Rosen & Barkin's 5-Minute Emergency Medicine Consult (553 page)

• Presence of free air or gas within the mediastinum (mediastinal emphysema)
  
• May originate from esophagus, lungs, or bronchial tree (
  aerodigestive
  process)
  
• May occur spontaneously (primary pneumomediastinum) or as result of trauma, surgery, or other pathologic processes (secondary pneumomediastinum)
  
• Spontaneous pneumomediastinum:
  
  • Caused by extrapleural tracheobronchial injury:
    
    • Increased intra-alveolar pressure, low perivascular pressures, or both
      
    • Terminal alveolar rupture into the lung interstitium and bronchovascular tissue sheath
      
    • Dissection of air into the hilum and subsequently the mediastinum along a pressure gradient
      
    • Mediastinal air then dissects into the fascial planes, most commonly into the tissues of the neck.
      
  • Often in setting of a Valsalva maneuver, forceful vomiting, in association with bronchospasm or inhalational drug use
    
  • Men > women (2:1 in some series)
    
  • Young > old (most common in 2nd/3rd decades of life in most series)
    
  • Pediatric patients have a bimodal age distribution of peak incidence (<7 and 13–17 yr)
    
• Relatively rare, 1/30,000–50,000 hospital admissions
  

• Primary or spontaneous pneumomediastinum:
  
  • Associated with forced Valsalva maneuvers:
    
    • Forceful vomiting
      
    • Forceful straining during exercise
      
    • Straining during defecation
      
    • Coughing/sneezing
      
    • Intense screaming
      
    • Labor and delivery
      
    • Playing wind instruments
      
    • Pulmonary function testing
      
    • Anorexia nervosa
      
    • Obesity
      
    • Pre-existing lung disorders (interstitial lung disease, pulmonary fibrosis, pneumonitis)
      
    • Illicit inhalation drug use (marijuana, cocaine, methamphetamine)
      
    • Tobacco abuse
      
  • A majority of cases will have no identified precipitating event/cause
    
  • Has been rarely described after dental extraction/procedures.
    
• Secondary pneumomediastinum:
  
  • Secondary to thoracic barotrauma
    
  • Common traumatic mechanisms:
    
    • Motor vehicle collision
      
    • Fall
      
    • Blows to chest or neck
      
    • Recent esophageal/tracheobronchial instrumentation
      
  • Positive-pressure ventilation
    
  • Esophageal rupture (Boerhaave syndrome)
    
  • In association with mediastinal infection caused by gas-forming organisms
    
• Tension pneumomediastinum:
  
  • Rare but life-threatening event
    
  • Usually in patients on positive-pressure ventilation
    
• May be associated with pneumopericardium and/or extension of a pneumothorax/tension pneumothorax
  

DIAGNOSIS

• Chest pain (most common symptom in multiple series):
  
  • Sharp
    
  • Pleuritic
    
  • Retrosternal
    
  • Radiating to back and arms
    
  • Often positional
    
• Dyspnea
  
• Neck pain:
  
  • Occurs in association with dissection of air into soft tissues of neck
    
  • Often described as “neck swelling,” “neck pain,” “throat pain,” or “difficulty swallowing”
    
• SC emphysema:
  
  • Most commonly located at the supraclavicular area and anterior neck
    
• Dysphagia/odynophagia
  
• Dysphonia/hoarseness
  
• Hamman crunch: Presence of a precordial crinkling or crepitance during systole:
  
  • Uncommon but pathognomonic
    
  • Best heard with patient in left lateral decubitus position
    
• Meckler triad (esophageal rupture): Vomiting, lower chest pain, and cervical SC emphysema following overindulgence of food or alcohol
  

• Inhalational drug use
  
• Asthma exacerbation
  
• Pre-existing lung disorders
  
• Forceful vomiting (such as in diabetic ketoacidosis [DKA], or hyperemesis)
  
• Preceding strenuous athletic activity
  

• SC emphysema
  
• Hamman crunch
  

• Exclude secondary causes, notably esophageal rupture.
  
• Chest radiography
  
• Chest CT (if high index of suspicion)
  

CBC if there is suspicion of mediastinitis (the most concerning consequence of esophageal rupture, with high morbidity and mortality)

• CXR:
  
  • Most valuable initial test
    
  • Important to include lateral view because mediastinal air is often missed on posterior–anterior view
    
  • Aids in excluding pneumothorax, pneumopericardium
    
  • Identification of a pleural effusion or parenchymal infiltrate may suggest an esophageal rupture.
    
