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Diagnostic Imaging Review

Extensive subcutaneous emphysema

A complication of traumatic pneumothorax

Ruan, Gordon MD; Edquist, Chris PA-C; Pagali, Sandeep MD

Author Information
Journal of the American Academy of Physician Assistants: January 2021 - Volume 34 - Issue 1 - p 52-54
doi: 10.1097/01.JAA.0000723964.15465.35
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CASE

A 77-year-old functionally independent woman presented to the ED for evaluation of right-sided lateral chest wall pain and shortness of breath after a traumatic injury.

History

The patient was downhill skiing and fell from a standing height after she was struck by another skier. She denied loss of consciousness. She has a history of chronic obstructive pulmonary disease (COPD), pulmonary hypertension, and polymyalgia rheumatica on chronic prednisone.

Physical examination

Initial evaluation in the ED revealed an SpO2 of 83%, requiring 15 L of supplemental oxygen via non-rebreather mask. Her other vital signs were within normal limits. She was alert and cooperative. She had no signs of external trauma but appeared in acute respiratory distress due to tachypnea and accessory muscle use. Her breath sounds were diminished on the right side, and wheezing was noted on the left side. The remainder of the examination was within normal limits.

Diagnostic testing

Laboratory evaluation demonstrated hemoglobin, 13.4 g/dL (normal range, 13.2 to 16.6 g/dL); platelets, 184,000 cells/mm3 (normal range, 135,000 to 317,000 cells/mm3); white blood cell count, 17,800 cells/mm3 (normal range, 3,400 to 9,600 cells/mm3); and normal sodium, potassium, creatinine, glucose, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate, and prothrombin time.

A chest radiograph was obtained in the ED and showed a large right-sided pneumothorax without mediastinal shift as well as a nondisplaced right eighth rib fracture (Figure 1). A 20 Fr chest tube was placed but was complicated by air leak. A repeat chest radiograph showed persistence of the large pneumothorax, so a second 24 Fr chest tube was placed, which alleviated her respiratory symptoms. However, this chest tube also was complicated by air leak. A repeat chest radiograph showed a small, right apical pneumothorax, two right-sided chest tubes, nondisplaced right eighth rib fracture, and small subcutaneous emphysema in the right chest wall (Figure 2).

FIGURE 1.
FIGURE 1.:
Large right-sided pneumothorax with no appreciable mediastinal shift and a nondisplaced right eighth rib fracture. Left side of the lung shows hyperinflation with intraparenchymal scarring.
FIGURE 2.
FIGURE 2.:
Small right apical pneumothorax along with two right-sided chest tubes. Subcutaneous emphysema can be seen in the right chest wall.

Following the patient's initial symptomatic improvement, the 20 Fr chest tube was removed because of a persistent air leak concern at the insertion site. On hospital day 2, the patient developed increased respiratory effort, dyspnea, hoarseness, and new swelling in her face and right upper extremity. Physical examination revealed an intermittent air leak from her remaining chest tube and extensive crepitus to palpation of the right chest, right upper extremity, and right side of the face. A repeat chest radiograph was obtained and showed increased subcutaneous emphysema over the right lateral chest wall and neck with a tiny apical pneumothorax (Figure 3). The medial right chest tube was in a stable position; the more lateral right chest tube had been removed. A CT of the chest also was obtained at this time to further characterize and understand the origin of the air leak. The CT did not reveal a specific source, but demonstrated extensive subcutaneous emphysema on the patient's right side extending to the neck (Figure 4).

FIGURE 3.
FIGURE 3.:
Increased subcutaneous emphysema over the right lateral chest wall and neck
FIGURE 4.
FIGURE 4.:
Subcutaneous and mediastinal air in the clinical context of subcutaneous emphysema. Small pericardial effusion.

Hospital course

Because of the patient's symptomatic decompensation, as noted by respiratory distress and swelling with significant crepitus diffusely involving the right upper extremity, chest wall, neck, and face tissues, another 24 Fr chest tube was immediately placed and thoracic surgery was consulted on hospital day 3. Both chest tubes continued to demonstrate ongoing air leak, so they were connected to continuous suctioning and monitored by daily chest radiographs and thoracic surgery evaluations. Despite continuous suctioning, the patient's subcutaneous emphysema expanded. Thoracic surgery performed a video-assisted thoracoscopic surgery and mechanical pleurodesis on the right side to stop the air leak in the clinical context of known COPD, along with placement of additional chest tubes and a pigtail catheter intraoperatively. Following this, the patient's apical pneumothorax resolved and chest tubes were removed before her discharge on hospital day 13. Her subcutaneous emphysema persisted at the time of discharge. Complete resolution of subcutaneous emphysema, both clinically and radiographically, was noted at the 2-week follow-up.

