Abstract
Skeletal muscle dysfunction and exercise intolerance are common in severe chronic obstructive pulmonary disease (COPD). We assessed the effectiveness of neuromuscular electrical stimulation (NMES) as a home-based exercise therapy. In this double-blind, placebo-controlled trial, undertaken across three UK National Health Service sites, we randomly assigned (1:1) adults with COPD, a forced expiratory volume in 1 s (FEV1) less than 50% predicted, and incapacitating breathlessness (Medical Research Council dyspnoea scale ≥4) to receive active or placebo NMES, daily over a 6-week period. Randomisation was by an independent system using minimisation to balance age, GOLD stage, and quadriceps strength. Participants and outcome assessors were masked to group allocation. The primary endpoint was change in 6-min walk test (6MWT) distance at 6 weeks. Analysis was by intention to treat. The trial was registered as ISRCTN15985261 and is now closed. Between June 29, 2012, and July 4, 2014, we enrolled 73 participants, of whom 52 participants were randomly assigned; 25 to receive active NMES and 27 to placebo NMES. Change in 6MWT distance was greater in the active NMES group (mean 29·9 [95% CI 8·9 to 51·0]) compared with in the placebo group (-5·7 [-19·9 to 8·4]; mean difference at 6 weeks 35·7 m [95% CI 10·5 to 60·9]; p=0·005). Sensitivity analyses for complete-cases and adjustment for baseline values showed similar results. 6 weeks after stopping the intervention the effect waned (7·3 m [95% CI -32·5 to 47·0]; p=0·50). The proportion of participants who had adverse events was similar between groups (five [20%] in the active NMES group and nine [33%] in the placebo group). Two participants, one from each group, reported persistent erythema, which was considered to be possibly related to NMES and the use of adhesive electrodes. NMES improves functional exercise capacity in patients with severe COPD by enhancing quadriceps muscle mass and function. These data support the use of NMES in the management of patients unable to engage with conventional pulmonary rehabilitation. More work is needed to study how to maintain the effect. National Institute for Health Research.
Highlights
Chronic obstructive pulmonary disease (COPD) is a major contributor to global morbidity and mortality; it affects an estimated 210 million people worldwide,[1] places financial burden on health-care systems,[2] and is projected to be the third most frequent cause of death by 2020.3 chronic obstructive pulmonary disease (COPD) has systemic impact and skeletal muscle dysfunction is a well recognised extrapulmonary manifestation, with preferential weakness and atrophy noted in the lower limbs—mainly as a consequence of physical inactivity.[4]
Trial participants had a mean age of 70 years (SD 10) and severe disease by spirometry criteria with a median of four (IQR 2–5) exacerbations in the previous year. 22 participants (42%) had at least one comorbidity
Our study shows that 6 weeks of neuromuscular electrical stimulation (NMES) to the quadriceps improved functional exercise capacity in patients with severe COPD and incapacitating levels of breathlessness
Summary
Chronic obstructive pulmonary disease (COPD) is a major contributor to global morbidity and mortality; it affects an estimated 210 million people worldwide,[1] places financial burden on health-care systems,[2] and is projected to be the third most frequent cause of death by 2020.3 COPD has systemic impact and skeletal muscle dysfunction is a well recognised extrapulmonary manifestation, with preferential weakness and atrophy noted in the lower limbs—mainly as a consequence of physical inactivity.[4]. A proposed alternative treatment is neuromuscular electrical stimulation (NMES) This uses a portable stimulator and skin electrodes to produce a controlled contraction of the muscle.[12] NMES can be selfadministered at home, unsupervised, and carries a low metabolic load, providing an acceptable therapy for patients living with a high-symptom burden who find travel to clinics and classes difficult.[13] The strengthening effect of NMES is well established among patients with severe disease compared with no exercise 12 and with lower limb resistance training.[14] The effect of NMES on functional exercise performance is not yet clear but is important to understand because this is a key determinant of health status, and relates to overall survival in this group.[6,12] data to help to embed
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