How to use a spirometer

Written by amanda herron
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Doctors and medical professionals use a spirometer to measure a patient's exhale capacity of air in litres. This device is often used during treatment for asthma and other lung problems. The patient blows into a tube attached to the spirometer, which will give a reading of his exhale strength. The reading will appear as a numerical table and a "tracing" graph.

Skill level:


    How to Perform a Spirometer Test

  1. 1

    Take a few practice breaths. Breathe deeply into your lungs. Try to fill your lungs as full as possible with air. Exhale quickly through you mouth. Blow the air straight out as fast and hard as you can.

  2. 2

    Place your lips over the end of the spirometer tube. Form an airtight seal by closing your lips around the end of the tube opening. Keep your lips sealed to prevent air escaping around the tube and resulting in an incorrect reading.

  3. 3

    Breathe in as deeply as possible. Fill your lungs with as much air as possible. Be sure your lips are closed over the end of the tube. Exhale as quickly as possible. Blow the air into the tube like a straw. Blow hard and fast for at least six seconds.

  4. 4

    Do not hesitate or cough during the first second of exhalation. Do not obstruct the tube opening with your tongue, teeth, dentures or lips.

  5. 5

    Repeat the spirometer test three different times to be sure the results have "reproducibility." This makes sure the tests results were not a fluke but an accurate representation of lung health. Retrieve the spirometer readings in either the numerical table or visual graph form. Discuss the results with your doctor.

    How to Read the Spirometer Table Results

  1. 1

    Review the results of your spirometer graph with your doctor. Locate the forced vital capacity (FVC or FEV6) reading on the graph. This number represents the amount of air, in litres, you exhaled when you used the spirometer, which is the maximum you can blow out at one time.

  2. 2

    Locate the forced expiratory volume per second (FEV1) reading on the spirometer graph. This number breaks the FVC into the amount, in litres per second, you breathed out in one second. Locate the spirometer's calculation of FEV1 divided by FVC. This ratio reading tells you the percentage of air you exhaled in the first second.

  3. 3

    Obtain charts with FVC and FEV1 spirometer readings for other people with statistics similar to yours. Find people of the same gender, age range and physical attributes to compare FVC and FEV1 readings. Contrast your numbers with the numbers considered normal for your statistics. If your numbers are considerably high or low, consult your doctor.

  4. 4

    Determine what the spirometer reading reveals about your lung health. A healthy respiratory system can exhale a large amount quickly and easily. Look at your spirometer readings. If they are significantly lower than those of comparable healthy people, your bronchial tubes could be obstructed or more narrow. A low spirometer reading means you are exhaling less or slower than a healthy person.

  5. 5

    Perform a test to see if you respond to asthma treatments, if your lungs show a reading like that of a person with clogged or narrow bronchial tubes. Take a fast working asthma medication, usually in inhaler form, and repeat the test. If your spirometer reading is higher the second time, your lungs are responding to asthma medication.

Tips and warnings

  • You must exhale a full six seconds for the spirometer reading to be accepted.
  • Hesitating or coughing during the exhalation will interfere with an accurate reading.
  • Do not exceed eight exhalation attempts on the spirometer. End testing and try again later.

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