EFFICACY OF INHALED NITRIC-OXIDE IN OLEIC ACID-INDUCED ACUTE LUNG INJURY

Objective: To assess the efficacy of inhaled nitric oxide in improving pulmonary hypertension and gas exchange following oleic acid-induced acute lung injury, Design: Prospective, pharmacologic study, Setting: Surgical research laboratory at the University of Pittsburgh, Pittsbur gh, PA. Subjects: Instrumented, intubated pigs weighing 16 to 27 kg. i nterventions: Intravenous oleic acid and inhaled nitric oxide, Measure ments and Main Results: All pigs treated with intravenous oleic acid ( 0.11 mL/kg) developed a severe lung injury with pulmonary hypertension , accompanied by impaired oxygenation, intrapulmonary shunting, and in creased extravascular lung water (p<.05 compared with baseline), Follo wing nitric oxide inhalation, although pulmonary hypertension decrease d in a dose-dependent fashion, no amelioration in pulmonary gas exchan ge was observed, as reflected by PaO2 and intrapulmonary shunt. Plasma nitrite and nitrate concentrations, the stable end products of nitric oxide metabolism, did not increase following nitric oxide exposure in this model of severe lung injury. Conclusions: The effect of inhaled nitric oxide, restricted to relieving pulmonary vasoconstriction in th is model of lung injury, may have limited benefit in improving pulmona ry gas exchange when diffusion is impaired by severe lung injury and i nflammatory thickening of the alveolar-capillary barrier. Nitric oxide inhalation may have better results when used at an earlier, less seve re stage of acute lung injury.