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WO2009046366A1 - Procédé et appareil destinés à prévenir les escarres de décubitus et à les traiter - Google Patents

Procédé et appareil destinés à prévenir les escarres de décubitus et à les traiter Download PDF

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Publication number
WO2009046366A1
WO2009046366A1 PCT/US2008/078839 US2008078839W WO2009046366A1 WO 2009046366 A1 WO2009046366 A1 WO 2009046366A1 US 2008078839 W US2008078839 W US 2008078839W WO 2009046366 A1 WO2009046366 A1 WO 2009046366A1
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stimulation
pressure
patient
muscles
muscle
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PCT/US2008/078839
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English (en)
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Hilton M. Kaplan
Gerald E. Loeb
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Alfred E. Mann Institute For Biomedical Engineering At The University Of Southern California
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Publication of WO2009046366A1 publication Critical patent/WO2009046366A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/36003—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation of motor muscles, e.g. for walking assistance
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/37205—Microstimulators, e.g. implantable through a cannula

Definitions

  • NMES neuromuscular electrical stimulation
  • PUs Pressure ulcers
  • PUs are common and debilitating wounds that arise when immobilized patients cannot shift their weight. Able-bodied people do not get PUs because they can voluntarily contract their muscles, thereby shifting their weight while activating trophic mechanisms that maintain muscle bulk, strength and circulation.
  • Pressure ulcers (PUs) are a debilitating pathology resulting from pressure and shear in the soft tissues of immobilized patients. Blood vessels become occluded and the soft tissues they supply necrose.
  • SCI spinal cord injury
  • the prevalence of SCI in the US has been estimated at 253,000 (225,000-296,000, June 2006), with an incidence of 1 1 ,000-12,000 new injuries each year (40 per million US population). SCI most commonly results in paralysis, as well as repeated and serious complications including PUs, incontinence, pneumonia, etc.
  • the incidence of PUs in SCI has been estimated by the Model Spinal Cord Injury Systems centers at one third (33.5%) during initial acute care and rehabilitation, and at 30% thereafter. Prevalence has been estimated at a similar percentage (Fuhrer, et al.
  • Stages I-IV 4-stage system
  • Flap reconstruction to provide well-vascularized, bulky tissue to repair PUs over bony prominences was pioneered by Davis in the 1930s. Since 1970, gluteal flaps have been widely used to this purpose (technique originally described by Ger 27,51 ). Although still the best option available, post-operative recurrence rates are high as the flap tissue in SCI patients is not truly healthy, thick, vascularized and resistant to PUs, as in healthy subjects. Reported recurrence rates vary widely. In 1992 Disa, et al. reported on 66 flaps: 61 % of PUs and 69% of patients had recurrences within a mean of 9.3 months, despite 80% having healed at discharge.
  • the recurrence rate for ischial flap closures was 21 %; the overall rate for all flaps in SCI patients was 23% (24% for paraplegics; 20% for tetraplegics).
  • PUs The pathogenesis of PUs derives from a host of compounding etiological factors. Such as pressure over bony prominences. A reciprocal relationship between pressure intensity and pressure duration has been recognized. Just as high pressures over a short time may result in PUs, so can lower pressures over a longer time. Immobility that results in the inability to shift weight are due to the tissues not experiencing periodic relief from the pressures on them. Sustained pressure reduces or occludes capillary circulation, resulting in hypoxia and necrosis of soft tissues.
  • Friction and shear can be other factors, because they can exacerbate the soft tissue damage. Tissue that is damaged, atrophied, scarred or infected demonstrates increased susceptibility to pressure. Elderly or immune compromised patients and patients with poor wound healing or collagen-vascular diseases are at greater risk too.
  • Stage I Non-blanchable erythema of intact skin. The heralding lesion of skin ulceration.
  • Stage II Partial thickness skin loss involving epidermis and/or dermis. A superficial ulcer that presents clinically as an abrasion, blister or shallow crater.
  • Stage III Full thickness skin loss involving damage or necrosis of subcutaneous tissue which may extend down to, but not through, underlying fascia.
  • the ulcer presents clinically as a deep crater with or without undermining of adjacent tissues.
