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Regional chest wall volumes during exercise in chronic obstructive pulmonary disease
  1. A Aliverti1,
  2. N Stevenson2,
  3. R L Dellacà1,
  4. A Lo Mauro1,
  5. A Pedotti1,
  6. P M A Calverley2
  1. 1Dipartimento di Bioingegneria, Politecnico di Milano, Italy
  2. 2University Department of Medicine, University Hospital Aintree, Liverpool, UK
  1. Correspondence to:
    Dr A Aliverti
    Dipartimento di Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy; andrea.alivertipolimi.it

Abstract

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.

  • chronic obstructive pulmonary disease
  • exercise
  • lung volume
  • dynamic hyperinflation
  • BMI, body mass index
  • COPD, chronic obstructive pulmonary disease
  • EELV, end expiratory lung volume
  • EEVcw, end expiratory chest wall volume
  • FEF, forced expiratory flow at a percentage of FVC
  • FEV1, forced expiratory volume in 1 second
  • FRC, functional residual capacity
  • FVC, forced vital capacity
  • IC, inspiratory capacity
  • OEP, optoelectronic plethysmography
  • Pab, abdominal pressure
  • Pdi, transdiaphragmatic pressure
  • Pga, gastric pressure
  • Poes, oesophageal pressure
  • Ppl, pleural pressure
  • RV, residual volume
  • TLC, total lung capacity
  • Vab, abdominal volume
  • Vcw, total chest wall volume
  • Vrc, rib cage volume

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Footnotes

  • This work was supported in part by the European Community CARED FP5 project (contract no QLG5-CT-2002-0893).