Spirometry

Spirometry is the most common pulmonary (lung) function test, used to measure how much air you can breathe in and out and how quickly you can exhale. During the test, you breathe into a mouthpiece connected to a device called a spirometer, which records the volume and speed of your breath as you perform specific breathing maneuvers.

The two most important measurements from spirometry are FVC (Forced Vital Capacity) — the total amount of air you can forcefully exhale after taking the deepest breath possible — and FEV1 (Forced Expiratory Volume in 1 second) — the amount of air you can forcefully exhale in the first second. The ratio of FEV1 to FVC is particularly useful for distinguishing between obstructive lung diseases (like asthma and COPD, where airways are narrowed) and restrictive lung diseases (where the lungs can't fully expand).

Spirometry is a simple, non-invasive test that takes only about 15 minutes. It's used to diagnose respiratory conditions, monitor the progression of known lung diseases, assess the effectiveness of treatment, evaluate lung function before surgery, and screen people at high risk for lung disease (such as long-term smokers).

If you've been referred for spirometry, your doctor wants to objectively measure your lung function. This test helps determine whether symptoms like shortness of breath, chronic cough, or wheezing are caused by an obstructive or restrictive lung condition, and how severe the impairment is. The results directly influence treatment decisions.

For people with asthma, regular spirometry helps track how well your condition is controlled and whether your medication regimen needs adjustment. For current or former smokers, spirometry can detect early COPD before significant symptoms develop, enabling earlier intervention.