High-frequency oscillatory ventilation and partial liquid ventilation after acute lung injury in premature lambs with respiratory distress syndrome

Objective: Conventional mechanical ventilatory support (CV) contributes to lung injury in premature lambs with respiratory distress syndrome, a diseas e that is characterized by progressive deterioration of gas exchange and in creased lung inflammation, Lung recruitment strategies, such as high-freque ncy oscillatory ventilation (HFOV) and partial liquid ventilation (PLV), im prove gas exchange and attenuate lung inflammation when instituted immediat ely after birth. However, whether these recruitment strategies are effectiv e as rescue treatment after established lung injury is unknown. To determin e the separate and combined effects of HFOV and PLV when initiated after th e establishment of acute lung injury in severe respiratory distress syndrom e, we studied the effects of these strategies on gas exchange and histologi c signs of acute lung injury in premature lambs. Design: Animals were intubated, treated with surfactant and ventilated with 1.00 F10(2) for 4 hrs, After 2 hrs, animals were either continued on CV (c ontrols) or treated with one of three strategies: HFOV; CV + PLV; or HFOV PLV, The response to low-dose inhaled nitric oxide (5 ppm) was measured in each group at the end of the study. Setting: An animal laboratory affiliated with University of Colorado School of Medicine, Subjects: A total of 20 premature lambs at 115-118 days of gestation (term = 147 days). Measurements and Main Results: In comparison with control animals, each of the rescue therapies improved Pao(2) after 1 hr of treatment. The HFOV and HFOV + PLV groups had higher pao(2) than CV + PLV or CV alone (p < .05), Me an airway pressure (Paw) was lower in the PLV groups during CV or HFOV comp ared with their controls (p < .05), Inhaled NO improved Pao(2) in all group s; however, the increase in Pao(2) was greatest in the HFOV + PLV group (p < .05), Histologic examination and myeloperoxidase assay were not different between groups, Conclusion: We conclude that each lung recruitment strategy improved oxygen ation in premature lambs with established lung injury.