Hilton Marc Kaplan & Anne-Caroline Dupont Salter



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NeuroMuscular Electrical Stimulation for PU Prevention

Neuromuscular electrical stimulation (NMES) for pressure-relief has been researched for well over 2 decades now, with multiple papers indicating the positive benefits of this therapy100,104,105. Current hypotheses of the mechanism that leads to prevention of pressure ulcers include weight shifting to relieve pressure and improve pressure distribution, increased muscle volume (more padding), and increased vascularity100,104,105.


A patent on using NMES for PU inhibition was filed with the USPTO in 1985, and issued in 1988. Assigned to The University of Michigan, it is based on transcutaneous NMES over potential PU sites and claims benefits from the resultant shifting of weight, muscle ‘blood pump’ effect, muscle hypertrophy (padding) and the ‘conditioning’ of atrophic muscles100.
In 2000 Bogie et al104 published an article in which the role of NMES in PU prevention was reviewed. They concluded that implantable NMES systems may have great potential for PU prevention, particularly for individuals who lack sensation or are physically unable to perform regular independent pressure relief.
Preliminary results of a more recent study by Bogie’s group105 were published in an abstract. They investigated the hypothesis that long-term use of NMES using an implanted stimulation system would produce a sustained improvement in tissue health, and may therefore provide an alternative technique for the prevention of pressure sores in veterans with spinal cord injury. Preliminary results show that interface pressures in the ischial region were significantly reduced (p<0.01). No details on stimulation parameters were offered.
Waiting for article / book (d.w. FJR pls Anne) to find out the particular paradigm used (what m.s were exercised, …) and what was measured (recurrence, …)?
It has been shown too that PU recurrence rates can be reduced from 20% to 6% using ES113.

Current Drawbacks

The limitations of current treatments are of great concern. Despite the wide variety of current preventive measures, PUs remain a significant pathology (as attested to by the high incidence of PUs (up to 38%150) and the extremely high recurrence rates even after flap surgery (61%133). ES – a therapy that has demonstrated significant potential benefits in the literature – remains unharnessed because of limitations imposed by the prerequisite “wiring” of patients.




BION Electrical Stimulation for Pelvic Pressure Ulcer Prevention

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 the proposed clinical application because of their small size (2mm diameter x 16mm long), hermetic packaging, stable fixation in connective tissue, and virtually unlimited lifetime. 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.


Two hypotheses guide this research: First we hypothesize that BION gluteal stimulation will reduce the incidence of PUs. Second, we hypothesize that the treatment will be accepted well by the subjects because it can be self-administered outside a clinic. Using BION microstimulators to electrically stimulate the gluteal muscles is a novel way to achieve the published benefits of ES, without the usual limitations as discussed above.
Fuhrer et al report that 65% of PUs are in the pelvic111.region. Gluteus maximus (gluteus) muscle stimulation will benefit both sacral and ischial lesions. These constitute 42-54% of all PUs according to four biennial national prevalence surveys108. Of these 30% are Stage III & IV111 (where surgery is the treatment of choice). We propose to achieve such gluteal stimulation with a single BION placed along the inferior gluteal neurovascular pedicle. Preliminary anatomic dissections and 3D CT reconstructions performed at the University of Southern California to map these pedicles indicate that the nerve trunk appears at a well-defined location as it exits from beneath the inferior edge of the piriformis muscle, before branching out under and into the substance of gluteus maximus109,110. Placement of a device at this site would facilitate full and reliable stimulation of gluteus.

Goal
The goal of this new treatment is two-fold:


  1. to improve dynamic, short-term pressure distribution and increase dynamic, short-term blood perfusion to the area during stimulation.

  2. to increase muscle mass, size and tone in that area so that there is a long-term decrease in peak pressure and density and a long-term increase in blood perfusion to the area in the periods between stimulation bouts (at rest).



Hypotheses
Primary hypotheses:

We hypothesize that



  1. The subjects will be compliant and receive at least 80% of their prescribed BION treatment.

  2. During stimulation, the BION will produce detectable contractions of the gluteus muscle.

  3. After 12 weeks of BION gluteal stimulation, localized pressure points when seated (at rest, not stimulated) will be diffused (lower pressure density) (when compared with pre-treatment values) in the gluteal region that was stimulated.



Secondary hypotheses:

We hypothesize that:



  1. During stimulation, peak pressure will be decreased significantly on the contralateral side of the contraction.

  2. After 12 weeks of BION gluteal stimulation, muscle size (both cross-sectional area and volume) will be increased (when compared with pre-treatment values) on the side of stimulation.

  3. Gluteal muscle perfusion will be increased during stimulation, when compared with value at rest.

  4. After 12 weeks of BION gluteal stimulation, perfusion of the gluteal maximus muscle (at rest and during stimulation) will be increased when compared with pre-treatment values.


Overview
Optimal placement of a BION for gluteal stimulation is near the 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 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 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 at Rancho. Moreover, all subjects will receive normal nursing pressure care in parallel to the BION therapy (including relief of pressure with cushion, etc).

