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Spirometry is a type of diagnostic test that may be performed to check lung function. The test determines the amount of air that an individual can take in and exhale out of the lungs, and the rate at which one can expel the air out of the lungs. A spirometry test could help detect asthma, chronic obstructive pulmonary disease, and other disorders that can cause breathing difficulties. If the test results show lower than average values it might indicate a problem with functioning of the lungs. The procedure is relatively quick, doesn’t cause pain, and may be done in a doctor’s office or at a hospital.
Typically, during a spirometry test the patient is instructed to breathe in fully to take in maximum air possible and exhale with force for six seconds into a tube like device which is linked to a spirometer. The spirometer is a machine that records the results. Generally, test readings are taken three times. Sometimes, the doctor may give the patient a bronchodilator, a medication that opens the airways of the lungs and facilitates passage of air. The test is then repeated and measurements taken before and after being given the bronchodilator are contrasted.
The measurements provided by a spirometry test include forced vital capacity (FVC) and forced expiratory volume in one second (FEV-1). FVC indicates the volume of air exhaled forcefully after maximum inhalation, and FEV-1 refers to the amount of air forced out in the first second. From the FEV and FVC measurements the doctor calculates the percentage and the results are compared with values of people of similar height, gender, ethnicity, and age group. Usually, the test results are also presented as a flow volume loop, which is a graph that plots the airflow rate and the volume. The shape of the flow volume loop may also assist in determining the type of respiratory disorder.
With a spirometry test a doctor can ascertain if there is an impairment of the airway that’s affecting the patient’s breathing. It could also assist in determining if medication can potentially help the patient breathe better. Besides being useful in asthma diagnosis, spirometry testing may aid in detection of chronic obstructive pulmonary diseases such as emphysema and indicate the stage of the disease. People being treated for chronic lung disorders are often advised to get a spirometry test done at intervals of one to two years. This enables the doctor monitor response to the prescribed medications, and change or improvement in symptoms experienced.
It is advisable to take certain precautions prior to a spirometry test. These include wearing clothes that fit comfortably, avoiding exposure to asthma triggers, and not eating a heavy meal before the test. The doctor may indicate if one needs to discontinue any medication for a period of time before undergoing the test. Precision of results depends on how well the patient carries out the instructions of the nurse or technician administering the test so one needs to be careful about following the test procedure.