The lungs are hyperexpanded and in a young patient, this should trigger thoughts of asthma. With asthmatic patients, look for a cause of their exacerbation (e.g. viral chest infection), but also look for secondary complications (e.g. pneumothorax, pneumomediastinum, surgical emphysema).
In the case of pneumothorax, use a good monitor, good viewing conditions and window to give yourself the best chance of finding it. Pneumothoraces are most likely to be apical in these patients, so give it a bit of zoom too.
Pneumothoraces are more common in asthmatics, but may also be the result of over-ventilation, either by hand-bagging or mechanical-ventilation.