The mediastinum is abnormal with multiple large rounded lucencies on the right side, displacing the heart to the left. Mild atelectasis and pleural effusion on the left at the base. Lucency in within the upper abdomen suggestive of pneumoperitoneum.
Conclusion
The mediastinal lucencies are not typical for pneumopericardium, rather pneumomediastinum. There is also a large hiatus hernia. Features are concerning for large hiatus hernia complicated by intrathoracic stomach perforation or volvulus. CT is recommended.