The frontal chest x-ray shows pneumomediastinum.

The continuous diaphragm sign seen as above indicates the presence of pneumomediastinum. There is also subcutaneous emphysema visible in the soft tissue on right side of the neck.

In a patient with acute asthma, alveolar distension and rupture of the alveoli leads to air tracking along the bronchovascular sheath and reaches the mediastinum (the Macklin effect).

The above patient received maximal medical therapy (oxygen via face mask, bronchodilators, intravenous steroids, intravenous aminophylline & magnesium infusion) and recovered in the intensive care unit.

Reference: https://emedicine.medscape.com/article/1003409-overview#a5