An 8-week-old baby girl born prematurely had been transferred and admitted to PICU after presenting to her local hospital with respiratory failure due to bronchiolitis. She was born at 30 weeks gestational age in good condition and had a straightforward course without any complications of prematurity. She was discharged home at 36 weeks weighing 2 kg. After 2 weeks at home, she developed respiratory symptoms, was brought to A&E and then admitted to her local PICU where she was intubated and ventilated for RSV bronchiolitis. By 5 days after PICU admission she had improved to such an extent that ventilation could be weaned to minimal support. Over the next 24 hours, however, she deteriorated rapidly with evolving four quadrant opacification on CXR (Figure 26.1), necessitating escalation of ventilation and cardiovascular support. Ventilation was further escalated to high frequency ventilation (HFOV). Piperacillin-tazobactam and gentamicin had been started.