  • Stage IV Full thickness skin loss with extensive destruction, tissue necrosis or damage to muscles, bone or supporting structures (e.g. tendon, joint, capsule, etc.).
  • Exemplary embodiments of the pressure ulcers (PUs) treatment and alleviation systems and methods include activating muscles that shift the position of the soft tissues that are at risk of pressure due to immobility; to achieve mechanical activation of said muscles; provide fully implanted means to deliver electrical stimulation to said nerves and muscles; to provide wireless means for transmitting electrical power and control signals from outside the body to said implanted electrical stimulators; alleviating pressure ulcers by one or more wireless miniature device that can be implanted in or near target muscles without the requiring leads for electrodes; to implant a miniature device through a tube, needle or any other injection device, in or near a target muscle to prevent or alleviate pressure ulcers.
  • Additional exemplary embodiments of the pressure ulcers (PUs) treatment and alleviation systems and methods include selectively controlling multiple implanted miniature devices to produce a variety of patterns of muscle contraction that will be effective and well tolerated by each patient; and triggering the appropriate stimulation of muscles for a given assumed posture by utilizing position sensors and to customize effective muscle stimulations patterns and/or programs person to person through fitting assessments to constitute effective pressure-relief programs.
  • PUs pressure ulcers
  • Figures 1 A and 1 B show incremental loading curves for models of different somatotypes.
  • Exemplary embodiments comprise PUP through neuromuscular electrical stimulation (NMES) using BIONs (wireless, injectable microstimulators), a method and apparatus for using NMES of appropriate muscles to shift immobile patients from any posture, for pressure ulcer prevention and treatment of all anatomic locations.
  • NMES neuromuscular electrical stimulation
  • BIONs wireless, injectable microstimulators
  • This approach may be utilized by patients with immobility such as due to SCI, stroke, dementia, or from any other cause.
  • BIONs are injectable, wireless electrical stimulators that receive power and command signals by inductive coupling from an external transmission coil(s).
  • One or more can be placed in or near 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.
  • any NMES stimulator may be suitable for this invention, BIONs are particularly suited because of their small size ( Approximately 2mm diameter x 16mm long), hermetic packaging, stable fixation in connective tissue, and virtually unlimited lifetime.
  • Transmission coil(s) to power and command the implants can be located within the wheelchairs, seats, beds or deep to any other supports that immobile patients require, so avoiding any direct contact with or penetration of the patient's already fragile skin.
  • Using BION microstimulators to electrically stimulate muscles is a useful way to achieve the benefits of NMES for preventing PUs, without the usual limitations associated with wired electrodes as discussed above.
  • the treatment may also be self-administer
  • NMES of appropriate muscles using BIONs stimulator, are capable of redistributing a patient's weight, so as to relieve pressure and prevent PUs.
  • Tissue health will be improved during NMES due to increased muscle perfusion.
  • Wound healing may be improved with increased wound-healing rates and/or decreased wound-healing complications.
  • BIONs may be implanted via percutaneous injection or during any concurrent surgery such as flaps for PU reconstruction ("healthy", although atrophic, muscle and skin are brought in to repair the deficient area, and to provide "healthy” tissue over bony prominences, while scars are designed to lie away from these areas). Together with the prophylactic NMES, all patients may receive standard nursing care (including relief of pressure with cushions, regular turnings, etc.).
  • NMES with BIONsTM injectable microstimulators
  • BIONsTM injectable microstimulators
  • the BION is a wireless, injectable microminiature stimulator (approximately 2.1 mm diameter x 15.5mm long). This new class of generic neural prosthetic device can deliver precise electrical stimulation pulses to an arbitrary number of nerve and muscle sites. BIONs receive power and digital command signals by RF telemetry from an external transmission coil.
  • An exemplary embodiment of the present system is for using neuromuscular electrical stimulation (NMES) of appropriate muscles to shift immobile patients from any posture, for PU prevention (PUP) and treatment of all anatomic locations.
  • NMES neuromuscular electrical stimulation
  • PUP PU prevention
  • This may involve a standard relief protocol for seated paraplegics / quadriplegics, and another for bed-ridden paraplegics / quadriplegics.
