Table 3.
Comparison of Dynamic Lung Hyperinflation Measured by Exercise Load and Hyperventilation
| Total | Emphysema | Nonemphysema | |
|---|---|---|---|
| n | 35 | 17 | 18 |
| IC measured by CLE | |||
| ICrest, L | 2.07 ± 0.07 | 2.02 ± 0.09 | 2.12 ± 0.11 |
| ICwarm-up, L | 2.07 ± 0.09 | 1.97 ± 0.11 | 2.17 ± 0.13 |
| ICcool-down, L | 1.91 ± 0.09 | 1.81 ± 0.13 | 2.01 ± 0.11 |
| IClowest, L | 1.86 ± 0.08 | 1.70 ± 0.11† | 2.00 ± 0.10 |
| −IClowest, L | −0.21 ± 0.06 | −0.32 ± 0.10 | −0.11 ± 0.05 |
| IC measured by MPIH | |||
| ICrest, L | 2.31 ± 0.08** | 2.25 ± 0.11 | 2.36 ± 0.10 |
| IC20, L | 2.22 ± 0.09 | 2.06 ± 0.13 | 2.36 ± 0.12 |
| IC30, L | 2.05 ± 0.09 | 1.85 ± 0.12 | 2.23 ± 0.12 |
| IC40, L | 1.92 ± 0.09 | 1.73 ± 0.12 | 2.10 ± 0.12 |
| IClowest, L | 1.90 ± 0.09 | 1.72 ± 0.11 | 2.08 ± 0.12 |
| −IClowest, L | −0.42 ± 0.06** | −0.54 ± 0.08† | −0.28 ± 0.08 |
Notes: Values represent the mean ± standard error of the mean; **p < 0.01 vs same IC index measured by constant load exercise (CLE) among total subjects. †p < 0.05 vs nonemphysema (emphysema-nondominant phenotype COPD).
Abbreviations: CLE, constant load exercise; IC, inspiratory capacity; MPIH, metronome-paced incremental hyperventilation; RR, respiratory rate; bpm, breaths/min; ICrest, IC at rest; ICwarm-up, mean IC at warm-up; ICcool-down, mean IC at cool-dawn; IClowest, lowest IC; −IClowest, decrease in IC from ICrest to IClowest; IC20, IC at RR of 20 bpm; IC30, IC at RR of 30 bpm; IC40, IC at RR of 40 bpm.