Dressing and Dressing Assembly for Preventing Pressure Ulcers

A dressing for guarding against the development of pressure ulcers has a recipient side and an environmental side. The dressing comprises a moisture barrier layer whose components include a sacral member, a left gluteal member and a right gluteal member. Each gluteal member has a base and an extension which extends longitudinally inferiorly further than the inferior edge of the sacral member by a dimension which is approximately no less than the longitudinal length of the sacral member. The dressing also includes a connective element on the recipient side of the dressing. The connective element is arranged to provide a zone of occlusion. In some embodiments the dressing includes electrodes and is a component of a dressing assembly which includes an exciter for stimulating gluteal muscles.

TECHNICAL FIELD

The subject matter described herein relates to a dressing and a dressing assembly for preventing pressure ulcers throughout a portion the human posterior region extending longitudinally from approximately the sacrum to the ischeal tuberosities and laterally across the gluteal muscles.

BACKGROUND

Individuals such as hospital patients who are immobilized in a bed for an extended time are susceptible to developing pressure ulcers. One anatomical region of special concern is the patient's posterior, particularly the region extending longitudinally from approximately the sacrum to the ischeal tuberosities (ITs) and laterally across the gluteal muscles particularly the gluteus maximus and gluteus medius. Pressure ulcers in the vicinity of the sacrum and the gluteal muscles are often the result of moisture on the skin and friction and shear acting on or experienced by the skin or the underlying tissue. Pressure ulcers associated with the ischeal tuberosities are sometimes a form of pressure ulcer referred to as a deep tissue injury (DTI). In their early stages of development deep tissue injuries might not present any external signs of their existence. As a result the presence of a deep tissue injury is often difficult to detect until the injury breaks through the skin, by which time the condition is painful, susceptible to infection, and difficult to treat successfully. Accordingly, it is desirable to develop ways of preventing the development of pressure ulcers. It is particularly desirable to develop devices that prevent pressure ulcers across a large portion of the posterior even though the preventive measures preferred for one anatomical sub-region (e.g. the sacral region) may differ from the preventive measures preferred for another anatomical sub-region (e.g. the ITs).

SUMMARY

A dressing for guarding against the development of pressure ulcers has a recipient side and an environmental side. The dressing comprises a moisture barrier layer whose components include a sacral member, a left gluteal member and a right gluteal member. Each gluteal member has a base and an extension which extends longitudinally inferiorly further than the inferior edge of the sacral member by a dimension which is approximately no less than the longitudinal length of the sacral member. The dressing also includes a connective element on the recipient side of the dressing. The connective element is arranged to provide a zone of occlusion. In some embodiments the dressing includes electrodes and is a component of a dressing assembly which includes an exciter for stimulating gluteal muscles.

DETAILED DESCRIPTION

FIGS. 1-2are schematic illustrations of an example preventive dressing100for a care recipient CR such as a hospital patient.FIG. 3Ashows the dressing applied to the care recipient.FIGS. 3B and 3Cshow anatomical features useful for describing the dressing in relation to human anatomy and for understanding its operation. Selected illustrations also include reference axes indicating longitudinal, lateral, and transverse directions. When describing the dressing, the thickness of the dressing or its components is the dimension in the transverse direction. Throughout this description features similar to or the same as features previously described may be identified by the same reference numerals. Features which are specific examples of more general features may also all be identified by the same or similar reference numerals.

The dressing is configured to cover a portion of a human body, specifically a posterior region extending longitudinally from approximately the sacrum to the ischeal tuberosities (ITs) and laterally across the gluteal muscles. The dressing is in the form of a thin sheet having sufficient flexibility that it can conform to anatomical contours. In the interest of clarity the thickness of the dressing may be exaggerated in the accompanying illustrations.

The dressing comprises a moisture barrier layer110having a recipient side112intended to face toward the care recipient and an environmental side114which is the side intended to face away from the care recipient. The environmental side is exposed to the external environment. The dressing also has a connective element120on the recipient side of the moisture barrier layer. The connective element has a recipient side122facing toward the care recipient and an environmental side124facing away from the care recipient but not necessarily exposed to the environment. The connective element is intended to hold the dressing in contact with the care recipient and is shown with its recipient side122in contact with the care recipient's skin S. One example of a connective element is an adhesive which adheres well to human skin but can be removed from the skin without undue difficulty or undue discomfort to the care recipient.

