High-frequency oscillatory ventilation (HFOV) is a possible mechanical method for open lung strategies. The aim of this study was to examine whether HFOV has a beneficial effect on
oleic acid-induced
lung injury, with emphasis on changes in extravascular lung water. Thirteen anesthetized sheep prepared with a lung lymph
fistula and
vascular catheters for monitoring were randomly allocated to two experimental groups. In experiment 1, sheep (n = 6) were ventilated using conventional
mechanical ventilation [CMV; 10 ml/kg of tidal volume, 70%
oxygen, and
positive end-expiratory pressure (PEEP) of 6 cmH(2)O after
oleic acid administration (0.08 ml/kg)]. In experiment 2, sheep (n=7) were ventilated using HFOV (frequency=15 Hz, stroke volume=120 ml, mean airway pressure=15 cmH(2)O) after administration of the same dose of
oleic acid as in experiment 1. Observation was continued for 4 h after
oleic acid administration, then bronchoalveolar lavage (BAL) was performed and the
lung wet-to-dry weight ratio was determined. Compared with CMV, HFOV significantly improved the deteriorated oxygenation during the late phase (2-4 h) of
oleic acid-induced
lung injury without any deterioration effects on pulmonary or systemic hemodynamics. HFOV showed significantly reduced lung lymph
protein clearance, which paralleled significant decreases in wet-to-dry ratios and neutrophil counts in BAL fluid in the HFOV group. These findings suggest that HFOV could contribute to decreased lung lymph filtration in pulmonary microcirculation and improved oxygenation following
oleic acid-induced
lung injury in sheep.