A prospective clinical study on inhaled nitric oxide therapy for neonates in Japan

Background: This is the first report about a prospective clinical investiga tion to study the efficacy and safety of nitric oxide (NO) inhalation in in fants with persistent pulmonary hypertension of the newborn (PPHN) in Japan . Methods: Patients in the present study had to meet the following entry crit eria: (i) they had to be younger than 7 days of age; (ii) they had to have evidence of PPHN as defined by echocardiograph; (iii) they had to have seve re systemic hypoxemia under mechanical ventilation at 100% oxygen supplemen tation; and (iv) they had to have a failure to respond to conventional ther apies. Patients were excluded from this trial if they had any of the follow ing: hypoplastic lung, structural cardiac lesions or severe multiple anomal ies. Results: Nitric oxide inhalation therapy was performed in 68 infants who ha d severe PPHN at 18 hospitals between May 1995 and May 1997. At birth, 21 o f 68 infants (31%) weighed less than 1500 g and 39 infants weighed more tha n 2500 g. The diagnoses associated with PPHN were as follows: 27 infants ha d meconium aspiration syndrome, 15 infants had dry lung syndrome, nine infa nts had congenital diaphragmatic hernia, six infants had respiratory distre ss syndrome, three infants had pneumonia and eight infants had other diagno ses. The mean oxygenation index (OI) before NO inhalation therapy in 68 inf ants was 43.2; 55 infants (81%) had good responses. Conclusions: These results may be valuable for further randomized controlle d and double-blind trials in Japan to evaluate whether NO inhalation therap y is more effective than conventional therapy in infants with severe PPHN.