Spontaneous Pneumomediastinum in a Critically Ill Patient with Influenza A (H1N1) Virus

A 43-year-old man who was a non-smoker was referred to the Department of Pulmonary Medicine with 8-day history of fever, dry cough, and symptoms of an acute lower respiratory tract infection. His past medical history, two years earlier, was unremarkable except for pneumonia. There was no prior history of autoimmune diseases or immunosuppressant use. He was examined by a general practitioner, who prescribed antibiotics (amoxicillin–clavulanic acid) and symptomatic treatment, which turned out to be ineffective. Examination revealed acute respiratory failure (SpO2, 92% on 6 L/min O2 mask). Discrete subcutaneous emphysema was palpated above the left clavicle. Chest radiography showed opacities in bilateral lung fields with a paracardiac air stripe (Figure 1A).