Figures
- FIGURE 1
a–f) Diaphragm electromyography (EMGdi) and selected ventilatory and indirect gas exchange responses to incremental cycle exercise test in patients with moderate chronic obstructive pulmonary disease (COPD) and age-matched healthy controls. Data are presented as mean±sem. Square symbols represent tidal volume-ventilation inflection points. EMGdi/EMGdi,max: an index of inspiratory neural drive to the crural diaphragm; V′E: minute ventilation; V′E/V′CO2: ventilatory equivalent for carbon dioxide; PETCO2: partial pressure of end-tidal carbon dioxide; SpO2: arterial oxygen saturation measured by pulse oximetry. *: p<0.05 for COPD versus healthy controls at rest, at standardised work rates or at peak exercise. Reproduced and modified from [17] with permission.
- FIGURE 2
a–f) Respiratory mechanical measurements during incremental cycle exercise in patients with moderate chronic obstructive pulmonary disease (COPD) and age-matched healthy controls. Data are presented as mean±sem. Square symbols represent tidal volume-ventilation inflection points. Pes: oesophageal pressure; Pes,max: maximal Pes; CLdyn: dynamic lung compliance; PEEPi: intrinsic positive end-expiratory pressure. *: p<0.05 COPD versus healthy controls at rest, at standardised work rates or at peak exercise. Reproduced and modified from [17] with permission.
- FIGURE 3
a) Operating lung volumes and b) breathing frequency (Fb) during incremental cycle exercise in patients with moderate chronic obstructive pulmonary disease (COPD) and age-matched healthy controls. Data are presented as mean±sem. Square symbols represent tidal volume-ventilation inflection points. TLC: total lung capacity; EILV: end-inspiratory lung volume; EELV: end-expiratory lung volume. *: p<0.05 COPD versus healthy controls at rest, at standardised work rates or at peak exercise. Reproduced and modified from [17] with permission.
- FIGURE 4
Exertional dyspnoea intensity is shown relative to a) work rate and b) diaphragm electromyography relative to maximum (EMGdi/EMGdi,max) during incremental cycle exercise in patients with moderate chronic obstructive pulmonary disease (COPD) and age-matched healthy controls. c) Selected qualitative dyspnoea descriptors at the end of incremental cycle exercise in patients with moderate COPD and age-matched healthy controls. d) The relationship between tidal volume (VT) as a function of predicted vital capacity (VCpred) and EMGdi/EMGdi,max. Square symbols represent the tidal volume-ventilation inflection points in panels a) and d) and the point at the highest equivalent ventilation (50 L·min−1) in panel b). Data are presented as mean±sem. *: p<0.05 COPD versus healthy controls at rest, at standardised work rates or at peak exercise. Reproduced and modified from [17] with permission.
- FIGURE 5
Proposed panel displays during interpretation of an incremental exercise test. Data showing selected perceptual, ventilatory control and dynamic respiratory mechanics to incremental cycle exercise in patients with mild chronic obstructive pulmonary disease (COPD) and age-matched healthy controls. Data are presented as mean±sem. V′E/V′CO2: ventilatory equivalent for carbon dioxide; IRV: inspiratory reserve volume; Fb: breathing frequency; PETCO2: partial pressure of end-tidal carbon dioxide; SpO2: arterial oxygen saturation measured by pulse oximetry; TLC: total lung capacity. *: p<0.05 mild COPD versus healthy controls at rest, at standardised work rates or at peak exercise. Reproduced from [45] with permission.
- FIGURE 6
Effects of chronic obstructive pulmonary disease (COPD) severity on different parameters of ventilatory inefficiency during incremental cardiopulmonary exercise testing (CPET). a) Minute ventilation (V′E)–carbon dioxide output (V′CO2) intercept increased and b) V′E–V′CO2 slope diminished as the disease progressed from Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1–4. c) As the V′E/V′CO2 nadir depends on both slope and intercept, it remained elevated (compared with controls) across disease stages. d) Increasing nadir–slope differences from GOLD stages 1–4 reflects the impact of a progressively higher intercept. *: p<0.05 COPD versus controls (panel b) or controls versus all COPD groups (panel c). Reproduced from [19] with permission.
- FIGURE 7
a) Tidal volume (VT) (presented as % predicted of vital capacity (VC)), b) breathing frequency (Fb), c) dynamic inspiratory capacity (IC) and d) inspiratory reserve volume (IRV) (presented as % predicted of total lung capacity (TLC)) are shown plotted against minute ventilation (V′E) in four disease severity quartiles based on forced expiratory volume in 1 s % predicted during constant work rate exercise. Note the clear inflection (plateau) in the VT/V′E relationship which coincides with a simultaneous inflection in the IRV. After this point, further increases in V′E are accomplished by accelerating Fb. Data are presented as mean values at steady-state rest, isotime (i.e. 2 min, 4 min), the VT/V′E inflection point and peak exercise. Reproduced from [37] with permission.
- FIGURE 8
Interrelationships are shown between exertional dyspnoea intensity and a) minute ventilation (V′E) and b) the tidal volume (VT)/inspiratory capacity (IC) ratio in four disease severity quartiles based on forced expiratory volume in 1 s % predicted during constant work rate exercise. After the VT/IC ratio plateaus (i.e. the VT inflection point) dyspnoea rises steeply to intolerable levels. There is a progressive separation of dyspnoea/V′E plots with worsening quartile. Data are presented as mean values at steady-state rest, isotime (i.e. 2 min, 4 min), the VT/V′E inflection point and peak exercise. Reproduced from [37] with permission.
Additional Files
Disclosures
Files in this Data Supplement:
