Persistent pulmonary hypertension of the newborn (PPHN), is defined as a failure of the pulmonary vasculature to relax at birth and consequently of the normal adaptation to extra uterine life of the fetal heart/lung system, resulting in hypoxemia. This condition, occurs in about 1-2 newborns per 1000 live births and despite significant improvements in treatment it is associated with substantial infant mortality and morbidity. Over the years wider application of inhaled nitric oxide (iNO) therapy and improved ventilation strategies including surfactant, high-frequency oscillatory ventilation has led to a decrease in the need for invasive life-sustaining therapies such as extracorporeal membrane oxygenation (ECMO). Mortality rate varies from 10 to 20 % of affected newborns in developed countries, but it is much higher when PPHN is refractory to the above reported therapies or when they are not available. As a consequence, development of new therapeutic strategies for severe PPHN is crucial. In particular, recent studies seem to show that sildenafil, a phosphodiesterase inhibitor type 5 that selectively reduces pulmonary vascular resistance may be a useful therapeutic adjunct to critically ill neonates with PPHN.
Division of Neonatology, Perrino Hospital, s.s. 7 per Mesagne, 72100 Brindisi, Italy.