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What Tests Can Be Done to Assess My Breathing?

Several tests can be done to find out if your health problem is related to your lungs. Each test serves a different purpose. Sometimes, only one type of test is needed. Other times, several tests might be needed to find out the source of your problem. These tests measure how much air you move in and out of your lungs, how successful your lungs are at getting oxygen into your blood stream or if there are problems in your lungs that can be seen on pictures of your lungs. Most tests require breathing through a mouthpiece and do not require needles for blood to be drawn. Tests are often repeated two to three times on the same visit to get the best test results. The most common problems people experience with these tests are light-headedness, dizziness or tiredness from the breathing maneuvers. You must not take certain medications or smoke before some of the tests. When you find out you will be having these tests, be sure to ask about any special instructions.

What are arterial blood gases (ABGs)?

Arterial blood gases (ABGs) evaluate several things in your blood. The ABG is the most precise and direct way of telling us how well your lungs are bringing oxygen into the blood and how well your lungs are getting rid of carbon dioxide. Unlike many blood tests that require a needle be placed into your vein, an ABG requires the needle to enter an artery. A needle placed into the artery can be more painful than a needle entering your vein because the arteries usually lie between muscles. To help make the needle stick less painful, the person doing the test may numb (or anesthetize) the area where the needle will enter the skin.

What are body body-box (plethysmography) (lung volume) studies?

Body plethysmography is a test to measure not only the amount of air you breathe out of your lungs with each breath, but also to measure how much air is left in your lungs after a complete exhalation. No matter how hard we try, we can never exhale all of the air from our lungs. With COPD, the amount of air left in our lungs may be more than normal. Measuring the amount of air remaining in the lungs gives your healthcare provider information about the severity of your COPD and helps guide them in your treatment.

During the test, you sit in a large, see-through box. You will be asked to breathe through a mouthpiece while breathing normally. You will then be asked to take a deep breath, then exhale out as much air as possible. Before or after the deep breath, you will be asked to take short, shallow breaths.

Are there special instructions I need to follow before the test?
If you are on oxygen, you will usually be asked to be off oxygen, but your oxygen level will be monitored during the test.

What are chest X-rays?

Chest x-rays are a way of taking a picture of your lungs. Chest x-rays (also called chest films) are a standard test for evaluating COPD. These x-rays not only show the lungs, but the heart and several major blood vessels in the chest. Chest x-rays are useful if other conditions, such as pneumonia or lung tumors, are suspected. A chest x-ray, however, can also appear normal in patients with milder forms of lung disease or with very small tumors. It is therefore not a precise test.

There is no discomfort with chest x-rays for those who can stand for a brief period of time. The risk of radiation from a chest x-ray is small. The amount of radiation you are exposed to during a chest x-ray is equal to a normal day’s exposure to the sun.

Can a chest x-ray diagnose COPD?
No, a chest x-ray can provide some guidance to your provider that you have COPD, but it is not used to diagnose COPD.

What are diffusion studies?

Diffusion tests (abbreviated DL,CO or TL,CO) determine how well your lungs take in air and move the oxygen contained in this air into the bloodstream. Therefore, this test measures how well gases in the air enter the lungs, move into the alveoli and then into the blood stream surrounding these air sacs.

The diffusion test requires precise measurements and is it done by breathing in and out through a mouthpiece connected to a machine. You will be asked to empty your lungs by blowing out. Then you will take a deep breath of a gas mixture and hold your breath for 10 seconds. Then you will be asked to breathe out.

Are there special instructions I need to follow before the test?
If you smoke, or are exposed to smoke in your home or work, it is important not to smoke and/or stay away from smoke exposure for 4 hours before this test.

What is a computed tomography (CT) scan of the lung?

Computed tomography (CT) scans are specialized pictures of the lungs. While a chest x-ray takes one or two large pictures of the lungs, the CT scan takes many small pictures. A CT scan can find out if air sacs are enlarged, as commonly seen in emphysema. CT scans can also find small tumors, which may not be seen on chest x-ray.

Unlike a chest x-ray, a CT scan is not routinely ordered, because the additional detail it provides compared to a chest x-ray is only occasionally needed. A CT scan also exposes you to more radiation than a chest x-ray and is more expensive.

CT scans of the chest are done by having you lie down on a table while a large cylinder passes over your chest. Your head will not be covered in the device, but some devices will cover you from your neck to your legs. Multiple pictures (20-30 pictures, called "slices") are taken during the 5-20 minutes of the test. Sometimes, an iodine dye may be injected into the vein in your arm. This dye allows the radiologist to evaluate the lungs differently from a test without the dye. Your healthcare provider will decide which of these two types of tests you should have. People allergic to iodine (or shellfish) or with kidney disease should discuss this with their healthcare provider or radiologist before having this test done.

