Table 2.
Adult acinar geometric parameters
| Regression Coefficients (P value) |
|||
|---|---|---|---|
| Parameter | Mean ± SD | α0 | α1 (age dependence) |
| R, μm | 310 ± 20 | 292 ± 8 (<2E-16) | 0.45 ± 0.2 (0.018) |
| h, μm | 140 ± 20 | 177 ± 8 (<2E-16) | −0.87 ± 0.2 (0.00011) |
| Lm, μm | 200 ± 40 | 150 ± 20 (4.7E-9) | 1.4 ± 0.4 (0.00084) |
| Nv, cm−3 | 110 ± 20 | 132 ± 8 (2.4E-13) | −0.46 ± 0.2 (0.028) |
| r, μm | 170 ± 40 | 120 ± 10 (2.5E-8) | 1.3 ± 0.3 (0.00040) |
| S/V, cm−1 | 200 ± 30 | 250 ± 10 (1.4E-15) | −1.1 ± 0.3 (0.00065) |
| VA, mm3 | 6.3E-3 ± 7E-4 | 6.7E-3 ± 4E-4 (3.6E-7) | −1.2E-5 ± 8E-6 (0.16) |
| VL, mm3 | 2.8E-3 ± 1E-3 | 7.1E-4 ± 6E-4 (0.238) | 5.3E-5 ± 1E-5 (0.00077) |
| SA, mm2 | 0.17 ± 0.01 | 0.191 ± 0.006 (<2E-16) | −3.3E-4 ± 1E-4 (0.036) |
| (r/R)2 | 0.34 ± 0.1 | 0.18 ± 0.04 (0.00011) | 3.9E-3 ± 9E-4 (0.00022) |
| FEV1, liter | 3.6 ± 1 | 5.0 ± 0.4 (4.7E-12) | −0.036 ± 0.009 (0.00040) |
| FVC, liter | 4.5 ± 1 | 5.7 ± 0.5 (1.3E-10) | −0.030 ± 0.01 (0.017) |
| FEV1/FVC, % | 80 ± 7 | 90 ± 3 (<2E-16) | −0.25 ± 0.07 (0.0015) |
Values are means ± SD. Parameters calculated from 3He lung morphometry (at functional residual capacity) and spirometry results fitted to a univariate linear model: parameter = α0 + α1 age (age in years). Significant P values are given in bold. R, acinar airway radius; h, alveolar depth; Lm, mean chord length; Nv, alveolar density; r, acinar airway lumen radius; S/V, surface-to-volume ratio; VA, alveolar volume; VL, acinar airway lumen volume; SA, surface area per alveolus; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.