Calculate Minute Respiratory Volume (MRV): A Simple Guide

A spirometry test allows doctors to find out how well a person's lungs take in and release air, while also measuring the lungs' ability to release gases, such as oxygen, into the body's circulatory system. Minute respiratory volume, or MRV, is the amount of air a person exhales in one minute. Calculating MRV is straightforward if you know the person's breathing frequency and tidal volume in milliliters.

Things You'll Need

• Respirometer
• Pencil
• Paper
• Stopwatch

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Instructions

• 1

  Ask the person you're measuring to lie down on a bed or sit comfortably in a chair.

• 2

  Determine the person's tidal volume (TV), or total amount of air they inhale or exhale in a breath. You'll need the person to inhale and exhale into a respirometer a few times to accurately measure the TV. As an example, the person has a TV of 50 mL, which is considered average.

• 3

  Start your stopwatch when the person inhales and begin counting the number of breaths the person is taking. One inhalation and one exhalation would count as one breath.

• 4

  Stop counting after one minute. Write down the number of breaths the person took in that minute (f). As an example, the person has an f of 16.

• 5

  Multiply the person's tidal volume by the number of breaths he took in one minute to calculate MRV. In the example, you would multiply 50 by 16 and get 800. The person has an MRV of 800 mL per minute.