A Pulmonary Function Test (PFT) is a non-invasive group of breathing tests that measures how well your lungs are working, including how much air they can hold and how effectively they transfer oxygen into the bloodstream. A typical, comprehensive PFT appointment generally lasts between 45 and 90 minutes, though the overall time can fluctuate depending on the specific tests ordered by your physician. This diagnostic procedure provides objective data about your lung capacity, airflow, and gas exchange, which is used to diagnose and monitor conditions like asthma and chronic obstructive pulmonary disease (COPD).
Core Testing Procedures and Individual Durations
The actual time spent performing the breathing maneuvers typically involves a series of three primary tests. Spirometry, the most common test, measures the volume and speed of air you can inhale and exhale, and usually requires about 10 to 15 minutes to complete. During this test, you are coached to take a deep breath and then forcefully exhale as quickly and completely as possible into a mouthpiece connected to a spirometer.
The second major component is the Lung Volumes test, often performed using body plethysmography, where you sit inside a small booth. This method accurately measures the total amount of air in your lungs, including the residual volume that cannot be exhaled. The setup and execution of this test generally add another 15 to 20 minutes to the total testing time.
The final core test is the Diffusion Capacity of the Lung for Carbon Monoxide (DLCO), which assesses how efficiently oxygen moves from the air sacs into your blood. This test requires you to take a quick, deep breath of a tracer gas mixture and hold it for about ten seconds before exhaling. The DLCO procedure typically takes 10 to 15 minutes. Technicians require at least three consistent and high-quality efforts for each test to ensure the results are accurate and repeatable.
Pre-Test Requirements That Add Time
Essential preparation steps occur before the physical breathing tests begin. Patient intake and registration involve confirming your identity, verifying the physician’s orders, and completing necessary paperwork. This initial administrative process requires a few minutes.
A respiratory therapist then reviews your medical history and provides detailed instructions on the specific breathing maneuvers. They ensure you understand the required forceful and sustained efforts needed for accurate data collection. The technician also reviews compliance with pre-test medication restrictions, as certain bronchodilators must be withheld for hours or even days before the appointment to obtain a true baseline reading.
A short rest period is incorporated before the baseline testing begins to ensure your breathing and heart rate are normalized. Physical activity, large meals, or smoking immediately before the appointment can temporarily alter lung function. This preparation time ensures the test results accurately reflect your resting lung function.
Factors That Extend or Shorten the Appointment
The largest factor that can extend a PFT appointment is the inclusion of a post-bronchodilator challenge, often called a reversibility test. This requires repeating the spirometry test after administering a short-acting bronchodilator medication, like albuterol. The technician must wait approximately 15 to 20 minutes for the medication to take full effect before the second set of maneuvers can be performed. This waiting period can increase the total appointment duration by a half-hour.
Patient cooperation and effort also play a substantial role in the overall time. If a patient is unable to perform the required forceful or sustained breathing maneuvers correctly, the technician must repeat the attempts until satisfactory data is collected. Logistical factors can also influence the duration, such as equipment availability or technician scheduling. If testing reveals a significant abnormality, the technician may require a brief consultation with the ordering physician, further extending the time.