Article Text
Abstract
Background: Not all patients with severe chronic obstructive pulmonary disease (COPD) progressively hyperinflate during symptom limited exercise. The pattern of change in chest wall volumes (Vcw) was investigated in patients with severe COPD who progressively hyperinflate during exercise and those who do not.
Methods: Twenty patients with forced expiratory volume in 1 second (FEV1) 35 (2)% predicted were studied during a ramp incremental cycling test to the limit of tolerance (Wpeak). Changes in Vcw at the end of expiration (EEVcw), end of inspiration (EIVcw), and at total lung capacity (TLCVcw) were computed by optoelectronic plethysmography (OEP) during exercise and recovery.
Results: Two significantly different patterns of change in EEVcw were observed during exercise. Twelve patients had a progressive significant increase in EEVcw during exercise (early hyperinflators, EH) amounting to 750 (90) ml at Wpeak. In contrast, in all eight remaining patients EEVcw remained unchanged up to 66% Wpeak but increased significantly by 210 (80) ml at Wpeak (late hyperinflators, LH). Although at the limit of tolerance the increase in EEVcw was significantly greater in EH, both groups reached similar Wpeak and breathed with a tidal EIVcw that closely approached TLCVcw (EIVcw/TLCVcw 93 (1)% and 93 (3)%, respectively). EEVcw was increased by 254 (130) ml above baseline 3 minutes after exercise only in EH.
Conclusions: Patients with severe COPD exhibit two patterns during exercise: early and late hyperinflation. In those who hyperinflate early, it may take several minutes before the hyperinflation is fully reversed after termination of exercise.
- EEVcw, end expiratory chest wall volume
- EFL, expiratory flow limitation
- EIVcw, end inspiratory chest wall volume
- EH, early hyperinflator
- fb, breathing frequency
- FEV1, forced expiratory volume in 1 second
- FVC, forced vital capacity
- FRC, functional residual capacity
- IC, inspiratory capacity
- IRVcw, inspiratory reserve chest wall volume
- LH, late hyperinflator
- OEP, optoelectronic plethysmography
- RER, respiratory exchange ratio
- RV, residual volume
- Tlco, carbon monoxide lung transfer factor
- TLC, total lung capacity
- TLCVcw, chest wall volume at total lung capacity
- Vcw, chest wall volume
- V˙e, minute ventilation
- V˙o2, oxygen uptake
- Vt, tidal volume
- Wpeak, peak workload
- chronic obstructive pulmonary disease
- exercise tolerance
- dynamic hyperinflation
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- EEVcw, end expiratory chest wall volume
- EFL, expiratory flow limitation
- EIVcw, end inspiratory chest wall volume
- EH, early hyperinflator
- fb, breathing frequency
- FEV1, forced expiratory volume in 1 second
- FVC, forced vital capacity
- FRC, functional residual capacity
- IC, inspiratory capacity
- IRVcw, inspiratory reserve chest wall volume
- LH, late hyperinflator
- OEP, optoelectronic plethysmography
- RER, respiratory exchange ratio
- RV, residual volume
- Tlco, carbon monoxide lung transfer factor
- TLC, total lung capacity
- TLCVcw, chest wall volume at total lung capacity
- Vcw, chest wall volume
- V˙e, minute ventilation
- V˙o2, oxygen uptake
- Vt, tidal volume
- Wpeak, peak workload
Footnotes
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Published Online First 17 June 2005
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This work was supported by the European Community CARED FP5 project (contract n. QLG5-CT-2002-0893) and by the Thorax Foundation.
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Competing interests: none declared.
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