Pulmonary Function Testing: What You Need to Know

Did you know that many people have hidden lung problems until a simple breathing test spots them? Pulmonary function testing (PFT) is the go‑to way doctors see how well your lungs move air in and out.

How the Test Works

A PFT appointment usually starts with spirometry. You’ll sit upright, clip a nose‑clip, and blow into a mouthpiece as hard and fast as you can. The machine records the volume of air you exhale and the speed of that flow. From this you get two numbers you’ll hear a lot: FEV1 (the amount you can force out in one second) and FVC (the total amount you can blow out). The ratio of FEV1 to FVC helps spot obstructive patterns like asthma or COPD.

Other parts of a PFT might measure lung volumes with a body plethysmograph or test how well oxygen passes from your lungs into the blood (diffusion capacity). These extra steps give a fuller picture if the basic spirometry shows anything odd.

Getting Ready for Your Appointment

Preparation is easy but makes a difference. Skip large meals and heavy exercise for a few hours before the test – a full stomach can compress the diaphragm and change results. If you use inhalers, ask your doctor whether to hold them for a certain period; sometimes they want you to stop short‑acting bronchodilators for four hours.

Wear loose, comfortable clothing and bring a list of all medicines, especially steroids, diuretics, or heart drugs, because they can affect lung numbers. Arrive a bit early to fill out a short health questionnaire; the more the technician knows, the cleaner the data.

During the test, keep breathing normally between forced blows. The device may ask you to inhale a deep breath and hold it for a few seconds – that’s for lung‑volume measurements. It feels a bit strange, but it only lasts a minute or two.

After the numbers are recorded, the doctor will compare them to predicted values based on your age, height, sex, and ethnicity. Lower than expected FEV1 usually points to airway narrowing, while a reduced diffusion capacity can mean problems with the tiny air sacs where gas exchange happens.

If the results are abnormal, the doctor might order repeat tests after treatment, a CT scan, or refer you to a pulmonologist. Good news: many lung issues improve quickly with medication, breathing exercises, or lifestyle changes, and PFTs help track that progress.

Remember, a PFT is just a snapshot. It tells you where you stand now, not the whole story of your lung health. Keep a record of your results if you need future appointments, and share any new symptoms like shortness of breath or chronic cough with your provider.