  • the full preventive protocols may require 5-7 BIONs per side in paraplegics and 10-15 per side in quadriplegics; however they may be modified or used in any of a variety of partial combinations if any specific sites are particularly at risk.
  • the proposed muscle groups which may require activation, and nerves which may require stimulation to achieve such include, but are not limited to those muscles which may actuate movements antagonistic to the at-risk posture, whether seated, prone, supine, or recumbent posture (on one's side) postures.
  • Fig. 1 As also discussed in the attached appendix I), when ones hips are extended in the supine position, gluteus maximus (GM) is a dominant hip extensor, and so the potential exists for GM stimulation to extend and abduct the hip and so roll bed-ridden patients axially. This may relieve both ischial and sacral pressures in supine patients and so may be a beneficial treatment for this group of PU patients.
  • other muscle groups may be employed as needed to facilitate pressure relief in any area of the body.
  • one or more microstimulators may be implanted in or near the appropriate nerve as suggested by examples in Tables 1 -4 below.
  • Scapula 4.4 Rectus Abdominis Flex hip pulling trunk forwards and Thoracoabdominal scapula away from seat back
  • Rib 1.0 lliacus Flex hip, alternating side to side, to Femoral (muscular raise and rock torso branch)
  • Rib 1.0 Rectus Abdominis Flex hip to raise trunk off bed (alternating Thoracoabdominal sides)
  • microstimulators are advantageously of a size and shape to be implantable through the lumen of a needle or needle-like insertion tool.
  • said microstimulators (10) may be approximately 2mm diameter by 16mm long.
  • the function, form and detailed design of such microstimulators, and of said insertion tool, have been described in detail in previous patents and patent applications that may be used in various embodiments are described in US 5,193,539; US 5,193,540; US 5,312,439; US 5,324,316; US 20030233125 and US 1 1/680,363, the contents of which are incorporated by reference in their entirety.
  • Each microstimulator may consist of three major elements: electronic subassembly and two electrodes.
  • Each separate microstimulator's electronic subassembly may receive power and individually addressed command signals by inductive coupling from transmission coil(s) located outside the body, advantageously in a pillow, seat cushion, seatback, mattress, clothing, or the like so as to guarantee proximity to the implanted microstimulators.
  • Transmission coil(s) may be energized with a radio frequency electrical current generated by a driver, and modulated according to a pattern that has been loaded into digital memory means contained within the controller.
  • the modulation pattern constitutes a string of command signals.
  • Each command may contain digital data identifying which microstimulator is to generate which electrical stimulation pulses and the timing and intensity required to evoke the desired muscle contraction.
  • microstimulator During the initial implantation, it may be advantageous to test the efficacy of potential sites for the implantation of microstimulators by applying stimulation pulses through conventional electrodes that may or may not be incorporated into or passed temporarily through the instruments used for implantation.
  • One instrument to utilize is the present inventors's own implant (microstimulator) injection device published as US 20030233125 which is incorporated by reference in its entirety. Through this device, practitioner is able to penetrate patient's body while the implant is held within the device, and further test the efficacy of the site before releasing the implant.
  • the modular design and addressability of said microstimulators is advantageous because it permits additional channels of stimulation to be added to the patient at any time without interfering with those channels installed previously.
  • an effective pattern of stimulation pulses can be accomplished by variously activating the implanted microstimulators via the transmission coil(s). This may be implemented while assessing pressure relief of the at-risk area of interest by visibly noting effective weight-shifting, measuring and analyzing the redistribution of interface pressures, assessing tissue health over time, and any combination of these or other methods (Gluteal area is discussed in the two appendices attached to and integral to this disclosure). In this way standard relief protocols may be designed and tailored to specific patients for specific postures, and these may be programmed into the controller at the fitting session(s).
  • the clinician may use specialized software in a personal computer to devise various stimulation patterns and to deliver them to the controller, which formats them for transmission to the implanted microstimulators via the transmission coil(s) and driver(s).
  • an effective stimulation program When an effective stimulation program has been identified, it may be loaded into the non-volatile memory in the controller so that the patient can use the controller to deliver the stimulation program(s) at home.
