RESUMEN
OBJECTIVE: Evaluate the influence of posture on ventilatory pattern, compartmental distribution of volume of chest wall and thoraco-abdominal kinematics of patients with severe chronic obstructive pulmonary disease (COPD). DESIGN: Cross-sectional study. METHODS: Twelve, male patients with severe COPD (Forced Expiratory Volume in the first second (FEV1) = 24.35 ± 4.52%, Forced Vital Capacity% (FVC%) = 60 ± 13.39% and relationship FEV1/FVC = 53.42 ± 14.47). The distribution of the volume of the ribcage [pulmonary rib cage (Rcp), abdominal ribcage (Rca) and abdomen (Ab)] during quiet breathing in a sitting position without back support (SWB), sitting with backrest (SB) and supine position (SUP) was determined using an opto-electronic plethysmograph. RESULTS: The following differences were observed: a greater tidal volume in the SWB position when compared to the SB position (p = 0.01); greater expiratory time in the SUP position in relation to the SWB (p = 0.03) and SB (p = 0.01); and increased abdominal contribution to the tidal volume in the SUP position in relation to the SWB (p < 0.01) and SB (p < 0.001). No difference was found in the thoraco-abdominal synchrony among the positions. CONCLUSION: Sitting position without back support enhances the activation of respiratory muscles by increasing the tidal volume and supine position seems to favor lung deflation by increasing the expiratory time. It seems appropriate to adopt these positions to optimize the ventilation/perfusion relationship and physiotherapeutic intervention in different clinical conditions.