Surgical emphysema involves what condition related to air?

Surgical emphysema specifically refers to the presence of air trapped in the subcutaneous tissue. This condition can occur when air from the respiratory tract or the surrounding environment enters the skin and underlying tissue, usually as a result of trauma, surgery, or certain medical procedures. The air can become trapped due to a rupture or a tear in the respiratory system, or it may enter through wounds that are connected to the atmosphere.

When air accumulates in the subcutaneous tissue, it can lead to a characteristic swelling and a crackling sensation upon palpation, often described as "crepitus." This condition is distinct from other forms of air collection, such as pneumothorax (air in the pleural cavity), pneumomediastinum (air in the mediastinum), or pneumoperitoneum (air in the abdominal cavity), each of which pertains to different regions of the body and different clinical implications. Understanding surgical emphysema is important in diving medicine and post-operative care, as it can indicate underlying issues with ventilation or injury to the thoracic structures.