The nitric oxide (NO) field has been one of the most exciting scientific ve
ntures over the past 10 years. Among the researches developed, the use of i
nhalation of NO gas allowed us to propose this therapy in lung diseases wit
h promising results. Because of its property as a "selective" pulmonary vas
odilator and because of its apparent clinical safety, inhaled NO has been p
roposed in acute lung injury (ALI) to improve severe hypoxemia. In this sit
uation, the abnormal ventilation-perfusion ratio is improved by inhaled NO,
limiting arterial hypoxia. The major clinical trials performed in adults,
however, have failed to show any benefit on mortality and on mechanical ven
tilation requirements. Inhaled NO has been shown as an efficient therapy in
pediatric ALI, probably because of a lower comorbidity. Because of the inh
aled NO uptake by the lung, the extra vascular lung effects might be in the
future the most important development in relation with platelet anti-agreg
ant and anti-infammatory properties.