A 76-year-old male was brought to our emergency department with a 10-day history of shortness of breath on exertion despite long-term oxygen therapy (1.0 L/min continuously). He complained of mild precordial discomfort, which was aggravated by movement. He had emphysema and a past medical history of pneumothorax, tuberculosis, gallstone surgery, and surgery for stomach cancer in 1987. He was in chronic distress and appeared emaciated. This laboratory examinations were as follows blood pressure 102/56 mmHg, heart rate 92 bpm, respiratory rate 28 bpm, body temperature 37.2°C. Oxygen saturation was 100% at a flow rate of 1.0 L/min. There were no audible rales in the chest. Blood tests showed a low concentration of serum albumin (3.1 g/dL). There were no electrocardiogram changes. Chest radiography demonstrated residual scarring from tuberculosis and mild pneumomediastinum. Computed tomography (CT) scan of chest demonstrated that the pneumomediastinum was limited mainly to the mediastinal tissues to the left of the trachea.

The day after admission we confirmed that the pneumomediastinum was improving by chest X-ray and the patient started to receive training in swallowing and voice production by a speech therapist. He complained that after the voice training his shortness of breath had been exacerbated and he had developed acute, severe chest pain, by which time he was having difficulty in breathing and speaking. Marked subcutaneous emphysema was found in the neck and supraclavicular area. Furthermore, the breathing sounds were weakened on both sides of the chest. X-ray and CT scan of chest demonstrated severe exacerbation of the pneumomediastinum associated with subcutaneous emphysema, subpleural bullae and the formation of adhesions between the lungs and the chest wall. (Figure 1) We immediately inserted a chest tube for drainage. However, the chest drainage did not work and bubbles formation through the water valve was not noted. We were unable to relieve the patient's symptoms. The patient became weaker because the patient was put on complete bed rest and oral intake was restricted for the treatment of severe pneumomediastinum.

On day-23 after admission, the patient died of acute bacteremia due to Serratia infection. After obtaining consent from his family, we conducted an autopsy. On dissection, it was noted that air leakage had spread hierarchically into the clefts between the chest wall and the endothoracic fascia (at gross dissection), the endothoracic fascia and the parietal pleura (at gross dissection), the visceral pleura, and the lung itself. There were multiple bullous or cystic formations on the surface of the lungs. These findings were consistent with those of chest computed tomography. Although we filled the chest cavity with water and infiltrated the lungs with air via the mouth and nose, we were unable to identify the primary lesion causing air leakage. The diagnosis of severe pneumomediastinum was confirmed pathologically. (Figure 2) The tip of chest drainage tube was located between chest wall and parietal pleura.

Pneumomediastinum is a rare disorder involving the presence of air within the mediastinum. It is classified by the site of origin of the air, [1] namely the upper respiratory tract, intrathoracic airways, lung parenchyma, gastrointestinal tract, or an external source. The causes of pneumomediastinum include diabetic ketoacidosis, asthma, delivery, sports trauma, and anorexia nervosa. In our patient, the initial pneumomediastinum was considered spontaneous, but the vocal exercise and state of malnutrition unfortunately triggered a series of events resulting in severe pneumomediastinum. This is the first case report about a pneumomediastinum exacerbated by vocal exercise in English literature. We confirmed histologically that the presence of air was limited to the lung parenchyma and did not extend to the pleural cavity.

Pneumomediastinum usually follows a benign and self-limiting course and usually occurs in younger patients. [2] The treatment required is bed rest, oxygen therapy, reassurance, and analgesia. [3] This case shows that the patient's nutritional status and past history of similar disease should be considered before vocal exercise is initiated; such exercises can impose a strain that is potentially life-threatening.

In pneumomediastinum, the presence of air is limited to the lung parenchyma and does not extend to the pleural cavity. Emaciation is one of the risk factors for this condition. Care should be taken in initiating vocal exercises in such patients.

We thank Dr. Hiromichi Tamaki for caring for the patient, Dr. Mizuto Otsuji for help with surgical treatment, and Dr. Naohiko Chohnabayashi for directing the patient's treatment.

1. David R. Park, Eric Valliéres. Pneumomediastinum and Mediastinitis. In: Mason RJ, Murray JF, Courtney V, editors. Murray and Nadel's Textbook of Respiratory Medicine. 4th ed. Amsterdam: Elsevier Saunders; 2005. pp. 2039–68.    
2. Macia I, Moya J, Ramos R, et al. Spontaneous pneumomediastinum: 41 cases. Eur J Cardiothorac Surg 2007;31(6):1110–4.   [CrossRef]   [Pubmed]    
3. Koullias GJ, Korkolis DP, Wang XJ, Hammond GL. Current and management of spontaneous pneumomediastinum: experience in 24 adult patients. Eur J Cardiothorac Surg 2004;25(5):852–5.   [CrossRef]   [Pubmed]