Occupational Asthma Management Beyond the Textbooks Paul Cullinan MD, FRCP

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1 Occupational Asthma 1 Professor of Occupational and Environmental Medicine Royal Brompton Hospital and Imperial College London LUNGS AT WORK Premise and plan Good respiratory physicians know a lot about occupational asthma But don t often see it And may not be sure about some of the intricacies Occupational asthma is rarely severe asthma but its consequences often are Intricacies by a single case report 2 Consider 3 47 year old No relevant past medical history Non-smoker September 2008: short of breath Dx chest infection by GP Christmas 2008: short of breath + wheeze 1/52 hospital Dx asthma Rx asthma since February 2009: returned to work Symptoms persist but better 2 week holiday in Crete: symptoms resolved Q1: what other information do you need? 1

2 Consider an occupational aetiology In every working adult with asthma that is: New Recurrent, or Deteriorating/Proving difficult to manage Especially if they are working with a recognised respiratory sensitising agent 4 Consider 22 years work in a factory making foam insulating board New process January

3 7 Consider 22 years work in a factory making foam insulating board New process January Q2: is it possible that his work is causally related to his diagnosis of asthma? or Is he working with a recognised respiratory sensitising agent? Most occupational asthma arises from specific sensitisation An agent at work is: Known to be a respiratory sensitiser (n 400) Known not to be a respiratory sensitiser Not known not to be respiratory sensitiser The last is tricky 9 3

4 Is your patient working with a respiratory sensitising agent? Agent on my familiar list? Consider OA 10 Respiratory sensitising agents: high molecular mass - Whole allergens 11 Occupation Baking Animal work Food processing Detergent manufacture Health care Exposure(s) Flour(s) Alpha amylase ( improver ) Egg Small mammals Large mammals Insects Latex Seafood Tea/coffee Eggs Flour Latex Etc. Enzymes Latex All induce specific IgE response Respiratory sensitising agents: low molecular mass + - Hapten-protein conjugates Occupation Spray painting Foam manufacture Electronic engineering Woodwork Hairdressing Dentistry Orthopaedics Textile printing Precious metal refining Exposure(s) Hexamethylene diisocyanate Toluene diisocyanate Methylene diphenyldiisocyanate Colophony fume Cyanoacrylate Persulphate salts Tropical wood dusts Persulphate salts Methacrylates Latex Reactive dyes Platinum salts 12 Some induce specific IgE response 4

5 Is your patient working with a respiratory sensitising agent? Agent on my familiar list? No/Not sure Seek advice obtain MSDS Consider OA R42? 13 No Take care Safety Data Sheet TECHNI GOLD 25 ES RTU TGOLD25ES/0 Page n. 1 of 4 Safety Data Sheet dated 23/7/2004, version 0 1. IDENTIFICATION OF THE PRODUCT AND THE COMPANY Trade name: TECHNI GOLD 25 ES RTU Trade code: TGOLD25ES Supplier: TECHNIC FRANCE 15rue de la Montjoie St Denis La Plaine 2. COMPOSITION/INFORMATION ON INGREDIENTS Hazardous components within the meaning of EEC directive 67/548 and corresponding classification: 1% - 5% sodium sulfite R20/22 1% - 5% ethylenediamine R10 R21/22 R34 R42/43 1% - 3% sulphuric acid R35 3. HAZARDS IDENTIFICATION If brought into contact with the eyes, the product causes irritation that may last for over 24 hours, and if brought into contact with the skin it causes significant inflammation with erythema, scabs, and oedema. If inhaled, the product may cause sensitisation of the airways, and if brought into contact with the skin it may cause sensitisation of the skin 14 All airborne proteins are (potentially) sensitising agents Many chemicals with powerful odours are not Solvents Thinners Perfumes Many (but not all) glues Some tips......and are thus improbable causes of sensitisation Be wary of diagnosing occupational asthma in anyone who is not working with a recognised respiratory sensitising agent 5

