RAPID IMPROVEMENT IN RESPIRATORY COMPLIANCE AFTER PORCINE SURFACTANT

Abstract

Treatment with surfactant is associated with a rapid improvement in oxygenation, but no work has yet demonstrated a rapid increase in respiratory compliance (Crs). Using a computerised passive expiratory flow technique, we measured respiratory compliance immediately before, at 3 hours and 12 hours after the first dose of surfactant (Curosurf) in 33 infants with respiratory distress syndrome and a/A ratio < 0.22. Using the same technique in an earlier reference population, no infant with Crs ≥ 2ml/cm H2O/m had biochemical evidence of surfactant deficiency. There was an increase of 6% in mean Crs at 3 hours after surfactant (NS: p = 0.227). Excluding 3 infants with initial Crs ≥ 2 ml/cm H2O/m, the increase in Crs at 3 hours was 13% (p = 0.016). In keeping with previous experience, there was rapid improvement in oxygenation, with a mean reduction in FiO2 of 45% of its initial value 3 hours after surfactant (p < 0.001). All 3 infants with an initial Crs of ≥2 ml/cm H2O/m had lower Crs 3 hours after surfactant. In the infants whose initial Crs was < 2 ml/cm H2O/m Crs increased by 38% (p<.001) and FiO2 decreased by 52% (p <.001) 12 hours after surfactant. These data suggest, for the first time, that porcine surfactant rapidly improves Crs, in parallel with improvements in oxygenation. This technique may identify infants who are most likely to benefit acutely from surfactant.