STATIC RESPIRATORY COMPLIANCE IN THE NEWBORN .3. EARLY CHANGES AFTER EXOGENOUS SURFACTANT TREATMENT

Static respiratory system compliance (Crs) was measured by a single br eath passive expiratory flow technique in 73 newborn infants treated w ith exogenous surfactant. The first 39 received Curosurf, a natural po rcine surfactant. The other 34 received Exosurf Neonatal, a synthetic surfactant. All had a diagnosis of respiratory distress syndrome with an arterial/alveolar oxygen ratio <0.22. Static Crs and arterial blood gases were measured shortly before, and at three and 12 hours after t he first dose of surfactant. In 32 infants treated with Curosurf with initial static Crs <1.8 ml/cm H2O/m body length, which is consistent w ith surfactant deficiency, static Crs improved by 18% at three hours a nd by 39% at 12 hours along with a median reduction in fractional insp ired oxygen (FIO2) at three hours by 0.32. In 26 infants treated with Exosurf with initial Crs <1.8 ml/cm H2O/m, Crs did not improve three a nd 12 hours after treatment and oxygenation improved less than after C urosurf, with a median reduction in FIO2 at three hours of 0.11. Fifte en of the 73 (21%) infants had initial static Crs of greater than or e qual to 1.8 ml/cm H2O/m, not consistent with surfactant deficiency. Th irteen of these 15 infants showed a fall in static Crs after surfactan t treatment, raising the question whether exogenous surfactant did the m more harm than good. Initial static Crs and surfactant type both app ear to determine the early response to the first dose of surfactant. O nly a considerably larger, randomised study can show which surfactant is more effective in reducing adverse clinical outcome.