The dressing also has a perimeter P and a longitudinally extending centerline C. As seen in the plan view ofFIG. 1the dressing has a sacral member130corresponding approximately to the sacrum of a care recipient having a target anatomy, for example the anatomy of a 50th percentile United States male. The sacral member has a longitudinal length LSM, a lateral width WSM, an inferior edge132and a superior edge134. Superior edge134of the sacral member may also be considered to be the superior edge of the dressing as a whole. Width WSMis approximately the width of the sacral base of the target care recipient. Accordingly, sacral member130extends laterally leftwardly to no more than about the location “A” (FIG. 3B) of the superior edge of the gluteus maximus muscle. The dressing also includes a left gluteal member136having a base138whose right edge140borders the left side of the sacral member, and a left extension142having a laterally inner edge144, a laterally outer edge146and a terminus or inferior edge148. Collectively, inner edge144outer edge146and terminus or inferior edge148define a margin of the left extension. The left extension extends longitudinally inferiorly of the inferior edge132of the sacral member by extension dimension LEXT. LEXTis approximately no less than the longitudinal length LSMof the sacral member. The dressing also includes a right gluteal member156having a base158whose left edge160borders the right side of the sacral member, and a right extension162having a laterally inner edge164, a laterally outer edge166, and a terminus or inferior edge168. Collectively, inner edge164, outer edge166and terminus or inferior edge168define a margin of the right extension. Taken together extension inferior edges148,168define an inferior edge of the dressing as a whole. The right extension extends longitudinally inferiorly of the inferior edge132of the sacral member by the dimension LEXT. The overall longitudinal length of the gluteal members, and therefore of the dressing as a whole, is LGMwhich is approximately equal to the sum of LSMplus LEXT.

The gluteal extensions each have a width WGE. The extensions define an intermember space180having a width WSmeasured about midway between the inferior edges148,168of the extensions and the inferior edge132of the sacral member. The dressing has a total width of WTOTwhich is WSplus twice WGE.

In the dressing ofFIG. 1inner edges144,164of the gluteal extensions and the inferior edge132of the sacral member are approximately linear. Curved edge segments182,184connect inferior edge132of the sacral member to the inner edges144,164of the extensions. In another embodiment shown inFIG. 4, the inner edges converge more decidedly toward each other.

FIGS. 5-12show various arrangements of connective element120. InFIGS. 5-6the connective element is a continuous strip of adhesive190extending along substantially the perimeter of the dressing, i.e. at perimeter P or near the perimeter but slightly offset therefrom to define a nonadhesive border192of the moisture barrier layer. The adhesive strip has an outer edge194, which is the edge closer to dressing perimeter P, and an inner edge196, which is the edge further away from the dressing perimeter. The configuration ofFIGS. 5-6is referred to as the strip adhesive configuration. InFIGS. 7-8the connective element comprises a sacral adhesive layer200distributed over substantially the entirety of the recipient side of the sacral member130and over substantially the entirety of the gluteal bases138,158. The connective element ofFIGS. 7-8further comprises a continuous strip of adhesive190extending along substantially the margins of the gluteal member extensions142,162. The arrangement ofFIGS. 7-8is referred to as the strip/distributed adhesive configuration. InFIGS. 9-10the connective element comprises an adhesive200which forms substantially all of the recipient side of the dressing. In other words the recipient side of the dressing is the recipient side of the adhesive. The arrangement ofFIGS. 9-10is referred to as the distributed adhesive configuration.

As seen inFIGS. 11-12, the strength of the adhesive need not be spatially uniform as indicated by the density of the crosshatching. InFIGS. 11-12the connective element comprises a first adhesive composition204forming substantially all of the recipient sides of sacral member130and gluteal bases138,158, and a second adhesive composition206forming substantially all of the recipient side of gluteal extensions142,162. The first adhesive composition adheres relatively more strongly to human skin and the second adhesive composition adheres relatively more weakly to human skin. The configuration ofFIGS. 11-12is referred to as the variable strength adhesive configuration.