  • the controller When the controller is turned on and running a stimulation program, the commands may be sent to the microstimulators inside the patient. This communication requires the patient to be within the magnetic field generated range by transmission coil(s) and driver(s).
  • the patient may initiate an appropriate program as needed by switching it on at the controller; or the appropriate program may be triggered automatically by position sensors worn on the patient which may register each current posture, such as accelerometers or much like commercially available activity monitors.
  • the stimulation pattern may be applied automatically and continuously to prevent pressure on the tissues in whichever posture the patient assumes.
  • the BION can be implanted next to each of the inferior gluteal neurovascular pedicle and the proximal sciatic nerve (which supply gluteus maximus and the remaining hamstring hip extensors respectively), BION Active Seating (BAS) can be used in seated paralyzed patients to build up gluteal muscle volume and blood circulation, and intermittently may unload the soft tissues under the ischium. Thereby preventing occurrences and recurrences of PUs.
  • BAS BION Active Seating
  • NMES Neuromuscular electrical stimulation
  • BIONsTM wireless microstimulators
  • Gluteus maximus has been considered an actuator for hip extension in trying to relieve seated pressures through NMES.
  • Surface stimulation experiments may be used to validate our findings in order to identify promising stimulation sites and strategies for such treatment.
  • gluteal stimulation may likely to reduce disuse atrophy and improve circulation, we show that it may neither be required, nor desired, to achieve hip extension by NMES. Instead hamstring stimulation may be required, and it may provide sufficient hip extension to relieve hydrostatic pressures in the soft tissues under the ischium.
  • NMES with BIONsTM can be used to activate maximal muscle contractions, and produce skeletal motion with associated increases in muscle bulk (hypertrophy), strength, and metabolic capacity. Hence it may counteract the three major etiological factors in PU development (immobility, soft-tissue atrophy, and hypoxia).
  • the BION Active Seating can be used to prevent occurrences and recurrences of PUs in paralyzed patients by separately building up gluteal muscle volume and blood circulation, and intermittently unloading the soft tissues under the ischium when seated.
  • hip torque was calculated at 63 Nm by assuming that the knee was initially located near the edge of the seat, that mBody was evenly distributed across the hips, that we wished to raise the body by 30°in 0.5 s, and that it would take 0.2 s to attain this angular velocity, as follows:
  • T torque
  • r moment arm
  • F force
  • ⁇ angle of F from I (90o, as we wish to calculate maximum T required)
  • a acceleration
  • v final linear velocity
  • u initial linear velocity (0 m/s)
  • t time (0.2 s)
  • ⁇ angular velocity (60 deg/s).
  • Total hip extensor torque Comparing the GM component sum and the HS component sum confirms that GM may be the dominant hip extensor during walking, i.e. between heel contact and toe-off of a regular gait cycle, when the hip angle range is approximately from +30°to -10°. When seated at approximately 90° of hip flexion, however, over 80% of the available extensor torque may originate from HS, and not from GM, a proportion that persists over as much as 20°of hip extension / unloading.
  • HS stimulation alone may provide ⁇ 100Nm of extension torque while only ⁇ 60Nm may be required for even extreme unloading (as detailed above).
  • GM stimulation provided only -20 Nm of extension torque in the seated posture, suggesting that even a non-atrophied GM would be insufficient to achieve ischial elevation.
  • the differential effects of GM and HS activation suggested here have been verified in both rigid body simulations (using the combined moments discussed below), as well as in the surface stimulation experiments used to validate the models (discussed below).
  • the first set of data was obtained previously using surface electrodes to stimulate hip extensors individually and in various combinations in ten healthy subjects.
  • a seat cushion with an 8 x 8 grid of air-filled cells seated interface pressures were measured both at rest, and during stimulation of different muscle configurations and voluntary shifting.
  • Surface NMES used a symmetrical biphasic waveform with a frequency of 35 pps and a 250 ⁇ s phase duration. Tests were randomized, and each was run three times to determine average rest and stimulation values. The muscle combinations assessed were: 1 ) Quads + GM; 2) Quads + gluteus minims; 3) HS + GM; 4) GM; 5) Quads; and 6) voluntary weight-shifting.
