How to Read Pulmonary Function Test Results

A pulmonary function test, or a spirometry test, is used to evaluate your lungs' airflow and capacity. During the test, you breathe into a device called a spirometer in a variety of ways, including both forced and rapid breathing. The spirometer records the rate and amount of air you breathe. Spirometry tests are used to diagnose lung disease, assess response to medication, and measure how contaminant exposure may affect lung function. Results are compared to a series of predicted values based on your age, gender, height, weight and ethnicity, and are expressed as a percentage of those values.

Instructions

• 1

  Review your test for your forced vital capacity, or FVC, results. FVC is a measurement of the volume that can be forcefully exhaled after maximum inhalation. A normal FVC reading is generally 85 percent of the predicted value. A smaller FVC can be indicative of an obstructive disease, which causes a smaller amount of air to be expended over time. It also may indicate a restrictive lung disease, which limits the volume of air that can be exhaled.

• 2

  Review your test for your FEV1 result. FEV1 stands for "forced expiratory volume in one second." It measures the volume of the air that can be forcibly exhaled in the first second of a full, forcible exhale. FEV1 is measured in liters. A normal FEV1 reading is generally 85 percent of the predicted value. A low FEV1 is often indicative of obstructive diseases such as asthma or emphysema.

• 3

  Review your test for your FVC/FEV1 ratio result. This reading is used to distinguish between obstructive and restrictive lung diseases. Low FVC alone is indicative of obstructive disease, whereas the combination of a low FVC and low FEV1 is indicative of a restrictive disease.