Inhaled nitric oxide as a selective pulmonary vasodilator in clinical anesthesia

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator in adult and pediatric patients. Inhaled NO diffuses into the pulmonary vascular smooth muscle where it results in vasodilation via stimulation of guanylyl cyclase. Systemic hemodynamics are not altered because inhaled NO is rapidly inactivated by hemoglobin. Oxygenation is also increased in certain patients as inhaled NO only vasodilates those segments of the pulmonary vasculature which are ventilated. There is growing evidence that inhaled NO may be a useful therapeutic agent in the treatment of pulmonary hypertension and hypoxemia from a variety of causes. Areas of greatest interest to anesthesia and critical care personnel may involve treatment of persistent pulmonary hypertension of the newborn (PPHN), adult respiratory distress syndrome (ARDS), and postoperative pulmonary hypertension secondary to cardiac disease. The potential toxicity of inhaled NO, particularly on immature and developing lungs, must be considered. While inhaled NO exerts acute beneficial effects, it is unclear if there are long-term benefits. Multicenter trials are currently underway to determine if inhaled NO decreases mortality from PPHN or decreases morbidity associated with ARDS.