Pulmonary hyperinflation and postural balance in COPD patients

COPD patients have impaired balance and pulmonary hyperinflation could contribute to balance deficits in this population. Aim: To evaluate the relationship between postural balance and pulmonary hyperinflation in COPD patients. Methods: 67 patients were included (12% mild, 44% moderate and 44% severe COPD). Postural balance was evaluated by centre of pressure displacement analysis using a portable force platform in 3 different sensory conditions: standing with eyes open, eyes closed and on a foam surface with open eyes. The variables analysed included total path length, path velocity and amplitude, in both anteroposterior (AP) and mediolateral (ML) directions. Pulmonary hyperinflation was evaluated using body plethysmography. Participants were classified into 2 groups: hyperinflated (Total lung capacity >120% predicted) and non-hyperinflated. The Mann-Whitney-U-test was used for group comparison. Results: The hyperinflated patients (N=23; 64.8±9.7 yrs; FEV 1 35.1±12.0% predicted) presented a smaller postural balance variation compared to non-hyperinflated patients (N=44; 67.5±8.8 yrs; FEV 1 46.7±13.8% predicted) in the total path length (28.7±10.7cm vs. 32.8±8.3cm, p=0.02), in the amplitude (1.95±0.95cm vs. 2.26±0.87cm, p=0.016) and path velocity (0.74±0.26cm/s vs. 0.88±0.24cm/s, p=0.01), respectively, in the AP direction in the condition standing with eyes open. No significant difference between groups were observed in the ML direction or for the more difficult tests (p>0.05). Conclusion: Hyperinflated COPD patients present less displacement in the anteroposterior direction possibly due to change in the centre of pressure. This lower displacement may have implications for falls.