The adhesive or other connective element is arranged to provide a zone of occlusion Z. As used herein a zone of occlusion is a zone protected from environmental moisture ingress by the adhesive and the moisture barrier layer. Such protection is desirable because moisture on the skin is a factor that can lead to development of pressure ulcers. Examples of environmental moisture include liquids originating outside the zone of occlusion (e.g. accidentally spilled water, or urine from an incontinent patient). Examples of environmental moisture also include the care recipient's perspiration through skin not covered by the zone of occlusion. The protection against environmental moisture ingress is illustrated schematically inFIGS. 13-14 and 15-16where the moisture barrier layer110protects against environmental moisture ingress principally in the transverse (thickness) direction while the adhesive protects against environmental moisture ingress in the lateral and longitudinal directions (solid arrows which terminate outside the occlusion zone). In the arrangement shown schematically inFIGS. 13-14the adhesive layer120is spatially coextensive with or nearly spatially coextensive with the moisture barrier layer110. The zone of occlusion is defined by the spatial extent of the adhesive. In the arrangement shown schematically inFIGS. 15-16the adhesive layer is a strip of adhesive190which forms a closed boundary defined by dashed borderline B. (Borderline B inFIG. 15and in other illustrations coincides with outer edge194of the adhesive strip but is shown slightly offset edge194to preserve the visibility of both the edge and the borderline.) The zone of occlusion is defined by the adhesive strip and includes the region within the closed boundary. In other words the zone of occlusion includes the width WADHof the adhesive strip.

Moisture in the form of the care recipient's perspiration through the skin covered by the zone of occlusion (dashed arrows) ofFIGS. 14 and 16is not environmental moisture. Therefore the status of zone Z as a zone of occlusion inFIGS. 13-16is not defeated by such perspiration.

Returning momentarily toFIGS. 5, 7, 9 and 11, dashed borderline B shows the zones of occlusion Z for each of the described adhesive configurations. InFIG. 5zone Z is the zone enclosed by outer edge194of adhesive strip190(or equivalently borderline B) InFIGS. 7, 9 and 11zone Z is the planform of the entire dressing because the spatially distributed adhesive200extends to dressing perimeter P (FIGS. 9, 11) and because outer edge194of adhesive strip190(FIG. 7) is exactly at perimeter P.

If the adhesive or other connective element is a strip as inFIGS. 5-6, or as shown along the margins of the gluteal extensions inFIGS. 7-8, the adhesive may or may not be one-way liquid absorbant. However in the examples of this specification the strip adhesive is always considered to be one-way liquid absorbant. If the adhesive is distributed as in the remainder ofFIGS. 7-8or as inFIGS. 9-10, the adhesive is one-way liquid absorbant. As shown schematically inFIG. 17the direction of the one-way absorbancy is the direction that draws moisture, such as perspiration, away from the care recipient's skin S thereby eliminating a risk factor (excessive moisture on the skin) for pressure ulcer development. Alternatively, as seen inFIG. 18, the adhesive may be one-way liquid permeable. The direction of the one-way permeability is the direction that transfers moisture away from the care recipient's skin. The one-way liquid permeability not only draws moisture away from the care recipient's skin (similar to the liquid absorbant layer ofFIG. 17) but also discharges the moisture to the environment where it can evaporate or be actively disposed of.

FIGS. 19-50 and 52-59are similar toFIGS. 5-12but show an auxiliary layer220in addition to the moisture barrier layer110and the adhesive layer (embodied as a spatially distributed layer200or as an adhesive strip190). The auxiliary layer comprises a liquid absorbant layer, a liquid permeable layer, a pressure equalizing layer or some combination of such layers. This specification employs the phrase “moisture management layer” to mean the liquid absorbant layer when used alone, the liquid permeable layer when used alone, or the liquid absorbant layer and liquid permeable layer used together.

FIGS. 19-30are similar toFIGS. 5-12but show the auxiliary layer220, embodied as a moisture management layer, specifically a one-way liquid absorbant layer. The direction of the one-way absorbancy is the direction that transfers moisture, such as perspiration, away from the care recipient's skin S, not toward the care recipient's skin (FIGS. 19-21) or that transfers moisture away from the adhesive (FIGS. 22-30) similar to the one-way liquid absorbancy of adhesive200ofFIG. 17.FIGS. 19-21show the liquid absorbant layer220used in the strip adhesive configuration (e.g. the configuration ofFIGS. 5-6). InFIGS. 19-21the liquid absorbant moisture management layer resides in the zone of occlusion. When applied to a care recipient the moisture management layer is in direct contact with the care recipient's skin S. The illustrated moisture management layer is confined to the sacral member, but could be present elsewhere in the occlusion zone instead of or in addition to being present in the sacral member. In the limit the moisture management layer is present throughout the zone of occlusion but not where it would intervene between adhesive strip190and the care recipient's skin. The liquid absorbant moisture management layer draws moisture away from the care recipient's skin and continues to do so until it reaches saturation.FIGS. 22-24show liquid absorbant layer220used in the strip/distributed adhesive configuration (e.g. the configuration ofFIGS. 7-8).FIGS. 25-27show the liquid absorbant layer220used in a distributed adhesive configuration (e.g. the configuration ofFIGS. 10-11).FIGS. 28-30show the liquid absorbant layer220used in the variable strength adhesive configuration (e.g. the configuration ofFIGS. 11-12). In the arrangements ofFIGS. 19-30, the moisture management220layer resides in the zone of occlusion and is transversely between moisture barrier layer110and the adhesive or other connective element120(which is illustrated as a distributed adhesive200inFIGS. 19-30).

