Scales
There are a number of non-equivalent scales used in the measurement of Peak Flow.
Graphs or tables are available of predicted normal values based on a person's sex, age and height, and online calculators are available. There is a wide natural variation in results from healthy test subjects.
- Wright scale
- EN 13826 or EU scale
- A.T.S. (American Thoracic Society) scale
In 2004 the UK switched from the original Wright scale to the newer, more accurate European scale. Wright values may be converted to the EU scale using the following formula:
The reverse calculation is:
Read more about this topic: Peak Expiratory Flow
Famous quotes containing the word scales:
“It cannot but affect our philosophy favorably to be reminded of these shoals of migratory fishes, of salmon, shad, alewives, marsh-bankers, and others, which penetrate up the innumerable rivers of our coast in the spring, even to the interior lakes, their scales gleaming in the sun; and again, of the fry which in still greater numbers wend their way downward to the sea.”
—Henry David Thoreau (1817–1862)
“In what camera do you taste
Poison, in what darkness set
Glittering scales and point
The tipping tongue?”
—Wallace Stevens (1879–1955)
“For these have governed in our lives,
And see how men have warred.
The Cross, the Crown, the Scales may all
As well have been the Sword.”
—Robert Frost (1874–1963)