Definition

Subcutaneous emphysema is the presence of air under the skin layer. This air presence can be a mild symptom or indicate a serious disease. This condition is quite rare.

Causes

Subcutaneous emphysema can be caused by various factors, ranging from medical procedures, trauma, infections, to even occurring spontaneously.

Medical Procedures

Medical procedures that can cause subcutaneous emphysema usually involve the placement of tubes in the body, including:

• Endoscopy is an imaging examination with a camera tube inserted through the mouth, passing through the esophagus and stomach
• Central venous catheterization is  a tube inserted into the large veins near the heart
• Endotracheal intubation is a procedure for inserting a breathing tube into the throat through the nose or mouth
• Bronchoscopy is an imaging examination with a camera tube inserted into the lower respiratory tract through the mouth

Trauma

Trauma or injuries that can cause subcutaneous emphysema include blunt trauma, blast injuries, stab wounds, and diving-related trauma. Conditions related to trauma and subcutaneous emphysema may include pneumothorax (trapped air in the chest cavity outside the lungs), which often occurs simultaneously with rib fractures, facial bone fractures, tears in the airways, and tears in the esophagus or other parts of the digestive tract. Damage to the esophagus can be caused by burns from strong acids or bases and excessive vomiting.

Infection

Air can also be found between the layers of the skin of the arms and legs after certain infections, especially bacterial infections that produce gas. Additionally, this condition can also occur after diving. People with asthma are more likely to experience this.

Risk Factor

The risk factors for subcutaneous emphysema are related to its causes. If someone experiences a condition that requires them to be intubated, the risk of subcutaneous emphysema increases. In addition to factors related to medical procedures, other risk factors may include:

• Trauma can cause air to be trapped between the layers of the skin, for example:
• Blunt trauma
• Blast trauma
• Stab wounds
• Diving-related trauma
• Diseases that cause vomiting or severe coughing leading to tearing of the digestive tract or respiratory tract walls.

Symptoms

In subcutaneous emphysema, when the skin is touched, a crackling sensation is felt, as if there is air within the layers of the skin (crepitus sound). In addition, symptoms that may appear include swelling or stretching of the abdomen, chest, neck, and face.

Diagnosis

Subcutaneous emphysema is a symptom, not a disease diagnosis. Therefore, the process of making a diagnosis is done to identify the cause of subcutaneous emphysema and its complications. Usually, this condition is found when a doctor observes or performs an examination by pressing on certain parts of the body. The doctor will inquire about the complete medical history and current complaints of the patient, which may indicate the possible causes of subcutaneous emphysema. Subcutaneous emphysema that occurs over a large area of the body may be accompanied by respiratory and circulatory disturbances, thus requiring further investigation.

Imaging tests such as X-rays and computed tomography scans (CT scans) can help investigate the causes of subcutaneous emphysema. These examinations will be performed on the parts of the body experiencing subcutaneous emphysema. If this condition occurs during intubation, the removal of the tube will be done carefully so that the doctor can check for any associated injuries. In such conditions, examinations that can be performed to examine the condition of the airways after intubation include bronchoscopy. Bronchoscopy is performed by inserting a camera-equipped tube into the airways. Meanwhile, in conditions of pneumothorax (trapped air in the chest cavity but outside the lungs), ultrasound examination can be performed to quickly detect subcutaneous emphysema.

Management

Monitoring

The management of subcutaneous emphysema involves addressing its underlying cause first. This is necessary because if the cause is addressed, subcutaneous emphysema will gradually disappear. Patients with mild illness will be monitored. If there is no tissue involvement, a corset can be used to increase comfort.

Oxygen Therapy

If the patient feels uncomfortable, the therapy that can be done is using high-concentration oxygen. Administration of oxygen can help eliminate nitrogen gas and dissolve other gas particles, especially in patients with pneumothorax. Subcutaneous emphysema usually resolves within 10 days if its cause is addressed.

Surgical Procedures

If subcutaneous emphysema occurs due to intubation, surgery can be performed. This surgery may involve tracheostomy, which is the creation of a hole in the trachea (windpipe). This surgery aims to facilitate air entry into the airways and prevent the spread of subcutaneous emphysema. 

If there are injuries to the airways, antibiotics may be given to prevent infection. If the patient is already connected to a ventilator machine (which functions to deliver oxygen at a certain pressure), the air pressure and volume delivered can be adjusted to resolve subcutaneous emphysema.

Skin Tissue Excision

If subcutaneous emphysema occurs extensively, excision of skin tissue can be performed to prevent its expansion. Invasive therapy options (involving major surgery) will be considered by the doctor in severe cases.

Complications

The accumulation of air under the skin potentially stiffens the chest wall. As a result, subcutaneous emphysema can narrow the space for chest cavity movement, leading to breathing problems. These problems can include decreased oxygen levels in the blood, respiratory failure, and even heart failure.

If free air spreads to the lungs, swallowing difficulties and airway blockages can occur. If the patient is receiving respiratory assistance from a ventilator machine, the pressure on the lungs will increase, leading to barotrauma (trauma due to high pressure) and the spread of pneumothorax.

If subcutaneous emphysema obstructs the space between the clavicle and the first rib (thoracic outlet), airflow restriction during breathing and decreased blood flow back to the heart may occur. This can lead to oxygen deprivation in the brain.

If subcutaneous emphysema spreads to the genital area, this air can compress the small blood vessels supplying that area. This can lead to the death of skin cells.

If the patient uses a pacemaker device, problems may occur with its function due to trapped air in the device.

Prevention

Subcutaneous emphysema that occurs spontaneously without a clear cause is difficult to prevent. However, subcutaneous emphysema with identifiable causes can be prevented. For example, trauma can be prevented by observing safety and health precautions while working. Meanwhile, subcutaneous emphysema that occurs after surgery can be prevented by being careful during intubation procedures, as intubation-related injuries to the airways can cause subcutaneous emphysema.

If a patient undergoes surgery involving the opening of skin and muscle layers, the skin and muscles should be tightly sutured to ensure no free air is trapped between these layers. Additionally, if someone has just undergone chest surgery, the lungs should be allowed to fully expand to fill the chest cavity and reduce the risk of subcutaneous emphysema.

When to See a Doctor?

If you have just experienced trauma, swelling due to infection, or postoperative swelling, you should consult a doctor. Subcutaneous emphysema can be one of the possible symptoms indicating a far more dangerous cause. If this cause is not promptly addressed, the condition could potentially be life-threatening.