No matter what kind of chest trauma the patient has, when the lung or the air passages are injured, air may enter the tissue planes and pass for some distance under the skin (eg, neck, chest). The tissues give a crackling sensation when palpated, and the subcu-taneous air produces an alarming appearance as the face, neck, body, and scrotum become misshapen by subcutaneous air. Fortunately, subcutaneous emphysema is of itself usually not a serious complication. The subcutaneous air is spontaneously absorbed if the underlying air leak is treated or stops sponta-neously. In severe cases in which there is widespread subcutaneous emphysema, a tracheostomy is indicated if airway patency is threatened.