Treatment schedule
The BION treatment schedule will have to incorporate the healing/treatment schedule of the flap surgery and in-patient time at Rancho.
Insert Study Plan Excel Sheet here


Week no.

1

2

3

4

5

6

7

8

9 – 12

13 – 20

Surgical Milestones

Flap surgery







Stitches removed










Discharge

12-wk follow-up


20-wk follow-up



Mobility

Lying

Lying with movement

Some Sitting


Wheelchair

Location

Rancho

Home

Follow up

x







x










x

x

x

BION Training










x

x

x

x

x

x x




BION Therapy



















x

x

x x x x x x x x

x x x x x x x x x x x x x x x x x x x x x

For three weeks after the surgery, the patient recovering from gluteal rotation flap surgery is in a prone position at Rancho. At the fourth week, the stitches are removed and the patient is allowed to perform movements but is still kept in a prone position. BION muscle strengthening (“BION Training”) would start as movement is allowed (in the 4th week). The patient starts sitting briefly during the 7th week and starting in the 9th week, the patient can sit in his wheelchair. During the 9th week, BION stimulation would start being used for pressure relief (“BION Therapy”). Can you start treatment while the patient is lying down to increase muscle strength and tone? May need a different coil…



The patient self-administers treatment by pressing one of three start buttons on a control box that can be programmed by the clinician with up to three different stimulation programs. The control box (called a Personal Trainer) records the pattern and duration of usage; this information is automatically uploaded into each patient’s personal database in the clinician’s personal computer whenever the patient returns for a follow-up visit.
BION Training:
Starting with 1 hour per day (broken down in 15 min sessions) and increasing to 5 hours per day (with sessions a maximum of 2 hours in length, sessions to be separated by at least 30 minutes of rest), 10 sec ON, 5 sec OFF at 5 Hz. The low frequency is chosen because it produces unfused contractions that are not very forceful in nature and therefore will not produce much movement of the buttock and leg area, but should facilitate circulation by their pumping action. Previous studies in rats with a model of disuse atrophy have shown that such low frequency stimulation is effective in preventing atrophy (), possibly because it activates the calcium kinase pathway responsible for maintenance and development of muscle mass. Previous clinical studies of BIONs to prevent shoulder subluxation following stroke and to strengthen quadriceps in patients with osteoarthritis have used 2-5pps stimulation with success ().
BION Therapy:
Starting when the patient starts sitting in his wheelchair, BION stimulation will be applied whenever the patient is in his wheelchair, for a minimum of 5 hours, with a cyclic paradigm : 3 sec ON, 7 sec OFF (at 20-33 Hz for a tetanic contraction). If the patient cannot sit (with stimulation) for at least 5 hours per day, the missed time will be made up with muscle strengthening time in order to maintain strength.
STIMULATION PROTOCOLS


 

 

 

 

STIMULATION PARAMETER

MUSCLE TRAINING

MUSCLE TREATMENT




 

 

 

 

 

 

 

AMPLITUDE

(mA)

1-8 (5)

1-8 (2)







intense pulse to recruit all fibres

lower pulse ... as much as is needed







 

 







 

 

FREQUENCY

(Hz)

1-2

20-33







low f : initiates minimal movement

high f : to achieve tetanic contractions







 

 







 

 

DUTY CYCLE

(s)

3 on, 3 off

2 on, 4 off

 

 

lower force contractions ... can use more of duty cycle without risking fatigue or compromising blood supply

as needed to shift weight, without becoming annoying; adequate rest to avoid fatigue or compromising blood supply

 

 

 

 


Testing:
Testing will be scheduled for before stimulation starts, at discharge from Rancho, and during follow-up visits at Rancho, for up to a total of 5 evaluation sessions. Testing includes MIR measurements of muscle cross-sectional areas and volume, Thalium scan, and pressure mapping Testing is in greater details in the Outcome Measure section.

Inclusion / Exclusion criteria
Inclusion:


  • Subject has had a spinal cord injury and has bilateral lower limb paralysis

  • Subject cannot contract voluntarily his gluteus muscle

  • Subject is between 18 and 70 years old

  • Subject sits in a wheelchair for at least 5 hours per day

  • Attending physician considers the subject in general good health (other than SCI and pressure ulcer wound)

  • Subject is having gluteal rotation flap surgery for pressure ulcer treatment in which the inferior gluteal pedicle will be exposed but not damaged or sacrificed in any way (for any pressure ulcer wound).

  • subject is mentally capable of understanding the goals and the application of therapy

  • subject is able to apply the therapy (with or without help) once discharged from Rancho

  • subject is willing and capable of giving informed consent

  • subject is willing and capable of traveling to testing center at the schedule described above


Exclusion:


  • subject is pregnant, nursing, or planning on becoming pregnant in the next 12 months

  • subject has an electronic implant (ex: heart pacemaker, etc)

  • subject has large metallic implant (e.g.: plates, hip joints) in the buttock/pelvic area (small metal implants, such as bone screws and metal sutures are acceptable).

