Pulmonary Function Tests

Pulmonary function tests are tests performed to make measurements of how your lungs and airways function. Results from pulmonary function tests enable your physician to evaluate your breathing, make diagnosis, recommend treatment and follow your progress. Pulmonary testing is also used in many research studies. We believe it is helpful for you to know what to expect during the tests and have included brief descriptions. During the testing you will be given instructions and encouraged to give your best effort. Please feel free to ask questions during your test.

Complete Pulmonary Function Test
Spirometry 
DLCO – Lung Diffusion Capacity Testing 
Pressure Volume Curve 
Forced Oscillation/Impulse Oscillimetry (IOS) 
Helium Dilution – Functional Residual Capacity (FRC) 
Muscle Strength – Maximum Inspiratory Pressures/ Maximum Expiratory Pressures  

Patient ready to be tested in the Body Plethysmography – Booth in which lung volumes are measured.

Complete Pulmonary Function Test

This test allows us to measure much more information about how your lungs are functioning. It is performed in a clear plexiglas booth. A technologist will instruct you on how to perform the test and coach and encourage you to do your best.

Performing the test

1. You will be seated in the booth with your mouth on the mouthpiece and noseclips on your nose
2. You will breathe normally and then a shutter will close. The shutter is closed for a second while you continue to breathe normally against the shutter
3. The shutter opens and after breathing normally you will be asked to slowly blow out until your lungs are empty
4. Then you will take a big deep breath in filling up your lungs completely
5. As soon as your lungs are full, you will blow out as hard and as fast as you can until you are absolutely empty
6. You will then take a breath in and come off of the mouthpiece
7. The door will be opened until you are ready to do another effort
8. You will be asked to repeat the test until there are three good efforts, which are reproducible

 

Technologist encouraging patient to give maximum effort.

This test allows us to measure:

• Lung volumes - Thoracic Gas Volume (TGV) / Functional Residual Capacity (FRC)
• Total lung capacity (TLC)
• Expiratory reserve volume (ERV)
• Inspiratory capacity (IC)
• Inspiratory reserve volume (IRV)
• Residual volume (RV)
• Airways resistance (Raw/Sgaw)
• Spirometry at absolute lung volumes (FVC, FEV1 and PEFR)

This chart shows the measurements made during the test.

How should you prepare for a routine pulmonary function test ?

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Spirometry testing shows how much air you can move in and out of your lungs and how fast you can move the air.

Spirometry

Spirometry is a simple test to measure how much (volume) and how fast (flow) you can move air into and out of your lungs. A technologist will instruct you on how to perform the test and coach and encourage you to do your best. A good effort during the test is important to get good results.

Performing the test

1. You will be asked to place a mouthpiece attached to the spirometer in your mouth. It is important to make a tight seal with your lips so all of the air will go into the spirometer to be measured. You will also wear noseclips to keep air from leaking out of your nose
2. After breathing normally you will be asked to slowly blow out until your lungs are empty
3. Then you will take a big deep breath in filling up your lungs completely
4. As soon as your lungs are full, you will blow out as hard and as fast as you can until you are absolutely empty.
5. You will be asked to repeat the test until there are three good efforts

This test allows us to measure your:

• Forced Vital Capacity (FVC) the amount of air you can force out of your lungs after a maximum inspiration
• Forced Expiratory Volume in the first second (FEV1)
• Peak Expiratory Flow Rate (PEFR) how fast you can blow out the air in your lungs
• Forced Inspiratory Vital Capacity (FIVC) the amount of air you can take into your lungs
• The shape of your Flow Volume Loop (FVC + FIVC) also provides information to you physician

Spirometry may be done alone or combined with other tests. For example, you may be asked to withhold taking some medications and then do the spirometry. You would then be given your medicine and asked to repeat doing the spirometry. Spirometry may also be done before and after exercise or during bronchial challenge testing.

How should you prepare for a spirometry test ?

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DLCO – Lung Diffusion Capacity Testing

This test measures how well gases (oxygen) move through the lung and into the bloodstream. A technologist will instruct you on how to perform the test and coach and encourage you to do your best.

