Subcutaneous emphysema is a rare complication of asthma exacerbation. The condition develops when air becomes trapped in the soft tissues under the skin. It can arise from surgical, traumatic, or infectious causes, but sometimes occurs spontaneously. Air accumulates in subcutaneous areas, dissecting along planes of the mediastinum to the tissues of the thorax, neck, and upper limbs. With pressure, the air may dissect to other planes, causing extensive subcutaneous spread which may lead to respiratory or cardiovascular collapse. Clinical findings include swelling and crepitus over the involved site, which is usually painless. Subcutaneous emphysema is closely linked with pneumomediastinum, which is characterized by chest pain, dyspnea, and the neck swelling associated with subcutaneous emphysema.
In children, exacerbations of asthma constitute the most common cause of subcutaneous emphysema, thought to be spurred by forced inhalation. It has also been suggested that patients who use inhaled corticosteroids may be at increased risk for tracheal injury with endotracheal intubation because mucosa is friable and thin.
Coupled with clinical symptoms, chest radiography can usually confirm subcutaneous emphysema, revealing air within the mediastinal space. Striations may be noted in the pectoralis major muscle group, a pattern which is referred to as a ginkgo leaf sign of the chest.
Subcutaneous emphysema is generally self-limiting and should resolve with treatment of the underlying cause. Conservative treatment with oxygen therapy may be beneficial.
Kyle A. Richards, MD, Assistant Professor, Department of Urology, University of Wisconsin-Madison; Chief of Urology, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
Kyle A. Richards, MD, has disclosed no relevant financial relationships