  • subject has any condition associated with wound healing abnormality (e.g.: connective tissue disorder, immune disorder, diabetes, clinical obesity)

  • subject is malnourished

  • the attending physician has concerns about the healing of this subject (e.g.: heavy smoking, excessive and poorly-managed incontinence)

  • subject has concurrent concomitant condition affecting the buttock/pelvic area, including other pressure wound not corrected by the flap surgery.

  • Claustrophobia or fear of having an MRI scan done.

  • subject has damage to the inferior or superior gluteal neurovascular pedicles.


Justification for inclusion and exclusion criteria:
Inclusion:


  • Spinal cord injury and paralysis of the lower limbs: This study is specifically designed for wheelchair-bound patients with SCI because this population is at high risk of developing pressure ulcers, partially because of the difficulty of relieving pressure on the buttocks when seated.




  • No voluntary contractions of the gluteus muscle: this therapy will stimulate the gluteus muscle to contract. If it can contract voluntarily, BIONs are unlikely to be necessary.




  • Age: subjects above the age of 70 are considered elderly and that population has been shown to be more prone to pressure ulcers because of two risk factors: compromised nutrition and reduced skin elasticity. Subjects under the age of 18 rarely show pressure ulcers and are often not responsible for their entire care.




  • Sits in wheelchair for a minimum 5 hours/day: the therapy and equipment are designed to be used in a wheelchair because that is when the person is at most risk of developing pressure sores.




  • Good health: other important generalized health problems may be confounding variables in this study as they could affect skin health as well.




  • Gluteal flap surgery: to reduce the number of surgical procedures and take advantage of the opportunity to see the nerve pedicle, the BION will be implanted during a gluteal flap surgery that is already necessary for the subject.




  • Mentally competent: the subject has to be able to give informed consent and has to be able to understand the why and the how to apply the therapy.




  • Able to apply the therapy (or have it applied): because this is a self-applied treatment, the subject has to be able to set up and apply the therapy on his/her own or to have a caregiver who can do it at the prescribed schedule in order to achieve compliance.




  • Informed consent: because this is a research project with an investigational device, the subject has to be willing and able to give informed consent.




  • Able to travel to Rancho at prescribed schedule: In order for this study to have valid data, we need to ensure that the subject is capable and willing to visit the center at the prescribed schedule for testing and treatment.


Exclusion:


  • Pregnancy and nursing: The effects of BION™ treatments in pregnant or nursing women have not yet been investigated fully. In addition, the uncommon occurrence of strokes in this vulnerable population may render the risk of including them greater than the potential benefit.




  • Electronic Implant: Patients with electronic implants will not be accepted into the trial because the electromagnetic field produced by the external coil might potentially interfere with a pacemaker or other electronic implants. The effects of electromagnetic fields on electronic implants such as pacemakers have yet to be characterized.




  • Metallic Implant: Patients with large metallic implants will not be accepted into the trial because these metallic implants might potentially interfere with the electromagnetic field produced by the external magnetic coil.




  • Healing condition: other health problems that may affect the healing capability of the skin are confounding variables.




  • Malnourishment: patients who are malnourished are at more risk for healing problems and recurrence of pressure sores because healing requires calories and protein and because extremely thin patients experience more pressure in areas of bony protuberances than people with more adipose tissue.




  • Concerns about healing: If the attending physician has concerns about healing that have not been mentioned here, he/she should be able to exclude the subject (e.g.: heavy smoker; badly managed incontinence).




  • Concomitant condition of the buttock/pelvic area, including other pressure wounds: any condition that may affect the healing rate and add a confounding variable to the study needs to be excluded; another pressure wound not treated by the flap surgery will require care and possibly prevent the subject to sit in his/her wheelchair, preventing BION treatment to be applied.




  • Claustrophobia: one of the primary outcome measures for this study is muscle volume, for which MRI scans will be required. A subject suffering from claustrophobia will not be able to have the MRI done.



Outcome measures

Primary Outcome Measures:


  • Compliance (diary and personal trainer)

  • peak pressure distribution (with pressure interface system):

    • peak pressure (absolute value)

    • average of 4 top peak pressure values

high pressure distribution – weighted average, showing where 50% of the pressure is applied (in the smallest region possible)

  • muscle cross-sectional and volume of gluteus (by MRI)

  • muscle perfusion (Tl-scint & DTI possibility – to rediscuss with Pat Colletti) before and after exercise, and before and after treatment

  • subject satisfaction questionnaire


Secondary Outcome Measures:


  • skin color and quality (by visual examination)

(PU scale: probably Braden / Norton … still to finalize)

  • reperfusion time (by pressure and visual examination)

  • recurrence of wounds (by visual examination, photography and history)

  • BMI

  • side-symmetry of pressure (distribution of pressure between the two sides)


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