Pulmonary Function Tests (PFTs) assess lung health by measuring how effectively air moves in and out of the lungs. These non-invasive tests help healthcare providers understand lung capacity, airflow rates, and gas exchange efficiency. PFTs assist in identifying potential issues and guiding medical management.
Understanding PFTs
Pulmonary function tests measure several aspects of lung performance. They assess how much air your lungs can hold, how quickly you move air, and how well oxygen transfers into your bloodstream. Spirometry, for example, measures air volume and flow rate, aiding in diagnosing conditions like asthma or chronic obstructive pulmonary disease (COPD).
Doctors order PFTs to diagnose lung conditions, monitor respiratory diseases, or evaluate lung function before surgical procedures. These tests can help pinpoint the cause of symptoms such as shortness of breath or persistent coughing. They also assess the effectiveness of ongoing treatments for lung disorders.
Preparing for Your Test
Preparation for a pulmonary function test is important for accurate results. Your healthcare provider will provide specific instructions. Following these guidelines helps avoid factors that could interfere with test outcomes.
Preparatory steps include avoiding certain medications, such as bronchodilators, for a specified period before the test. It is also recommended to refrain from smoking, caffeine, or heavy meals for at least four hours prior. Wearing loose, comfortable clothing can help ensure unrestricted breathing.
The Testing Procedures
Pulmonary function tests involve several distinct procedures, each designed to measure different facets of lung function. A technologist will guide you through each step, providing clear instructions. The entire process is non-invasive and safe, though you might experience some lightheadedness or coughing due to the forced breathing maneuvers.
Spirometry
Spirometry measures how much air you can inhale and exhale, along with the speed of exhalation. During this test, you will wear nose clips and seal your mouth around a disposable mouthpiece connected to a spirometer. The technologist will instruct you to take a deep breath and exhale as forcefully and quickly as possible until your lungs are empty. Multiple attempts are often required for consistent and accurate readings.
Measuring Lung Volumes
Measuring lung volumes determines the total amount of air your lungs can hold. One common technique, body plethysmography, involves sitting in a small, airtight booth. Inside the booth, with nose clips on and your mouth around a mouthpiece, you will perform specific breathing maneuvers. Changes in air pressure within the sealed chamber help calculate your lung volumes, including residual volume (air remaining after maximal exhalation) and total lung capacity (maximum air your lungs can hold). Another method involves breathing a special gas mixture through a tube for a short period.
Diffusion Capacity Test
The diffusion capacity test (DLCO) assesses how effectively gases, such as oxygen, transfer from your lungs into your bloodstream. For this test, you will wear nose clips and seal your lips around a mouthpiece. You will be asked to inhale a small amount of a tracer gas, hold your breath for approximately 10 seconds, and then exhale. The machine analyzes the exhaled air to determine how much tracer gas was absorbed, providing an indication of gas exchange efficiency.
Interpreting Your Results
After completing the pulmonary function tests, the collected data is analyzed by a healthcare professional. This analysis involves comparing your measurements to predicted normal values, established based on your age, height, gender, and ethnicity.
The results help your doctor diagnose specific lung conditions, assess the severity of any identified issues, or monitor treatment effectiveness. For instance, certain patterns in the test results can indicate obstructive lung diseases, like asthma, or restrictive lung diseases that limit lung expansion. Your healthcare provider will discuss the findings, explaining what they mean for your lung health and any recommended next steps.