A previously healthy 42-year-old man presented to the emergency department with progressive weakness, lightheadedness, nausea, and lower extremity edema. Evaluation revealed hypotension, pulsus paradoxus, leukocytosis, hepatic and renal dysfunction, and an air-fluid level in the mediastinum. Emergency department ultrasound confirmed the presence of a large pericardial fluid collection. The patient was admitted to the medical intensive care unit with a diagnosis of pyopneumopericardium for emergent pericardiocentesis.