Subcutaneous emphysema, sometimes abbreviated SCE or SE and also called tissue emphysema, or Sub Q air occurs when gas or air is present in the subcutaneous layer of the skin. Subcutaneous refers to the tissue beneath the cutis of the skin, and emphysema refers to trapped air. Since the air generally comes from the chest cavity, subcutaneous emphysema usually occurs on the chest, neck and face, where it is able to travel from the chest cavity along the fascia.