Asthma is a respiratory disease that causes the airways to swell and become narrow. It can begin in childhood and lasts a lifetime. The National Institutes of Health lists multiple asthma triggers including animal hair and dander, certain medications, weather changes, airborne chemicals, chemicals in food, dust, exercise and mold. Symptoms of asthma include trouble breathing, rapid breathing, shortness of breath even with minimal exertion, chest tightening and coughing.
Poor Lung Function
A lung function test is just one of the several ways a doctor can diagnose asthma. Simply listening to the lungs with a stethoscope is insufficient because the airways tend to sound normal between asthma episodes, indicates the National Institutes of Health. Spirometry is a type of lung function test that measures the narrowing of the bronchial tubes. It looks at how much air an individual can exhale after a deep breath, as well as how fast the person can breathe out, according to MayoClinic.com. An individual performing poorly on the lung function test will be administered a bronchodilator, an inhaled medicine that stimulates the airways to reopen. The spirometry test will then be repeated. If the individual performs better after the medication, it is likely that the doctor will make a diagnosis of asthma.
Peak Flow
Peak flow meters can used at home to help an asthmatic identify subtle changes in the flow of air through the bronchial tubes. Lower readings can indicate asthma is about to flare up. the Mayo Clinic points out that a medical professional can assist an individual in learning her own base levels of air flow. Following a poor flow reading, an individual will be administered a bronchodilator. The test will then be repeated. If the individual performs better on the peak flow meter after the medication, it is likely that the doctor will make a diagnosis of asthma.
Bronchial Challenge
Methacholine is a known asthma trigger. The Mayo Clinic reports that the drug will be given to a patient to inhale. The doctor will observe the patient for symptoms of asthma. Typically, this test is performed when the lung function or peak flow tests were normal.