  • HS + GM stimulation was statistically no different from voluntary weight-shifting. These data have been reanalyzed here and compared and combined with the surface stimulation results collected subsequently as follow.
  • Surface stimulation of the hip extensors was performed in a single healthy subject (male, 39 y/o, 76 Kg, 5' 8").
  • Oval electrodes 1.5" x 2.5" Gentle Stim R Plus; Medical Devices Intl, Saint Louis, MO
  • the subject was seated in a wheelchair with foot and arm rests: thighs were flat; hips, knees, ankles and elbows were flexed to 90° and calves were restrained.
  • Interface pressures were measured using an 18" x 18" (36 x 36 cell) array of sensors (X36 System; XSensor Technology, Calgary, AB, Canada) placed between the subject and a standardized 4" high-density foam cushion (45 kg/ms), on top of a flat hard board.
  • This system uses a thin vinyl interface mat containing capacitive elastomeric sensors.
  • Each of the 1 ,296 sensing elements 0.5 in 2 dielectric between two conductive elements. Calibrated accuracy is ⁇ 1.3 kPa (10 mmHg) for both observed pressure measurements and inter-trial comparisons.
  • Range used 1.3-26.7 kPa (10-200 mmHg). Data was collected in real-time at 10 Hz per cell (13 kHz for the full mat). Stimulation used a symmetrical square waveform at 35 pps delivered as 10 s trains interspersed with 10 s pauses (FastStart EMS; Vision Quest, Irvine, CA). Individual pulse duration was fixed at 300 ⁇ s and amplitude was varied between 60-100 mA to control recruitment. Seating pressure distributions were recorded to obtain average records from 3 runs each of GM, HS and Quads stimulation, individually and in all combinations.
  • MPZ Mean Pressure Zone: user-defined areas in each quadrant for the comparison of average pressure at rest and during stimulation. They were the same size and shape in all four quadrants. Their sizes were normalized at 80% of the contact surface beneath the ipsilateral ischium (i.e. on the side of stimulation). For the buttock quadrants they were centered under the ischiae, and for the thigh quadrants they were placed symmetrically at the most distal edges of measured thigh contact. The average pressure in these zones was compared before and after stimulation.
  • PPA Peak Pressure Area: an area of those cells with pressures exceeding 8kPA (60mmHg) or higher, beneath the ipsilateral buttock. This may be the maximal surface pressure for which we may predict capillary flow can be maintained in the deep soft tissues.
  • the PPA's size (area) and position (% overlap and centroid shift) were compared at rest and during stimulation. PPA centroids were calculated using a weighted average by area as follows:
  • HS stimulation demonstrates an 88% reduction in PPA size and in PPA overlap, with only one cell remaining unrelieved through both rest and stimulation phases(i.e. above 8kPA (60mmHg)).
  • the middle and R. panels demonstrate progressively worsening results, with the PPA size and % overlap progressively increasing, and the centroid shift progressively decreasing.
  • GM stimulation actually increased the recorded seating pressures ipsilaterally (mean +16%), with a small reduction in contact surface area (mean -9%).
  • the distribution of pressures suggests that the bulging of the stimulated GM muscle served to concentrate seating pressure in a smaller region ipsilaterally, even slightly off-loading the contralateral buttock (-4%).
  • HS stimulation reduced seating pressures both ipsilaterally (mean -26% as above) and contralateral ⁇ (mean -8%), while increasing pressures under the distal thigh.
  • the weight of the torso may remain unchanged; only its distribution over different portions of the seating surface can change.
  • Such weight shifts to the thighs may therefore indicative of successful unloading at the buttocks. They may be of little concern because these areas have no boney prominences and may not be at risk for PUs. They may be the normal areas to which mobile individuals can unload when shifting weight.
  • PPA size area
  • HS stimulation resulted in almost complete elimination of PPA area (mean -94%; from mean 4.0 in ⁇ at rest to 0.25 in ⁇ during stimulation); while GM stimulation resulted in over a trebling of PPA area (mean +213%; from mean 4 in ⁇ at rest to 12.5 in ⁇ during stimulation).
  • PPA position % overlap and centroid shift: HS stimulation resulted in only a 6% PPA area remaining within the at-rest PPA area; while with GM stimulation 100% of the PPA area overlapped with the at-rest PPA area (i.e. none of the at-rest PPA area was relieved during stimulation).