DISCUSSION

Pneumothorax is a common complication of traumatic rib injury. Management of large pneumothorax includes chest tube placement. Subcutaneous emphysema occurs when air infiltrates the subcutaneous layer of skin; this often occurs around a chest tube insertion site or in the chest wall and neck, with the most common sign and symptom being swelling and crepitus of the subcutaneous tissue.1 The many causes of subcutaneous emphysema include pneumothorax, barotrauma, blunt or penetrating trauma, malignancy, iatrogenic complication from surgical procedures, and infection such as necrotizing fasciitis. Subcutaneous emphysema also can be spontaneous. Because the presentation can be sudden and a delay in diagnosis can result in significant complications, such as respiratory collapse, cardiac collapse, or compartment syndrome, early recognition and prompt diagnosis is critical.2 The overall incidence of subcutaneous emphysema ranges from 0.43% to 2.34%, and 71% of patients are male.1 The condition is divided into five grades; the case patient was grade 5 (extensive involvement).1

The pathognomonic examination findings for a patient with subcutaneous emphysema are crepitus on palpation and swelling. If these findings are present, imaging studies can aid in rapidly confirming the suspected diagnosis. Anteroposterior and lateral chest radiographs are the initial test of choice, and can show radiolucent streaks throughout the subcutaneous tissue and muscle at the site of clinical suspicion. The patient also may have a ginkgo leaf sign—striations of gas along the pectoralis major that resemble a ginkgo leaf.3

The diagnostic sensitivity of chest radiographs for subcutaneous emphysema is almost 90%, but this often is insufficient to determine the underlying cause.4-6 CT scan can aid in the diagnosis and guide treatment, but is most effectively used to identify intrathoracic injury leading to subcutaneous emphysema, which cannot often be seen on chest radiograph alone. CT findings include dark pockets in the subcutaneous tissue indicating the presence of gas. Although ultrasound can be used to diagnose subcutaneous emphysema, clinicians must use caution. Because of the acoustic disruption caused by air that results in a reflection of ultrasound waves, underlying lung parenchyma often is obscured, limiting the ability of ultrasound to determine a cause for subcutaneous emphysema.7

Treatment involves identifying and managing the underlying cause of subcutaneous emphysema. In mild cases, conservative management is appropriate and emphysema often resolves within 10 days if the source of air leak is controlled. However, the case patient's subcutaneous emphysema led to significant discomfort and respiratory distress. Complications of severe subcutaneous emphysema include compartment syndrome, prevention of thoracic wall expansion, tracheal compression, and tissue necrosis. If these complications develop, respiratory and cardiovascular compromise can occur without rapid intervention. The patient may need surgical decompression or “blowhole incisions” to let air escape.1

CONCLUSION

Chest radiograph is the key diagnostic imaging for following up chest tube placement and monitoring until a patient's pneumothorax resolves. Subcutaneous emphysema is a complication of air leak into the subcutaneous tissue. Consider thoracic intervention to control the air leak when the patient's clinical condition worsens with progression of subcutaneous emphysema.

REFERENCES

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3. Medeiros BJDC. Subcutaneous emphysema, a different way to diagnose. Rev Assoc Med Bras. 2018;64(2):159–163.
4. Caceres M, Ali SZ, Braud R, et al. Spontaneous pneumomediastinum: a comparative study and review of the literature. Ann Thorac Surg. 2008;86(3):962–966.
5. Perna V, Vilà E, Guelbenzu JJ, Amat I. Pneumomediastinum: is this really a benign entity? When it can be considered as spontaneous? Our experience in 47 adult patients. Eur J Cardiothorac Surg. 2010;37(3):573–575.
6. Iyer VN, Joshi AY, Ryu JH. Spontaneous pneumomediastinum: analysis of 62 consecutive adult patients. Mayo Clin Proc. 2009;84(5):417–421.
7. Ma OJ, Mateer JR, Reardon RF, Joing SA. Ma and Mateer's Emergency Ultrasound. 3rd ed. New York, NY: Mc-Graw Hill-Education; 2014.
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