Objective: We determined whether inhaled nitric oxide (NO) could improve systemic oxygenation in human neonates with hypoplastic lungs.
Methods: A multicenter nonrandomized investigation was performed to study the efficacy of short-term NO inhalation. Inhaled NO was administered at 80 ppm to nine neonates without evidence of structural cardiac disease by echocardiography. Lung hypoplasia was due to congenital diaphragmatic hernia (CDH) in eight patients and to oligohydramnios in one patient. A total of 15 trials of NO inhalation were performed in these nine patients. Eight trials in seven patients were performed before extracorporeal membrane oxygenation ((ECMO); one patient had two trials) and seven trials were performed in five patients after decannulation from ECMO (two patients had two trials each).
Results: NO inhalation before ECMO did not change postductal PaO2 (42 +/- 3 mmHg vs 42 +/- 4 mmHg), oxygen saturation (SpO2; 89% vs 88%) or oxygenation index (31 +/- 4 cm H2O/torr vs 31 +/- 4 cm H2O/torr) for the group. All patients required ECMO support, which lasted from 5 to 17 days (mean 9). After decannulation from ECMO, NO inhalation increased postductal PaO2 from a median of 56 mm Hg (range 41 to 94) to a median of 113 mm Hg (range 77 to 326), P < .05. It decreased the oxygenation index from a median of 23 cm H2O/torr (range 11 to 7) to a median of 11 cm H2O/torr (range 4 to 21), P < .05. It increased SpO2 from 91% to 96% (P < .05) and pH from 7.48 +/- .03 to 7.50 +/- .03.
Conclusion: In our patients with hypoplastic lungs, inhaled NO was effective only after ECMO. This could be due to maturational changes such as activating the endogenous surfactant system. Inhaled NO may be effective in neonates with hypoplastic lungs who have recurrent episodes of pulmonary hypertension after ECMO, even if they were previously unresponsive.