The aim of this work was to describe treatment response and outcome data for preterm infants with pulmonary hypoplasia treated with inhaled nitric oxide (iNO).

We hypothesised that an acute oxygenation response to iNO would be associated with survival.

A retrospective observational study design was used to identify cases of pulmonary hypoplasia in preterm infants <34 weeks’ gestation reported to the European iNO Registry.

Demographic and clinical data were collected including oxygenation and echocardiographic parameters.

The primary outcome was acute oxygenation response defined as a reduction in fractional inspired oxygen of >0.15. Outcome data included chronic lung disease (CLD) and death.