Thoracoabdominal asynchrony decreases chest wall volume and affects respiratory kinematics in COPD

COPD patients usually present thoracoabdominal asynchrony (TAA) that occurs due to an opposite motion among chest wall compartments decreasing tidal volume; however, the proper effect of TAA on chest wall volume remains unclear. Aim: to compare chest wall volume and respiratory kinematics among healthy and COPD patients with and without TAA. Methods: In this cross-sectional study 22 COPD (FEV 1 40±10%pred) and 13 healthy controls (FEV 1 98±14%pred) were assessed during rest and exercise (70% maximum workload) in a cycle ergometer. TAA was evaluated via optoelectronic plethysmography by calculating the phase angle (Lissajous approach) among upper and lower ribcage and abdomen. COPD patients were classified in two groups: those presenting asynchrony (TAA+) or not (TAA-) based on reference values of phase angle (mean ± 2*standard-deviation from controls). Chest wall volume and compartmental contribution were estimated. ANOVA was used for comparison. Results: Controls and COPD were homogenous for age, gender and BMI. Asynchrony occurred during rest and exercise in the lower ribcage. At rest, lower ribcage contribution was decreased in TAA+ compared to controls (9±10.7 vs. 18±9.2, p Conclusion: Thoracoabdominal asynchrony decreases chest wall volume in COPD and changes respiratory kinematics, decreasing lower ribcage and increasing abdominal contributions during exercise.