Inhaled nitric oxide (NO) in neonates: Responders and nonresponders. A review

Critical hypoxemia due to extra-pulmonary right-to-left-shunting is a typical feature of neonates with persistent pulmonary hypertension of the newborn (PPHN). To improve oxygenation, inhaled nitric oxide (NO) has been used for the last three years in neonatal intensive care units during mechanical ventilation, thus lowering pulmonary vascular resistance. However, sustained improvement in oxygenation is only noted in one third up to two fifths of treated newborns (responders) if PPHN develops due to primary pulmonary disease. NO has only been used for term neonates until recently, when a growing interest for its administration in preterm babies with hyaline membrane disease (HMD) came up. Since intrapulmonary right-to-left shunting is the main reason for hypoxia in HMD, inhaled NO should prove to be a potent selective pulmonary vasodilator in future studies. Further clinical and experimental studies with animals will be helpful to evaluate the individual newborn as being a potential responder or nonresponder.