pneumomediastinum; mediastinal emphysema

Introduction

Air in the mediastinum. See pneumothorax

Etiology

• tracheobronchial injury resulting from
  • trauma to the chest wall
  • acute asthma exacerbation
  • clinical procedures procedures
    • bronchoscopy
    • esophagoscopy (Boerhaave syndrome)
  • air entering mediastinum from the retroperitoneal space
• Mycoplasma pneumonia
• obesity

Pathology

• rupture of aveoli resulting from small airway obstruction
• movement of free air along the airways & blood vessels to the mediastinum by dissecting through supporting soft tissue

Clinical manifestations

• severe central chest pain, neck pain, throat pain
• dsypnea, cough, wheezing
• voice distortion
• subcutaneous emphysema, affecting face, neck, & chest
• Hamman's sign
  • crunching, rasping sound, synchronous with the heartbeat, heard on ausculation over the precordium (crunching sound during systole)
• crepitus with palpation of midline upper thorax

Radiology

• chest X-ray shows a white outline around the heart & mediastinum
• CT of the thorax

Differential diagnosis

• cardiac tamponade

Management

• conservative management
  • spontaneous resolution common
  • high flow oxygen as needed
  • pain management
  • avoidance of actions that increase pulmonary pressure
  • needle decompression for cardiogenic shock
  • if collapsed lung, lie on side of collapsed lung, manage pain
• treat asthma exacerbation
• surgery may be needed to repair trachea, esophagus or bowel may be indicated

More general terms

• pneumothorax
• emphysema