RT Journal Article
SR Electronic
T1 Regional chest wall volumes during exercise in chronic obstructive pulmonary disease
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 210
OP 216
DO 10.1136/thorax.2003.011494
VO 59
IS 3
A1 A Aliverti
A1 N Stevenson
A1 R L Dellacà
A1 A Lo Mauro
A1 A Pedotti
A1 P M A Calverley
YR 2004
UL http://thorax.bmj.com/content/59/3/210.abstract
AB Background: Dynamic hyperinflation of the lungs impairs exercise performance in chronic obstructive pulmonary disease (COPD). However, it is unclear which patients are affected by dynamic hyperinflation and how the respiratory muscles respond to the change in lung volume. Methods: Using optoelectronic plethysmography, total and regional chest wall volumes were measured non-invasively in 20 stable patients with COPD (mean (SD) forced expiratory volume in 1 second 43.6 (11.6)% predicted) and dynamic hyperinflation was tracked breath by breath to test if this was the mechanism of exercise limitation. Resting ventilation, breathing pattern, symptoms, rib cage and abdominal volumes were recorded at rest and during symptom limited cycle ergometry. Pleural, abdominal, and transdiaphragmatic pressures were measured in eight patients. Results: End expiratory chest wall volume increased by a mean (SE) of 592 (80) ml in 12 patients (hyperinflators) but decreased by 462 (103) ml in eight (euvolumics). During exercise, tidal volume increased in euvolumic patients by reducing end expiratory abdominal volume while in hyperinflators tidal volume increased by increasing end inspiratory abdominal and rib cage volumes. The maximal abdominal pressure was 22.1 (9.0) cm H2O in euvolumic patients and 7.6 (2.6) cm H2O in hyperinflators. Euvolumic patients were as breathless as hyperinflators but exercised for less time and reached lower maximum workloads (p<0.05) despite having better spirometric parameters and a greater expiratory flow reserve. Conclusions: Dynamic hyperinflation is not the only mechanism limiting exercise performance in patients with stable COPD. Accurate measurement of chest wall volume can identify the different patterns of respiratory muscle activation during exercise.