucinactant and poractant-a groups at 1 hour (pH: 7.3 ± 0.1 vs 7.4 ± 0.1; Paco 2 : 8 ± 18 mm Hg vs 40 ± 8 mm Hg; Pao 2 : 167 ± 52 mm Hg vs 259 ± 51 mm Hg; dynamic compliance: 0.3 ±0.1 mL/cm H 2 O per kg vs 0.3 ±0.1 mL/cm H 2 O per kg). The improvements in lung function were sustained, with no differences between groups. Cardiovascular profiles remained stable in both groups. CONCLUSIONS. Among preterm lambs with severe RDS, lucinactant produced improvements in gas exchange and lung mechanics similar to those observed with a porcine-derived surfactant.