Ventilatory responses at the limit of tolerance in chronic obstructive pulmonary disease patients and age-matched healthy subjects
| Healthy | GOLD | |||
| Stage II | Stage III | Stage IV | ||
| Subjects n | 11 | 14 | 14 | 14 |
| V′E L.min−1 | 68.7±13.8 | 38.4±8.9# | 36.5±8.4# | 27.6±7.2#,¶,+ |
| VT L | 2.37±0.57 | 1.33±0.34# | 1.21±0.27#,¶ | 1.10±0.32#,¶,+ |
| ƒR breaths.min−1 | 29±4 | 30±6 | 30±6 | 26±10#,¶,+ |
| tI s | 0.95±0.12 | 0.97±0.27 | 0.71±0.14#,¶ | 0.81±0.21#,¶,+ |
| tE s | 1.21±0.18 | 1.26±0.30 | 1.15±0.24 | 1.61±0.39#,¶,+ |
| tI/ttot | 0.44±3.44 | 0.41±0.45 | 0.38±0.52# | 0.33±0.48# |
| VT/tE L.s−1 | 2.03±0.58 | 1.19±0.40# | 1.07±0.31# | 0.89±0.34#,¶ |
| ICSP L | 2.87±0.76 | 1.87±0.48#,§ | 1.48±0.34#,¶ | 1.37±0.34#,¶ |
| ΔICSP L | 0.01±0.10 | -0.28±0.12# | -0.54±0.24#,¶ | -0.63±0.35#,¶ |
| ICOEP L | 2.85±0.89 | 2.02±0.63# | 1.48±0.37#,¶ | 1.39±0.37#,¶ |
| ΔEIVcw mL | 2036±658 | 1608±527# | 1740±591# | 1764±609# |
| ΔEEVcw mL | -339±619 | 85±288# | 454±509#,¶ | 562±363#,¶ |
| IRVcw mL | 573±374 | 530±467 | 221±273#,¶ | 167±322#,¶ |
Data are presented as mean±sd, unless otherwise stated. GOLD: Global Initiative for Chronic Obstructive Lung Disease; V′E: minute ventilation; VT: tidal volume; ƒR: breathing frequency; tI: inspiratory time; tE: expiratory time; tI/ttot: duty cycle; VT/tE: expiratory flow rate; ICSP: inspiratory capacity (IC) calculated by spirometry; ΔICSP: change from rest in spirometric IC; ICOEP: IC assessed by optoelectronic plethysmography; ΔEIVcw: end-inspiratory chest wall volume as a difference from rest; ΔEEVcw: end-expiratory chest wall volume as a difference from rest; IRVcw: inspiratory reserve chest wall volume. #: p<0.05 compared with healthy subjects; ¶: p<0.05 compared with GOLD stage II patients; +: p<0.05 compared with GOLD stage III patients; §: p<0.05 compared with ICOEP.