Pneumomediastinum complicating diabetic ketoacidosis

Abstract

Pneumomediastinum is an uncommon finding in patients with diabetic ketoacidosis (DKA) and may occur spontaneously or secondary to an effort rupture of the oesophagus. Excluding oesophageal rupture is important, as delaying treatment increases the risk of mortality. We discuss a case of DKA complicated by vomiting, pneumomediastinum, pneumopericardium and air in the epidural space. Instead of fluoroscopic oesophagography, chest CT was used to investigate oesophageal rupture. We present an overview of case reports and retrospective studies illustrating the utility of chest CT in the investigation of oesophageal rupture over fluoroscopic oesophagography.

Keywords: Diabetes; Gastrointestinal surgery; Oesophagus; Pneumomediastinum; Radiology.

Figure 1

Anteroposterior chest X-ray (upper image) with a corresponding coronal CT image (lower left image) and illustration (lower right image). Air demarcates the right cardiac border and surrounds the aortic arc. A pneumopericardium is visible, with air seperating the left cardiac border from the pericardium and mediastinal parietal pleura.

Figure 2

Axial chest CT image (upper image) and illustration (lower image) displaying the heart and lower mediastinum at the level of the seventh thoracic vertebra. Air surrounds the heart and right lower pulmonary vein. Air is also seen in the posterior mediastinum, covering the anterior surface of oesophagus and descending aorta.

Figure 3

Axial chest CT image (upper image) and illustration (lower image) displaying the upper mediastinum at the level of the third thoracic vertebra. Air covers the great vessels and trachea. Subcutaneous emphysema is seen anterior to the sternum. A small amount of air is visible in the spinal canal.

Figure 4

Axial chest CT images without intravenous contrast from admission (left two images) and with intravenous contrast after 7 days (right two images). Air surrounding the heart and great vessels diminishes over time.

Figure 5

Diagram illustrating the emergence of a pneumomediastinum. Air escapes from ruptured alveoli lining the vessel walls into the pulmonary interstitium (on the left). It moves along the vascular sheaths towards the mediastinum. When mediastinal pressure rises, air may spread through the loose mediastinal fascia to subcutaneous tissue of the neck (upper arrow), upper extrimities (lateral arrows) or enter the pericardial space (lower arrow).