TABLE 2.

Regional F_gas and Ventilation Distributions

Parameter	Young healthy	Age-matched healthy	COPD
Fgas (%)	64 ± 5	68 ± 5	72 ± 7
Fgasgrad (10−2 cm−1)	1.6 ± 1.0	1.8 ± 0.2	0.5 ± 0.4*,†
CV2Fgas	0.022 ± 0.011	0.018 ± 0.002	0.022 ± 0.008
$\text{s}{\dot{\text{V}}}_{\text{r}}$ (10−3 s−1)	0.090 ± 0.060	0.082 ± 0.023	0.043 ± 0.014*,†
$\text{s}{\dot{\text{V}}}_{\text{r grad}}$ (10−3 s−1 cm−1)	−1.2 ± 0.6	−1.3 ± 0.4	0.0 ± 0.4‡,§
${\dot{\text{V}}}_{\text{r grad}}$ (10−4Cm−1)	−5.1 ± 2.2	−6.9 ± 2.5	0.3 ± 2.7*,∥
${{\text{CV}}^2}_{\text{s}{\stackrel{.}{\text{V}}}_{\text{r}}}$	0.151 ± 0.043	0.206 ± 0.064	0.401 ± 0.103§,¶

^*P < 0.05 COPD vs. young healthy subjects.

^†0.05 < P < 0.10 COPD vs. age-matched healthy subjects.

^‡P < 0.005 COPD vs. young healthy subjects.

^§P < 0.01 COPD vs. age-matched healthy subjects.

^∥P < 0.005 COPD vs. age-matched healthy subjects.

^¶P < 0.0005 COPD vs. young healthy subjects.

Values are mean ± SD.

Fgas_grad = vertical gradient of F_gas; CV²_Fgas = squared coefficient of variation of F_gas; $\text{s}{\dot{\text{V}}}_{\text{r grad}}$ = vertical gradient of specific ventilation; ${\dot{\text{V}}}_{\text{r grad}}$ = vertical gradient of ventilation; ${{\text{CV}}^2}_{\text{s}{\stackrel{.}{\text{V}}}_{\text{r}}}$ = squared coefficient of variation of specific ventilation.