Characteristics of Respiratory Mechanics in Chronic Obstructive Pulmonary Disease.

UNLABELLED 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.