If you've ever hiked a trail above 7,000 feet and found yourself more winded than usual, or watched a visiting family member struggle to catch their breath the first few days of their trip, you've experienced something your lungs and blood are working hard to manage: ALTITUDE.

At White Mountain Regional Medical Center, our cardiopulmonary team helps patients understand exactly what's happening inside their chest when breathing feels harder than it should, and what a simple test can reveal about it.

What Is a Pulmonary Function Test?

A Pulmonary Function Test, or PFT, is a painless breathing test that measures how well your lungs are working. It's one of the most useful tools we have for understanding shortness of breath, diagnosing conditions like asthma or COPD, and tracking how well a treatment is working over time.

A PFT looks at three main things: how much air you can move, how much air your lungs can hold, and how well oxygen actually gets from your lungs into your bloodstream. Each of these tells a different part of the story.

Airflow: Picture Your Lungs Like a Bunch of Grapes

To understand airflow, it helps to picture your lungs like a bunch of grapes on the vine. The thick stem is your windpipe and the larger airways, branching again and again into smaller and smaller stems, those are your bronchioles. At the very end of each tiny stem are the grapes themselves: your alveoli, the tiny air sacs where oxygen and carbon dioxide actually trade places with your blood.

Healthy alveoli are like healthy grapes, plump, flexible, and able to expand and contract easily. But two things can go wrong. Some alveoli can become overly stretched out and lose their elasticity, meaning they get stuck in an expanded position and can't push air back out effectively. Others can become stiff and shrunken, losing surface area, which means there's less room for oxygen and carbon dioxide to exchange at all. Conditions like asthma add another wrinkle by tightening the muscles around the airways themselves, narrowing the path air has to travel.

When any of this happens, the amount of air you can move in and out, what's measured as your airflow goes down, and that shows up clearly on a PFT.

Lung Volume: How Much Room Do You Have?

The second measurement is lung volume, simply, how much air your lungs are able to hold. Your results are compared to a "predicted" value calculated from factors like your age, height, weight, and sex, which gives your care team a personalized benchmark rather than a one-size-fits-all number.

You may also notice your results reference broader population data used to build these predicted values. This is an area of ongoing conversation in medicine, and pulmonary specialists continue to refine how these comparisons are calculated to make sure every patient gets the most accurate, individualized picture of their own lung health.

Diffusion: The "Life Rafts" That Carry Your Oxygen

The third measurement, called diffusion capacity, looks at something even more specific: how well oxygen actually crosses from your alveoli into your bloodstream, and how well carbon dioxide crosses back the other way.

Here's a helpful way to picture it. Think of your red blood cells' hemoglobin, the protein that carries oxygen, as a fleet of life rafts. Their job is to pick up oxygen at the lungs and ferry it out to your muscles and organs. If you don't have enough hemoglobin, you don't have enough life rafts, and oxygen can't get where it needs to go efficiently, even if your lungs themselves are working perfectly fine. That's why this test is often paired with a simple blood test that measures hemoglobin levels, it helps your care team understand whether a breathing problem is really about the lungs, the blood, or both.

Why This Matters So Much for Life in the White Mountains

Here's where this becomes especially relevant to our community. We live at high elevation, and the air up here simply has less oxygen available in every breath compared to lower elevations like the Valley. Your body can absolutely adapt to this. For most people, the body begins building additional hemoglobin, additional "life rafts," within days of arriving at elevation, with a meaningful increase typically in place within one to two weeks.

Think of it like a water park ride designed to carry six people per raft. Down at a lower elevation, every raft heading out is full, six riders, six seats, no wasted capacity. Move up to our altitude, and suddenly your line of "riders" (oxygen molecules) gets shorter, but you're still sending out the same number of rafts. Some go out half-empty. Your body's answer is to build more rafts, more hemoglobin, so it can still deliver enough oxygen with fewer available molecules per trip.

This is exactly why visitors and seasonal residents, whether they're here to snowboard, hike, or just visit family, sometimes feel unusually tired, short of breath, or "off" during their first week or two at elevation, even if they're perfectly healthy. It's also part of why climbers preparing for extreme peaks like Mount Everest ascend in stages, resting at progressively higher camps along the way so their bodies have time to build the red blood cells they'll need higher up.

If you or a visiting loved one are dealing with shortness of breath that doesn't seem to be improving, or if you've noticed breathing that feels harder than it used to, that's worth a conversation with your provider. A pulmonary function test is a quick, straightforward way to see exactly what's going on, whether it's your airways, your lung volume, your blood's oxygen-carrying capacity, or simply your body still adjusting to life at elevation.

Getting Tested

WMRMC's cardiopulmonary team performs pulmonary function testing right here in Springerville, so you don't need to travel to get answers about your breathing. If shortness of breath, a nagging cough, or unexplained fatigue has you wondering what your lungs are trying to tell you, talk with your primary care provider about whether a PFT is right for you.