Using a Peak Flow Meter for a Lung Function Test

Get step-by-step directions on how to use a peak flow meter to measure a child's lung function.

A peak flow meter is a simple, portable, handheld device that measures the amount of air coming out of your child's lungs. The device can be used on asthmatic children of all ages, including those in preschool, and it allows you to assess lung function by recording readings at home for your child's doctor and for yourself. When the child blows into the device as hard as possible, the marker on the scale moves, measuring the amount of air exhaled.

A peak flow meter can help you:

  • Recognize drops in airflow and signs of an asthma flare-up.
  • Discern how well asthma treatments are working.
  • Recognize when fast-acting medication is required or if an adjustment is needed.
  • Track peak flow rate for documentation.
  • Follow your child's personal best improvement as he grows.

There are different peak flows meters designed for various lung capacities and ages. A basic peak flow meter is inexpensive and requires you to record readings manually while electronic models automatically record peak flow readings.

How to Measure a Child's Lung Function

Measuring your child's lung function with a peak flow meter is a quick, easy way to keep tabs on an asthma condition. Your pediatrician may ask that you record peak flow meter readings daily for several weeks to gain an accurate measurement of the condition?s severity. You child's highest peak flow number over this period, his personal best, is the benchmark for creating a daily asthma plan.

Here's how it works:

  1. Have your child sit up straight or stand.
  2. Set the meter's scale marker to zero.
  3. Have your child take a deep breath, fill her lungs with air, and hold it.
  4. Ask your child to blow out the air as quickly and as strongly as she can into the meter. Be sure her lips are tight around the mouthpiece and her tongue is not in the way.
  5. Record the reading on the scale.
  6. Have your child blow into the meter two more times. Record both readings. The highest number of the three readings is the peak flow rate (also called peak expiratory flow or PEF). This is the number that should be used as the reading for the test.

Using a peak flow meter at the same time each day when asthma is under control makes it more accurate to monitor your child's lung capacity. During an asthma attack, the muscles in your child's airways tighten, narrowing the airways. A peak flow meter can alert you to changes in your child's airways, sometimes hours or days before other asthma symptoms surface. By knowing your child's normal and personal best flow rates, you can head off airway restriction and avert a more severe asthma attack.

Copyright © 2012 Meredith Corporation.

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