Effectiveness of neuromuscular electrical stimulation for the rehabilitation of moderate-to-severe COPD: a meta-analysis

Figures & data

Table 1 Characteristics of randomized controlled trials included in the meta-analysis

Study, year	Number of patients (m/f)	Grade	Stage	BMI, kg/m^2 (NMES/sham)	Age, years (NMES/sham)	FEV1% (NMES/sham)	Study group (n)	NMES group			Control group	Study design
								Training protocol	NMES parameters	Outcomes
Bourjeily-Habr et al,^Citation19 2002	18 (10/8)	Moderate- to-severe	Stable COPD	26.2/27.1	58.5/61.5	35.6/40.7	NMES (9); control (9)	6 week ×3 sessions/week; 20 min/per session	Frequency: 50 Hz; pulse duration: NA; intensity: 56.7–95 mA; duty cycle: 0.2 s on/1.3 seconds off	SWT; quadriceps strength (isokinetic peak torque)	Control: sham NMES (same instruction and electrode position, but no stimulation)	RCT, double-blind
Neder et al,^Citation20 2002	15 (9/6)	Moderate- to-severe	Stable COPD	24.8/25.6	66.6/65	38/39.5	NMES (9); control (6)	6 week ×5 sessions/week; 15 min in the 1st week and 30 min thereafter	Frequency: 50 Hz; pulse duration: 300–400 us; intensity: 10–20 mA to 100 mA; duty cycle: 2 s on/18 s off to 10 s on/30 s off	Quadriceps strength (peak torque), exercise endurance	Usual care	RCT, double-blind
Zanotti et al,^Citation18 2003	24 (17/7)	NA	Stable COPD in ICU	24.5/22.4	66.2/64.5	NA	NMES + UR (12); UR (12)	4 week ×5 sessions/week; 30 min/per session	Frequency: 8–35 Hz; pulse duration: 250–350 us; intensity: NA; duty cycle: NA	Peripheral muscle strength	ALM	RCT, double-blind
Vivodtzev et al,^Citation17 2006	17 (11/6)	Severe	Stable COPD	18.1/18	59/68	27/34	NMES + UR (9); UR (8)	4 week ×4 sessions/week; 30 min/per session	Frequency: 35 Hz; pulse duration: 400 us; intensity: max tolerable (21–46 mA); duty cycle: 47%	Quadriceps strength (MVC); 6MWT; dyspnoea	4 days per week of ALMs	RCT, single-blind
Vivodtzev et al,^Citation12 2012	20 (13/7)	Severe	Stable COPD	21/21	70/68	34/30	NMES (12); sham (8)	6 week ×5 sessions/week; 35 min of stimulation of the quadriceps followed by 25 min of stimulation of the calf	Frequency: 50 Hz; pulse duration: 400 us; intensity: max tolerable (20–31 mA); duty cycle: 2 s on/16 s off	Quadriceps strength; exercise endurance; SWT; dyspnoea	Sham: Frequency: 5 Hz, pulse duration =100 us	RCT, double-blind
Sillen et al,^Citation25,Citation26 2014	81 (43/38)	Severe	Stable COPD	24.1/24.9	64.4/64	33/33	HF-NMES (41); strength training (40)	8 week ×5 sessions/week; 18 min/per session	Frequency: 75 Hz; pulse duration: 400 us intensity: max tolerable; duty cycle: NA	Quadriceps muscle strength (isokinetic quadriceps muscle strength); 6MWT; exercise endurance; dyspnoea; SGRQ	Strength training	RCT, single-blind
Vieira et al,^Citation27 2014	20 (20/0)	Moderate- to-severe	Stable COPD	27.47/27.6	56.3/56.4	36.5/39.6	NMES (11); control (9)	8 week ×5 sessions/week; 60 min/per session	Frequency: 50 Hz; pulse duration: 300–400 us; intensity: max tolerable (15–20 mA to 100 mA); duty cycle: 2 s on/18 s off to 10 s on/30 s off	6MWT; dyspnoea; exercise endurance; SGRQ	Sham NMES (same instruction and electrode position, but no stimulation)	RCT, double-blind
Tasdemir et al,^Citation23 2015	27 (24/3)	Moderate- to-severe	Stable COPD	25.1/27.4	62.1/62.9	29/42.5	NMES + cPR (13); Sham + cPR (14)	10 week ×2 sessions/week; 20 min/per session	Frequency: 50 Hz; pulse duration: 300 us; intensity: max individual tolerance (29.43–35.81 mA); duty cycle: 10 s on/20 s off	SWT; dyspnoea; quadriceps muscle strength; exercise endurance; MRC; SGRQ	cPR: mainly exercise training Sham: NMES (Intensive: 5 mA), insufficient to elicit a tetanic muscular contraction	RCT, double-blind
Maddocks et al,^Citation22 2016	52 (21/31)	Severe	Stable COPD	25.7/27.8	70/69	30.8/30.7	NMES (25); placebo (27)	6 week ×7 sessions/week; 30 min/per session	Frequency: 50 Hz; pulse duration: 350 us; intensity: max tolerable; duty cycle: 2 s on/15 s off to 10 s on/15 s off	6MWT; quadriceps muscle strength (MVC); SGRQ	Placebo NMES (I: 0–20 mA), insufficient to elicit a tetanic muscular contraction	RCT, double-blind

