1. Carlin, Brian MD
  2. Roitman, Jeffrey L. EdD

Article Content

Collins EG, Langbein WE, Fehr L, O'Connell S, Jelinek C, Hagarty E, Edwards L, Reda D, Tobin MJ, Laghi F Am J Respir Crit Care Med. 2008;177(8):844-852.


Background and Objectives: Exercise induced dynamic hyperinflation contributes to decreased exercise tolerance in COPD. It is unknown whether respiratory retraining (ventilation feedback (VF) training) can affect exercise-induced dynamic hyperinflation and increase exercise tolerance. This study was conducted to determine whether patients with COPD would achieve longer exercise duration if randomized to a combination of exercise training plus VF training than either form of training on its own.


Methods: A total of 64 patients with COPD were randomized to one of three groups: VF plus exercise, exercise alone, and VF alone. VF used a system consisting of a pneumotach interfaced with a computer. Patient interaction with the computer screen was then afforded so as to allow the patient to adjust their respiratory rate and expiratory time based upon the computer generated algorithm. As exercise training progressed, the respiratory rate goal was decreased by 1 breath/minute and the expiratory time was increased by 0.05 seconds for a given workload. Exercise duration before and after 36 training sessions and exercise-induced hyperinflation and respiratory pattern before and after training were measured.


Results: 49 patients completed training. The duration of constant work-rate exercise was 40.0 +/- 20.4 minutes (mean + SD) with VF plus exercise, 31.5 +/- 17.3 minutes with exercise alone, and 16.1 +/- 19.3 minutes with VF alone. Exercise duration was longer in VF plus exercise than VF alone (P < 0.0001) but did not reach predetermined statistical significance when VF plus exercise was compared with exercise alone (P = 0.022). After training, exercise induced dynamic hyperinflation, measured at isotime, in VF plus exercise was less than in exercise alone (P = 0.014) and less than in VF alone (P = 0.019). After training, expiratory time was longer in VF plus exercise training (P < 0.001), and it was not significantly different in the other two groups.


Conclusions: The combination of VF plus exercise training decreases exercise induced dynamic hyperinflation and increases exercise duration more the VF alone. An additive effects to exercise training from VF was not demonstrated by predetermined statistical criteria.


Editor's Comment. Exercise-induced dynamic hyperinflation is a major contributor to decreased exercise tolerance in patients with COPD. Exercise training is an essential component to pulmonary rehabilitation. Improving the effectiveness of exercise training is an important question that needs to be asked and answered. "Training" the patient to use a slower, deeper ventilatory pattern through the use of a feedback system was shown in this study to improve gains in exercise tolerance and may be a means to further improve the effectiveness of exercise training during pulmonary rehabilitation.