In chronic obstructive pulmonary disease (COPD) the changes in respiratory thoracoabdominal mechanics result from both hyperinflation and functional and structural skeletal muscle alterations.
Aim: Evaluation of the particularities of respiratory movement in COPD and identification of inter-relations between respiratory thoraco-abdominal mechanics and clinical and functional respiratory status.
Materials and methods: This study comparatively analyzed the respiratory thoracoabdominal mechanics recorded by polygraphy, using piezoelectric film belts, in 34 COPD patients and 30 healthy subjects, during rest, and during 6-minute walk test.
Results: In COPD patients, phase angle between direction of thoracic and abdominal respiratory movements presented significantly higher values compared to the control group, for supine (p = 0.023) and sitting position (p = 0.001), revealing the presence of paradoxical respiratory movements. Furthermore, phase angle dynamics increased significantly during walking test compared to sitting position (p = 0.001). Quantitative difference of end-expiratory pulmonary volume (qDEEL) correlated with pack-years (r = 0.372, p = 0.03) in supine position, and with body mass (r = 0.338, p = 0.05) and St. George activity score (r = 0.353, p = 0.041) during walking test. Rib cage inspiratory contribution to tidal volume ratio (%RCi) inversely correlated with pack-years (r = -0.417, p = 0.014) and body mass index (r = - 0.344, p = 0.047) in supine position, and with St. George activity score (r = 0.345, p = 0.046) in sitting position.
Conclusions: In COPD patient thoracoabdominal mechanics is characterized by paradoxical respiratory movements, more prominent during exercise. The alteration of thoracoabdominal mechanics correlated with St. George activity score, pack-years and body mass.