Neuromuscular electrical stimulation in respiratory conditions : a systematic review

Abstract

Neuromuscular Electrical Stimulation (NMES) has emerged as a promising adjunctive intervention in the management of respiratory conditions, particularly chronic obstructive pulmonary disease, where skeletal muscle dysfunction contributes to reduced functional capacity and poor quality of life. This systematic review synthesises evidence on Neuro Muscular Electrical Stimulation applications in both acute and chronic respiratory contexts, focusing on its effects on peripheral muscle strength, exercise tolerance, pulmonary function, and health-related quality of life. A structured literature search was conducted across PubMed, Google Scholar and MEDLINE and CINAHL accessed via the HyDi platform, covering publications from inception to 2025. In PubMed, both Medical Subject Headings (MeSH) and free-text terms were used, while database-specific subject headings and keywords were adapted for MEDLINE and CINAHL. Eligible studies included randomised controlled trials, systematic reviews, and meta-analyses investigating NMES in patients with COPD, acute exacerbations, or critical illness. A total of 61 articles were reviewed from which 5 were chosen. Key outcomes extracted included muscle strength, exercise capacity, pulmonary function indices, Health Related Quality of Life, and adverse events. Methodological quality and risk of bias were critically appraised to contextualise findings. Synthesis of the included meta-analyses demonstrated that NMES yields significant improvements in peripheral muscle function and functional capacity. Pooled results indicated a statistically significant increase in the six-minute walk distance (6MWD) of approximately 35–40 m following NMES compared with control interventions and a marked enhancement in quadriceps force production, particularly in severely deconditioned patients. Furthermore, systematic review data confirmed clinically meaningful improvements in health-related quality of life (HRQoL) and a reduction in exertional dyspnoea. A methodological appraisal via AMSTAR-II revealed high confidence in the systematic reviews, although the absence of pre-registered protocols was noted as a minor methodological deficit. NMES represents a safe and feasible adjunct to pulmonary rehabilitation and critical care, particularly for patients unable to engage in conventional exercise training. Nevertheless, long-term effectiveness, cost-effectiveness, and patient-centered outcomes remain underexplored. Future research should focus on protocol standardisation, integration with wearable and tele-rehabilitation technologies, and robust multicenter trials to clarify its role in routine respiratory rehabilitation.