Spirometry is a lung function test that measures how much air you can inhale and exhale, as well as how forcefully you can breathe out. It’s a simple but important test used to diagnose and monitor lung conditions like asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. If your doctor has recommended spirometry, you might be wondering what the test involves, how to prepare, and what the results mean.
During the test, you’ll breathe into a tube connected to a device called a spirometer. The goal is to measure how well your lungs are functioning by assessing two key values: forced vital capacity (FVC) and forced expiratory volume in one second (FEV1).
FVC measures the total amount of air you can forcefully exhale after taking a deep breath, while FEV1 shows how much air you can push out in the first second of exhaling. These numbers help doctors determine whether you have a lung condition and how severe it might be.
Spirometry is an essential tool for diagnosing lung diseases, tracking their progression, and evaluating how well treatments are working. If you’ve already been diagnosed with a respiratory condition, your doctor may use spirometry periodically to check if your current treatment plan is effective. The test is also sometimes used before surgery to ensure that your lungs are strong enough to handle anesthesia and recovery.
A few simple steps can help ensure accurate results. Your doctor may ask you to avoid smoking for several hours before the test and to skip certain medications that could affect lung function.
Eating a large meal beforehand can make deep breathing more difficult, so it’s best to keep meals light. Comfortable, loose-fitting clothing is also recommended, as anything too tight around the chest or abdomen can restrict breathing.
The test itself is quick and noninvasive. You’ll be seated and may wear a nose clip to ensure that all airflow is directed through your mouth. When instructed, you’ll take a deep breath and exhale forcefully into the spirometer. This process is repeated multiple times to ensure consistent results.
In some cases, the test may be performed twice—once before and once after using a bronchodilator medication—to see if the drug improves airflow.
Spirometry is safe for most people, though it can cause temporary dizziness, coughing, or shortness of breath. These effects usually pass quickly. However, the test may not be suitable for individuals recovering from recent surgery, those with severe heart conditions, or people who have experienced a collapsed lung.
Your results will be compared to predicted values based on your age, height, gender, and ethnicity. A normal spirometry test typically shows FEV1 and FVC values that are 80% or more of the predicted range. If your numbers are lower than expected, it may indicate an obstructive or restrictive lung disease.
The specific pattern of your results helps doctors determine whether your condition is making it harder to breathe out (as seen in asthma or COPD) or expand your lungs fully (as seen in pulmonary fibrosis).
If your results are abnormal, your doctor may recommend additional tests, such as chest X-rays, CT scans, or blood work, to get a clearer picture of your lung health. If a condition is diagnosed, treatment may involve inhalers, medication, or lifestyle changes. For those with chronic lung diseases, spirometry may be repeated periodically to monitor progress and adjust treatment as needed.
Spirometry is one of several tests used to assess lung function. Depending on your symptoms, your doctor may recommend additional tests for a more complete evaluation.
A peak flow test measures how quickly you can exhale and is often used to monitor asthma. A lung volume test determines how much air your lungs can hold, which is helpful in diagnosing restrictive lung diseases.
If your doctor needs to assess how well oxygen moves from your lungs into your bloodstream, they might order a diffusion capacity test. These tests, along with spirometry, help build a clearer picture of your respiratory health.
While some lung conditions are unavoidable, there are steps you can take to maintain or even improve your lung function.
Quitting smoking is one of the most important things you can do to protect your lungs. Regular exercise—especially activities that increase heart rate and breathing—can help keep your lungs strong. Practicing breathing exercises such as diaphragmatic breathing or pursed-lip breathing can improve lung efficiency, particularly for those with conditions like COPD or asthma.
Avoiding air pollution and allergens whenever possible, staying up to date on vaccines (such as flu and pneumonia shots), and maintaining a healthy diet can also contribute to better lung function over time.
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.