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Respiratory Management (Rehab Phase)

Abdominal Neuromuscular Electrical Stimulation

Abdominal neuromuscular electrical stimulation can be used in conjunction with voluntary efforts (depending on the level of SCI) to improve forced expiratory maneuvers including cough.

Author Year; Country
Score
Research Design
Total Sample Size

Methods Outcome

McCaughey et al. 2015; United States Cohort
N=10

Population: N=10* ventilator-dependent tetraplegic SCI patients (8M, 2F) & N=9 retrospectively matched control patients (8M, 1F)
Mean (SD) age**: 48.2 (18.0) years Median (SD) DOI**: 22.2 (12.0) years *1 male excluded in analysis **Applicable to intervention group only.
Treatment: Abdominal functional electrical stimulation (AFES).
Outcome Measures: VT, VC, time to ventilation weaning.

  1. Significantly greater VT in AFES group compared to control group in 1 of 9 sessions, but not significant longitudinally.
  2. Significantly greater VC in final 2 sessions (AFES) or 3 sessions (control), compared to respective first session; no significant between-group difference.
  3. No significant difference between groups in change of VT and VC per week.
  4. No significant between group difference in time to wean.

McBain et al. 2015; Australia
Pre-Post
N=7

Population: N=7 SCI patients (7M 0F) Mean (SEM) age: 56 (4) Mean (SEM) DOI: 18 (7.5) years All with motor impairments above C7
Treatment: Abdominal muscle electrical stimulation.
Outcome Measures: Gastric (Pga) and esophageal (Pes) pressure, PEFR during cough (PEFcough).

  1. Significant increase in mean Pga, Pes, PEFcough and total expiratory volumes from near TLC and expiratory volume below FRC during stimulated cough.
  2. Significantly greater increase in Pga, Pes, PEFcough and total expiratory volumes from near TLC with increasing stimulus intensity.
  3. Pga & Pes did not plateau except in 1 patient at intensity of 400mA.
  4. PEFcough plateaued in all patients at a mean (SD) intensity of 211 (29) mA and expiratory volume of 4.0(0.4)L.

McBain et al. 2013; Australia Randomized crossover design N=15
PEDro =5

Population: N=15 males with SCI (C4- T5); mean (SD) age: 45(4); DOI: 11.9(4.3) yrs.
Treatment: All participants trained for 6 weeks, 5 days per week (5 sets of 10 coughs per day). Participants coughed voluntarily at the same time as a train of electrical stimulation was delivered over the abdominal muscles via posterolaterally positioned electrodes (50Hz, 3s).
Outcome measures: Pes and Pga expiratory pressures, peak expiratory flow (PEFcough) produced before, during, and after the training.

  1. During voluntary coughs, FES cough stimulation improved Pga, Pes, and Pescough acutely, 20-fold, 4-fold, and 50%, respectively.
  2. Six weeks of cough training caused further improvements. It significantly increased Pga (SD) from 37.1 (2.0) to 46.5 (2.9) cmH2O, Pes from 35.4 (2.7) to 48.1 (2.9) cm H2O, and PEFcough from 3.1 (0.1) to 3.6 (0.1) L/s.
  3. Cough training also improved pressures and flow during voluntary unstimulated coughs.

McLachlan et al. 2013; UK Longitudinal study N=12

Population: N=12 participants with tetraplegia (11M;1F); median age: 31 yrs (range: 18-73); 7 AIS A, 5 AIS C; median DOI: 5 months (range: 2-94).
Treatment: 3 weeks of abdominal muscle conditioning using transcutaneous abdominal functional electrical stimulation (AFES).
Outcome measures: FVC, FEV1, PEFR , MEP.

  1. Mean (SD) FVC increased by 0.36 (0.23) L during training.
  2. No significant changes were found in mean FEV1 and PEF.
  3. No significant change was found in the outcome measures during a 1- week pre-training control phase and during a 3-week post-training phase.

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Hascakova-Bartova et al. 2008; Belgium Prospective controlled trial
N = 10

Population: 10 SCI participants, age range 23 – 71 years; 9M 1F, lesion level T10 – C5; 6 with AIS-A, 4 with AIS-B or C.
Treatment: 4 participants were assigned to abdominal neuromuscular ES for 25 minutes daily for 8 weeks. 3 participants receive placebo, and 3 had placebo followed by ES.
Outcome Measures: FVC.

  1. ES significantly worsened FVC when measured during non-stimulation in the ES group.
  2. In the placebo controlled group there were no differences in FVC.
  3. In the placebo-followed by ES group, after ES all participants has worsened FVC.

Spivak et al. 2007; Israel
Pre-Post
N=10

Population: 10 male patients aged 22-60 years with tetraplegia. AIS- A n=2; AIS B n=7l; AIS C n=1
Treatment: Respiratory tests: 1) without assistance; 2) with manually assisted expiration; 3) FES-assisted expiration activated by a caregiver; 4) manually self- activated FES-assisted expiration; and 5) FES-assisted expiration activated by EMG signals elicited from the patient’s own muscle.
Outcome Measures: PEF, FVC, MVV.

  1. With unassisted breathing, PEF, FVC, MVV were 60% lower than that expected in people without SCI.
  2. Manual assistance significantly improved the mean PEF by 36.7%, and FVC by 15.4%. MVV improved but was not significant.
  3. FES did not significantly change the measurements, however, EMG- activated FES significantly increased PEF and FVC by 15.8 and 18.9% respectively when compared to patient-activated FES.

Discussion

A recent RCT (McBain et al. 2013) showed that electrical stimulation delivered over abdominal muscles via posterolaterally positioned electrodes during cough improved abdominal and esophageal pressures during cough as well as the cough expiratory flow rate. With 6 weeks of cough training, these pressures showed even greater improvements. Cough training also improved pressures during unstimulated coughs. Less promising results have been shown by others (McLachlan et al. 2013; Hascakova-Bartova et al. 2008) who also studied the effect of abdominal neuromuscular electrical stimulation (ES) on FVC. Smaller sample sizes, different methods, and shorter training periods may in part, explain their conflicting results.

Conclusion

There is level 2 evidence (McBain et al. 2013) that abdominal electrical stimulation during cough improved cough pressure. After cough training, pressure was improved in unstimulated voluntary cough.

There is level 2 evidence (Hascakova-Bartova et al. 2008) that abdominal neuromuscular electrical stimulation (ES) decreases the FVC.

There is level 4 evidence (Spivak et al. 2007) that EMG-activated FES significantly improves both PEF and FVC in tetraplegia patients, when compared to patient-activated FES.

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