Pulmonary Hypertension in Preterm Infants: Applicability of Inhaled Nitric Oxide

Pulmonary hypertension is more common in preterm infants compared to term infants, and the incidence increases as gestational age decreases.In preterm infants, pulmonary hypertension is a risk factor that increases mortality.Inhaled nitric oxide (iNO) is an approved treatment for pulmonary hypertension in preterm infants in Korea.Since January 2021, iNO has been used for hypoxic respira tory failure associated with early acute persistent pulmonary hypertension of the newborn (PPHN) in preterm infants.Although studies suggest that iNO improves oxygenation and reduces mortality in preterm infants with pulmonary hypertension, there are concerns about its effectiveness and potential adverse effects.In addition, there are several challenges in administering iNO therapy to pre term infants in Korea that need to be addressed.The current therapeutic indications in Korea allow iNO therapy to be administered only if treatment is started within 14 days of life, so it cannot be used for late pulmonary hypertension.Additionally, iNO therapy requires meeting the criteria for hypoxic respiratory failure, which includes calculating the oxygenation index (OI) using PaO 2 values obtained from arterial blood gas analysis (ABGA).To evaluate treatment response, PaO 2 values from ABGA are also necessary.However, invasive arterial blood sampling is a particularly challenging procedure in preterm infants.Therefore, alternative criteria beyond OI are needed.Furthermore, echocardiographic findings are essential to determine the therapeutic indication for PPHN in iNO therapy.However, not all neonatal intensive care units have consistent access to echocardiography.These issues must be addressed and resolved through further research and evidence.