BION TM Neuromuscular Stimulation for Pressure Ulcer Prevention
Hilton Kaplan, MD, Alfred Mann Institute, University of Southern California
Introduction
Pressure ulcers (PUs) are a debilitating pathology resulting from pressure and shear in the soft tissues of immobilized patients. The fact that so many therapies are available is ironically testament to the relatively poor success of the available treatments. Despite the wide variety of current preventive measures, PUs remain a significant pathology (attested to by the high incidence of up to 38% and extremely high recurrence rates of 61% even after flap surgery). Neuromuscular Electrical Stimulation (NMES) for pressure-relief has been researched for well over 2 decades now, with multiple papers indicating positive benefits. Current hypotheses of mechanisms that lead to prevention of pressure ulcers include weight shifting to relieve and redistribute pressure, increased muscle volume (more padding), and increased vascularity. However NMES remains unharnessed because of limitations imposed by the prerequisite
“wiring” of patients.
BION Active Seating (BAS)
BIONs are injectable, wireless electrical stimulators that receive power and command signals by inductive coupling from an external transmission coil. One or more can be placed near or in various muscles and nerves and selectively activated with precise control of pulse current, duration and timing. BIONs have been demonstrated to be safe and effective in chronic studies in animals and human subjects. They are particularly suitable for use in this proposed clinical application because of their small size (2mm x 16mm), hermetic packaging, stable fixation in connective tissue, and virtually unlimited lifespan. The transmission coil to power and command the implants can be located in a cushion, seat or back of a wheel chair, avoiding any direct contact with or penetration of already fragile skin. Using BION microstimulators to electrically stimulate the gluteal muscles is a novel way to achieve the published benefits of NMES, without the usual limitations discussed above.
Optimal placement of a BION for gluteal stimulation is near the inferior gluteal pedicle. Unfortunately, external landmarks for the pedicle are not reliable, especially in individuals who have atrophied gluteus muscles. During gluteal flap surgery to repair pressure ulcers in the buttock area, the inferior gluteal pedicle is exposed, giving the surgeon the opportunity to implant a BION with full view of the area. We propose to implant a BION near the inferior gluteal pedicle during gluteal flap surgery and subsequently stimulate the gluteus muscle daily in order to provide short and long-term pressure relief and reduction of pressure ulcer reoccurrence.
The BION treatment schedule will be incorporated into the healing / treatment schedule of the flap surgery and in-patient time. Moreover, all subjects will receive normal nursing pressure care in parallel to the
BION therapy (including relief of pressure with cushions, etc). Patients will be followed up for 1 year.
Therapy: BION Conditioning (BC) to strengthen the gluteus maximus muscle would start as movement is allowed (in the 4th week). During the 9th week, once the patient can sit in his/her wheelchair, BION
Active Seating (BAS) would begin (NMES used to achieve pressure relief). Both BC and BAS are noninvasive.
Follow up investigations: Clinical Examination x 7 (non-invasive); Seating Pressure Mapping x 6
(non-invasive); MIBI-SPECT Scan x 3 (a very common procedure for assessing cardiac and other muscle perfusion: a safe amount of radio-tracer is given intravenously allowing scintigraphy of the muscles); MRI
Scan x 2 (non-invasive); and Seated X-Rays x 2 (2 conventional X-Rays).
Risks & Benefits
Risks: The risks during the implantation of the BIONs are the same as for the gluteal rotation flap surgery; however, because these patients are already undergoing flap surgery, the only concern here is the added risk of having the BION implanted during the surgery.

During the gluteal rotation flap surgery, both the superior and inferior gluteal neurovascular pedicles will be exposed and easily in reach. Possible further risks can occur at 2 stages during the procedure. Firstly, once the inferior gluteal pedicle is palpated (the pulsatile artery can be felt easily), the BION will be laid alongside this pedicle under vision, and so some limited elevation of the flap will be required to visualize this (with possibly an additional light source e.g. a headlamp). At no time will the pedicle be opened or further dissected out, other than with the usual normal blunt dissection approach. It is unlikely, though possible, that the artery and or nerve will be mistakenly cut or damaged. Secondly, to prevent the BION from moving in the early post-operative period until the tissues stick back down and the spaces developed close up, it will be affixed via a single 5/0 Vicryl suture around the tantalum stem / tube at either end of the implant. It will secure the BION to adjacent connective tissue or gluteus maximus fascia, and must be placed so as not to injure the pedicle. It is unlikely, but possible, that tissue will be damaged during the suturing.
We anticipate that both of these 2 stages together will require minimal increased duration (an increased surgical time of 5-10 minutes at most, in a 1-2 hour procedure); or risk (for patients who are undergoing this surgery already).
There is a small possibility that a foreign body reaction to the device may occur; in this case, the device could be removed in a short procedure.
Benefits: A possible benefit for subjects in this study is the possible decrease in pressure wound recurrence, as well as better gluteal muscle health (including increased muscle size and increased blood perfusion) on the stimulated side.
A possible benefit for society is a better understanding of stimulation parameters for this particular application, as well a better understanding of wound healing in general.