Asthma can be difficult to diagnosis because its signs may mimic symptoms of other conditions, such as bronchitis, emphysema, pneumonia or other respiratory problems. A doctor can usually diagnose the disorder by looking into a patient's medical history, asking questions about symptoms and performing lung function tests that measure how much air moves in and out during breathing, the Mayo Clinic explains.
Identification
The doctor usually asks when or how often the asthma symptoms occur and if there is a family history of asthma. The patient should let the doctor know what seems to cause the asthma episodes or if the symptoms occur at certain times of the year or in certain places, according to the National Heart Lung and Blood Institute. A physical exam may be performed to check for swollen nasal passages, wheezing, allergic skin reactions or other signs of asthma.
Lung Functioning Tests
Lung functioning tests include spirometry, which examines the bronchial tubes by measuring how much air a patient can exhale after taking deep breaths. A peak flow meter may be used to measure how hard a patient can breathe out. If the peak readings are low it indicates the lungs are not working well. The patient is often given a bronchodilator, an inhaled drug that is taken before and after the tests, according to the Merck Manual Online Medical Library. If lung function improves after using the bronchodilator, asthma is suspected.
Other Tests
Doctors may use other tests, including inhaling a chemical called methacholine, which triggers asthma. A patient who reacts to the trigger most likely has asthma, according to the Mayo Clinic. Another way to diagnose asthma is through a nitric oxide test. Asthmatics have high levels of nitric oxide in their breath. According to the National Heart Lung and Blood Institute, chest x-rays may be performed to rule out any other disease and additional tests are sometimes done to see if the patient suffers from another disease with similar symptoms such as reflux disease, vocal cord dysfunction or sleep apnea.
Expert Insight
After detailed questioning and testing, the doctor usually determines the severity of the asthma using one of several classifications, the Mayo Clinic notes. Mild intermittent asthma means mild symptoms for up to two days a week or two nights a month. Symptoms that develop more than twice a week, but no more than once a day are classified as mild persistent asthma. Moderate persistent asthma includes symptoms that occur once a day and more than one night a week, while severe persistent asthma occurs throughout the day on most days and at night.
Prevention/Solution
Following the diagnosis, the doctor and patient discuss proper treatment. Asthma can be treated with medication. Patients can use inhalers when asthma attacks strike and cause difficulty when breathing. Patients also learn to avoid allergens that trigger asthmatic episodes.
