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Occupational Asthma PowerPoint Presentation

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Description : This medical presentation titled "Occupational Asthma" provides information on occupational asthma.

Tags : Immediate, hypersensitivity reaction, bronchospasm, Isolated late response, Sleep disorder, Variable, dual response, Types,

Published on : Apr 26, 2021 | Views : 2527 | Downloads : 4

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Slide 1-

Occupational Asthma Tee L. Guidotti The George Washington University
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Presentation of Occ Asthma Immediate hypersensitivity reaction Immediate bronchospasm Isolated late response (usually sensitizer-induced) Sleep disorder Variable/dual response
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Types of Occupational Asthma New Onset - Sensitizer-induced - Irritant induced Aggravation of underlying asthma Reactive airways dysfunction syndrome (RADS) Cold air- or exercise-induced syndrome Airways reactivity secondary to hypersensitivity pneumonitis
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Occupational Asthma Sensitizer-induced Specific antigen Minimal exposure Stereotyped response PPE often insufficient to control symptoms Medical removal usually necessary Irritant-induced Any irritant Moderate to heavy exposure Often variable PPE often effective in preventing episodes Medical removal the last resort
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Sensitizer-Induced Occ Asthma Sensitization to a specific antigen - low molecular-weight, “hapten” - high molecular weight Reaginic Ab, mostly IgE, mediated Presentation variable - late phase reactivity - immediate sensitivity - dual or variable responsiveness
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Sensitizer-Induced Asthma 2 Sensitization may occur at
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Common Sensitizers(Incomplete List!) Low MW Isocyanates Anhydrides Metal salts Epoxy resins Fluxes Persulfate Aldehydes High MW Pharmaceuticals Animal proteins Latex Cereals Seafood Proteolytic enzymes Wood constituents
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Irritant-Induced Occupational Asthma More common, clinically, than sensitizer-induced Often represents clinical expression of airways hyperactivity + irritant exposure May be induced by any irritating exposure Usually history of intolerance to second-hand tobacco smoke Some irritant exposures may also be sensitizing: CHO, TDI,TMA Classic example is “hot wire” asthma
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RADS Acute onset following exposure to irritant Generally exposure of moderate severity Prognosis good but may have several years of airway hyperactivity and sequelae Often associated with: upper airway problems sleep disorder Independent of prior history of airways reactivity Conventional management
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Aggravational Asthma Very common Existing airways reactivity: asthma hay fever and rhinitis other airways disease (e.g. COPD) Initial condition not occupational Moderate irritant exposure Provokes airways response Usually self-limited
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Patterns of Airways Response
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Immediate response Same shift, rapid onset Reaginic antibody if sensitizer-induced Acute mediators Responds to conventional asthma Rx Often difficult to distinguish from conventional asthma Irritant-induced tends to be milder
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Late Responders Onset of bronchospasm hours after exposure Usually wheezing post-shift Often presents as a sleep disorder If isolated, usually associated with certain antigens (Western red cedar, TDI) Often combined
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Dual/Variable effects Dual responders may combine immediate + late responses Variations may include cyclic bronchospasm (esp. Western red cedar) May be prolonged, sustained response (TDI, byssinosis) Usually slow recovery, relatively refractory to conventional Rx
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Special Cases The following subsets of occupational asthma have special features: Laboratory animal sensitivity (high risk of anaphylaxis) Cotton dust, byssinosis Grain dust Hypersensitivity pneumonitis may have an airways component
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Cold Air / Exercise-Induced Asthma May be associated with: dry cold air exertion hyperventilation Work in cold, dry climates Immediate response, short duration Further exercise may improve airflow! Mechanism: airway drying and cooling stimulates vagal receptors histamine, mediator release from mast cells
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Principles of Evaluation Demonstrate airways reactivity - History - Presence of wheezing Spirometry Methacholine challenge Bronchoprovocation or substitute - Symptom diary - Pre/post shift
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Methacholine Challenge + Test confirms airways reactivity only A functional test not specific for asthma - atopy - transient reactivity Bronchoprovocation with with specific antigen preferable to diagnose sensitizer-induced asthma -Tests can occur with quiescent occ asthma
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Risks of Bronchoprovocation Anaphylaxis Iatrogenic reaction Sensitization
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Ancillary Tests Clinical immunology - skin prick tests - RAST - ELISA PEF or FEV1, symptom and medication diary Pre/post shift and/or holiday PFTs Work place HHE
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Management Conventional Rx for asthma Medical removal – consider options Physician’s First Report Impairment Assessment (c.f. AMA guidelines) Avoid irritants Evaluate PPE
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Compensation Management Document causation Document impairment (episodic?) Medical removal required? Claimant factors - degree of impairment - age - retraining Impairment – Disability
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Pop Health Management Treat as “Sentinel event” Surveillance Identification of specific hazard when possible Hazard Control - engineering controls - PPE