Figures
- Figure 1–
The nonlinear relationship between age and forced expiratory volume in 1 s (FEV1) in a) males and b) females. Data obtained from Caucasian subjects in 8.
- Figure 2–
Comparison between prediction equations from Wang et al. 26 (–––) and Hankinson et al. 21 (········) in males during childhood. At the stage at which the Cystic Fibrosis Foundation recommends switching between Wang et al. 26 and Hankinson et al. 21 (17 yrs and 15 yrs in males and females, respectively), there is a difference in predicted forced expiratory volume in 1 s (FEV1) of ∼1% in males and 2% in females (data not shown); however, the individual change can be up to 8% predicted. Reproduced with permission from the CF Foundation Registry Committee Task Force on Reference Equations (www.cff.org).
- Figure 3–
Predicted median for forced expiratory volume in 1 s in L (- - - - -), forced vital capacity (FVC) in L (––––) and forced expiratory flow at 25–75% of FVC in L·s−1 (·········).
- Figure 4–
Between-subject variability in males measured by the coefficient of variation (CV). The CV is defined as 100×(sd/median). When the CV is 10% (as is the case for forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) in young adults) the normal range on either side of 100% predicted is 80–120% pred. By contrast, in younger and older subjects, the lower limit of normal for FEV1 will drop to 70% predicted when CV is 15%, whereas that for forced expiratory flow at 25–75% of FVC (FEF25–75) may be 40% (CV of 30%) or lower. ––––: FVC males; - - - -: FEV1 males; ······: FEF25–75 males.
- Figure 5–
Screen-shot from Spiro.xls (www.growinglungs.org.uk 42) in LMSgrowth demonstrating how an individual's sex, age, height and spirometry results can be entered to obtain z-scores (standard deviation scores; SDS) or % predicted. The same method can be applied for an entire dataset by using the measurement SDS function to retrospectively analyse data.
Tables
- Table 1– Examples of predicted values in males and females across the age range studied
Age yrs Height cm Sex Predicted FEV1 L FEV1 LLN L FEV1 LLN% pred 3 99 Male 0.79 0.58 73.4 5 115 Female 1.17 0.89 76.1 7 122 Male 1.45 1.14 78.6 11 133 Male 1.80 1.45 80.6 15 150 Male 2.71 2.20 81.2 20 159 Female 3.12 2.52 80.8 25 170 Female 3.61 2.92 80.9 30 186 Female 4.32 3.49 80.8 40 162 Male 3.38 2.71 80.2 50 175 Male 3.79 2.97 78.4 60 183 Male 3.85 2.93 76.1 70 172 Female 2.52 1.92 76.2 80 169 Male 2.55 1.81 71.0 These data are presented as an example and should not be used to define abnormal results in individual patients. FEV1: forced expiratory volume in 1 s; LLN: lower limit of normal.
