Work-Related Asthma

Sep 16, 2019 admin HÔ HẤP 0

Work-Related Asthma

Aka: Work-Related Asthma, Occupational Asthma, Work-Aggravated Asthma, Asthma in the Workplace, Occupational Lung Disease

II. Epidemiology

  1. Occupational Asthma accounts for 15% of new Asthma cases in adults
    1. Estimated 1.9 million new cases/year (2012)
    2. (2012) MMWR Morb Mortal Wkly Rep 25;61(20):375-8 [PubMed]

III. Types: Occupational Lung Disease

  1. Work-Aggravated Asthma
    1. Preexisting Asthma worsened by workplace exposure
    2. See Intrinsic Asthma
  2. Occupational Asthma
    1. Allergic Occupational Asthma (90% of cases)
      1. Caused by sensitizers (immune-mediated response)
      2. High molecular weight sensitizers induce IgE response and are most common
    2. Irritant-induced Asthma (10% of cases)
      1. Reactive Airway Dysfunction Syndrome
      2. Irritants cause direct cell damage and inflammation
  3. Non-Asthma Occupational Lung Disease
    1. Occupational COPD (accounts for 15-19% of all COPD cases)
      1. Associated with exposures to coal dust, silica, cotton dust, and cadmium fumes
      2. Compounded by concurrent Tobacco use
    2. Interstitial Lung Disease
      1. Asbestosis
      2. Eosinophilic Pneumonia
      3. Hypersensitivity Pneumonitis or extrinsic allergic alveolitis (bird fancier’s lung, farmer’s lung)
      4. Silicosis

IV. Risk Factors

  1. Atopy
  2. Tobacco abuse

V. Findings

  1. See Asthma

VI. Approach

  1. Diagnose Asthma
    1. Spirometry
  2. Determine if Asthma is work related
    1. Pre-work and post-work Spirometry
    2. Serial Peak Expiratory Flow log four times daily
    3. Symptoms improve on days away from work
  3. Determine type of Occupational Asthma (see above)
    1. Work-Aggravated Asthma (Preexisting Asthma worsened by workplace exposure)
    2. Allergic Occupational Asthma
    3. Irritant-induced Asthma

VII. Management

  1. Completely avoid causative agent
    1. However, up to 70% of patients have persistent symptoms for years after exposure cessation
  2. Treat with standard Asthma Management (e.g. Inhaled Corticosteroids, Bronchodilators)
    1. See Asthma Management
    2. Tobacco Cessation

VIII. Prevention

  1. Offending irritant or allergen exposure
  2. Adequate respiratory protection

IX. Resources

  1. National Institute Occupational Safety Health (NIOSH)
    1. http://www.cdc.gov/niosh/homepage.html
  2. Occupational Safety and Health (OSHA)
    1. http://www.osha.gov/index.html
  3. American Thoracic Society – Occupational Lung Disease
    1. https://www.thoracic.org/patients/patient-resources/breathing-in-america/resources/chapter-13-occupational-lung-diseases.pdf

X. References

  1. Bebko (2016) Am Fam Physician 93(12): 1000-6 [PubMed]
  2. Chan-Yeung (1995) Chest 108:1084-117 [PubMed]
  3. Friedman-Jimenez (2000) Am J Ind Med 37:121-41 [PubMed]
  4. Youakim (2001) Am Fam Physician 64(11):1839-48 [PubMed]

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