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Asthma By: Shamsizadeh, Shahrooz 1386. 08. 23
Asthma (Introduction) Respiratory diseases cause loss of 5 -38 million days per year. Asthma is the most common occupational respiratory disease In under development countries. 5 -10% of U. S member. 15 -20% of asthma cause from work.
Asthma (Definition) 1. 2. 3. Airway inflammation Airway obstruction Airway hyper responsiveness (+/-) Ø Ø Ø Reversible obstruction(+/- treatment). As a consequence of working environment. Not to stimuli of the outside the work.
Occupational Asthma(O. A) Sensitizer-induced O. A(immunologically) Irritant-induced O. A(non-immunologically) Aggravation of asthma
Sensitizer O. A High molecular weight ◦ ◦ ◦ Animal derived Planet derived Enzymes Irritant agents ◦ ◦ ◦ Chlorine Acetic acid Isocyanides Low molecular weight ◦ ◦ ◦ Spray paint Wood dust Acid anhydride biocides Colophony-fluxes
Sensitizer O. A H. M. W is protein & polysaccharide >5 kd ØIg-E dependent or not dependent ØMast cell & macrophage ØLym CD 4+, IL 4, 5, 13 L. M. W unknown cause ØHapten (platinum , isocyanat , anhydrid) ØPlatinum is with Ig-E ØPMN, Lym CD 8+, IL 2, INF
Pathophysiology of Sensitizer O. A Air way inflammation paramount feature of asthma. Air way inflammation cause: ◦ Obstruction ◦ Hypersensitivity Air way response include: ◦ Rapid(1 -2 h) ◦ Late (4 -8 h) ◦ Dual (1 -2 & 4 -8 h)
Irritant-induced O. A Rapid Airway Dysfunction Syndrome (RADS) Single high level of exposure to irritant fume , gases and smoke. Short duration between exposure and response. Immunologic and neurological inflammation is the mechanism of RADS. Is RADS come to asthma?
Irritant-induced asthma criteria With onset of 24 h Persistence symptom for at least 12 w Objective evidence of asthma: ◦ Hyper responsiveness ◦ Response to bronchodilator No previously asthma or COPD Calcium oxide , nitrogen oxides , welding fumes , spray paint, …
Exposure factors Dose-response relationship Duration of sensitization(>1 m up to 2 year) and dependent to: ◦ Dose ◦ Duration ◦ Susceptibility Skin contact (isocyanate) such as respiratory contact is important. Environmental agents (smoking, platinum, O 3, diesel gases , air allergen. )
Host factors 1. 2. 3. 4. 5. Atopy : HMW such as detergent enzymes. Smoking: 1. platinum worker is the highest risk factor 2. Laboratory animal handler 3. Tetracholorophthalic anhydride. non-allergic bronchial hyper-responsiveness. Genetic(diisocyanate, platinum, red cedar) Upper air way symptom(rhinitis &conjunctivitis).
Work related asthma Prior asthma and aggregated with work: 1. 2. 3. 4. 5. 6. Drugs(asprin, beta bloker, tarterazin, sulphit agent) Environment(O 3, SO 2, NO 2). Infections(RSV, influenza, para flu, rhinovirus). Exercise (cold and dry ventilation). Psychological conditions(vogues and endorphin). Non active smokers.
Work related asthma Related to: ◦ Air way hyper sensitivity ◦ Severity of asthma ◦ Pharmalogical control of asthma Patient can come back to work if ◦ Exposure limited ◦ Well treated with drugs How about sensitized O. A?
Clinical features Dyspnea , cough , wheezing. Some or all of persons involved. Latency(month to years or acute) Onset(rapid , late , dual) History of atopy , rhinitis , conjunctivitis Environmental investigation ◦ Ventilation , protective devices ◦ Proper usage
Diagnosis 1. 2. 3. 4. 5. 6. Spirometry (base and serial) for work related ↓ 10% of FEV 1 before and after. Methacholine or histamin challenge test after 10 -14 holydays associated with 3 time ↑Pc 20. P. E. F serial (the best test for O. A). Immunological tests(specific Ig. E→HMW &platinum) Fe. NO, sputum induced analysis(4 -6 h and Eos) C. X. R
4 Rule of diagnosis I. III. IV. Occupational symptoms. Serial P. E. F Serial spirometry Challenge test
O. A Algorithm
Screening questionnaire Current health(during the last 4 weeks) 91% sensitivity and 96 % specificity If you run or climb stairs fast do you ever: • Cough? • Wheeze? • Get tight in the chest? Is you sleep ever broken by: • Wheeze? • Difficulty with breathing? Do you ever wake up in the morning with: • wheeze? • Difficulty with breathing? Do you ever wheeze: • If you are in a smoky room? • If you are in a very dusty place? Yes/no Yes/no Yes/no
Prevention 1. 2. 3. 4. 5. 6. 7. 8. Substitution Ventilation Change of procedure Restriction of employment Free from smoke Accidental education Environmental screening Protective devices
Treatment Ø Ø Loss of exposure Protective devices for RADS and work agg asthma Avoid from smoking , dust , fume (for irritant) Follow up with: a. Serial PFT b. Specific challenge tests
Treatment Step Symptom Night Symptom Lung function medication STEP 1: Mild intermittent Symptoms two times a week Asymptomatic and normal PEF between exacerbations two times a month FEV 1 or PEF 80 percent predicted PEF variablity <20 percent Exacerbations may occur, A course of systemic corticosteroids is recommended. STEP 2: Mild persistent Symptoms > two times a week but < one time a day Exacerbations may affect activity > two times a month FEV 1 or PEF 80 percent predicted PEF variablity 20 to 30 percent Lo w-dose inhaled corticosteroids STEP 3: Moderate persistent Daily symptoms Exacerbations two times a week > one time a week FEV 1 or PEF >60 but <80 percent predicted PEF variablity >30 percent Low-to-medium dose inhaled corticosteroids and long-acting inhaled beta 2 -agonists. STEP 4: Severe persistent Continual symptoms Limited physical activity Frequent exacerbations Frequent FEV 1 or PEF 60 percent predicted PEF variablity >30 percent High-dose inhaled corticosteroids AND Long-acting inhaled beta 2 agonists
Prognoses Associated with: ◦ ◦ ◦ Exposure duration Exposure amount after clinical symptom Severity of symptoms(by PFT , challenge tests) Sensitivity to west red cedar , Isocyanides Corticosteroid inhalation Reduce exacerbation: ◦ Proper environmental control ◦ Proper education ◦ Proper drug treatment