A 64-year-old woman with a longstanding diagnosis of mixed connective tissue disorder and pulmonary fibrosis is admitted with symptoms of recent increase in postprandrial retrosternal distress, heaburn, and nocturnal cough. Her ECG shows nonspecific T-wave changes and she finds minimal relief of her symptoms with sublingual NTG. On examination, she is not in any acute distress and is afebrile. Chest exam reveals bilateral crackles. CXR is shown . The cause of this patient's acute symptoms may be

This chest x-ray shows a large, air-containing, hyperlucent opacity in the middle poion of the thorax representing a large hernia in the mediastinum. The lung parenchyma shows increased linear and reticular markings, predominantly in the lower zones, consistent with the diagnosis of interstitial disease. The symptoms described are due to an acid reflux disorder, and the chest x-ray shows a large hiatal hernia. Hiatal hernia represents herniation of the stomach through the esophageal hiatus and is frequently found in adults. It occurs as an oval retrocardiac mass, most often with an air-fluid level, and is due to laxity, stretching, and widening of the hiatus. Obesity and increased intraabdominal pressures are contributing factors. The majority of hernias spontaneously reduce and are called sliding hernias. A paraesophageal hernia occurs when the stomach herniates next to the distal esophagus. Patients may be asymptomatic or may have symptoms of reflux.