Currently, "whole body" scans are being offered in the community to anyone willing to pay the cost. Before whole body scans became available, these scans were only done on people with a suspected abnormality and only on areas believed to be at risk. Never before were they done on so many "normal" people. As a result, many non-serious abnormalities are being found, such as small scars not requiring treatment. In most cases, it is not possible to determine whether a non-serious finding is present with one scan. This means that a whole body scan may lead to numerous additional scans to be certain that a serious abnormality is not present. It is not known whether the risk of added radiation exposure and additional tests (for example biopsies) resulting from these findings on CT are of value, given the few serious abnormalities that are found.

What is a pulmonary function test (PFT)?

Several tests can be done to find out if your health problem is related to your lungs. Each test serves a different purpose. Sometimes, only one type of test is needed. Other times, several tests might be needed to find out the source of your problem. These tests measure how much air you move in and out of your lungs, how successful your lungs are at getting oxygen into your blood stream or if there are problems in your lungs that can be seen on pictures of your lungs. Most tests require breathing through a mouthpiece and do not require needles for blood to be drawn. Tests are often repeated two to three times on the same visit to get the best test results. The most common problems people experience with these tests are light-headedness, dizziness or tiredness from the breathing maneuvers. You must not take certain medications or smoke before some of the tests. When you find out you will be having these tests, be sure to ask about any special instructions Pulmonary function tests (PFTs) are breathing tests to find out how your lungs function compared to people like yourself with normal lungs. Test scores vary depending upon a person’s age, whether they are male or female, or short or tall. Spirometry, diffusion studies and body plethysmography may all be done as part of complete pulmonary functions testing or may each be done alone to find out detailed information about a specific breathing function.

What is an exercise test?

An exercise test is done in a laboratory, either by having you walk on a treadmill or pedaling a bicycle. As you exercise, you will usually be asked to breathe through a mouthpiece connected to a machine. This machine measures how much effort (energy expenditure) it takes you to exercise. You will be asked to exercise at faster and faster speeds while working against greater and greater resistance. On a bicycle, this means you will have a harder time pedaling. With a treadmill, the angle of the treadmill is made steeper, making it feel like you are walking uphill. The amount of exercise you will be asked to do will depend on how physically fit you are. To best understand your problem, it is important that you exercise as much as you possibly can. Frequently, you will also be connected to a heart and an oxygen monitor. Oxygen levels may be monitored for the entire test by a tube placed into your artery (called an arterial line). The heart monitor will measure the performance of your heart during strenuous exercise.

Exercise tests are done to stress your heart and lungs. Therefore, one of the after effects of the test should be breathlessness and tiredness. People with COPD having this test sometimes limit their performance during the exercise because of fears of developing breathlessness. This test is the perfect time to exercise as much as you possibly can in a safe, supervised setting.

What is oximetry testing?

Oximetry testing is a way of indirectly measuring oxygen levels in your blood. The test is done by placing a small strap around your finger or a clip on your ear. This test is not painful or dangerous since it measures oxygen with light rays. The oximeter test is done to find out how much of the oxygen (called oxygen saturation, abbreviated Sa,CO2) in your body is in red blood cells. Unfortunately, oximetry machines can be unreliable. They may not read accurately depending on your skin color, if you have a low blood count, have poor circulation or if the device is not properly maintained. Therefore, when trying to make an important decision about how much oxygen is in your blood and whether to give you supplemental oxygen, an ABG is the preferred test.

What is spirometry?

Spirometry is the most commonly ordered test for people with suspected breathing problems and is the test usually performed to find out if a person has COPD. The results, by themselves, may not totally explain your breathing problem, but are evaluated along with your history of health problems and other test results.

This test is done by having you breathe into a tube connected to a machine. This machine measures the amount of air you move in and out of your lungs and how well the air moves. You will be asked to perform a series of breathing maneuvers. Commonly, this includes breathing in and out normally, then exhaling all the air out that you possibly can, followed by inhaling as much as possible, then blowing out as hard and fast as you can.

Are there special instructions I need to follow before the test?
You will often be asked not to use your inhaled bronchodilators, such as albuterol/salbutamol or metoproteronol/terbutaline, and possibly to stop other medications for a specific amount of time before the test is done. Taking medications such as these affect the test results and may require you to repeat the test at another time. Always ask if there are any special instructions to be followed before taking the test.


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