Table 3

Derived equations for various spirometric parameters of male subjects

Parameter	Equations	r²	see
<21 yrs
FVC^#	0.04202H+0.09678A−4.322	0.90	0.46
Lower limit of normal	0.0370H+0.09678A−4.322	0.91
FEV₁^#	0.03569H+0.09030A−3.683	0.90	0.46
Lower limit of normal	0.0310H+0.09030A−3.683	0.92
FEV₁/FVC %	0.011935H−0.13572A+88.2983	0.02	3.57
Lower limit of normal	0.101108H−0.13572A+88.2983
PEF^¶	0.07238H+0.246A−7.720	0.81	1.26
Lower limit of normal	0.058H+0.246A−7.720	0.91
FEF_25–75^¶	0.03310H+0.150A−3.523	0.84	0.59
Lower limit of normal	0.0270H+0.150A−3.523	0.87
FEF₂₅^¶	0.04621H+0.287A−5.082	0.82	1.06
Lower limit of normal	0.034H+0.287A−5.082	0.90
FEF₅₀^¶	0.03646H+0.1799A−3.8492	0.82	0.733
Lower limit of normal	0.02796H+0.1799A−3.8492	0.84
FEF₇₅^¶	0.02376H+0.0512A−2.3791	0.70	0.488
Lower limit of normal	0.01917H+0.0512A−2.3791	0.85
≥21 yrs
FVC^#	0.05651H−0.0252A−4.093	0.52	0.53
Lower limit of normal	0.052H−0.0252A−4.093	0.78
FEV₁^#	0.045302H−0.02566A−2.78204	0.56	0.43
Lower limit of normal	0.040619H−0.02566A−2.78204	0.76
FEV₁/FVC %	−0.0978H−0.104A+107.21	0.15	3.04
Lower limit of normal	−0.124H−0.104A+107.21	0.36
PEF^¶	0.07759H−0.0435A−1.369	0.15	1.96
Lower limit of normal	0.061H−0.0435A−1.369	0.19
FEF_25–75^¶	0.02625H−0.0360A+1.782	0.32	0.76
Lower limit of normal	0.020H−0.0360A+1.782	0.47
FEF₂₅^¶	0.05913H−0.0347A+0.280	0.15	1.586
Lower limit of normal	0.04513H−0.0347A+0.280	0.21
FEF₅₀^¶	0.03357H−0.0301A+1.423	0.19	1.0
Lower limit of normal	0.025H−0.0301A+1.423	0.33
FEF₇₅^¶	0.01563H−0.0273A+0.582	0.36	0.50
Lower limit of normal	0.011H−0.0273A+0.582	0.58

FVC: forced vital capacity
FEV₁: forced expiratory volume in one second
PEF: peak expiratory flow
FEF_25–75: expiratory flow from 25–75% of the vital capacity
FEF₂₅, FEF₅₀, FEF₇₅: instantaneous expiratory flows at 25%, 50% and 75% of FVC, respectively; H: height in cm
A: age in years
r²: coefficient of determination
see: standard error of the estimate
^#: volumes are in L
^¶: flows are in L·s⁻¹