FIGS. 31-42are similar toFIGS. 5-12but show the moisture management layer embodied as a one-way liquid permeable layer220. The direction of the one-way permeability is the direction that transports moisture, such as perspiration, away from the care recipient's skin S, not toward the care recipient's skin (FIGS. 31-33) or that transports moisture away from the adhesive (FIGS. 34-42) similar to the one-way liquid permeability of adhesive200ofFIG. 18. A noteworthy difference between the liquid permeable layer ofFIGS. 31-42and the liquid absorbant layer ofFIGS. 19-30is that the liquid permeable layer is in communication with or otherwise exposed to the external environment. InFIGS. 31-42the liquid permeable layer is exposed to the environment by virtue of extending longitudinally to inferior edge132and superior edge134of sacral member130. Because inferior and superior edges230,232of the liquid permeable layer are exposed to the environment, liquid absorbed by the layer can be discharged to the environment. However because the one-way permeability of the liquid permeable layer is in a direction that transports liquid away from the zone of occlusion, the fact that edges230,232are exposed to the environment does not compromise the occlusive nature of the zone of occlusion.

FIGS. 31-33show liquid permeable layer220used in the strip adhesive configuration (e.g. the configuration ofFIGS. 5-6). InFIGS. 31-33the liquid permeable moisture management layer resides in the zone of occlusion. When applied to a care recipient the moisture management layer is in direct contact with the care recipient's skin S. The illustrated moisture management layer is confined to the sacral member, but could be present elsewhere in the occlusion zone instead of or in addition to being present in the sacral member. In the limit the moisture management layer is present throughout the zone of occlusion but not where it would intervene between adhesive strip190and the care recipient's skin. The liquid permeable moisture management layer draws moisture away from the care recipient's skin and discharges it to the environment.FIGS. 34-36show the moisture permeable layer220used in the strip/distributed adhesive configuration (e.g. the configuration ofFIGS. 7-8).FIGS. 37-39show the moisture permeable layer220used in a distributed adhesive configuration (e.g. the configuration ofFIGS. 10-11).FIGS. 40-42show the moisture permeable layer220used in the variable strength adhesive configuration (e.g. the configuration ofFIGS. 11-12). In the arrangements ofFIGS. 31-42, the moisture management layer resides in the zone of occlusion and is transversely between moisture barrier layer110and the adhesive or other connective element120which is illustrated as a distributed adhesive200inFIGS. 31-42.

FIGS. 43-50are similar toFIGS. 5-12but show the auxiliary layer embodied as a pressure equalizing layer220.FIGS. 51A-51Cillustrate the function of the pressure equalizing layer. Referring first toFIG. 51A, a mattress has an undeflected thickness tU, which is substantially uniform in the lateral direction. The weight of the care recipient CR deforms the mattress to a laterally nonuniform deflected thickness tDas indicated by the dashed line profile. The deflection d is relatively small in the vicinity of the care recipient's sacrum and larger along the gluteal muscles. Referring additionally to the dashed line ofFIG. 51B, the corresponding interface pressure PINTis therefore smaller at the sacrum and larger along the gluteal muscle. The pressure gradients at the steep portions240ofFIG. 51Bcorrespond to a region of high shear both at the skin and transversely through the muscle tissue. Referring toFIGS. 43-50 and 51C, the pressure equalizing layer220is a layer of material which spans laterally across centerline C of the dressing in the zone of occlusion to define a pressure equalizing zone ZPE. The thickness and/or stiffness of the pressure equalizing material layer causes the pressure equalizing zone to exhibit a stiffness (i.e. a resistance to deflection) which is greater than the stiffness of the dressing laterally to the left and right of the pressure equalizing zone. As seen inFIG. 51Ccompared toFIG. 51A, this causes thickness tDand deflection d to be more laterally uniform. As a result the lateral gradient of interface pressure is reduced (FIG. 51Bdot-dashed profile versus the dashed profile) and therefore so is shear.

