Wide Mediastinum

1. See Also
   1. Penetrating Trauma (Gunshot Wound, Stab Wound)
   2. Blunt Chest Trauma
2. Causes
   1. Emergent Conditions
      1. Aortic Dissection
      2. Aortic Rupture
      3. Pneumomediastinum (perforated lung, esophagus, trachea)
      4. Thoracic Aortic Aneurysm
      5. Thoracic Vertebral Fracture with Hematoma (high mechanism blunt Trauma)
   2. Non-emergent Conditions
      1. Lung Mass
      2. Mediastinal Mass (e.g. Lymphoma)
      3. Mediastinal Lymphadenopathy
      4. Pulmonary artery engorgement
      5. Hiatal Hernia
      6. Atelectasis
      7. Thyromegaly
      8. Thymoma
   3. Incidental findings
      1. Anatomic variants (azygous vein, duplicated SVC)
   4. Imaging technique
      1. Patient rotation
      2. Supine positioning
      3. Poor inspiration
      4. AP View Chest XRay (Magnifies mediastinum)
3. Exam
   1. Blood Pressure in both arms
      1. Difference >10 mmHg between arms may suggest Aortic Rupture
      2. Difference may be evident on checking pulses in both arms
4. Imaging: Chest XRay
   1. Widened Mediastinum Criteria
      1. Superior mediastinum >8 cm wide at the aortic knob (on PA View) OR
      2. Mediastinum >33% of the transthoracic dstance at the aortic knob (on supine AP View)
   2. Aortic Injury Findings
      1. Apical pleural cap (Pleural Effusion in the lung apex)
      2. Left mainstem Bronchus deviated downward
      3. Tracheal or esophageal deviation to the right
      4. High Rib Fracture (first or second rib)
5. Imaging: Evaluation of Wide Mediastinum
   1. If initial xray was AP supine, repeat Chest XRay
      1. Obtain upright PA Chest XRay (maximize inspiration and avoid torso rotation)
   2. FAST Exam (serial exams)
      1. Pericardial Effusion (or Cardiac Tamponade)
      2. Pneumothorax (esp. Tension Pneumothorax)
      3. Hemothorax
   3. CT Angiogram Chest (typically with Abdomen and Pelvis to follow aorta)
      1. Preferred imaging evaluation of Wide Mediastinum
6. Approach: Wide Mediastinum
   1. See Penetrating Trauma
   2. See Blunt Chest Trauma
   3. Obtain large bore Intravenous Access
      1. Obtain on the side opposite the injury
      2. Ready for Massive Transfusion (but do not overload with crystalloid)
   4. Imaging
      1. See Evaluation of Wide Mediastinum as above
   5. Emergent thoracic surgery or trauma Consultation indications
      1. Arterial bleeding (esp. aorta) identified on imaging
      2. Uncontrolled bleeding from pentrating Trauma
      3. Large or enlarging thoracic Hematoma (esp. airway compromise)
      4. Hemodynamic instability
   6. Hypertension Management in suspected aortic injury
      1. Target Blood Pressure 110 mmHg
      2. Esmolol drip (requires very close monitoring) or repeated Labetalol boluses
7. Resources
   1. Radiology Master Class: Mediastinal Abnormalities
      1. https://www.radiologymasterclass.co.uk/tutorials/chest/chest_pathology/chest_pathology_page9
   2. Radiopaedia: Mediastinal Widening
      1. https://radiopaedia.org/articles/mediastinal-widening-differential
8. References
   1. Swadron and Inaba in Herbert (2018) EM:Rap 18(30): 4-6, 8-9