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.
The systematic review and meta-analysis of McCaughey et al. (2016b) showed that abdominal functional electric stimulation is an effective technique for improving respiratory function in both an acute (as measured by cough peak flow) and chronic manner (as measured by forced vital capacity, vital capacity, and peak expiratory flow) in people with SCI. However, low participant numbers and heterogeneity of participants and outcomes across studies reduced the power of the meta-analysis and the establishment of the clinical efficacy of this technique.
To date, there are only two studies assessing abdominal (and pectoralis major) NMES in patients with SCI in the acute phase. McCaughey et al. (2015) showed that a program of abdominal FES applied for between 20 and 40 minutes per day, five times per week on four alternate weeks provided improvements in VT and VC and faster weaning rates from mechanical ventilation in patients with ventilator-dependent tetraplegia (mean time since injury 22.0 days) in comparison with their matched-controls. Cheng et al. (2006) showed that a conventional therapy program plus neuromuscular electrical stimulation to the clavicular portion of the pectoralis major and abdominal muscle (30 minutes daily, 5 days a week for 4 weeks) provided significant improvements in pulmonary function (as measured by vital capacity, forced vital capacity, FEV1, peak expiratory flow, MIP, and MEP) immediately after the intervention, at 3-month, and at 6-month follow-up. Pulmonary complication rates were also assessed at 6 months, and it was shown that patients in the intervention group had fewer complications than patients in the control group (p < 0.05) (Cheng et al. 2006). studied 13 participants with tetraplegia with a mean time since injury of 1.3 years; program than after the expiratory (plus electrical stimulation) program (Zupan et al. 1997). It is important to consider that measurements were taken under four sets of conditions: the patients’ unassisted efforts, their efforts combined with pressure manually applied by a therapist to the upper part of their abdomen, and their efforts accompanied by electrical stimulation of the abdominal muscles during the early phase of expirium, once triggered by the therapist and once by the patients themselves (Zupan et al. 1997). After one month of training, the patient’s voluntary effort combined with electrical stimulation (when the stimulation was triggered by the therapist and when it was triggered by the patient himself) was more effective than voluntary effort alone (Zupan et al. 1997).
There is level 2 evidence (from one RCT: Cheng et al. 2006) that a conventional training program and additional neuromuscular electrical stimulation sessions for the clavicular portion of the pectoralis major and abdominal muscle provides significant improvements in pulmonary function both short-term and long-term, and reduces the respiratory complication rates at 6 months follow-up; compared with a conventional training intervention alone in patients with acute SCI.
There is level 2 evidence (from one cohort study: McCaughey et al. 2015) that a program of abdominal FES provides improvements in VT and VC and faster weaning rates from mechanical ventilation in patients with ventilator-dependent tetraplegia in comparison with their matched-controls.