How to Calculate Spirometry Measurements

Spirometry is a medical assessment tool that measures the amount of air that can be inhaled and exhaled by the lungs. It is used to diagnose respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD). It is also used in hospitals with patients after surgery. A spirometer consists of a blow-tube attached to another tube with a piston that moves as air is exhaled into it or inhaled from it. Hand-held portable spirometers are most commonly used in doctor's offices and in homes.

Things You'll Need

  • Spirometer
  • Calculator
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Instructions

    • 1

      Sit in a supported upright position. Make sure the indicator tab on the spirometer is set at zero.

    • 2

      Take a deep breath and place the mouthpiece in your mouth and seal the tube with your lips. Exhale as hard as you can and blow out as much air from your lungs as possible. Or to assess inhalation, first blow all the air out of your lungs. Form a seal on the blow-tube with your lips and breathe in as much as possible.

    • 3

      Remove the tube from your mouth and look at the indicator position. Record the number of milliliters then return the indicator back to zero. Repeat this three times.

    • 4

      Add the total milliliters from all three trials together and divide the total by three. This average represents your breathing ability.

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