When to ask for a spirometry test
Spirometry is a measure of how much and how quickly you can move air in and out of your lungs. If you answer yes to one or more of these questions ask your doctor about a spirometry test.
- Do you cough regularly?
- Do you cough up phlegm regularly?
- Do even simple chores make you short of breath?
- Do you wheeze when you exert yourself, or at night?
- Do you get frequent colds that last longer than others?
A spirometry test includes a basic measure of
FEV1 and FVC:
- FEV1 - forced expiratory volume measures how much air you can exhale in 1 second during a forced exhale
- FVC - forced vital capacity is the total amount of air you exhale
This test may also be called “simple spirometry” or “pre- and post-bronchodilator spirometry” or “reversible bronchodilator testing.” A bronchodilator is a medicine that helps your small airway muscles relax. These muscles are over-activated or too tight in respiratory conditions such as asthma.
It’s best to do this test while you have symptoms and before you start taking any lung medicines. If you take respiratory medicines, you may be asked to stop taking them for 1 or 2 days before your test.
Spirometry is good at diagnosing some diseases, like asthma or chronic obstructive lung disease (COPD). But has limited success when looking for the diagnosis of other lung diseases such as interstitial lung disease (ILD) or interstitial pulmonary fibrosis (IPF). In some cases, a full pulmonary function test may be required.
When to ask for a full pulmonary function test
If you have symptom of shortness of breath and the cause is not yet known, or cannot be identified on spirometry.
Ask your doctor about a
full pulmonary function test or
PFT. It may also be called a “full PFT” or “complete PFT.” This test includes these measures:
- spirometry
- lung volumes (how much air your lungs can hold)
- TLC - total lung capacity is the total amount of air your lungs can hold
- RV - residual volume is the amount of air left in your lungs after you exhale
- VC - vital capacity is the total amount of air you can exhale after taking a deep breath
- diffusion capacity (measures how well your lungs can move gas from the air you breathe to your bloodstream)
- DLCO - measures how well your lungs transfer a small amount of carbon monoxide into your blood
Both spirometry and PFT results should come back with an interpretation of the results. The interpretation will be done by a
respirologist. The result may only include information on the type of disease pattern, but not a specific respiratory disease.
The disease patterns mentioned in interpreted results often fall into 2 categories:
- obstructive lung disease – includes asthma and COPD
- restrictive lung disease – includes interstitial lung disease and pulmonary fibrosis
When you have breathing difficulty, the first test will always be to investigate the lungs. There are some reasons for shortness of breath that won’t be diagnosed by a lung test. Sometimes breathing difficulty is caused by a different organ, such as the heart or nerves.
You are an important part of your healthcare team. Be sure to ask questions if there are things you don’t understand.
