Your doctor will evaluate suspected asthma by following a sequential course of action including a detailed medical history, physical examination and a lung function test. Other laboratory tests, such as chest X-rays, blood and urine tests and sputum analysis, are sometimes also used.
Two of the most common devices for testing lung function are the spirometer and the peak flow meter. The spirometer is a non-portable device, mainly used in hospitals and specialists' consulting rooms, which measures breathing capacity and the degree of bronchial narrowing. Peak flow meters are small, portable, inexpensive devices which are designed to be accurate instruments in assessing lung function. Most doctors have them, and all asthmatics are encouraged to keep one at home to monitor lung capacity on a daily basis. (The peak flow meter is described in Chapter Four.) The bronchial provocation test is yet another method of diagnosing asthma. This test requires a susceptible person to inhale chemicals or allergens that are known to trigger asthma attacks.