From the Guidelines
The best next investigation for a post chest trauma patient with air in the mediastinum is a Chest CT. While a water-soluble contrast swallow might seem appropriate to evaluate for esophageal injury, a CT scan is preferred initially because it provides comprehensive evaluation of all mediastinal structures simultaneously. According to the World Journal of Emergency Surgery guidelines 1, CT esophagography has high sensitivity (95%) and specificity (91%) rates in detecting upper digestive tract perforation. Some key points to consider:
- CT can identify the source of air leak whether from the esophagus, tracheobronchial tree, or lung parenchyma, and can detect associated injuries like pneumothorax, hemothorax, or vascular damage.
- It has higher sensitivity than contrast studies for small esophageal perforations and doesn't risk further contamination of the mediastinum with contrast material if a perforation exists.
- If the CT suggests esophageal injury specifically, then a contrast esophagram would be the appropriate follow-up study.
- Water-soluble contrast swallow is not the best initial choice because it may miss up to 30% of small esophageal perforations and requires a stable and cooperative patient 1. This stepwise approach ensures thorough evaluation while minimizing risks in the trauma setting.
From the Research
Best Next Investigation for Post Chest Trauma Patient
- The patient has air in the mediastinum, which could indicate a possible esophageal injury.
- The best next investigation would be to use a diagnostic tool that can accurately identify or rule out esophageal injury.
Diagnostic Options
- Chest CT: This is a highly sensitive tool for detecting aerodigestive tract injuries, including esophageal injuries 2, 3.
- Oesophagoscope: While this can be used to directly visualize the esophagus, it may not be the first line of investigation in this case.
- Angiography: This is not typically used for diagnosing esophageal injuries.
- Water soluble contrast swallow: This can be used to diagnose esophageal injuries, but the evidence suggests that Chest CT is a more sensitive and preferred initial screening tool 4, 2, 3.
Rationale for Choosing Chest CT
- Studies have shown that Chest CT has a high sensitivity and specificity for detecting aerodigestive tract injuries, including esophageal injuries 2, 3.
- The use of water soluble contrast swallow is not recommended as the initial investigation, as it may not be as sensitive as Chest CT in detecting esophageal injuries 4.
- The evidence suggests that pneumomediastinum is rarely associated with esophageal injury, and that Chest CT is a reliable tool for ruling out this condition 4, 5, 6.