  • Negative in up to 30–35% of cases
    
  • Spinnaker sail sign or “angel wing” sign (produced by air lifting the thymus off the heart and major vessels)
    
  • Continuous diaphragm sign (air collecting between the diaphragm and the pericardium)
    
  • SC or superior mediastinal emphysema
    
• Chest CT:
  
  • Imaging test of choice if suspicion is high but CXR is negative (CXR has high false-negative rate)
    
• Esophagram with water-soluble contrast material:
  
  • Study of choice to exclude diagnosis of esophageal rupture
    

• Esophagoscopy:
  
  • Limited usefulness (overutilized)
    
  • May be used to further delineate injuries identified with CT and/or esophagram
    
• Laryngoscopy/bronchoscopy:
  
  • Limited usefulness (overutilized)
    
  • May be used to exclude diagnosis of laryngeal/tracheobronchial injury
    
• Pericardiocentesis:
  
  • Only in the setting of tension pneumopericardium in the crashing patient
    
• Tube thoracostomy:
  
  • Only in the setting of concomitant pneumothorax of sufficient size, or one that is rapidly progressing
    

• Aortic dissection
  
• Coronary ischemia
  
• Esophageal diverticula
  
• Esophageal webs
  
• Mediastinitis
  
• Myocarditis
  
• Pericarditis
  
• Pneumonia
  
• Pneumopericardium
  
• Pneumothorax/tension pneumothorax
  
• Pulmonary embolus
  
• Schatzki rings
  

TREATMENT

• Resuscitation of the acutely ill patient (as in the patient with septic mediastinitis)
  
• In the appropriate setting, standard care of the trauma patient
  
• Withhold PO intake
  
• Rapid patient evolution and transport to an appropriate facility
  

• IV access
  
• Oxygen
  
• Cardiac monitoring
  
• Pulse oximetry
  

• Spontaneous pneumomediastinum:
  
  • Usually a benign, self-limiting condition
    
  • Does not require specific treatment
    
  • Efforts should focus on pain relief and reassurance once diagnosis is confirmed.
    
  • High-flow oxygen may facilitate the reabsorption of nitrogen and provide comfort.
    
  • Withhold PO intake if suspected esophageal source (pending diagnostic studies)
    
  • Condition is self-limiting and may be expected to resolve over 2–5 days.
    
• Secondary pneumomediastinum:
  
  • Once diagnosis is made, direct invasive diagnostic modalities toward the most likely underlying cause (esophagoscopy, laryngoscopy, bronchoscopy).
    
  • Direct therapy toward underlying cause.
    

• Treat underlying cause aggressively (e.g., asthma exacerbation or DKA).
  
• Oxygen 15 L via nonrebreather mask
  
• Analgesia (non-narcotic and narcotic as necessary)
  
• Antibiotics have limited use, but in the setting of concern for mediastinitis use broad-spectrum coverage to include GI flora, resistant organisms, and
  Pseudomonas
  :
  
  • Vancomycin 10–15 mg/kg IV q12h
    and
    
  • Piperacillin/tazobactam 3.375–4.5 g IV q6h
    and
    
  • Clindamycin 600–900 mg IV q8h
    or
    Metronidazole 500 mg IV q8h
    

FOLLOW-UP

• Secondary pneumomediastinum
  
• Associated pneumothorax
  
• Possibility of esophageal rupture has not been excluded
  
• Abnormal vital signs
  
• Ill/toxic-appearing patient
  
• Intractable pain
  
• Underlying disorder requires admission (asthma exacerbation, exacerbation of lung disorder, DKA).
  
• Social situation prevents compliance or follow-up
  
• Extremes of age (pediatric and elderly)
  
• Immunosuppression
  
• Failure of outpatient management
  

• Spontaneous pneumomediastinum
  
• Normal vital signs
  
• No pneumothorax
  
• No significant comorbidities
  
• Period of observation in the ED with resolution of symptoms
  
• Close outpatient follow-up
  

• Patients should be followed up for re-evaluation of clinical symptoms and imaging for resolution of the process.
  
• Recurrent spontaneous pneumomediastinum may warrant cardiothoracic consultation for further diagnostic evaluation (invasive studies).