August 30, 2016
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Occupational Asthma (cont.)

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What are symptoms and signs of occupational asthma?

Symptoms usually begin with wheezing, shortness of breath, and chest tightness weeks to years after workplace exposure. Often, runny nose (rhinorrhea) and inflammation of the lining around the eyes (conjunctivitis) are present as well and may even occur before any wheezing or shortness of breath develops. Occasionally cough with or without phlegm (sputum) production may be present as well.

Initially, patients may notice that their symptoms are worse at work and better during weekends or holidays away from work. If no action is taken, patients may develop constant symptoms.

The latency period between the time of exposure to the time of onset of symptoms is highly variable. The latency period for occupational asthma caused by low-molecular weight compounds seems to be shorter than that for high-molecular weight compounds. The latency period for high-molecular weight compounds is often several years. Again, in the case of reactive airways dysfunction syndrome (RADS), symptoms will occur within the first 24 hours of a massive exposure.

How is occupational asthma diagnosed?

Your doctor will usually begin with a thorough history and physical examination. Your doctor will likely ask you questions about your symptoms, when they get worse and better, and when they began. It will be important to tell your doctor about your work history, including specifically what you do in the workplace. It's not enough to say, "I work in a restaurant"; your doctor will need to know if you work with flour, clean with chemicals, and what exposures you may have had. Your doctor may ask you to obtain Material Safety Data Sheets (MSDS), which is a form containing data about potential agents. These will generally be on site in your workplace.

Your doctor may perform a test to measure the flow of air in and out of your lungs, called a pulmonary function test. This test is used to confirm the diagnosis of asthma. This test may involve giving an inhaled medicine called a bronchodilator to relax or dilate the airways. Alternatively, the test may involve administering a medicine to see how excessively responsive, or "twitchy," the airways are (bronchoprovocation test).

Your doctor may give you a small device called a peak expiratory flow meter to measure your airflow during exhalation both at home and at work. Typically, you will be required to record your results daily for a few weeks to see if there is a difference between airflow when at work and when away from work.

Sometimes your doctor will examine your sputum (phlegm) for elevated levels of a type of white blood cell called eosinophils. This can help your doctor diagnose both asthma or another type of non-asthma respiratory disease called eosinophilic bronchitis. The respiratory therapist may have you inhale a saltwater solution to help you cough deeply enough to produce sputum from deep in your airways to look for eosinophils.

Skin tests can be done, where an agent thought to cause your symptoms is introduced below the first layer of skin with a small needle to see if this agent triggers an inflammatory response. However, skin tests are not available for most agents that cause occupational asthma.

Sometimes pulmonary function tests can be done with a dose of the suspected offending agent used to see if the agent is causing the airway to be excessively responsive. These special pulmonary function tests are usually done at specialized laboratory centers or occasionally they can be done in the workplace environment.

Medically Reviewed by a Doctor on 4/30/2015


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