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Overview :
The
forced expiratory flow rate (FEF) at different percentages of the vital
capacity in adults can be predicted based on physical characteristics.
NOTE:
Some of these equations (Knudson at FEF25% and Cherniack at FEF75%) give
discrepant results. I have checked the equations versus the sources and do not
see an obvious transcription error. It is interesting to note that FEF25% for
Knudson is close to the value for Cherniack at FEF75% and vice versa. The
coefficients for both sets of equations move in opposite ways (increase from
25-75% for Cherniack, decrease for Knudson). The authors may be using different
definitions, so that FEF75% Cherniack is equivalent to FEF25% Knudson.
FEF25%
in liters per second for White males 15-79 years (Cherniack, 1972) =
=
(0.036 * (height in inches)) - (0.041 * (age in years)) + 1.984
FEF25%
in liters per second for White females 15-79 years (Cherniack, 1972) =
=
(0.023 * (height in inches)) - (0.034 * (age in years)) + 2.216
FEF25%
in liters per second for White males 25-85 years (Knudson, 1976) =
=
(0.088 * (height in cm)) - (0.035 * (age in years)) - 5.618
FEF25%
in liters per second for White females 20-88 years (Knudson, 1976) =
=
(0.043 * (height in cm)) - (0.025 * (age in years)) - 0.132
FEF50%
in liters per second for White males 15-79 years (Cherniack, 1972) =
=
(0.065 * (height in inches)) - (0.031 * (age in years)) + 2.403
FEF50%
in liters per second for White females 15-79 years (Cherniack, 1972) =
=
(0.062 * (height in inches)) - (0.023 * (age in years)) + 1.426
FEF50%
in liters per second for White males 25-85 years (Knudson, 1976) =
=
(0.069 * (height in cm)) - (0.015 * (age in years)) - 5.40
FEF50%
in liters per second for White females 20-88 years (Knudson, 1976) =
=
(0.035 * (height in cm)) - (0.013 * (age in years)) - 0.444
FEF50%
in liters per second for White males 18-86 years years (Roberts, 1991) =
=
(-0.044 * (age in years)) + 6.456
FEF50%
in liters per second for White females 18-86 years (Roberts, 1991) =
=
(-0.038 * (age in years)) + 5.556
FEF75%
in liters per second for White males 15-79 years (Cherniack, 1972) =
=
(0.090 * (height in inches)) - (0.199 * (age in years)) + 2.726
FEF75%
in liters per second for White females 15-79 years (Cherniack, 1972) =
=
(0.069 * (height in inches)) - (0.019 * (age in years)) + 2.147
where:
• The
factor for age is given as 0.1987 in the original table, but this gives
negative results at higher ages. The 0.019 is from Wanger et al.
FEF75%
in liters per second for Hispanic males 25-80 years (Coultas, 1976) =
=
(0.0145 * (height in cm)) - (0.0346 * (age in years)) + 3.1578
FEF75%
in liters per second for Hispanic females 25-80 years (Coultas, 1976) =
=
(0.00786 * (height in cm)) - (0.0240 * (age in years)) + 1.2749
where:
• The
factor for height in cm for Hispanic females is given as 0.7086, but this gives
absurd results. Even the equation used gives results different from the other
authors.
FEF75%
in liters per second for White males 25-85 years (Knudson, 1976) =
=
(0.044 * (height in cm)) - (0.012 * (age in years)) - 4.143
FEF75%
in liters per second for White females 20-88 years (Knudson, 1976) =
=
(-0.014 * (age in years)) + 3.042
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