A 25 week gestation male infant, birth weight 520 g, is transferred ex utero to your neonatal unit for intensive care. On day 19 he remains ventilator dependent and is hypoxic on 60–95% oxygen. The oxygenation index (OI; a measure of respiratory failure) is 18. Chest x ray shows clear lung fields. Echocardiography by a senior paediatric cardiologist shows evidence of pulmonary hypertension. In view of these findings it is felt that a pulmonary vasodilator may help. You discuss entering the INNOVO trial (a multicentre randomised controlled trial of addition of inhaled nitric oxide (inNO) to babies with severe respiratory failure) with the parents, who agree; the baby is entered into the control (no addition of inNO) arm. In spite of this, parents ask for “everything” (including inNO) to be tried. Reluctantly you agree and inNO is administered as per the trial protocol (you …