A baby with noisy breathing

A 13 week old boy presented to accident and emergency with fever, breathing difficulties, and reduced feeding. On examination, his respiratory rate was 60 breaths/min, pulse was 180 beats/min, oxygen saturation was 91% in air, and temperature was 37.8oC. He had intercostal and subcostal recession and a tracheal tug. Auscultation of the chest showed widespread wheeze and crackles and heart sounds were normal. A chest radiograph showed an obscured right heart border and generalised hyperinflation. Blood tests showed a white cell count of 22.0×109/l, and a nasopharyngeal aspirate was positive for respiratory syncytial virus on polymerase chain reaction testing. The boy was born at term by normal delivery with a birth weight of 4100 g. The antenatal course was uneventful. He was kept in hospital for two days after delivery because he was “mucousy.” His parents described him as a noisy and “snuffly” breather since birth, with frequent coughing and “choking” episodes. Because of this he had been seen by his general practitioner and in casualty several times, but he had not been admitted to hospital before. He had been breast fed and was thriving well. A few hours after admission he suddenly deteriorated after a feed. His pulse rose to 230 beats/min and respiratory rate to 80 breaths/min. Capillary gas showed pH 7.03, partial pressure of carbon dioxide 12.18 kPa, bicarbonate 17 mmol/l, and base excess −7.4. He was admitted to paediatric intensive care and was intubated and ventilated. He remained intubated for 10 days and two attempts to extubate failed because he developed stridor. Once extubated successfully, we performed further investigations to check for any underlying abnormality. The following radiological image was obtained (fig 1⇓).