2.4 | Surfactant depletion by lavage and LPS-induced lung injury
After the baseline cardiopulmonary data had been collected, all rats received lung lavage with 10 mL/kg normal saline intratracheally via a tracheostomy tube for both sides of the lungs. An additional saline lavage was given 5 min later if Spo2 remained above 90%. When PaO2 dropped to less than 150 torr (20 kPa) (at FiO2 = 1.0), the rat was considered to have reached surfactant depletion. Subsequentially, a dose of 50 µg/kg LPS diluted by saline to a total volume of 1 mL was intratracheally instilled into the lungs to induce ALI. An additional 15 min period of postinjury stabilization was allowed before the subsequent procedures.