P34 Optimal electrode position for Abdominal Functional Electrical Stimulation
McCaughey EJ[1,2], Boswell-Ruys CL[1,2,3], Hudson AL[1,2], Gandevia SC[1,2,3], Butler JE[1,2]
- NeuRA, Randwick, NSW 2031, Australia
- School of Medical Sciences, University of New South Wales, Kensington, NSW 2052, Australia
- Prince of Wales Hospital, Randwick, NSW 2031, Australia
Background: Abdominal Functional Electrical Stimulation (Abdominal FES) improves respiratory function.(1,2,3) Despite this, clinical uptake remains low. One reason is a lack of agreement on the optimal electrode position to improve respiratory function. Therefore, this study aimed to ascertain the optimal electrode position for Abdominal FES.
Methods: Ten able-bodied participants received Abdominal FES using electrodes placed: 1) posterolateraly on the abdominal wall; and at the motor points of 2) the external oblique muscles 3) the external oblique and rectus abdominis muscles. Gastric (Pga) and esophageal (Pes) pressure were measured using a gastroesophageal catheter. Single stimulation pulses were applied at functional residual capacity during step-wise increments in stimulation current to maximal tolerance or until Pga plateaued.
Results: Stimulation applied posterolateraly on the abdominal wall led to 95% and 56% greater Pga and Pes compared to stimulation of the external oblique muscles alone (p<0.001), and 71% and 53% greater Pga and Pes compared to stimulation of the external oblique and rectus abdominis muscles (p<0.001). Stimulation of the external oblique and rectus abdominis muscles led to an 18.3% decrease in Pga compared to stimulating only the external oblique muscles (p=0.040), with no effect on Pes (p=0.809).
Conclusion: Abdominal FES applied via electrodes placed in a posterolateral position on the abdominal wall generated higher pressures than stimulating at the motor points of the rectus abdominis and external oblique muscles. As pressure generation is a good indicator of expiratory muscle strength, and thus cough efficacy,(4) we recommend this electrode position for future applications of Abdominal FES.
- McCaughey EJ et al. (2016) Spinal Cord 54, 628-639
- Butler JE et al. (2011) Neurorehabilitation and Neural Repair 25, 158-167
- Jung JH et al. (2014) J Phys Ther Sci 26, 73-76
- Lim J et al. (2007) J Appl Physiol 102, 1612-1617