Abdominal NMES can be used in conjunction with voluntary efforts (depending on the level of SCI) to improve forced expiratory maneuvers including cough.
McCaughey et al. (2016) showed that abdominal functional electric stimulation is an effective technique for improving respiratory function in both an acute (as measured by cough peak flow [CPF]) and chronic manner (as measured by FVC, VC, and PEF) in people with SCI. However, low participant numbers and heterogeneity across studies reduced the power of the meta-analysis and the establishment of the clinical efficacy of this technique.
A RCT (McBain et al. 2013) showed that ES delivered over abdominal muscles via posterolaterally positioned electrodes during cough improved abdominal and esophageal pressures 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 NMES on FVC. Smaller sample sizes, different methods, and shorter training periods may in part, explain their conflicting results.
There is level 2 evidence (from one RCT: McBain et al. 2013) that abdominal ES during cough improved cough pressure. After cough training, pressure was improved in unstimulated voluntary cough.
There is level 2 evidence (from one prospective controlled trial: Hascakova-Bartova et al. 2008) that abdominal NMES decreases the FVC.
There is level 4 evidence that (from one pre – post study: Spivak et al. 2007) EMG-activated FES significantly improves both PEF and FVC in patients with tetraplegia, when compared to patient-activated FES.