Respiratory distress syndrome increases the risk of death and bronchopulmonary dysplasia (BPD) in premature infants. Inhaled nitric oxide (iNO) may reduce these risks. Recent meta-analyses have suggested that iNO is effective only at doses higher than 5 ppm and in infants born to Black mothers. In a randomized, double-blinded, controlled trial, infants born before 32 0/7 weeks gestation, weighing <1500 g, and requiring respiratory support were assigned to receive iNO for either seven days (short iNO), or until 33 0/7 weeks PMA (long iNO). The primary outcome was death or BPD. A total of 273 patients were enrolled, of whom 83 receiving long iNO (61.5%) experienced the primary outcome, compared with 65 (47.1%) receiving short iNO (relative risk (RR) 1.37; 95% confidence interval (CI), 1.06-1.79; p = 0.017). This increase was due solely to increased BPD in infants weighing 750-999 g (RR 1.33, 95% CI 1.07-1.66, p = 0.009). However, there was no difference in the numbers of infants requiring supplemental oxygen at 40 weeks PMA. Among infants < 750 g, long-iNO-treated infants had a lower cumulative probability of death (χ2 5.12, p = 0.02). Long iNO increased the primary outcome in non-Black infants (RR 1.93, 95% CI 1.20-3.24) but not in Black infants. Understanding how maternal racial identity determines responses of premature infants to iNO may help narrow the gap in health outcomes between Black and non-Black infants.
Keywords: bronchopulmonary dysplasia; outcomes; prematurity; respiratory distress syndrome.