Nitric oxide inhalation in pulmonary hypertension and severe respiratory failure

Inhalation of nitric oxide (NO) can cause selective pulmonary vasodilation in aerated lung regions; thus, it may be of benefit in the treatment of various forms of pulmonary hypertension and respiratory distress due to a mismatch of pulmonary ventilation and perfusion. The specific characteristics of inhaled NO exclude long-term treatment, but NO has been successfully used as a test substance to screen patients for response to oral vasodilators. Furthermore, inhalation of NO has been shown to improve gas exchange and right ventricular performance and to reduce the need for other, more invasive therapies in various settings of acute pulmonary hypertension. However, the improvement of arterial oxygenation seen in patients with the acute respiratory distress syndrome does not result in increased survival, questioning the future importance of inhaled NO in the treatment of this pulmonary disorder.