Spontaneous Pneumomediastinum

AUTHORS:
Timothy R. Oeltmann, MD, and Jeff W. Singley, MD
Naval Health Clinic Quantico, Virginia

CITATION:
Oeltmann TR, Singley JW. Spontaneous pneumomediastinum. Consultant. 2016;56(10):955-957.

DISCLAIMER:
The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the US Government.

A 26-year-old healthy man presented with 3 days of increasing shortness of breath, chest tightness, and a mild, nonproductive cough. His symptoms had begun acutely while driving after having worked an extended night shift, during which he had consumed more than his usual amount of coffee. He described his breathing difficulties as intermittent and worse with deeper breaths. He described his chest tightness as moderate but persistent and without sharp pains or radiation. He also mentioned that he had recently run a 3-mile race in under 19 minutes without any chest pain.

History. He had no history of trauma, allergies, lung disease, or cardiac illness. His immunizations were up to date, and the results of a recent purified protein derivative test were negative for tuberculosis. There were no recent illnesses, hospitalizations, or surgical procedures. He had no family history of sudden death, heart disease, or diabetes. His grandparents were all living and reportedly doing well.

He denied alcohol use but reported smoking half a pack of cigarettes weekly. He had no known drug allergies and was not taking medications.

A review of systems was significant for left-sided ear fullness and mild maxillary sinus pressure. He denied fever, sick contacts, drug use, headache, rhinorrhea, sneezing, sore throat, neck swelling, palpitations, wheezing, hemoptysis, nausea, vomiting, diarrhea, and lower extremity edema.

Physical examination. The patient’s vital signs were as follows: temperature, 37°C; blood pressure, 100/69 mm Hg; heart rate, 84 beats/min; respiratory rate, 14 breaths/min; oxygen saturation, 98%; height, 175 cm; weight, 61.25 kg; body mass index, 19.93 kg/m². He was a normal-appearing man who was breathing comfortably in no apparent distress.

His oropharynx appeared normal, without tonsillar enlargement. He had intact, clear tympanic membranes and was without sinus tenderness. Bilateral crackling with palpation was noted in the anterior neck. The neck veins were not distended.

The lungs were clear to auscultation bilaterally, with symmetric inflation. Cardiac examination revealed regular rate and rhythm without murmurs, rubs, or gallops. Physical examination findings of the abdomen, extremities, and skin were normal.

Diagnostic tests. An electrocardiogram showed normal sinus rhythm with a rate of 70 beats/min, with normal axis and intervals and no ST-T wave changes. Chest radiographs showed extensive pneumomediastinum extending into the neck (Figures 1 and 2) without pneumothorax.

Based on these findings, he received a diagnosis of spontaneous pneumomediastinum. Given the extent of the findings, a pulmonologist and cardiothoracic surgeon were consulted. A computed tomography scan of the chest (Figures 3-6) showed diffuse pneumomediastinum with a small amount of air surrounding the thecal sac and mild bronchiectasis involving right middle lobe and anteromedial lingula. He was considered stable and was not admitted. A barium swallow radiograph was obtained the following day, the results of which were normal (Figure 7).

Outcome of the case. The man continued to improve daily and began light exercise on his own without significant shortness of breath after 1 week. A follow-up plain radiograph of his chest 10 days later (Figure 8) demonstrated slight but noted interval improvement. At the 3-week interval, he reported no symptoms and had resumed his rigorous exercising routine without symptoms.

Discussion. Pneumomediastinum is an uncommon disorder identified by the presence of air in the mediastinum caused either by the rupture of alveoli or neck soft tissue (including the esophagus and trachea) or by air arriving from the abdominal cavity. Spontaneous pneumomediastinum, or mediastinal emphysema, is the presence of air in the mediastinum in the absence of trauma.

A synchronous crunching sound on auscultation of the chest can indicate air trapped between the chest wall and anterior parietal pericardium and is known as the Hamman crunch.¹

A relatively benign condition with hospital stays averaging 2 to 4 days, spontaneous pneumomediastinum follows a predictable course, with full resolution within approximately 1 to 3 weeks.^2,3 Pneumothorax is often found in conjunction with pneumomediastinum and presents in approximately one-third of cases.² In rare cases, tension pneumothorax may evolve, which may require needle decompression.⁴

Men in their 20s are at particular risk for pneumomediastinum. Other risk factors include preexisting lung disease (eg, asthma, bronchiectasis, chronic obstructive pulmonary disease, cystic fibrosis), excessive vomiting, coughing or Valsalva maneuver, illicit drug use, scuba diving, and rigorous physical activity.^5,6 Barium swallows, while often obtained, rarely demonstrate causal effect.^7,8

References:

1. Hamman L. Spontaneous mediastinal emphysema. Bull Johns Hopkins Hosp. 1939;64:1-21.
2. Iyer VN, Joshi AY, Ryu JH. Spontaneous pneumomediastinum: analysis of 62 consecutive adult patients. Mayo Clin Proc. 2009;84(5):417-421.
3. Freixinet J, García F, Rodríguez PM, Santana NB, Quintero CO, Hussein M. Spontaneous pneumomediastinum long-term follow-up. Respir Med. 2005;​99(9):1160-1163.
4. Rim T, Bae JS, Yuk YS. Life-threatening simultaneous bilateral spontaneous tension pneumothorax: a case report. Korean J Thorac Cardiovasc Surg. 2011;​44(3):253-256.
5. Brody SL, Anderson GV Jr, Gutman JBL. Pneumomediastinum as a complication of “crack” smoking. Am J Emerg Med. 1988;6(3):241-243.
6. Macia I, Moya J, Ramos R, et al. Spontaneous pneumomediastinum: 41 cases. Eur J Cardiothorac Surg. 2007;31(6):1110-1114.
7. Caceres M, Ali SZ, Braud R, Weiman D, Garrett HE Jr. Spontaneous pneumomediastinum: a comparative study and review of the literature. Ann Thorac Surg. 2008;86(3):962-966.
8. Bakhos CT, Pupovac SS, Ata A, Fantauzzi JP, Fabian T. Spontaneous pneumomediastinum: an extensive workup is not required. J Am Coll Surg. 2014;​219(4):713-717.