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.
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.
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.