Modified protocols for surfactant therapy in experimental meconium aspiration syndrome

In adult rats with experimental meconium aspiration syndrome, we investigated whether the therapeutic effect of exogenous surfactant was increased by addition of dextran or preceding airway lavage with diluted surfactant. Animals (n = 72) ventilated with pure oxygen were given human meconium suspension (50-75 mg kg(-1)) through the airways. When the PaO(2) had decreased to <20 kPa (mean +/- SD 12 +/- 3.9 kPa), the rats were randomly allocated to ten groups (G). G 6-10 underwent lung lavage with diluted Curosurf (5 mg ml(-1), 20 ml kg(-1)), whereas G 1-5 did not. G 1 and 6 received no additional material through the airways. G 2 and 7 received Curosurf (100 mg kg(-1)), and G 3 and 8 received Curosurf (100 mg kg(-1)) plus dextran (75 mg kg(-1)); G 4 and 9 received Curosurf (200 mg kg(-1)), and G 5 and G 10 received Curosurf (200 mg kg(-1)) plus dextran (75 mg kg(-1)). All rats in G 1 died before 180 min after randomization. In G 2, 3, 6, 7, and 8, the PaO(2) transiently increased to 30-40 kPa. In G 4, 5, 9, and 10, the PaO(2) remained >30 kPa for 180 min. Both airway lavage and supplementation with dextran improved the therapeutic effects of surfactant; however, a large dose (200 mg kg(-1)) was nevertheless required to optimize gas exchange.