Pneumopericardium represents air within the pericardium, thus surrounding the heart.
Underlying causes include:
- positive pressure ventilation
- thoracic surgery/pericardial fluid drainage
- penetrating trauma
- blunt trauma (rare)
- infectious pericarditis with gas-producing organisms
- between the pericardium and an adjacent air-containing organ (i.e. stomach or esophagus)
Plain radiograph and CT
On both chest radiographs and CT, appearances are characteristic, the heart being partially or completely surrounded by air, with the pericardium sharply outlined by air density on either side.
A pneumopericardium can usually be distinguished from pneumomediastinum, since air in the pericardial sac should not rise above the anatomic limits of the pericardial reflection on the proximal great vascular pedicle. Also on radiographs obtained with the patient in the decubitus position, air in the pericardial sac will shift immediately, while air in the mediastinum will not shift in a short interval between films.
Occasionally, it may not be possible to distinguish pneumopericardium from pneumomediastinum on plain film.
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