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:
“As deaths have accumulated I have begun to think of life and death as a set of balance scales. When one is young, the scale is heavily tipped toward the living. With the first death, the first consciousness of death, the counter scale begins to fall. Death by death, the scales shift weight until what was unthinkable becomes merely a matter of gravity and the fall into death becomes an easy step.”
—Alison Hawthorne Deming (b. 1946)
“Love once
Tipped the scales but now is shadowed, invisible,
Though mysteriously present, around somewhere.”
—John Ashbery (b. 1927)
“In what camera do you taste
Poison, in what darkness set
Glittering scales and point
The tipping tongue?”
—Wallace Stevens (1879–1955)