Aspiration pneumonia and pneumonitis

(Redirected from Pneumonitis)

Background

  • Difficult to predict which patients with pneumonitis will go on to develop pneumonia, aspiration alone does not cause pneumonia
  • Witnessed aspiration key to distinguishing between the two
  • Aspiration pneumonitis
    • Inflammatory chemical injury of tracheobronchial tree and pulmonary parenchyma
    • Due to inhalation of regurgitated sterile gastric contents
    • Must aspirate at least 20-30mL of gastric contents with pH <2.5
    • Usually resolves after 24-48 hrs with supportive care only
    • Can lead to aspiration pneumonia due to pulmonary defense mechanism injury
  • Aspiration pneumonia
    • Alveolar space infection secondary to inhalation of pathogenic material from oropharynx
    • Result of a complex interplay of the aspirated material, aspirated volume, pH, patient physiology and pulmonary defense mechanisms
    • Increased in patients with periodontal disease, chronic colonization of upper airways, or taking PPI/H2-blockers
    • Accounts for up to 20% of community-acquired pneumonia in elderly, majority of nursing home-acquired pneumonia
    • Microbiology

Risk factors

  • Advanced age
  • Altered level of consciousness
  • Anatomic abnormality of upper airway
  • Dementia
  • Esophageal disorders
  • Gastroesophageal reflux
  • Neuromuscular disease
  • Poor oral hygiene
  • Prior history of aspiration
  • Prolonged supine position
  • Retained gastric material
  • Tube feedings

Clinical Features

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

Evaluation

Aspiration pneumonia in a ventilated person with a central line and nasogastric tube.
Chest X-ray of the patient showing (left) multifocal patchy consolidation consistent with aspiration pneumonitis and (right) the decreased extent of pulmonary opacification in both central lung areas 3 days after initiation of the treatment.

Work-Up

  • CXR
    • Unilateral focal or patchy consolidations in dependent lung segments
    • Right lower lobe is most common area; bilateral patterns can also be seen
    • Lower lobe infiltrate when aspiration occurs in upright position
    • Upper lobe infiltrate when aspiration occurs in recumbent position
  • CT
    • Increased sensitivity, specificity, and overall accuracy compared to CXR
    • Reasonable to obtain even if CXR negative if clinical suspicion is high
    • Aspiration is a risk factor for pulmonary abscess formation

Management

Aspiration pneumonitis

  • Suction upper airway if aspiration is witnessed
  • Caused by aspiration of gastric contents. Usually resolves in 24-48 hrs w/o treatment
  • Antibiotics only recommended if symptoms persist >48hr
    • Same as those for community-acquired aspiration pneumonia below

Aspiration pneumonia

  • Treat same as community acquired pneumonia (see below)
    • Routinely adding anaerobic coverage beyond the standard empiric treatment for community-acquired aspiration pneumonia is no longer recommended unless lung abscess, empyema, healthcare-associated, periodontal disease, or SBO[1]

Outpatient

Coverage targeted at S. pneumoniae, H. influenzae. M. pneumoniae, C. pneumoniae, and Legionella

Healthy[2]

No comorbidities (chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia) and no or risk factors for MRSA or Pseudomonas aeruginosa (include prior respiratory isolation of MRSA or P. aeruginosa or recent hospitalization AND receipt of parenteral antibiotics (in the last 90 d))

  • Amoxicillin 1 g three times daily (strong recommendation, moderate quality of evidence), OR
  • Doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence), OR
  • Macrolide in areas with pneumococcal resistance to macrolides <25% (conditional recommendation, moderate quality of evidence).
  • Duration of therapy 5 days minimum

Unhealthy[3]

If patient has comorbidities or risk factors for MRSA or Pseudomonas aeruginosa

  • Combination therapy:
    • Amoxicillin/Clavulanate
      • 500 mg/125 mg TID OR amox/clav 875 mg/125 mg BID OR 2,000 mg/125 mg BID. Duration is for a minimum of 5 days and varies based on disease severity and response to therapy; patients should be afebrile for ≥48 hours and clinically stable before therapy is discontinued[4]
    • OR cephalosporin
    • AND macrolide
      • Azithromycin 500 mg on first day then 250 mg daily
      • OR clarithromycin 500 mg BID OR clarithromycin ER 1,000 mg daily]) (strong recommendation, moderate quality of evidence for combination therapy)
    • OR doxycycline 100 mg BID (conditional recommendation, low quality of evidence for combination therapy)
  • Monotherapy: respiratory fluoroquinolone (strong recommendation, moderate quality of evidence):

Inpatient

  • Monotherapy or combination therapy is acceptable
  • Combination therapy includes a cephalosporin and macrolide targeting atypicals and Strep Pneumonia [5]
  • The use of adjunctive corticosteroids (methylprednisolone 0.5 mg/kg IV BID x 5d) in CAP of moderate-high severity (PSI Score IV or V; CURB-65 ≥ 2) is associated with:[6]
    • ↓ mortality (3%)
    • ↓ need for mechanical ventilation (5%)
    • ↓ length of hospital stay (1d)

Community Acquired (Non-ICU)

Coverage against community acquired organisms plus M. catarrhalis, Klebsiella, S. aureus

Hospital Acquired or Ventilator Associated Pneumonia

Ventilator Associated Pneumnoia

  • High Risk of MRSA: Use 3-Drug Regimen. Several options are available, but recommendation is to include an antibiotic from each of these categories:[8]

ICU, low risk of pseudomonas

ICU, risk of pseudomonas

Disposition

  • Generally admit all patients with aspiration pneumonia
  • For aspiration pneumonitis, consider discharge if:
    • Otherwise healthy and non-toxic
    • Give outpatient antibiotics if symptomatic for >48hrs
  • For aspiration pneumonitis, consider admission for:
    • Chronically ill or immunocompromised
    • Nursing home patient

See Also

References

  1. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45–e67.
  2. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67
  3. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67
  4. IDSA. Mandell 2007
  5. Chokshi R, Restrepo MI, Weeratunge N, Frei CR, Anzueto A, Mortensen EM. Monotherapy versus combination antibiotic therapy for patients with bacteremic Streptococcus pneumoniae community-acquired pneumonia. Eur J Clin Microbiol Infect Dis. Jul 2007;26(7):447-51
  6. Siemieniuk RA, Meade MO, Alonso-Coello P, Briel M, Evaniew N, Prasad M, Alexander PE, Fei Y, Vandvik PO, Loeb M, Guyatt GH. Corticosteroid Therapy for Patients Hospitalized With Community-Acquired Pneumonia: A Systematic Review and Meta-analysis. Ann Intern Med. Aug 11, 2015
  7. Luther MK, Timbrook TT, Caffrey AR, Dosa D, Lodise TP, LaPlante KL. Vancomycin Plus Piperacillin-Tazobactam and Acute Kidney Injury in Adults: A Systematic Review and Meta-Analysis. Crit Care Med. 2018;46(1):12-20.
  8. Kalil AC, Metersky ML, Klompas M et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016 Sep 1;63(5):e61-e111.