咳嗽性哮喘Cough-variant asthma

咳嗽變異性哮喘(Cough variant asthma ，CVA)也稱咳嗽型哮喘
What Is Cough-Variant Asthma?

Cough-variant asthma is a type of asthma in which the main symptom is a dry, non-productive cough. People with cough-variant asthma often have no other "classic" asthma symptoms, such as wheezing or shortness of breath.

Cough-variant asthma is sometimes called chronic cough to describe a cough that has lasted longer than six to eight weeks. The coughing with asthma can occur during the day or at night. If you have nighttime asthma, it can interrupt sleep. People with cough-variant asthma often notice that coughing increases with exercise, called exercise-induced asthma. Coughing may increase when they are exposed to asthma triggers or allergy-causing substances like dust or strong fragrances, or when they are in cold air.
 

Who Gets Cough-Variant Asthma?

Anyone can get cough-variant asthma at any time, but it is common in young kids with childhood asthma. Cough-variant asthma may lead to the development of "classic" asthma, with symptoms that include shortness of breath and wheezing.

What Causes Cough-Variant Asthma?

Like "classic" or "typical" asthma, no one really knows what causes cough-variant asthma. However, coughing may start after people are exposed to allergens, or when they are breathing in cold air. Coughing may also follow an upper respiratory infection. For example, sinusitis with asthma is common.

In addition, a cough that begins after a person has begun taking beta-blockers is likely to be cough-variant asthma. Beta-blockers are drugs used to treat high blood pressure, heart disease, heart failure, migraines, palpitations, and other conditions. Beta-blockers are also found in eye drops to treat glaucoma and other eye problems. These eye drops can bring on asthma symptoms, including cough. Aspirin-sensitivity is another cause of coughing with asthma.

How Is Cough-Variant Asthma Diagnosed?

Cough-variant asthma is somewhat difficult to diagnose because the cough may be the only symptom, and cough itself may appear to be bronchitis or cough associated with postnasal drip.

Your health care provider will ask you questions about your medical history and will examine you and listen to you breathe. However, people with cough-variant asthma often have normal physical exams, chest X-rays, and spirometry. Spirometry involves measuring how much air you can exhale after first taking a deep breath, and how quickly you can empty your lungs. The asthma test uses a device called a spirometer to do the measuring.

A methacholine challenge test may be performed if your symptoms and spirometry test do not clearly show asthma. When inhaled, methacholine causes the airways of everyone -- even non-asthmatics -- to spasm and narrow. However, it will indicate asthma if it triggers symptoms at a low dose. During this test, you inhale increasing amounts of methacholine aerosol mist before and after spirometry. The methacholine test is considered positive -- meaning asthma is present -- if the lung function drops by at least 20%. A bronchodilator (airway-opening drug) is always given at the end of the test to reverse the effects of the methacholine.

Another way health care providers diagnose cough-variant asthma is by treating the cough with asthma medications. If the cough improves with treatment, you will be diagnosed with cough-variant asthma.

How Is Cough-Variant Asthma Treated?

Cough-variant asthma is treated in the same way that typical asthma is treated. You may be given an asthma inhaler with albuterol, ipratropium, and/or inhaled steroids (anti-inflammatory agents). You should see a gradual improvement in asthma symptoms over six to eight weeks.

http://www.webmd.com/asthma/guide/cough-variant-asthma

 

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