Understanding COPD: Spirometry

Spirometry is a noninvasive breathing test that determines how well a person’s lungs work. It is done with a device called a spirometer. A spirometer measures the amount of air a person can blow out and how fast they can blow the air out of the lungs. The test is very simple and only takes a few minutes.

How does it work?
The person being tested is asked to take in a full breath and then seal his or her lips around the mouthpiece of the spirometer. The person will then have to blow out as hard and fast as possible for at least six seconds, which is the approximate time it takes for normal lungs to empty. A nose clip may be applied to ensure no air escapes from the nose.

This routine will be repeated at least three times to ensure that the test is done correctly and provides accurate results. Spirometry is an effort-dependent test and some people may become tired, but this is expected.

What does it measure?
Spirometry measures airflow over time. It provides two numeric values that are helpful in the assessment and monitoring of patients with impaired lung function.

          Forced Vital Capacity (FVC): total amount of air that can be exhaled following as deep
                    an inhalation as possible

          Forced Expiratory Volume measured over one second (FEV1): the flow of air during the
                    first second of the Forced Vital Capacity

          FEV1/FVC: the proportion of air in a person’s lungs that can be blown out in one second

What can the measurements show?
Spirometry will help determine if a person has any airflow problems and is used to help:
  • diagnose and stage the severity of COPD
  • identify people who smoke or have smoked who are developing COPD
  • diagnose and categorize asthma severity
  • diagnose restrictive lung disease
  • measure the effectiveness of treatment with bronchodilators or corticosteroids
  • evaluate the effects of workplace exposure to irritants, among others
Who should be tested?
  • People who have ever or currently smoke
  • People 40 years of age and older
  • Anyone exposed to fumes or irritants in their workplace
In addition, anyone experiencing the following symptoms should be tested:
  • a persistent cough with colored mucus, especially in the morning
  • difficulty or painful breathing, wheezing or frequent chest infections
  • fatigue, shortness of breath at rest or while exercising, walking, climbing stairs, or engaging in everyday activities
  • snoring, restless sleep, or sleep apnea
  • weight loss, heart failure, fever, chills, or osteoporosis
  • extreme discomfort with routine activities

Are there any side effects?
Spirometry is a very low risk test. Sometimes if a person used too much effort to blow out it might make him or her feel dizzy. For some people, blowing out hard may cause an increase in the pressure of the chest, abdomen and eye, so spirometry is not advised for people who have:
  • unstable angina
  • recently had pneumothorax (air trapped beneath the chest wall)
  • recently had a heart attack or stoke
  • recently had eye or abdominal surgery

Spirometry should be done with certain precautions if a person is pregnant, is under 18 years old, has had a recent respiratory or ear infection or has any type of pain that increases with breathing.

Before performing the test, a health care provider will take precautions and give instructions.  It is also recommended that patients do not wear tight clothing that may interfere or make it difficult to take a deep breath. Also, people who are about to have a test should not eat a large meal, drink alcohol, use their bronchodilator inhaler (if possible) or do vigorous exercise for a few hours before the test.

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