  • centroid shifts with HS and GM stimulation were both similar (mean 0.5" and 0.45" respectively), but due to a large PPA area with GM stimulation (12.5 irte) as opposed to a much smaller one with HS stimulation (0.25 iru?), the significance of centroid shift as a predictive index is unknown at this time. Larger data sets will help clarify its predictive value.
  • GM stimulation may likely be of value for reducing such atrophy and improving vascular capacity.
  • the latter mechanism may account for the favorable results reported clinically for GM stimulation.
  • Substantial pressure reductions may be achieved by SE stimulation under both ischiae. Therefore, two BIONs may be implanted in each patient: one adjacent to the proximal sciatic nerve (to achieve BAS via SE stimulation), and the other adjacent to the inferior gluteal nerve (to achieve improved tissue health and vascularity via GM stimulation). Both nerves are easily and simultaneously accessible during gluteal rotation flap surgery. Supplemental clinical implications of this approach are discussed in the companion appendices I and II.
  • the patients at risk for PUs may require bilateral stimulation of one or both muscle groups. Because the weight of the trunk is constant, relief of pressure on one part of the seating surface may be accompanied by increases in pressure elsewhere. We were concerned that elevation of one ischium can be at the expense of increased pressure contralateral ⁇ , leading to an increased risk of contralateral PUs. Contractions of SE muscles in one leg actually reduced pressure under both ischiae by transferring pressure to the ipsilateral distal thigh. Lower contralateral reduction of seating pressure can be sufficient to provide any useful protection. Hypoxic tissue damage may likely to arise from constant hydrostatic pressure in excess of that required to occlude circulation. Soft tissues may be able to handle even higher pressure peaks that are relieved by intermittent periods of low pressure during which circulation is reestablished.
  • GM may be the dominant hip extensor when the hip is in an extended posture, such as during upright locomotion and when lying in bed.
  • Excitation may propagate along muscle fibers according to the conduction velocity of action potentials along the sarcolemma, which is 3-5m/s; activation and contraction of myofilaments may be tied closely to excitation, so the pressure wave may move at a similar velocity.
  • Muscle contractions have been used to assist in pumping blood out of the capillary bed and veins to reduce stasis, but this works only if the hydrostatic force between contractions is sufficiently low to allow arterial pressure to refill these vessels.
  • Erythrocyte capillary transit velocity at rest 1 mm/s; and after exercise increases to 4mm/s.
  • Arteriolar pressure that drives this flow rate may be ⁇ 50mmHg.
  • the 4 mm/s capillary flow rate from a 50mmHg head of pressure described above can be extrapolated to a capillary flow rate of 180mm/s.
  • the pressure wave traveling at 3m/s may overtake and occlude the blood flow advancing at 180 mm/s within 60ms, at which time there can be no further blood flow / pumping (because the pressures equilibrate in the contracted portions of the muscle at this time).
  • NMES gluteal stimulation
  • Gluteal stimulation is reserved for muscle conditioning, during non-weight bearing periods, and that hamstring stimulation alone may be used for pressure relief during periods of weight bearing.
  • Gluteal stimulation could be valuable for muscle conditioning (by reducing disuse atrophy and improving circulation), but bulging of the active gluteus maximus appears to aggravate surface interface pressures without providing sufficient hip extension to elevate the ischium.
  • at least two independently controllable stimulation channels may need to be provided to address ipsilateral PUs; four may be necessary to protect both sides.
  • NMES neuromuscular electrical stimulation
  • NMES neuromuscular electrical stimulation
  • GM gluteus maximus
  • SE sciatic nerve
  • Tissue pressure sensors can be mounted on surgical drains but they may interfere with actual tissue pressure distributions. They also may have to be removed well before patients are able to resume weight-bearing on the surgical site. Instead, noninvasive measurements obtained from the surface stimulation experiments were used to develop, drive and validate finite element analysis (FEA) models of the buttock soft-tissues under different loading conditions, and for different somatotypes.
  • FEA finite element analysis
  • Internal tissue pressure changes may be predicted in a non-invasive way, in real-time, and whenever needed.
