Surfactant phosphatidylcholine assessment
RECRUITMENT
Endotracheal aspirates through a closed in-line tracheal suction system were taken from all patients before surfactant nebulization and at 8, 16, 24, 48 and 72 h after recruitment. Samples were filtered and centrifuged at 400 g for 10 min at 4 °C. The supernatant was then lipid extracted by a modified Bligh and Dyer method