A 29-week gestation female infant was born by spontaneous vaginal delivery with a birth weight of 1.180 kg. She received surfactant and was briefly ventilated on day 1 before extubation onto biphasic continuous positive airway pressure (BiPAP). On day 5, she was reintubated and ventilated in view of increasing respiratory distress and a moderate respiratory acidosis. A postintubation chest x-ray was taken (figure 1) and the endotracheal tube (ETT) was pulled back by 0.5 cm. Blood gases normalise promptly with minimal pressure ventilation; however, over the subsequent 12 h her oxygen requirements increase from 21% …