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Peak expiratory flow measurement
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Peak expiratory flow is a simple way to measure how the lungs are doing. It is measured with a peak flow meter, a small tube with a scale on it, and what it gives you is an objective measure of airflow limitation, that is, of whether air is having trouble getting out. It measures the top speed of the air going out, not how much air fits inside.
For the result to be valid, it takes maximal effort: fill your chest as fully as you can, then blow out as hard and as fast as possible.
And the lungs are not the only thing being measured. The result is influenced by the depth of the breath taken in beforehand, the caliber of the airway, muscle strength and how much voluntary effort goes into the maneuver.
In brief
Peak expiratory flow is an indicator of lung function: it gives an objective measure of airflow limitation.
It measures the top speed of the air going out, not how much air fits inside.
It is measured with a peak flow meter and requires maximal effort: breathe in as deeply as possible, then blow out as hard and as fast as you can.
Several factors contribute to the reading: the depth of the breath taken in, the caliber of the airway, muscle strength and voluntary effort.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPeak Flow Rate Measurement, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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