A quantitative, pooled analysis and systematic review of controlled trials on the impact of electrical stimulation settings and placement on pressure ulcer healing rates in persons with spinal cord injuries

Pressure ulcers (PrUs) are among the most common secondary complications following spinal cord injury (SCI). External electrical current applied to a wound is believed to mimic the body's natural bioelectricity and to restart and stimulate endogenous electrical fields to promote wound healing. A systematic review was conducted to critically appraise and synthesize updated evidence on the impact of electrical stimulation (ES) versus standard wound care (comprising cleansing, dressing, nutrition, and debridement as necessary) and/or sham stimulation on PrU healing rates in persons with SCIs. Medline, Embase, the Cumulative Index for Nursing and Allied Health Literature (CINAHL), PsycINFO, and Cochrane Central were searched using the terms spinal cord injury, electrical stimulation, and pressure ulcer in free text and MESH terms. Publications were limited to peer-reviewed, randomized controlled trials (RCTs) and non-RCTs (CCTs) published in English from 1985 to 2014. The methodological quality of the RCTs was evaluated using the Jadad scale; CCTs were assessed using the Downs and Black tool. Pooled analyses were performed to calculate the mean difference (MD) for continuous data, odds ratio (OR) for dichotomous data, and 95% confidence intervals (CI). A total of 8 trials were reviewed - 6 RCTs and 2 CCTs included a total of 517 SCI participants who had at least 1 PrU. The number of patients per study ranged from 7 to 150 and the number of wounds from 7 to 192. Comparison models included ES irrespective of current type and placement of electrodes against sham/no ES (7 trials), ES delivered by electrodes overlaid on the ulcer versus sham/no ES (4 trials), ES delivered by electrodes placed on intact skin around the ulcer versus sham/no ES (4 trials), ES delivered by electrodes overlaid on the wound bed versus placed on intact skin around the ulcer (1 trial), ES with pulsed current versus sham/no ES (6 trials), ES with constant current versus sham/no ES (2 trials), pulsed current ES versus constant current ES (1 trial), number of PrUs closed (2 trials), and incidence of PrU worsened by ES versus sham/no ES (2 trials). The overall quality of studies was moderate; 2 trials were rated as good quality, 2 were poor quality, and 4 were moderate. Evidence showed ES increased the rate of PrU healing in patients with SCI (MD 4.97, 95% CI 1.97-7.98, P = 0.00; N = 7 studies and 559 ulcers), and a higher proportion of ulcers healed (OR 2.68, 95% CI 1.17-6.14, P = 0.02; N = 2 studies and 226 ulcers). The data suggest pulsed current ES increased the healing rate (MD 6.27, 95% CI 2.77-9.78, P = 0.0005; N = 6 studies and 509 ulcers) more than constant current (MD 4.50, 95% CI 1.19-10.18, P = 0.12; N = 2 studies and 200 ulcers). In addition, wounds with electrodes overlaying the wound bed seemed to heal ulcer faster than wounds with electrodes placed on intact skin around the ulcer. Future preclinical, in vivo models and clinical trials examining the impact of electrodes configuration for PrU healing are warranted