Pneumomediastinum



Pneumomediastinum


Daniel J. Podberesky, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Asthma


  • Straining against Closed Glottis


  • Aspiration


  • Blunt Chest Trauma


  • Iatrogenic


  • Surfactant Deficiency Disease


  • Pulmonary Interstitial Emphysema


Less Common



  • Infection


  • Extension of Pneumoperitoneum or Pneumoretroperitoneum


Rare but Important



  • Esophageal Tear


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Potential sources for pneumomediastinum



    • Trachea and bronchi


    • Lung


    • Esophagus


    • Pleural space


    • Head/neck


    • Peritoneal space


    • Retroperitoneal space


  • Helpful radiographic signs in pneumomediastinum



    • Thymic sail sign: Elevation of thymus by large amount of pneumomediastinum


    • Continuous diaphragm: Air trapped posterior to pericardium


    • Ring around artery sign: Air surrounding pulmonary artery branch


    • Air in inferior pulmonary ligament: Retrocardiac extension of pneumomediastinum


    • Double wall sign: Intramural gas along proximal airways


    • Associated pneumothorax, pneumopericardium, or subcutaneous emphysema


  • Pneumomediastinum is frequently asymptomatic and self-limited


  • History is extremely helpful in determining possible source of pneumomediastinum



    • Is there trauma history?


    • Is there history of recent instrumentation?


    • Is the patient asthmatic?


Helpful Clues for Common Diagnoses



  • Asthma



    • Airway narrowing and mucous plugging leads to air-trapping and alveolar rupture


    • History of asthma exacerbation helpful in making diagnosis


    • Hyperinflated lungs


  • Straining against Closed Glottis



    • History helpful



      • Vomiting


      • Giving birth to child


      • Weight-lifting


    • No specific imaging features


  • Aspiration



    • Results from air-trapping and alveolar rupture


    • Meconium aspiration



      • History of meconium-stained amniotic fluid helpful


      • Coarse interstitial and patchy opacities


      • Hyperinflation


    • Foreign body aspiration



      • Peanuts most common in children


      • Frequency of right vs. left bronchial tree involvement is equal in young children


      • Right > left bronchial tree involvement in older children and adults


      • Unilateral hyperinflation


      • Atelectasis


      • Decubitus views can be helpful if radiolucent foreign body is suspected


  • Blunt Chest Trauma



    • History helpful



      • Motor vehicle crash


      • Fall


      • Sports injury


    • Alveolar rupture &/or tracheobronchial injury


    • Other signs of trauma



      • Fractures


      • Pulmonary contusions


      • Mediastinal injuries


      • Pleural effusions


  • Iatrogenic



    • Mechanical ventilation


    • Instrumentation can result in



      • Tracheobronchial injury


      • Esophageal injury


    • Postoperative patients


    • History helpful


  • Surfactant Deficiency Disease




    • Premature neonates


    • Reticulogranular opacities


    • Air leak from alveolar rupture can lead to pneumomediastinum


  • Pulmonary Interstitial Emphysema



    • Premature infants


    • Barotrauma from mechanical ventilation


    • Reticular and cystic opacities


    • Alveolar rupture with air leak into pulmonary interstitium


    • Can progress to pneumomediastinum and pneumothorax


Helpful Clues for Less Common Diagnoses

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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Pneumomediastinum

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