Acute effects of Expiratory Positive Airway Pressure (EPAP) on different levels in ventilation and electrical activity of sternocleidomastoid and parasternal muscles in Chronic Obstructive Pulmonary Disease (COPD) patients: a randomized controlled trial.

Small single-centre trial in stable COPD; the paper reports 35 enrolled, seven not randomized and seven lost during follow-up, and the baseline table gives gender counts of 6/4 and 3/7 rather than an explicit analysed total, so it may not apply to more severe, unstable, oxygen-dependent or higher BMI patients. The paper reports 35 enrolled, seven not randomized and seven lost during follow-up, but the baseline table gives gender counts rather than an explicit analysed total; the exact analysed number is unclear. Outcomes were acute changes during and shortly after one 20 minute EPAP application, not long-term symptom, exercise, exacerbation or function outcomes. End-expiratory lung volume was not measured, so the effect on hyperinflation, an important COPD problem, is unknown. The different SCM and parasternal responses were not explained by baseline disease severity or expiratory muscle strength, and the authors could not determine why pressure levels produced opposite patterns. Sample size planning used pilot data and indicated six subjects per group could detect a parasternal sEMG difference after 20 minutes, which is a very small basis for a clinical trial. Ventilation measures were short-term and the device precision was described as 3-4% variation, so respiratory rate and tidal volume changes should be interpreted with caution.

Do not choose EPAP 15 as the better pressure because it increased tidal volume more. In this study, EPAP 10 increased parasternal activity more and reduced SCM activity, while EPAP 15 increased SCM activity. The effects were measured only during a single 20 minute application, so they do not show long term benefit or optimal pressure.