Hypersensitivity Pneumonitis

Importance: Interstitial lung disease (ILD) consists of a group of pulmonary disorders characterized by inflammation and/or fibrosis of the lung parenchyma associated with progressive dyspnea that frequently results in end-stage respiratory failure. In the US, ILD affects approximately 650 000 people and causes approximately 25 000 to 30 000 deaths per year.

Observations: The most common forms of ILD are idiopathic pulmonary fibrosis (IPF), which accounts for approximately one-third of all cases of ILD, hypersensitivity pneumonitis, accounting for 15% of ILD cases, and connective tissue disease (CTD), accounting for 25% of ILD cases. ILD typically presents with dyspnea on exertion. Approximately 30% of patients with ILD report cough. Thoracic computed tomography is approximately 91% sensitive and 71% specific for diagnosing subtypes of ILDs such as IPF. Physiologic assessment provides important prognostic information. A 5% decline in forced vital capacity (FVC) over 12 months is associated with an approximately 2-fold increase in mortality compared with no change in FVC. Antifibrotic therapy with nintedanib or pirfenidone slows annual FVC decline by approximately 44% to 57% in individuals with IPF, scleroderma associated ILD, and in those with progressive pulmonary fibrosis of any cause. For connective tissue disease-associated ILD, immunomodulatory therapy, such as tocilizumab, rituximab, and mycophenolate mofetil, may slow decline or even improve FVC at 12-month follow-up. Structured exercise therapy reduces symptoms and improves 6-minute walk test distance in individuals with dyspnea. Oxygen reduces symptoms and improves quality of life in individuals with ILD who desaturate below 88% on a 6-minute walk test. Lung transplant may improve symptoms and resolve respiratory failure in patients with end-stage ILD. After lung transplant, patients with ILD have a median survival of 5.2 to 6.7 years compared with a median survival of less than 2 years in patients with advanced ILD who do not undergo lung transplant. Up to 85% of individuals with end-stage fibrotic ILD develop pulmonary hypertension. In these patients, treatment with inhaled treprostinil improves walking distance and respiratory symptoms.

Conclusions and relevance: Interstitial lung disease typically presents with dyspnea on exertion and can progress to respiratory failure. First-line therapy includes nintedanib or pirfenidone for IPF and mycophenolate mofetil for ILD due to connective tissue disease. Lung transplant should be considered for patients with advanced ILD. In patients with ILD, exercise training improves 6-minute walk test distance and quality of life.

Author/s:

Toby M Maher

Occupational hypersensitivity pneumonitis after polyurethane adhesive exposure

Rowan Hutchins — Sat, 06 Aug 2022 05:00:00 +0000

Date Added:

August 6, 2022

Journal/Publication:

Canadian medical Association Journal

Publisher:

Canadian Medical Association

Publication Date:

August 2, 2022

Issue:

Volume:

194

URL:

Occupational hypersensitivity pneumonitis after polyurethane adhesive exposure

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

https://doi.org/10.1503/cmaj.220052

Keywords

adhesives

Polyurethanes

pneumonitis

Hypersensitivity Pneumonitis

PMID (1):

35918092

MeSH

Alveolitis

Extrinsic Allergic* / diagnosis

Extrinsic Allergic* / diagnostic imaging

Occupational Diseases* / chemically induced

Occupational Exposure* / adverse effects

Polyurethanes / adverse effects

A concise review of hypersensitivity pneumonitis. James W. Mold, MD, MPG

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Key points
• Hypersensitivity pneumonitis is a type of interstitial lung
disease that requires early diagnosis and treatment as it may
lead to progressive pulmonary fibrosis.
• An occupational history is essential when evaluating patients
with respiratory symptoms.
• Causes of hypersensitivity pneumonitis include infectious
agents; enzymes; animal, insect and plant proteins; low-
molecular-weight chemicals and metals.
• Patients with respiratory symptoms who have had exposure to
isocyanates should avoid the exposure and be assessed for
asthma and hypersensitivity pneumonitis.

Author/s:

Arbaaz, Hasany, Aasim, Tarlo, Susan M.

Occupational causes of hypersensitivity pneumonitis: a systematic review and compendium

Saige Blanchard — Tue, 05 Oct 2021 05:00:00 +0000

Date Added:

October 5, 2021

Journal/Publication:

Occupational Medicine

Publisher:

Oxford University Press

Publication Date:

October 1, 2021

Issue:

6-7

Volume:

Pages:

255-259

URL:

Occupational causes of hypersensitivity pneumonitis: a systematic review and compendium

Type:

Meta-analyses, Reviews, and Guidelines

Format:

Article

DOI (1):

10.1093/occmed/kqab082

Keywords

Hypersensitivity Pneumonitis

Systemic Review

Compendium

Occupational Health

PMID (1):

34370035

MeSH

Alveolitis, Extrinsic Allergic

agriculture

A list of causes of hypersensitivity pneumonitis from a review of the literature. James W. Mold, MD, MPH

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Background: Hypersensitivity pneumonitis (HP) is caused by a variety of antigens and low-molecular-weight chemicals, often through occupational exposure. Making a diagnosis of HP and identifying a cause are challenging. Cryptogenic cases are frequently reported, and missing or incomplete exposure histories can cause misclassification.

Aims: To provide an evidence-based compendium of sources of exposure and causes of HP for the clinician, through systematic review of medical literature.

Methods: Articles related to HP causative agents and occupational exposure were searched from the databases OVID Medline (1946 to October 2020) and EMBASE (1974 to October 2020). Abstracts and full texts of articles were screened by two reviewers. Data on causative antigens, occupational source of exposure and any associated eponymous name were extracted and grouped according to source of exposure.

Results: A total of 1790 articles were identified, from which 305 articles met the inclusion criteria. An additional 22 articles were identified from citation lists of the selected review articles. Sources of exposure identified for HP were sorted into 14 categories of work (agricultural, plant matter processing, wood, animal-related, foodstuff, food processing, metal processing, polymers, other manufacturing, chemicals, aerosolized water, service, waste and sewage and wind instruments).

Conclusions: This work is a comprehensive list of occupational causative agents and exposures causing HP. Cases are grouped by source of exposure, allowing an immediately accessible compendium of causes for use during occupational exposure assessment, which could also form the basis for a clinical questionnaire.

Keywords: Aetiology; extrinsic allergic alveolitis; occupational disease; occupational exposure; occupational health.

Author/s:

Kongsupon , N., Walters, G. I., Sadhra, S. S.