Subcutaneous/surgical emphysema (SCE, SE) is when gas or air is in the layer under the skin.
Aetiology
Trauma:
Fractures of the facial bones with sinus involvement
Neck surgery
Penetrating gunshot injuries of head & neck or chest
Penetrating trauma to gastrointestinal/respiratory systems
Iatrogenic:
Anesthesia either during endotracheal/naso-tracheal intubation
Laparoscopy—tearing of the tracheal mucosa during intubation, increased pressure in the alveoli because of excessive ventilation pressure, improper chest tube placement during chest surgery, dental high speed hand pieces)
Rupture of broncho-alveolar walls with escape of air into the subcutaneous plane.
Clinical features
Swelling around neck + chest pain (M/C & visible sign)
Classification of severity:
Classification for severity of SE | Aghajanzadeh, M., Dehnadi, A., Ebrahimi, H., Fallah Karkan, M., Khajeh Jahromi, S., Amir Maafi, A., & Aghajanzadeh, G. (2015). Classification and Management of Subcutaneous Emphysema: a 10-Year Experience. The Indian Journal of Surgery, 77(Suppl 2), 673–677. https://doi.org/10.1007/s12262-013-0975-4
Diagnosis
Imaging
X-ray:
A chest X-ray of a right sided pulmonary contusion associated with flail chest and subcutaneous emphysema | Karim – http://www.trauma.org/index.php/main/image/32/, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3988435
CT-scan:
Abdominal CT of a patient with severe subcutaneous emphysema. (arrows) | http://gruntdoc.com/2005/09/subcutaneous-emphysema.html, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4118853
Chest CT of a patient with severe subcutaneous emphysema. Bubbles of air in the subcutaneous tissue (arrow) feel like mobile nodules that move around easily | http://gruntdoc.com/2005/09/subcutaneous-emphysema.html, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4118942
Pelvic CT of a patient with severe subcutaneous emphysema. Subcutaneous air (arrows) can be seen as black areas on this pelvic CT scan. | http://gruntdoc.com/2005/09/subcutaneous-emphysema.html, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4120161