Performing the test

1. You will be on a mouthpiece wearing noseclips. It is important to keep a tight seal on the mouthpiece. You will breathe normally
2. You will then be asked to blow out all your air until you are empty
3. You will then be told to take a big deep breath and fill up completely
4. You will hold your breath for a very short time
5. Then you will be asked to blow it out
6. We will analyze the gas you blow out to see how much went through your lungs into your bloodstream

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Pressure Volume Curve

This test allows us to measure the elasticity or stiffness and compliance of your lungs. The relationship between the pressure at different volumes is plotted on a graph, this assists the physician in knowing which disease processes may be happening in the lung. It is performed in the booth with an esophageal catheter passed through the nasal passage into the esophagus, which is attached to a pressure transducer. A technologist will instruct you on how to perform the test and coach and encourage you to do your best.

Performing the test

1. After completing the lung volume and spirometry testing, you will be asked to breathe normally on the mouthpiece
2. The shutter will close. The shutter is closed for a second while you continue to breathe normally against the shutter
3. The shutter will open and you will return to normal breathing
4. You will then be asked to take a SLOW deep breath in until your are completely filled (TLC)
5. The shutter will close and you will relax against it
6. The shutter will then open and you will slowly sigh out a little air
7. The shutter will close and you will again relax against it
8. This will be repeated until you are empty
9. You will then take a breath in and sit back off of the mouthpiece

This test helps determine whether there is a restrictive process e.g. interstitial lung disease, airways disease or an obstructive process e.g. emphysema or asthma. This test may be done alone or combined with other tests; for example, with the DLCO test and/or muscle strength. It may also be done before and after an inhaled bronchodilator medication is given.

How should you prepare for a pressure volume study?

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Young patients breathes normally on the IOS.

Forced Oscillation/Impulse Oscillimetry (IOS)

This test is often used with patients too young or patients unable to perform other pulmonary testing.

It is a technique used to measure resistance of the airways using application of sine waves to the airway. It requires minimum cooperation from the patient.

Performing the test

1. The patient places the mouthpiece in past the teeth, with the tongue under it and keeps a tight seal on the mouthpiece
2. The patient breathes normally for 15 to 30 seconds as the sound waves pulse through the airways
3. The patient comes off of the mouthpiece. Three reproducible efforts are needed

IOS measures resistance, respiratory impedance, reflectance and distribution disorders. This test may be done with or without bronchodilator or with a bronchial challenge.

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Helium Dilution – Functional Residual Capacity (FRC)

This test measures the Functional Residual Capacity (FRC). In people with normal lungs the FRC is equal to the Thoracic Gas Volume (TGV) measured in the body plethysmograph. The helium dilution method only measures the air in the lung that under goes gas exchange. The plethysmograph method measures all air in the lung, including any trapped air. Inspiratory and expiratory volumes must also be measured with the FRC. A technologist will instruct you on how to perform the test and coach and encourage you to do your best.

Performing the test

1. You will be asked to come on the mouthpiece with noseclips on and to breathe normally
2. You will be asked to slowly blow out all of your air until you are empty
3. You will then return to normal breathing for a few minutes
4. Then you will be asked to slowly blow out until empty and then to take a slow deep breath in until your lungs are completely filled
5. You will then be asked to blow out slowly until you are completely empty
6. You will then return to normal breathing for a few breaths before coming off the mouthpiece
7. You will rest 5 to 10 minutes before repeating the test

This test will measure static lung volumes:

• Functional Residual Capacity (FRC)
• Inspiratory Capacity (IC)
• Expiratory Residual Volume (ERV)
• Slow Vital Capacity (SVC)
• Total Lung Capacity (TLC)

After a short rest period, the test is repeated until there are two reproducible tests. This test may be done with or without a bronchodilator.

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Muscle Strength – Maximum Inspiratory Pressures/ Maximum Expiratory Pressures

This test measures the amount of pressure your inspiratory and expiratory muscles can exert. It is helpful in evaluating possible respiratory muscle weakness.

Performing the test

1. You will be asked to come on the mouthpiece with noseclips on and to breathe normally. The door is left open during this test
2. You will be asked to blow out until you are empty
3. The shutter will close and you will be asked to inhale against the shutter as hard as you can for at least 1 second
4. You will repeat until there are 3 good inspiratory efforts
5. Next your expiratory pressures will be measured. You will be asked to come on the mouthpiece with noseclips on and to breathe normally
6. You will then breathe normally and take in a complete breath
7. The shutter will close and you will blow as hard as possible against it for at least 1 second
8. You will repeat until there are 3 good efforts

 

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