Eggmann S1,2, Kindler A1, Luder G1, Norman S2
1Inselspital, Bern University Hospital, Department of Physiotherapy, Bern, Switzerland, 2Centre for Medical Education, School of Medicine, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom
Background: Muscle weakness is commonly experienced by critical care survivors leading to long-term functional disability. Guidelines advocate light sedation and early mobilisation to counter these complications, yet active participation remains challenging. Neuromuscular electrical stimulation (NMES) generates involuntary muscle contractions and early application might therefore induce neuromuscular adaptations. However, NMES is rarely used in clinical practice; reasons include conflicting evidence from other cohorts for instance with chronic obstructive pulmonary disease or concerns regarding its time-effectiveness ratio.
Purpose: The aim of this literature review is to determine the safety and effectiveness of NMES, when compared to no stimulation or sham stimulation, on preserving lower limb muscle strength and function of critically ill adults.
Methods: Six electronic databases (Medline, CINHAL, Cochrane Library, Scopus, Pubmed, Web of Science) were systematically searched by two independent reviewers until July 25, 2018. Titles and abstracts (n=8534) were reviewed to include, full text, high-level (systematic reviews, meta-analysis and randomised controlled trials (RCT) only), contemporaneous (January 2013-July 2018) evidence investigating lower-limb NMES in critically ill adults. Studies commencing NMES post critical care, investigating unilateral NMES or other outcomes than muscle strength were excluded. All studies were critically appraised (Cochrane risk of bias and AMSTAR tool) and rated for their level of evidence.
Results: Nine studies met the inclusion criteria and were reviewed; two meta-analyses, one systematic review and six RCTs. Two meta-analyses reported that muscle strength may be maintained with NMES, whilst the systematic review claimed very low evidence for NMES but early exercise therapy induced several short-term improvements. This was supported by the six RCTs, which found no significant improvement of muscle strength with NMES compared to standard therapy, although one RCT showed a tendency towards higher recovery of walking function with NMES at hospital discharge. Harm was infrequently reported and two RCTs had a trend for higher mortality in the NMES group. Half of the RCTs were underpowered and recruitment was terminated early in two trials questioning the feasibility of NMES in this population. The two meta-analyses demonstrated serious risk of bias, inappropriate pooling and low generalisability to people with acute critical illness, whereas the systematic review was moderate to high quality. Five of the six RCTs were recently published and not yet included in these reviews. However, we did not perform quantitative analysis due to heterogeneity and underreporting.
Conclusion(s): The effectiveness and safety of NMES in the critically ill adult have not been sufficiently reported and therefore cannot be recommended (Grade C) for routine use in clinical practice. Further assessor-blinded, sham-controlled, sufficiently powered trials are needed to explore feasibility, cost-effectiveness and the potential for harm.
Implications: Despite a trend toward strength preservation, NMES does not seem as effective as early physical rehabilitation interventions in adults with critical illness. It is further unclear, if a potential increase in muscle strength might translate into functional benefits. Consequently, clinical practice should focus on mobilisation and targeted exercise therapy until further evidence from large RCTs becomes available. However, physiotherapists should evaluate the application of NMES on an individual basis as an adjuvant therapy.
Keywords: Critical care, neuromuscular electrical stimulation, muscle strength
Funding acknowledgements: No funding has been received.
Purpose: The aim of this literature review is to determine the safety and effectiveness of NMES, when compared to no stimulation or sham stimulation, on preserving lower limb muscle strength and function of critically ill adults.
Methods: Six electronic databases (Medline, CINHAL, Cochrane Library, Scopus, Pubmed, Web of Science) were systematically searched by two independent reviewers until July 25, 2018. Titles and abstracts (n=8534) were reviewed to include, full text, high-level (systematic reviews, meta-analysis and randomised controlled trials (RCT) only), contemporaneous (January 2013-July 2018) evidence investigating lower-limb NMES in critically ill adults. Studies commencing NMES post critical care, investigating unilateral NMES or other outcomes than muscle strength were excluded. All studies were critically appraised (Cochrane risk of bias and AMSTAR tool) and rated for their level of evidence.
Results: Nine studies met the inclusion criteria and were reviewed; two meta-analyses, one systematic review and six RCTs. Two meta-analyses reported that muscle strength may be maintained with NMES, whilst the systematic review claimed very low evidence for NMES but early exercise therapy induced several short-term improvements. This was supported by the six RCTs, which found no significant improvement of muscle strength with NMES compared to standard therapy, although one RCT showed a tendency towards higher recovery of walking function with NMES at hospital discharge. Harm was infrequently reported and two RCTs had a trend for higher mortality in the NMES group. Half of the RCTs were underpowered and recruitment was terminated early in two trials questioning the feasibility of NMES in this population. The two meta-analyses demonstrated serious risk of bias, inappropriate pooling and low generalisability to people with acute critical illness, whereas the systematic review was moderate to high quality. Five of the six RCTs were recently published and not yet included in these reviews. However, we did not perform quantitative analysis due to heterogeneity and underreporting.
Conclusion(s): The effectiveness and safety of NMES in the critically ill adult have not been sufficiently reported and therefore cannot be recommended (Grade C) for routine use in clinical practice. Further assessor-blinded, sham-controlled, sufficiently powered trials are needed to explore feasibility, cost-effectiveness and the potential for harm.
Implications: Despite a trend toward strength preservation, NMES does not seem as effective as early physical rehabilitation interventions in adults with critical illness. It is further unclear, if a potential increase in muscle strength might translate into functional benefits. Consequently, clinical practice should focus on mobilisation and targeted exercise therapy until further evidence from large RCTs becomes available. However, physiotherapists should evaluate the application of NMES on an individual basis as an adjuvant therapy.
Keywords: Critical care, neuromuscular electrical stimulation, muscle strength
Funding acknowledgements: No funding has been received.
Topic: Critical care; Cardiorespiratory
Ethics approval required: No
Institution: Cardiff University
Ethics committee: School of Medicine Research Ethics Committee
Reason not required: Literature review with no involvement of human participants, material or data outside of the published, primary studies
All authors, affiliations and abstracts have been published as submitted.
