Is there an optimal level of positive expiratory pressure (PEP) to improve walking tolerance in patients with severe COPD?

Background: The application of positive expiratory pressure (PEP) devices during exercise had been proposed in order to counteract the pulmonary hyperinflation, reduce the dyspnea and thus increase the exercise tolerance in patients with severe chronic obstructive pulmonary disease (COPD). This randomized controlled crossover trial investigated the effect of two different levels of PEP (1 cmH(2)O and 10 cmH(2)O) on distance covered at 6 minute walk test (6 MWT) in patients with severe COPD. Secondary outcomes were the evaluation of PEP effects on physiological and pulmonary function variables.Methods: Seventy-two severe COPD patients, referred to our hospitals as in and out patients, were recruited. A basal 6 MWT without devices was performed on the first day, and then repeated with PEP 1 cmH(2)O (PEP1) and 10 cmH(2)O (PEP10), with a randomized crossover design. Slow and forced spirometries, including the inspiratory capacity measure, were repeated before and after each 6 MWT.Results: 50 patients (average age 69,92 year, mean FEV1 41,42% of predicted) concluded the trial. The 6 MWT improved significantly among both PEP levels and baseline (323,8 mt at baseline vs. 337,8 PEP1 and 341,8 PEP10; p < .002 and p < .018, respectively). The difference between PEP10 and PEP1 did not reach the significance. No improvements were found in pulmonary function, symptoms and physiological variables after the 6 MWT.Conclusions: In patients with severe COPD, the application of 1 cmH(2)O of PEP seems to improve the exercise tolerance as 10 cmH(2)O, with similar dyspnea. Further studies should investigate the effects of low levels of PEP on aerobic training programs.