The skin is slightly swollen and smooth, and the presence of gas can be felt on the skin when pressed. Subcutaneous emphysema is often caused by trauma, such as rib fractures, pneumothorax and injuries to the trachea, bronchus and oesophagus, where gas escapes from the broken area and accumulates under the skin.
In addition, localised trauma leading to infection, such as gas gangrene, can also produce gas due to bacterial fermentation, which can accumulate in the subcutaneous tissue and lead to subcutaneous emphysema. Milder cases of subcutaneous emphysema do not require special treatment and can absorb on their own, but the cause needs to be identified to avoid delay.