The frontal & lateral chest x-rays reveal pneumomediastinum & pneumopercardium.
The patient was not unstable. The x-rays were initially misinterpreted as normal and the patient was recalled. They underwent a repeat chest x-ray 24 hours after initial presentation which showed resolution of mediastinal air and were clinically asymptomatic.
A sinister cause for above presentation not to be missed is oesophageal rupture.