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Overview :
The
peak expiratory flow (PEF) is used in the evaluation of airway obstruction,
particularly in patients with asthma. The equations proposed by Nunn and Greff
can be used to estimate a patient's expected PEF for age, gender and height.
Patient
selection:
•
Adult men and women from 15 to 85 years of age
•
Lifelong non-smoking was the criterion used to determine "normality"
in PEF.
predicted
peak expiratory flow in L/min =
=
EXP (X)
X
for men =
=
(0.544 * LN(age in years)) - (0.0151 * (age in years)) - (74.7 / (height in
cm)) + 5.48
X
for women =
=
(0.376 * LN(age in years)) - (0.0120 * (age in years)) - (58.8 / (height in
cm)) + 5.63
patient's
observed PEF as percent of predicted =
=
(observed PEF) / (predicted PEF) * 100
Limitations:
•
"Normalcy" is affected by many variables.
•
The effect of race was not included in the evaluation.
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