Body Plethysmography: A Clear Look At Your Lungs

It’s a feeling many of my patients describe – that frustrating catch in your breath, like you just can’t get enough air. Or maybe it’s a cough that’s overstayed its welcome, making you wonder what’s really happening inside your chest. When these worries crop up, we need to get a good, honest look at how your lungs are working. That’s where a special test called body plethysmography comes in. It sounds a bit complicated, I know, but it’s actually a straightforward way for us to learn a lot about your lung health.

Table of Contents

So, What Exactly is Body Plethysmography?

Think of body plethysmography (pleh-thiz-MOG-ruh-fee – quite a mouthful, right?) as a detailed check-up for your lungs. It’s a type of pulmonary function test, or PFT, and the great thing is, it’s noninvasive. That means no needles or anything going inside you.

This test helps us understand two key things:

How much air your lungs can hold when you take your deepest possible breath in.
How much air is left in your lungs after you breathe out as much as you can.

It might sound simple, but these measurements give us incredibly valuable information. It’s safe, pretty comfortable, and helps us create the best plan for you. You might also hear it called lung plethysmography or pulmonary plethysmography.

Why Might We Suggest a Body Plethysmography Test?

I often recommend this test if you’re experiencing symptoms that point to a possible lung or airway issue. We’re trying to get to the bottom of things. This test can help us:

Diagnose conditions: Such as asthma, chronic obstructive pulmonary disease (COPD), or pulmonary fibrosis (a condition where lung tissue becomes scarred).
See how you’re doing: We can compare your lung function to what’s typical for someone your age, height, and so on. We can also track changes if you’ve had previous tests.
Monitor chronic lung diseases: If you have a long-term lung condition, this test shows us how it’s affecting your breathing over time.
Catch problems early: Sometimes, subtle changes in lung function can show up on this test before you even notice major symptoms, allowing us to adjust your treatment if needed.
Check for environmental impact: If we suspect something at home or work might be affecting your lungs.
Assess fitness for procedures: It can help us understand if your lungs are up to certain medical treatments or surgery.

Signs That Might Lead to This Test

If you’ve been dealing with any of these, it might be a reason we’d consider body plethysmography:

A feeling of tightness, pain, or pressure in your chest.
A persistent cough, especially if you’re bringing up mucus.
Trouble taking a really deep breath.
Shortness of breath (what we call dyspnea).
A wheezing sound when you breathe.

If the test results are abnormal, it helps confirm that something might be limiting how much air your lungs can effectively hold.

Getting Ready for Your Test: A Few Simple Steps

To make sure we get the most accurate results from your body plethysmography, there are a few things to keep in mind:

Feeling unwell? If you’ve got a cold, the flu, or any other respiratory bug that could be contagious, it’s best to reschedule.
Medications: Let us know about everything you’re taking. We might ask you to pause certain medications just for the day of the test.
On the day:
Try not to smoke for at least an hour beforehand.
Avoid alcohol for at least four hours prior.
No heavy exercise for about 30 minutes before.
Wear loose, comfy clothes. You want to be able to breathe easily, and tight clothing around your chest or tummy can actually skew the results.
Don’t eat a big meal for at least two hours before your test.

These little things really do help!

What Happens During the Body Plethysmography Test?

Alright, let’s talk about the test itself. You’ll be sitting inside a clear, airtight booth – it kind of looks like a small phone booth. Now, if tight spaces make you uneasy (claustrophobia is pretty common!), please tell us. We can sometimes offer medication to help you relax. And remember, you can see out, we can see you, and we’ll be talking you through it. If you need a breather, literally, just let the technician know.

Here’s the rundown:

A friendly respiratory therapist will usually conduct the test. They’re experts in this.
They’ll place soft clips on your nose. This is just to make sure all your breathing happens through your mouth.
You’ll breathe into a special mouthpiece. The therapist will guide you on how to breathe – sometimes quick pants, sometimes deep breaths.
Once you’re settled, the door to the booth will be sealed.

As you breathe, your chest moves, and this changes the air pressure inside the sealed booth ever so slightly. Sensors pick up these tiny changes. The mouthpiece also has sensors measuring airflow and pressure. It’s all quite clever, really! The whole thing usually takes about 15 minutes.

If you normally use supplemental oxygen, you won’t use it during the test.

Will It Hurt?

This is a question I get a lot! The good news is, no, body plethysmography isn’t painful.

You might feel a bit dizzy, lightheaded, or even a little tired from the breathing maneuvers. Sometimes, blowing into the mouthpiece can make you cough. These feelings usually pass very quickly once the test is done. And again, if you need a moment, just say so.

Very rarely, if the test takes a long time, there could be a risk of too much carbon dioxide or too little oxygen in your blood, but this is uncommon. The test can also temporarily speed up your heart rate, so if you have any heart conditions, like a previous heart attack, be sure to let us know beforehand.

What We Learn: The Nitty-Gritty

This test measures a few important volumes:

Total Lung Capacity (TLC): This is the maximum amount of air your lungs can hold after you’ve taken the biggest breath possible.
Functional Residual Capacity (FRC): This is the air left in your lungs after a normal, relaxed exhale.
Residual Capacity (RC) or Residual Volume (RV): This is the air that still remains in your lungs even after you’ve blown out as much air as you possibly can.

How does it do this? The science is based on something called Boyle’s Law, which relates gas pressure and volume. It’s pretty neat, but you don’t need to worry about the physics! A pulmonologist, a doctor specializing in lung conditions, will review your results.

After the Test

Once you’re done, you can usually get right back to your day. If you felt a bit off during the test, we’ll make sure you’re feeling okay before you head off.

Understanding Your Body Plethysmography Results

What’s “normal” for a body plethysmography test isn’t a one-size-fits-all number. It depends on several things like your age, height, sex, race, and whether you smoke. We use all this to figure out what a typical reading would be for you. So, your “normal” might be different from someone else’s.

You should hear from us with your results within a few days. If you haven’t heard back, please do give us a call. If the test helps us diagnose a chronic lung issue, we might recommend regular lung function tests, perhaps yearly, to keep an eye on things.

You Might Have Heard of Spirometry…

Spirometry is another common lung function test, and it’s very useful. However, body plethysmography gives us a more complete picture. Spirometry can’t measure that residual volume (the air left after a full exhale) or your total lung capacity as accurately. Body plethysmography can also measure things like airway resistance (how easily air flows through your airways) and the intrathoracic gas volume (the total volume of gas in your chest). It just gives us a bit more detail when we need it.

Take-Home Message: Key Things to Remember About Body Plethysmography

Here’s a quick recap of what’s important to know:

Body plethysmography is a safe, non-invasive test to measure how much air your lungs can hold and how much remains after you exhale.
It helps diagnose and monitor lung conditions like asthma, COPD, and pulmonary fibrosis.
Preparation is simple: wear loose clothes, avoid smoking/alcohol/heavy exercise/large meals right before.
The test involves breathing into a mouthpiece while sitting in a clear, airtight booth for about 15 minutes. It’s not painful.
Results are compared to what’s typical for your profile and help us understand your lung health better.

Body Plethysmography: A Clear Look at Your Lungs