Intermittent electrical stimulation redistributes pressure and promotes tissue oxygenation in loaded muscles of individuals with spinal cord injury

Intermittent electrical stimulation redistributes pressure and promotes tissue oxygenation in loaded muscles of individuals with spinal cord injury

Gyawali et al, 2011 [n= 17; male and female; from 22 to 60 years old] aimed to assess the effectiveness of IES, in ameliorating the factors leading to DTI in individuals with spinal cord injury. Specifically, if IES-induced contractions in the gluteal muscles can 1) reduce pressure in tissue surrounding bony prominences susceptible to the development of DTI and 2) increase oxygenation in deep tissue. Each volunteer participated in two sessions. A two-channel stimulator (BioMedical Life Systems, Vista, CA) was used to administer current (biphasic, cathodic-first, charge-balanced pulses, 200 μs in duration and 40 Hz frequency) to the gluteus maximus muscles. The threshold amplitude eliciting a minimal contraction and the amplitude producing a maximal contraction were determined. Pairs of nonmagnetic, 50 mm × 100 mm surface electrodes (PureCare, Sherwood Park, AB, Canada) were placed bilaterally on the gluteus maximus muscles with the cathode over the motor point and the anode positioned rostrally along the muscle. Stimulus amplitudes producing maximal contractions were used. The main IES pattern consists of a short “ON” phase (∼10 s long) during which electrical stimulation is administered to induce a concurrent contraction in the gluteus maximus muscles. This brief “ON” period is followed by a substantially longer “OFF” phase (∼10 min long) during which no stimulation was administered. Two IES paradigms were investigated in this study: 1) continuous stimulation, in which the “ON” phase of IES consisted of bilateral gluteal stimulation for either 7 or 13 s, followed by a 10 min “OFF” phase; and 2) bursting stimulation, during which three bursts of stimuli were delivered bilaterally to the gluteus maximus muscles, each 3 s long with a brief 2-s rest period between. This also was followed by a 10-min “OFF” phase. It was observed that both IES paradigms significantly reduced pressure around the bony prominences in the buttocks by an average of 10–26% (P < 0.05). Furthermore, both IES paradigms induced significant increases in T2* signal intensity (SI), indicating significant increases in tissue oxygenation, which were sustained for the duration of each 10-min trial (P < 0.05). The results suggest that IES directly targets factors contributing to the development of DTI in people with reduced mobility and sensation and may therefore be an effective method for the prevention of deep pressure ulcers.
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  • Gyawali S, Solis L, Chong SL, Curtis C, Seres P, Kornelsen I, et al. Intermittent electrical stimulation redistributes pressure and promotes tissue oxygenation in loaded muscles of individuals with spinal cord injury.

    J Appl Physiol. 2011;

    110(1):246-255.