What is subcutaneous emphysema

Subcutaneous emphysema occurs when air that escapes the pleural space and enters the subcutaneous tissues under the skin 1). This most often occurs in the skin covering the chest wall or neck, but can also occur in other parts of the body.

Subcutaneous emphysema can often be seen as a smooth bulging of the skin. When a health care provider feels (palpates) the skin, it produces an unusual crackling sensation as the gas is pushed through the tissue.

Subcutaneous emphysema can spread throughout the chest, arms, neck and face, which can result in obstructed vision. It can cause temporary disfigurement and psychological stress for patients and their family. Rarely, it may lead to more physiological problems including pneumomediastinum, pneumopericardium and respiratory arrest 2), 3). Subcutaneous emphysema that persists despite adequate thoracic drainage has been described as recalcitrant (recalcitrant subcutaneous emphysema). In retrospective series, recalcitrant subcutaneous emphysema is commonly associated with larger pulmonary resections (i.e, in lobectomy vs wedge resection) and reoperations. Patients with forced expiratory volume in 1 s >50% of predicted and patients with diffusion capacity >50% of predicted have lower rates of subcutaneous emphysema 4).

The main risk of subcutaneous emphysema is rapid and massive accumulation of air in the deep fascial planes at the level of the thoracic inlet 5). Therefore, a massive accumulated air can compress the trachea and the great vessels, which can severely compromise the airway, venous return, and blood flow to the head and neck.

A few treatments for subcutaneous emphysema, such as needle aspiration, small-bore-catheter insertion, chest tube insertion, and multiple skin incision-like ‘blow-holes,’ have been reported 6). Recently, negative pressure wound therapy, as known as vacuum-assisted closure (VAC), has been emerging as an effective treatment modality for wounds ranging from simple wounds to complex septic wounds. This therapeutic method, firstly introduced by Argenta and Morykwasin in 1997 7), is based on the effects of a negative pressure of 75 to 150 mmHg on wound healing.

Subcutaneous emphysema causes

This is a rare condition. When it does occur, possible causes include:

  • Collapsed lung (pneumothorax), often occurring with a rib fracture
  • Facial bone fracture
  • Ruptured bronchial tube
  • Ruptured esophagus

Subcutaneous emphysema can happen due to:

  • Blunt trauma.
  • Breathing in cocaine.
  • Corrosives or chemical burns of the esophagus.
  • Diving injuries.
  • Forceful vomiting (Boerhaave syndrome).
  • Gunshot wounds.
  • Pertussis (whooping cough).
  • Stabbing.
  • Certain medical procedures that insert a tube into the body. These include endoscopy (tube into the esophagus and the stomach through the mouth), a central venous line (thin catheter into a vein close to the heart), endotracheal intubation (tube into the throat and trachea through the mouth or nose), and bronchoscopy (tube into the bronchial tubes through the mouth).

Air can also be found in between skin layers on the arms and legs or torso after certain infections, including gas gangrene, and after scuba diving.

When to Contact a Medical Professional

Most of the conditions that cause subcutaneous emphysema are very severe, and you are likely already being treated by a provider. Sometimes a hospital stay is needed. This is more likely if the problem is due to an infection.

If you feel subcutaneous air in relation to any of the situations described above, particularly after trauma, call your local emergency services number immediately.

  • DO NOT administer any fluids.
  • DO NOT move the person unless it is absolutely necessary to remove them from a hazardous environment. Protect the neck and back from further injury when doing so.

Subcutaneous emphysema treatment

The main objective of subcutaneous emphysema treatment is to decrease the source of air insufflating into the subcutaneous space, which allows the proper expansion of the lung and apposition of the pleura surfaces, which, in turn, allows the injured parenchyma to recover 8). Treatment modalities include observation, tissue squeezing, fenestrated angiocatheter insertion into the subcutaneous space, larger semi-rigid catheter insertion, incising the skin and subcutaneous fascia to create a ‘blow-hole’ 9) to allow air to escape, or trocar chest tubes and VATS or open thoracotomy with repair of parenchymal injury 10).

Your health care provider will measure and monitor the your vital signs, including:

  • Temperature
  • Pulse
  • Breathing rate
  • Blood pressure

Symptoms will be treated as needed. The person may receive:

  • Breathing support, including oxygen, endotracheal intubation (tube through the nose or mouth into the trachea) and ventilator (breathing machine)
  • Blood tests
  • Chest tube — tube through the skin and muscles between the ribs into the pleural space (lining of the lungs) if there is lung collapse
  • CAT/CT scan (computerized axial tomography or advanced imaging) of the chest and abdomen or area with the subcutaneous air)
  • EKG (electrocardiogram or heart tracing)
  • Fluids (intravenous or through the vein)
  • Medicines to treat symptoms
  • X-rays of chest and abdomen and other body parts that may have been injured

The prognosis depends on the cause of the subcutaneous emphysema. If associated with major trauma, a procedure or infection, the severity of those conditions will determine the outcome.

