Rosen & Barkin's 5-Minute Emergency Medicine Consult (554 page)

• Ensure that underlying causes are excluded.
  
• Be aware of typical presenting features (chest pain, dyspnea, and neck swelling), pre-existing conditions, and precipitating factors associated with pneumomediastinum.
  
• Hamman crunch is pathognomonic but not commonly seen.
  
• Remember Meckler triad:
  
  • Vomiting
    
  • Lower chest pain
    
  • Cervical SC emphysema
    

• Al-Mufarrej F, Badar J, Gharagozloo F, et al. Spontaneous pneumomediastinum: Diagnostic and therapeutic interventions.
  J Cardiothorac Surg
  . 2008;3:59.
  
• Caceres M, Ali SZ, Braud R, et al. Spontaneous pneumomediastinum: A comparative study and review of the literature.
  Ann Thorac Surg.
  2008;86:962–966.
  
• Dissanaike S, Shalhub S, Jurkovich GJ. The evaluation of pneumomediastinum in blunt trauma patients.
  J Trauma
  . 2008;65(6):1340–1345.
  
• Houn LK, Chang YL, Wang PC, et al. Head and neck manifestations of spontaneous pneumomediastinum.
  Otolaryngol Head Neck Surg.
  2012;146(1):53–57.
  
• Iyer VN, Joshi AY, Ryu JH. Spontaneous pneumomediastinum: Analysis of 62 consecutive adult patients.
  Mayo Clinic Proc
  . 2009;84(5):417–421.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Pneumothorax
  
• Vomiting, Adult
  

The author gratefully acknowledges the contributions of Jennifer De la Pena and Leon D. Sanchez for previouseditions of this chapter.

CODES

518.1 Interstitial emphysema

BASICS

• Epidemiology:
  
  • 7th leading cause of death and leading cause from infectious disease in US
    
• Highest mortality in elderly and patients with the following coexisting conditions:
  
  • Chronic heart, lung, liver, and kidney disease
    
  • Diabetes mellitus
    
  • Alcoholism
    
  • Malignancy
    
  • Asplenia
    
  • Immunosuppression
    
  • Use of antimicrobials within last 3 mo
    
• Classifications:
  
  • Source based:
    
    • Community acquired (CAP)
      
    • Health care associated (HCAP)
      
    • Hospital acquired (HAP)
      
    • Ventilator associated (VAP)
      
  • Symptom based:
    
    • Typical
      
    • Atypical
      
• Complications:
  
  • Bacteremia
    
  • Sepsis
    
  • Abscess
    
  • Empyema
    
  • Respiratory failure
    

• CAP (typicals):
  
  • Streptococcus pneumoniae
    
  • Haemophilus influenzae
    
  • Klebsiella pneumoniae
    
  • Moraxella catarrhalis
    
  • Streptococcus pyogenes
    
  • Staphylococcus aureus
    
• CAP (atypicals):
  
  • Mycoplasma pneumoniae
    
  • Chlamydophila pneumoniae
    
  • Legionella pneumophila
    
  • Viral
    
• HCAP/HAP/VAP:
  
  • Gram negatives (
    Pseudomonas, Stenotrophomonas
    )
    
  • Methicillin-resistant
    S. aureus
    (MRSA)
    
• Immunosuppressed:
  
  • Mycobacterium tuberculosis
    
  • Pneumocystis jirovecii
    
• Aspiration:
  
  • Chemical pneumonitis ± oral and gastric anaerobes
    

DIAGNOSIS

• Typical:
  
  • Acute onset
    
  • Fever
    
  • Chills
    
  • Rigors
    
  • Cough
    
  • Purulent sputum
    
  • Shortness of breath
    
  • Pleuritic chest pain
    
• Atypical:
  
  • Subacute onset
    
  • Viral prodrome
    
  • Nonproductive cough
    
  • Low-grade fever
    
  • Headache
    
  • Myalgias
    
  • Malaise
    
  • Absence of pleurisy and rigors
    

• Vital signs:
  
  • Tachypnea
    
  • Tachycardia
    
  • Hypoxia
    
  • Fever
    
• Pulmonary exam:
  
  • Dullness to percussion
    
  • Tactile fremitus
    
  • Egophony
    
  • Rales
    
  • Rhonchi
    
  • Decreased breath sounds
    
• Note that pneumonia may be present in the absence of the above signs of consolidation.
  

• Elderly patients have higher morbidity and mortality from pneumonia.
  
• Atypical presentations are more common.
  

Combination of clinical and radiographic diagnosis

• General:
  
  • CBC with differential
    
  • Serum chemistry
    
• Others:
  
  • Blood cultures (ICU only)
    
  • Sputum cultures and Gram stain (ICU only)
    
  • Urine antigen tests for
    S. pneumoniae
    &
    Legionella
    
  • C-reactive protein possibly helpful
    
  • Lactate may be helpful
    
  • Influenza viral test
    

Chest radiograph:

• General:
  
  • Findings are nonspecific for particular infectious etiologies.
    
  • May be deferred in young, healthy patients receiving empiric outpatient management.
    
  • Negative imaging should not preclude antimicrobial therapy in patients with clinical diagnosis.
    
• Suggestive findings:
  
  • Silhouette sign (R. heart border = RML, L. heart border = lingula, R. hemidiaphragm = RLL, L. hemidiaphragm = LLL)
    
  • Air bronchograms
    
  • Segmental or subsegmental consolidation
    
  • Diffuse interstitial opacities
    
  • Pleural effusion
    
  • Empyema
    
  • Abscess
    
  • Cavitation
    

Thoracentesis:

• For large effusions, enigmatic pneumonia, and patients who fail to respond to standard therapy
  

• Asthma
  
• Bronchitis
  
• CHF
  
• COPD
  
• Foreign-body aspiration
  
• Occupational or environmental exposure
  
• Pneumothorax
  
• Pulmonary embolism
  
• Tumor
  

TREATMENT

• IV access
  
• Supplemental oxygen
  
• Cardiac monitor
  
• Consider inhaled bronchodilators.
  
• Consider endotracheal intubation in cases of severe respiratory distress.
  

• IV access and fluid resuscitation as needed
  
• Supplemental oxygen
  
• Cardiac monitor
  
• Inhaled bronchodilators
  
• Endotracheal intubation in cases of severe respiratory distress as indicated
  

• American Thoracic Society guidelines for empiric therapy:
  
• Outpatient:
  
  • Previously healthy, no coexisting conditions:
    
    • Macrolide (azithromycin) OR doxycycline
      
  • Significant coexisting conditions (see above):
    
    • Combination β-lactam (ceftriaxone, cefuroxime, cefpodoxime, high-dose amoxicillin, Augmentin) PLUS macrolide (azithromycin) OR
      
    • Respiratory floroquinolone (levofloxacin, moxifloxacin) alone
      
• Inpatient:
  
  • Noncritical care:
    
    • Combination β-lactam PLUS macrolide OR
      
    • Respiratory floroquinolone alone
      
  • Critical care:
    
    • Combination β-lactam PLUS macrolide OR respiratory floroquinolone
      
    • For
      Pseudomonas
      , consider adding antipseudomonal agent (piperacillin/tazobactam, imipenem, meropenem, cefepime) PLUS antipseudomonal fluoroquinolone (high-dose levofloxacin) OR antipseudomonal agent (see above) PLUS aminoglycoside (gentamicin) PLUS macrolide (azithromycin).
      
    • For MRSA, consider adding vancomycin OR linezolid.
      
    • For aspiration, consider adding clindamycin OR metronidazole.
      
    • For drug-resistant
      S. pneumoniae
      , consider adding vancomycin.