Euan McCaughey – Abstract

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]

  1. NeuRA, Randwick, NSW 2031, Australia
  2. School of Medical Sciences, University of New South Wales, Kensington, NSW 2052, Australia
  3. 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.

  1. McCaughey EJ et al. (2016) Spinal Cord 54, 628-639
  2. Butler JE et al. (2011) Neurorehabilitation and Neural Repair 25, 158-167
  3. Jung JH et al. (2014) J Phys Ther Sci 26, 73-76
  4. Lim J et al. (2007) J Appl Physiol 102, 1612-1617