Background Animal studies show that the amount of exogenous surfactant does not affect surfactant half-life. No information is available in humans.
Objective To study surfactant disaturated phosphatidylcholine (DSPC) half-life in infants with respiratory distress syndrome (RDS), treated with 200 or 100 mg/kg exogenous surfactant.
Methods DSPC half-life was studied in 61 preterm infants with RDS, who needed mechanical ventilation and early rescue exogenous surfactant. Infants were treated with 200 (GR200, n = 21) or 100 mg/kg (GR100, n = 40) porcine surfactant at the discretion of the attending neonatologist. Clinical and respiratory parameters were recorded at study recruitment and then every 6 h. DSPC kinetics were calculated from the decay of DSPC 13C-enrichment from serial tracheal aspirates. Comparisons were made by t test and χ2 test.
Results Clinical characteristics were not different between groups. In GR200, only six infants (28.6%) received a second dose and one received three doses, whereas in GR100, 28 (70%) received a second dose and nine (22.5%) a third dose. Mortality, the incidence of bronchopulmonary dysplasia and duration of mechanical ventilation were not different. Infants in the GR200 group exhibited a greater and significant reduction in the oxygenation index compared with the GR100 group. DSPC half-life was 53 ± 23 h and 38 ± 19 h (p = 0.029) for the first dose and 75 ± 19 h and 50 ± 28 h (p = 0.025) for the second dose in GR200 and GR100, respectively.
Conclusion Doses of 200 mg/kg of porcine surfactant given to infants for RDS resulted in significantly longer DSPC half-life, reduced the need for re-treatment and better oxygenation indexes compared with doses of 100 mg/kg.