Persistent pulmonary hypertension in preterm-infants.

Persistent pulmonary hypertension of the newborn (PPHN) is a cyanotic syndrome that occurs primarily in full-term and postmature infants and causes right-to-left shunts at the atrial or ductal levels or both. Term babies with PPHN show structural changes in pulmonary vascular smooth muscle as a result of chronic prenatal distress. It is our opinion that in preterm babies the PPHN syndrome also exists. In this group of patients the potential pathways to the persistence of high pulmonary vascular resistence are only functional vascular changes precipitated by acute perinatal stress. The cyanosis of PPHN is rapidly regredient in preterm infants and clinical resolution occurs promptly if the diagnosis is correct and the treatment is started as early as possible in centers capable of extensive monitoring and neonatal supportive care to minimize the risks of Tolazoline therapy.