Subcutaneous emphysema involves the presence of air or gas within the layers of tissue directly beneath the skin. This condition often results in a distinctive crackling sensation when the affected area is touched. While visible and palpable, it indicates an underlying issue where air has escaped its normal confines.
What is Subcutaneous Emphysema?
Subcutaneous emphysema refers to air trapped in the subcutaneous tissue, the deepest layer of the skin. This layer, also known as the hypodermis, consists primarily of fat and connective tissues. When air accumulates here, it can cause swelling or bulging of the skin. A hallmark sensation of this condition is crepitus, a crackling or crunching feeling that can be heard and felt when the skin is gently pressed. This differs from other forms of swelling as it is caused by gas rather than fluid accumulation.
How Does Air Get Under the Skin?
Air commonly enters the subcutaneous tissues through leaks from the respiratory or gastrointestinal systems. For instance, a collapsed lung (pneumothorax) can allow air to escape the chest cavity and migrate under the skin, often following trauma. Medical procedures involving the chest or airways, such as mechanical ventilation, intubation, or bronchoscopy, may also lead to air leakage. Injuries or perforations of the esophagus or other GI tract injuries can also release air into surrounding tissues.
Other sources of air include certain types of infections that produce gas as a byproduct. Gas gangrene, for example, can generate gas that becomes trapped beneath the skin. Trauma to areas such as the face or sinuses may also allow air into the subcutaneous space. Sudden changes in pressure, known as barotrauma, can force air into these tissues. Subcutaneous emphysema can also be a complication of various surgical procedures.
What Are the Signs?
Primary signs of subcutaneous emphysema include visible swelling or bulging of the skin. Upon touching the affected area, a crackling or popping sensation, known as crepitus, can be felt. This sensation is often likened to touching warm Rice Krispies. The air tends to accumulate in areas with less tissue resistance, frequently appearing in the neck, chest, and face, but it can occur anywhere on the body.
Depending on the extent and location of the air accumulation, individuals might experience a feeling of tightness or fullness in the affected region. If the emphysema is significant, it can lead to more pronounced symptoms such as difficulty breathing, trouble swallowing, or changes in speech. Neck pain or a sore throat may also be present due to the pressure exerted by the trapped air.
Getting a Diagnosis and Treatment
Diagnosing subcutaneous emphysema typically begins with a physical examination to feel for the characteristic crepitus. Imaging tests, such as X-rays or CT scans, are used to confirm the presence of air and to pinpoint the source of the air leak. These scans help visualize the air pockets and identify underlying injuries or conditions.
Treatment focuses on addressing the root cause of the air leak rather than the subcutaneous emphysema itself. Once the underlying issue is managed, the body reabsorbs the trapped air, typically resolving the condition within about 10 days. For mild cases, observation, supplemental oxygen, and pain medication may be sufficient. In more extensive cases, procedures to release the air, such as inserting a chest tube or making small incisions, might be necessary to alleviate pressure. Because subcutaneous emphysema can indicate a serious underlying condition, prompt medical evaluation is advised.