Use of expiratory positive airway pressure delivered by a spring load resistor during exercise: a new tool to optimize exercise training in patients with COPD?

In this issue of the RESPIRATORY CARE, Monteiro and colleagues1 contribute to the scientific literature of COPD by applying in these patients a modality of noninvasive ventilation that has not yet been studied in depth during exercise: expiratory positive airway pressure (EPAP). The authors evaluated the effects of EPAP delivered by a spring load resistor face mask on dynamic hyperinflation during exercise. The study was conducted with COPD patients who developed dynamic hyperinflation during a previous submaximal timelimited exercise test. Those patients repeated the exercise test 48 hours later, using the face mask coupled with a spring load resistor which delivered an EPAP of around 5–10 cm H2O. When comparing the lung volumes measured before and immediately after exercise in both conditions (without and with EPAP), the authors found that inspiratory capacity and functional residual capacity changed significantly less when EPAP was applied (inspiratory capacity 0.57 0.45 L vs 0.18 0.35 L, P .021, functional residual capacity 0.69 1.10 L vs 0.22 0.68 L, P .02). The authors hypothesize that this attenuation in dynamic hyperinflation with the use of EPAP during exercise is probably linked to reduced expiratory dynamic airway compression and collapse, in addition to a reduction in the inspiratory threshold load on hyperinflated lungs of patients with COPD, enhancing neuromuscular coupling.