Subcutaneous emphysema associated with scuba diving is most often less serious.

There are few scientific studies comparing different subcutaneous emphysema treatment modalities. With observation alone, in which air is gradually reabsorbed by soft tissues, it can take several weeks for significant subcutaneous emphysema to resolve. Subcutaneous insertion of a small- or large-bore catheter with fenestrations is widely used as a form of drainage of subcutaneous emphysema. These methods used fenestrated angiocatheters or drains placed subcutaneously and set to continuous suction and can significantly reduce subcutaneous emphysema in several days. However, the catheter can easily become blocked by blood, and may need to be re-inserted 11). A ‘blow-hole’ incision is widely performed to release the trapped subcutaneous air and to minimize further progression of air dissection into the face and neck. In this method, a small (approximately 2 cm) incision in the infraclavicular area skin and blunt dissection is used to create short tracks down to the level of the prepectoral fascia at the bedside under local anesthesia. This method is frequently used and relies on the passive diffusion of trapped air out of the incision. The tracks work for a short time, but factors such as tissue recoil and plasma clot can cause them to collapse and close the tracks 12). Therefore, the wound is typically packed with gauze and the dressing is changed twice a day. Blow-hole placement can be effective in decreasing massive subcutaneous emphysema over the course of several days; however, complete resolution in cases of significant subcutaneous emphysema can take several days or more. The most invasive method of subcutaneous emphysema treatment requires surgical repair and control of the source of leaking air. A prospective trial by Cerfolio et al. 13) has shown VATS to be an excellent means of controlling an air leak site.

Recalcitrant subcutaneous emphysema treatment

Although most subcutaneous emphysema is relieved by the placement of a chest tube, treatment of recalcitrant subcutaneous emphysema is challenging. Several strategies have been attempted including increased intrathoracic chest tube suction, the insertion of a second pleural chest tube, insertion of an angiocatheter into the subcutaneous space, the creation of ‘blowhole’ incisions and surgical pneumolysis 14), 15). Once the pleural air leak is addressed, observation alone typically results in gradual reabsorption of air from the subcutaneous tissues, but often requires a prolonged time period to achieve complete resolution. Insertion of subcutaneous catheters (such as angiocatheters) may aid in the resolution of recalcitrant subcutaneous emphysema, but the insertion site may act as a source of infection and catheters obstruct frequently 16). The creation of ‘blowhole’ incisions also serves as an opening in the epidermal barrier, allowing passive egress of air from tissue contiguous to the incision. This procedure can be performed with local anaesthesia, but frequently fails due to wound closure and tissue coagulation 17). Placement of a Negative pressure wound therapy (NPWT) is an extension of the ‘blowhole’ technique, with the sponge maintaining incisional patency and the continuous suction improving egress of trapped air.

Cerfolio et al 18) suggested thoracoscopic pneumolysis and placement of a new pleural tube as the preferred treatment for patients with recalcitrant subcutaneous emphysema. Cerfolio et al study showed that ∼66% of patients demonstrated improved subcutaneous emphysema by increasing chest tube suction. Among the 85 patients (34%) with recalcitrant subcutaneous emphysema, thoracoscopic pneumolysis and placement of a new chest tube led to resolution of subcutaneous emphysema in all but 1 patient 19). While effective, this method involves intrathoracic surgery, general anaesthesia, and single lung ventilation, thereby exposing the patient to accordant operative risks.

The use of negative pressure wound therapy dressings has been described in a variety of clinical settings, including wound healing and reconstructive surgery. The system creates a negative pressure gradient at the wound, which removes air and fluid, reduces bacterial load, and accelerates healing by reducing tissue oedema and stimulating fibroblast recruitment 20). There are very few complications associated with negative pressure wound therapy dressing, but cases of wound infection secondary to retained dressing material and bleeding have been reported.

Limited reports have described the use of negative pressure wound therapy devices to treat recalcitrant subcutaneous emphysema. They hypothesize that the negative gradient in the wound facilitates evacuation of trapped air from the subcutaneous tissues and promotes resolution of the underlying air leak 21). Byun et al 22) described the use of unilateral negative pressure wound therapy dressings to treat recalcitrant subcutaneous emphysema in four patients. Each required negative pressure wound therapy for 2–4 days to allow for the complete resolution of subcutaneous emphysema. The treatment was successful in all four patients with no recurrence or complications reported.

Wound site pain is a common complication after negative pressure wound therapy. It is controlled with pressure adjustment between 75 mmHg and 150 mmHg. Other considerations, such as increased wound care needs, the potential for development of wound infections, and equipment costs must be carefully evaluated prior to initiation of negative pressure wound therapy for subcutaneous emphysema 23).

References   [ + ]

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