6 Recall 22 years work in a factory making foam insulating board New process January 2008 Q2: is he working with a recognised respiratory sensitising agent?... foam is a polymer made using polyol and MDI MDI = methylene phenyldiisocyanate 16 Hence Adult onset asthma Shortly after introduction of new process Works with known respiratory sensitising agent Symptoms improve on holiday Q3: what is the (prior) probability that this man has occupational asthma? Q4: how important is it to know (and how certain do you want to be)? 17 Occupational asthma or work-exacerbated asthma Occupational asthma (OA): That which has arisen de novo from an exposure encountered at work Work-exacerbated asthma (WEA): Pre-existing, recurrent or coincidental asthma that is exacerbated by exposure(s) in the workplace 18 6

7 Occupational asthma or work-exacerbated asthma: why does it matter? Continued exposure: Treatment: RPE: Cure? Legal? Relocation: Compensation: OA Worsens prognosis Useless Often useless (but ) 19 Occupational asthma or work-exacerbated asthma: why does it matter? OA WEA Continued exposure: Worsens prognosis Doesn t affect prognosis Treatment: Useless Effective RPE: Often useless Effective Cure? (but ) No Legal? No Relocation: Generally no Compensation: yes No 20 Getting it right matters Locating your patient: understanding the context (UK) In-house External provider Family doctor Occupational health (Surveillance) HSE Referral for opinion R I D D O R Case of OA Employer 21 Avoidance of further exposure relocation 7

8 Relocation of an employee with occupational asthma Avoidance of further exposure Retention in job, adjustment to tasks Re-training, protected position Re-location within firm Redundancy Size of workforce Attitude of employer/oh Experience of OA Self-employed So... Are you sure that you (both) want to go the whole way? On the one hand: You have a good chance of curing their asthma You will certainly stop it getting worse If you miss an occupational cause then treatment is useless On the other: They are likely to suffer major disruption at work and may become fairly unpopular there They may very well need to change (lose) their job and find it difficult to get another Hence: Getting it wrong can be disastrous Beware being on the safe side 24 Back to the case 1 Adult onset asthma Shortly after introduction of new process Works with known respiratory sensitising agent Symptoms improve on holiday Q5: is immunology going to be helpful? Negative specific IgE test for MDI Specific IgE in diisocyanate asthma is of: Low sensitivity (lots of false negatives) High specificity (few false positives) Hence helpful if positive 8

9 Using immunology intelligently in occupational asthma No, or not sure Is it a protein? IgE tests are: Highly sensitive Widely available Hence helpful when negative Ask for the right one(s) 25 Ask for expert help Back to the case 2 Adult onset asthma Shortly after introduction of new process Works with known respiratory sensitising agent Symptoms improve on holiday Specific immunology negative Q6: what might you do next? Comparison of function at and away from work Serial measurement of PEF: 26 Every two hours (six times daily) Four weeks At and away from work Plot of daily measurements: Mean Maximum Minimum Peak flow (max, mean, min) L/minute 27 9

10 28 Now where are you? Adult onset asthma Shortly after introduction of new process Works with known respiratory sensitising agent Symptoms improve on holiday Immunology unhelpful Serial PEFs look negative Q7: is this enough? How sure do you (both) need to be? Is there anything else on offer? Specific inhalation challenge Specific inhalation challenge 29 Controlled exposure to workplace agent Inpatient procedure Requires experience and expertise Available in few centres Used when: Other diagnostic approaches have not proved definitive A previously unrecognised agent is under consideration It s important to distinguish two or more agents Not for legal purposes Results of specific inhalation challenge 30 2 mins polyol 2.5 mins MDI 20 mins MDI 25 mins MDI 15 % change in baseline FEV Minutes Hours 10

11 Outcome Back at work Asymptomatic Off treatment Not everything is asthma Probably all infective Note that working with exposed to A brief summary Suspect an occupational cause in all cases of new, recurrent or deteriorating asthma in working adults Understand respiratory sensitising agent Have a feeling for your patient s location within the workplace Go in with all (4) eyes open Get it right: A positive diagnosis can be curative A false positive diagnosis can be disastrous Be specific about the agent(s) Act fast Caution is not always the better part of anything 33 11