Notes: Data shown are mean ± SD unless otherwise indicated. (%), percentage predicted value.

Abbreviations: BMI, body mass index; FEV₁, forced expiratory volume in 1 second; NMES, neuromuscular electrical stimulation; NA, not available; COPD, chronic obstructive pulmonary disease; UR, usual rehabilitation; HF-NMES, high frequency neuromuscular electrical stimulation; SWT, shuttle-walk test; 6MWT, 6-minute walk test; MVC, maximum voluntary contraction; SGRQ, St George’s Respiratory Questionnaire; RCT, randomized controlled trial; ALMs, active limb mobilizations; M, male; F, female; ICU, intensive care unit; cPR, comprehensive pulmonary rehabilitation; MRC, Medical Research Council scale; I, intensive.

Figure 1 Study-selection flowchart.

Figure 2 Risk-of-bias analysis.

Figure 3 Quality assessment of quadricep strength and exercise capacity.

Abbreviations: SMD, standardized mean difference; CWT, constant-work test; SWT, shuttle-walk test; 6MWT, 6-minute walk test.

Figure 4 Quality assessment of SGRQ.

Abbreviations: SGRQ, St George’s Respiratory Questionnaire; CI, confidence interval; GRADE, Grades of Recommendation, Assessment, Development, and Evaluation.

Figure 5 Meta-analysis of randomized controlled trials evaluating the effects of NMES on quadricep strength.

Abbreviations: NMES, neuromuscular electrical stimulation; SD, standard deviation; IV, inverse variance; CI, confidence interval.

Figure 6 Meta-analysis of randomized controlled trials evaluating the effects of NMES on exercise distance.

Abbreviations: NMES, neuromuscular electrical stimulation; SD, standard deviation; IV, inverse variance; CI, confidence interval; 6MWT, 6-minute walk test; SWT, shuttle-walk test.

Figure 7 Meta-analysis of randomized controlled trials evaluating the effects of NMES on exercise endurance time.

Abbreviations: NMES, neuromuscular electrical stimulation; SD, standard deviation; IV, inverse variance; CI, confidence interval; CWT, constant-work test; SWT, shuttle-walk test.

Figure 8 Meta-analysis of randomized controlled trials evaluating the effects of NMES on St George’s Respiratory Questionnaire scores.

Abbreviations: NMES, neuromuscular electrical stimulation; SD, standard deviation; IV, inverse variance; CI, confidence interval.

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