  • An embodiment may compute what reduction in measurable surface pressures could avoid circulatory occlusion in the muscles.
  • Intramuscular pressures may fall below the arterial capillary closing pressure of -30 mmHg.
  • Systems such as the skin, fat and muscles have a combination of properties that make them difficult to model using FEA.
  • these fluid-filled tissues may be incompressible but may have large and nonlinear compliances.
  • Their mesh dimensions may undergo large deformations from unloaded to maximally loaded conditions, which may result in compounding of errors and computational instability. They can also be difficult to characterize due to model friction, shear, and dynamic viscous creep etc. between discrete layers with different properties.
  • model data during simulations also compared favorably with experimental data during the low deformation portions of a graded seating experiment. This involved lowering a subject from a gantry onto a pressure sensor mat and recording contact areas and pressures at progressively increasing degrees of seating contact and ischial loading.
  • Figs. 1A-B provides incremental loading curves for models of different somatotypes.
  • panel of Fig. 1 B comparing ischial loading with contact surface area, an expected non-linear plateau pattern is noted at high ischial loads for all 3 somatotypes (upper panel).
  • Figs. 1A-B provides incremental loading curves for models of different somatotypes.
  • Fig. 1 B the changes in intramuscular pressures (Pm, solid curves) and surface pressures (Ps, dashed curves) are compared with progressive loading for the 3 somatotypes. While all 3 groups demonstrate similar average intramuscular pressures, note again that ectomorphs differ clearly from endomorphs and mesomorphs (upper panel). In the lower panel at low-loading conditions, for intramuscular pressures to fall below 30mmHg (capillary closing pressure), surface pressures fall below 60 mmHg in endomorphs and mesomorphs; but below 100 mmHg in ectomorphs.
  • Pm intramuscular pressures
  • Ps dashed curves
  • Ectomorphs are thin and bony and generally may be at higher risk for PUs than endomorphs and mesomorphs.
  • the model predicts that intramuscular capillary flow will be maintained at a higher surface pressure ( ⁇ 100mmHg) in ectomorphs than in meso- and endomorphs ( ⁇ 60mmHg); the difference just about compensates for the different surface pressures predicted for these body types.
  • ectomorphs may be at greater risk for superficial PUs specifically (associated with friction, shear and cutaneous pressure increases), but at similar risk for deep PUs.
  • Superficial PUs are easier to detect and are associated with a lower morbidity than deep ones.
  • Disuse atrophy of SE muscles may well cause them to have insufficient strength and fatigue resistance to provide sufficient, repetitive unloading of the ischium over the course of the desired period of sitting in a wheelchair.
  • Disuse atrophy of GM muscles reduces the padding and the availability of musculocutaneous blood supply for the overlying skin.
  • Low frequency stimulation can be applied to condition both SE and GM muscles during the 5-8 week post-operative period during which the skin and muscles cannot be subjected to large contractile forces or sitting pressures.
  • Proposed initial treatment parameters are provided in Table 6. These may be titrated as required to achieve the desired outcomes (described above).
  • the sciatic nerve is a mixed sensory and motor nerve that innervates not only the SE, but also most of the distal leg.
  • SCI patients are largely insensate, postural shifts, as well as reflex effects on spasticity and autonomic dysfunction may be evaluated clinically to identify safe and effective stimulus parameters for the sciatic site.
  • the outermost and most medial nerve fascicles supply the muscles of interest and may have lower thresholds than the deeper fascicles.
  • Careful exploration with a handheld probe stimulator may help to identify a placement of the BION that will provide some degree of selective stimulation.
  • the relatively low frequencies of stimulation that may be required to produce fused muscle contractions are also may unlikely cause large reflex effects from proprioceptive afferents (Table 6). Gradual ramp-up of each stimulation train could reduce mechanically evoked spasticity.
  • Musculoskeletal and soft tissue models support the aspect having the BION Active Seating (BAS) will improve pressure distribution and tissue health.
  • BAS BION Active Seating
  • the models and analyses discussed above can be used to guide clinical treatment and evaluate results, for the eventual application of BAS to prophylaxis, with percutaneously injected, bilateral implants used to prevent PUs from forming.

