A 55-year-old man was brought to the emergency room by EMS after being found outside with breathing difficulties. Prehospital providers feared an anaphylactic reaction and administered 0.3 mg intramuscular epinephrine (1:1000).
The patient was dyspneic, leaning on his right side and attempting to remove the mask without a rebreather in the emergency room. He provided no history.
A review of his records revealed that the patient suffered from chronic obstructive pulmonary disease and schizophrenia. His initial vital signs were blood pressure 117/71 mm Hg, heart rate 103 bpm, respiratory rate 32 bpm, with SPO2 79% on a mask without rebreather of 15 L/min. The patient’s left lung was decompressed by needle and he was intubated in rapid sequence using succinylcholine and etomidate. A thoracostomy tube was placed on the left side with audible air release.
The patient was stabilized and then underwent a CT scan of the abdomen and thorax pelvis, which demonstrated left pneumothorax with extensive subcutaneous emphysema, fractures to ribs five to eight on the left, pneumomediastinum and gas extraperitoneal moving up the neck and down the pelvis, scrotum and lower extremities. No central airway or esophageal lesions were identified, and the radiologist stated that given the prominent bullae and severe bullous emphysematous disease, chest wall trauma likely resulted in pneumothorax and emphysema. pulmonary interstitial in the mediastinum and soft tissues.
Due to the persistence of the pneumothorax, a second left thoracostomy tube was inserted by the trauma department and the patient was admitted to intensive care. He then underwent pleurodesis and blebectomy, and was successfully extubated several days later with removal of the post-extubation thoracostomy tube. His stay was complicated by behavioral issues related to his schizophrenia, and he was transferred to an inpatient psychiatric ward despite being medically stable.
Subcutaneous emphysema is defined as the infiltration of air into the subcutaneous tissue residing below the dermal layer. Depending on etiology, time course, and distribution, this condition may also be associated with inappropriate air accumulation in other areas, resulting in pneumomediastinum, pneumoperitoneum, pneumopericardium, and pneumocephalus. Pneumomediastinum will classically present with signs of swelling and crepitus, the so-called Hamman Crunch (J Fam Practice. 1994;38:284), in the extravasated air zone. (Am J Surg. 2013;206:1001.)
It is a rare disease with an incidence of less than 2.3% and 70% of patients are men with an average age of 53 (+/-14.83). (Indian J Surg. 2015;77[Suppl 2]:673; http://bit.ly/2Mvzlxo.) The majority of patients with this disease are post-surgical following a laparoscopic procedure. (JSLS. 2014;18:1; http://bit.ly/3tm2agd.) Some studies, however, suggest that spontaneous pneumothorax with underlying COPD is the most common cause. (Indian J Surg. 2015;77[Suppl 2]:673; http://bit.ly/2Mvzlxo.)
Subcutaneous emphysema can range from largely benign with few symptoms to life-threatening. This can be of particular concern in patients with pacemakers due to malfunction of the pulse generator. (Chest. 1982;82:651.) Subcutaneous emphysema usually resolves without intervention (Am J Urgent Med. 1994;12:463), and is simply a cosmetic problem in mild cases. (Arch Bronconeumol. 2014;50:47.)
Subcutaneous emphysema can be life-threatening, however, as it can lead to complications, including thoracic outlet obstruction, which in turn elevates intrathoracic pressures and reduces preload and subsequently cerebral perfusion and cardiac output. (Respiratory care. 2007;52:191; http://bit.ly/3rkxn1K.)
The pathophysiology of this condition is varied. The presence of severe emphysematous bullae secondary to COPD, noted in our patient, predisposes to subcutaneous emphysema. In fact, 80% of patients with bullae will have underlying emphysema. (Nookala v. Bullous Emphysema. StatPearls. 2020; https://bit.ly/3riEEyT.)
With the formation of emphysematous bullae commonly seen in advanced COPD, alveolar air can spread from the alveolus along the fascial planes and into the subpleural space. The air spreads from the ruptured emphysematous bullae to the pulmonary interstitial tissue and then into the perivascular spaces to the mediastinum. Subcutaneous emphysema is manifested when the extravasation of air in this context exceeds the capacity for pleural reabsorption. (Chest. 1992;102:503; Chest. 2002;121:647.)
Subcutaneous emphysema can also result from infectious sources, including gas gangrene and other gas-forming infections. This can also be seen with positive pressure ventilation, especially at high peak pressures. (Respiratory care. 2007;52:191; http://bit.ly/3rkxn1K.) Blunt trauma can result in an aberrant pressure gradient between the perivascular and intra-alveolar spaces. (Arch Med Intern. 1984;144:1447; Chest. August 2001;120:543.)
A quarter of all deaths in trauma patients are the result of chest injuries. (Trauma. 1994;36:401; Niger J Surg. 2014;20:30 ; http://bit.ly/3oKDP0i.) The presence of subcutaneous emphysema can predict pneumothorax with an odds ratio of 5.47. (Wound. 2009;40:44.)
This case provides an unusual case presentation of subcutaneous emphysema. The absence of clear evidence of external trauma at initial assessment coupled with minimal availability of patient history complicated the presentation of this patient. The mechanism by which blunt trauma entrains subcutaneous air, called the Macklin effect, is described as a three-part mechanism by which blunt trauma entrains pneumomediastinum. Blunt trauma results in rupture of the alveoli with air dissection along the bronchovascular sheaths and eventual spread into the mediastinum. (Chest. August 2001;120:543; AJR Am J Roentgenol. 1999;172:129.)
The presence of severe emphysematous bullae secondary to COPD as noted in our patient predisposes to subcutaneous emphysema. In fact, 80% of patients with bullae will have underlying emphysema. (Nookala v. Bullous Emphysema. StatPearls. 2020; https://bit.ly/3riEEyT.)
With the formation of emphysematous bullae commonly seen in advanced COPD, alveolar air can spread from the alveolus along the fascial planes and into the subpleural space. The air spreads from the ruptured emphysematous bullae to the pulmonary interstitial tissue and then into the perivascular spaces to the mediastinum. Subcutaneous emphysema manifests itself in this context when the extravasation of air exceeds the capacity for pleural reabsorption. (Chest. 1992;102:503; Chest. 2002;121:647.)
Treatment consists of controlling the underlying pathology and resolution usually occurs within 10 days, whether secondary to trauma or emphysematous bullae, both observed in our patient. (J Oral maxillofacial surgery. 2015;14:515; http://bit.ly/3auvPv7.) Rarely, subclavicular incisions may be made to relieve trapped air. (Indian J Surg. 2015;77[Suppl 2]:673; http://bit.ly/2Mvzlxo.)
Drs. Grattan and Carlsonare emergency physicians at Bon Secours Mercy/St. Vincent Medical Center in Toledo, OH.