Beneficial effect of NMES in COPD wanes after programme completion
Authors: Vasiliki Gerovasili
Journal: The Lancet Respiratory Medicine (2015)

Chronic obstructive pulmonary disease (COPD) is predicted to become the third leading cause of death by 2030.1World Health OrganizationProjections of mortality and causes of death, 2015 and 2030.http://www.who.int/healthinfo/global_burden_disease/projections/en/Google Scholar COPD is now considered a systemic disease, with patients often presenting with symptoms beyond the respiratory system and coexisting comorbidities.2Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD).http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.htmlDate: 2015Google Scholar The musculoskeletal system is affected early in the disease process with sarcopenia and exercise intolerance being more evident in moderate to severe COPD.2Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD).http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.htmlDate: 2015Google Scholar, 3Seymour JM Spruit MA Hopkinson NS et al.The prevalence of quadriceps weakness in COPD and the relationship with disease severity.Eur Respir J. 2010; 36: 81-88Crossref PubMed Scopus (345) Google Scholar More importantly exercise intolerance carries important prognostic information.4Waschki B Kirsten A Holz O et al.Physical activity is the strongest predictor of all-cause mortality in patients with COPD: a prospective cohort study.Chest. 2011; 140: 331-342Summary Full Text Full Text PDF PubMed Scopus (675) Google Scholar In a disease that is both incurable and progressive, important goals of effective management include symptom control, avoidance of exacerbations and complications, and improvement of exercise tolerance.2Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD).http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.htmlDate: 2015Google Scholar Pulmonary rehabilitation is considered one of the cornerstones of COPD management because it not only improves exercise capacity, thus enabling patients to maintain higher levels of physical activity and preserve their independence, but also improves quality of life and symptom control.2Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD).http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.htmlDate: 2015Google Scholar, 5McCarthy B Casey D Devane D Murphy K Murphy E Lacasse Y Pulmonary rehabilitation for chronic obstructive pulmonary disease.Cochrane Database Syst Rev. 2015; 2 (CD003793.)PubMed Google Scholar Pulmonary rehabilitation is also recommended for avoidance of exacerbations.2Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD).http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.htmlDate: 2015Google Scholar Nevertheless, a major proportion of patients with COPD are unable to attend a structured pulmonary rehabilitation programme. Reasons are of course multifactorial; however, patients with COPD, especially those with advanced disease, could often be housebound, too weak for conventional rehabilitation programmes, or simply unwilling to participate in a structured rehabilitation programme. These patients are therefore deprived of the aforementioned benefits of physical exercise. Neuromuscular electrical stimulation (NMES) is an alternative exercise method that has been effectively used even in critically ill patients as it does not require patient cooperation.6Routsi C Gerovasili V Vasileiadis I et al.Electrical muscle stimulation prevents critical illness polyneuromyopathy: a randomized parallel intervention trial.Crit Care. 2010; 14: R74Crossref PubMed Scopus (196) Google Scholar Moreover, NMES has minimal ventilatory and cardiovascular requirements.7Gerovasili V Tripodaki E Karatzanos E et al.Short-term systemic effect of electrical muscle stimulation in critically ill patients.Chest. 2009; 136: 1249-1256Summary Full Text Full Text PDF PubMed Scopus (77) Google Scholar Usually the quadriceps—a muscle that is pivotal for walking—is stimulated. More importantly though, NMES has been shown to induce a systemic effect.7Gerovasili V Tripodaki E Karatzanos E et al.Short-term systemic effect of electrical muscle stimulation in critically ill patients.Chest. 2009; 136: 1249-1256Summary Full Text Full Text PDF PubMed Scopus (77) Google Scholar Unsurprisingly, several studies have therefore evaluated the effect of NMES in patients with COPD.8Maddocks M Gao W Higginson IJ Wilcock A Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease.Cochrane Database Syst Rev. 2013; 1 (CD009419.)Google Scholar In The Lancet Respiratory Medicine, Matthew Maddocks and colleagues9Maddocks M Nolan CM Man WD-C et al.Neuromuscular electrical stimulation to improve exercise capacity in patients with severe COPD: a randomised double-blind, placebo-controlled trial.Lancet Respir Med. 2015; (published online Dec 14.)http://dx.doi.org/10.1016/S2213-2600(15)00503-2PubMed Google Scholar in a double-blind, placebo-controlled study evaluated the effect of 6 weeks home-based NMES on exercise capacity and muscle function. First, the study design is very robust in that it includes both sham NMES and blinding of the patients and the outcome assessors. The authors very appropriately focused on a subgroup of patients with severe COPD and incapacitating breathlessness. They have also included a plethora of outcome measures with exercise capacity as their primary endpoint in an attempt to achieve an integrated evaluation of the intervention. Most studies so far that assessed the role of NMES in patients with COPD had several limitations with the methods (such as lack of blinding) and did not incorporate a wide range of outcome measures.8Maddocks M Gao W Higginson IJ Wilcock A Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease.Cochrane Database Syst Rev. 2013; 1 (CD009419.)Google Scholar However, there are issues of the methods used that merit attention and could have lead to underestimating the results of the intervention. The authors reported that 6 weeks of NMES induced a moderate—but clinically significant—improvement in exercise capacity (change in 6-min walk test distance in the active NMES group [mean 29·9 (95% CI 8·9–51·0)] compared with in the placebo group [–5·7 (−19·9 to 8·4)]; mean difference at 6 weeks 35·7 m [95% CI 10·5–60·9]; p=0·005) as well as in quadriceps strength and cross-sectional area. However, looking at the data, the quadriceps mass of some patients in the sham NEMS group also seemed to increase. Possibly in an attempt to avoid unmasking, the authors chose to use relatively high sham current amplitudes (mean value 15·5 mA by the end of the programme), which are similar to amplitudes used in the active NMES group in other studies.8Maddocks M Gao W Higginson IJ Wilcock A Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease.Cochrane Database Syst Rev. 2013; 1 (CD009419.)Google Scholar, 10Dal Corso S Nápolis L Malaguti C et al.Skeletal muscle structure and function in response to electrical stimulation in moderately impaired COPD patients.Respir Med. 2007; 101: 1236-1243Summary Full Text Full Text PDF PubMed Scopus (69) Google Scholar The so-called intensity of the stimulus is determined by several characteristics of the current, but because NMES also has a systemic effect, some of the changes noted in the sham group might be attributable to NMES after all, thus leading to smaller between group differences. Interestingly, the results of the programme seemed to wane 6 weeks after its completion (7·3 m [95% CI −32·5 to 47·0]; p=0·50. This is the first study to follow patients after the completion of an NMES programme. Disappointing as they may be, the results are not surprising; but they do raise several questions. Should NMES be used as a bridge to conventional pulmonary rehabilitation? Should it be coupled with lifestyle and behavioural changes in order for patients to engage in daily physical activities that would help them to maintain the beneficial effects of the programme? Future studies should also focus on optimisation of some of the characteristics of NMES as well as the duration of the programme, because 6 weeks is probably the minimum time required for beneficial results. In summary, the study by Maddocks and colleagues is a well designed and executed study assessing a clinically relevant issue. NMES seems to render beneficial, albeit short-lived, results in patients with severe COPD unable to complete a conventional rehabilitation programme. Further studies are necessary to assess the optimum characteristics of NMES, the duration of the programme, and to better define the role of NMES in the arsenal of pulmonary rehabilitation. I declare no competing interests. Neuromuscular electrical stimulation to improve exercise capacity in patients with severe COPD: a randomised double-blind, placebo-controlled trialNMES 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. Full-Text PDF Open Access