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  • Electrotherapy Devices (AREA)

Abstract

L'invention a pour objets des procédés et un système d'utilisation d'une stimulation électrique neuromusculaire sans fil des muscles appropriés pour faire basculer les patients immobiles à partir de n'importe quelle position. Les procédés et l'appareil s'appliquent à toute personne immobile, qu'elle souffre d'une blessure de la moelle épinière, ait subi une attaque cérébrale, soit atteinte de démence ou autre. En conséquence, les escarres de décubitus peuvent être évitées ou traités dans tout site anatomique en fonction des stimulations électriques des muscles efficaces à l'égard dudit site. Les stimulations électriques neuromusculaires des muscles permettent aux personnes immobiles de faire basculer leur poids. L'invention a également pour objets des protocoles complets de prévention des escarres de décubitus à l'aide d'une pluralité de microstimulateurs implantés dans des sites cibles à l'intérieur du corps du patient, à savoir, des sites particulièrement à risque.
PCT/US2008/078839 2007-10-04 2008-10-03 Procédé et appareil destinés à prévenir les escarres de décubitus et à les traiter WO2009046366A1 (fr)

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CN103949012A (zh) * 2014-05-21 2014-07-30 上海谨诺医疗科技有限公司 多地址可控微型神经肌肉电刺激系统
WO2015054423A1 (fr) * 2013-10-08 2015-04-16 Leaf Healthcare, Inc. Procédés, dispositifs et techniques de détection d'escarres
WO2019060332A1 (fr) * 2017-09-19 2019-03-28 The United States Government As Represented By The United States Department Of Veteran Affairs Stimulateur de tissu implantable flexible et procédé pour le fabriquer et l'utiliser
US11478631B2 (en) 2012-02-02 2022-10-25 The United States Government As Represented By The Department Of Veterans Affairs Methods of using an integrated surface stimulation device for wound therapy and infection control
EP4021366A4 (fr) * 2019-11-04 2022-11-23 Zorluteks Tekstil Ticaret Ve Sanayi Anonim Sirketi Système de stimulation électrique

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US6051017A (en) * 1996-02-20 2000-04-18 Advanced Bionics Corporation Implantable microstimulator and systems employing the same
US20020055761A1 (en) * 1998-07-06 2002-05-09 Mann Carla M. Implantable stimulator systems and methods for treatment of incontinence and pain
US20070016265A1 (en) * 2005-02-09 2007-01-18 Alfred E. Mann Institute For Biomedical Engineering At The University Of S. California Method and system for training adaptive control of limb movement

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US6051017A (en) * 1996-02-20 2000-04-18 Advanced Bionics Corporation Implantable microstimulator and systems employing the same
US20020055761A1 (en) * 1998-07-06 2002-05-09 Mann Carla M. Implantable stimulator systems and methods for treatment of incontinence and pain
US20070016265A1 (en) * 2005-02-09 2007-01-18 Alfred E. Mann Institute For Biomedical Engineering At The University Of S. California Method and system for training adaptive control of limb movement

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11478631B2 (en) 2012-02-02 2022-10-25 The United States Government As Represented By The Department Of Veterans Affairs Methods of using an integrated surface stimulation device for wound therapy and infection control
WO2015054423A1 (fr) * 2013-10-08 2015-04-16 Leaf Healthcare, Inc. Procédés, dispositifs et techniques de détection d'escarres
CN103949012A (zh) * 2014-05-21 2014-07-30 上海谨诺医疗科技有限公司 多地址可控微型神经肌肉电刺激系统
WO2019060332A1 (fr) * 2017-09-19 2019-03-28 The United States Government As Represented By The United States Department Of Veteran Affairs Stimulateur de tissu implantable flexible et procédé pour le fabriquer et l'utiliser
US11458309B2 (en) 2017-09-19 2022-10-04 United States Government As Represented By The Department Of Veterans Affairs Flexible implantable tissue stimulator and methods of making and using same
EP4021366A4 (fr) * 2019-11-04 2022-11-23 Zorluteks Tekstil Ticaret Ve Sanayi Anonim Sirketi Système de stimulation électrique

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