As described above the thickness of the pressure equalizing layer may cause the pressure equalizing zone to exhibit an increased stiffness in comparison to regions of the dressing outside the planform of the pressure equalizing layer and pressure equalizing zone. However an increased thickness of the pressure equalizing layer, relative to the thickness of the dressing outside the pressure equalizing zone/layer, may be sufficient to create a pressure equalizing zone even if the increased thickness is not accompanied by an increase in stiffness. In that case the increased thickness of the pressure equalizing layer acts on its own to yield the pressure equalization ofFIG. 51B, although the increased thickness may diminish patient comfort.FIGS. 51D and 51Eeach show a dressing with a pressure equalization zone whose thickness tIexceeds the baseline thickness tBof the dressing outside the planform of the pressure equalization zone. InFIG. 51Dthe local increase in thickness is attributable to the thickness of auxiliary layer220. InFIG. 51Ethe local increase in thickness is attributable to a local increase in thickness of moisture barrier layer110.

FIG. 51Fshows a dressing with a pressure equalizing zone having a customizable thickness. The customizable thickness is the result of moisture barrier layer110being comprised of multiple peel-away sublayers, for example110a,110b,110c,110dsuch that sublayer110acan be peeled off sublayer110b, sublayer110bcan be peeled off sublayer110cand sublayer110ccan be peeled off sublayer110d. In practice a caregiver may leave all the sublayers in place or may peel away one or more sublayers. As successive sublayers are removed the pressure equalizing property of the pressure equalizing zone is diminished.

FIG. 51Gshows a variation on the theme ofFIG. 51F.FIG. 51Gshows a stockpile of classified dressings, for example classes A through Z. Zone PZEis a classified zone having a class specific thickness. The thickness of zone PZEin a given class differs from the thickness of zone PZEin the other classes. A manufacturer would produce dressings in each of two or more classes each of which corresponds to a class specific thickness. In practice the caregiver selects a dressing from the class he believes is best suited for the patient under his care.

In one embodiment the pressure equalizing zone is confined to the sacral member, i.e. is confined to the immediate vicinity of the care recipient's sacrum, and does not extend laterally to edges140,160of gluteal bases138,158. In another embodiment the pressure equalizing zone extends laterally to the edges140,160of the gluteal bases. Either way the stiffness of the pressure equalizing zone is greater than the stiffness of the left gluteal base138and is also greater than the stiffness of the right gluteal base158. In yet another embodiment the pressure equalizing zone may extend beyond edges140,160and into the gluteal bases. In addition, the dash-dot profile ofFIG. 51Bdemonstrates that the phrase “pressure equalizing” does not mean that the pressure equalizing layer must cause the interface pressure to be substantially uniform in the lateral direction, only that it attenuate the lateral pressure gradients.

FIGS. 43-44show pressure equalizing layer220used in the strip adhesive configuration of the dressing (e.g. the configuration ofFIGS. 5-6).FIGS. 45-46show the pressure equalizing layer220used in the strip/distributed adhesive configuration of the dressing (e.g. the configuration ofFIGS. 7-8).FIGS. 47-48show the pressure equalizing layer220used in the distributed adhesive configuration (e.g. the configuration ofFIGS. 10-11).FIGS. 49-50show the pressure equalizing layer220used in the variable strength adhesive configuration (e.g. the configuration ofFIGS. 11-12). In the arrangements ofFIGS. 45-50the pressure equalizing layer is transversely between moisture barrier layer110and the adhesive or other connective element120.

FIGS. 52-59are similar toFIGS. 5-12but show the auxiliary layer220embodied as a pressure equalizing layer220PE in conjunction with a moisture management layer220MM. The moisture management layer may be a liquid absorbant layer as previously described, a liquid permeable layer as previously described, or both. As seen inFIGS. 53, 55, 57 and 59moisture management layer220MM is on the recipient side of the pressure equalizing layer so that when the dressing is applied to a care recipient the moisture management layer is in direct contact with the care recipient's skin S or is closer to the skin than is the pressure equalizing layer. The pressure equalizing layer220PE spans laterally across centerline C of the dressing in the zone of occlusion to define a pressure equalizing zone. In one embodiment the pressure equalizing zone is confined to the sacral member, i.e. is confined to the immediate vicinity of the care recipient's sacrum, and does not extend laterally to edges140,160of gluteal bases138,158. In another embodiment the pressure equalizing zone extends laterally to the edges140,160of the gluteal bases. Either way the stiffness of the pressure equalizing zone is greater than the stiffness of the left gluteal base138and is also greater than the stiffness of the right gluteal base158. In yet another embodiment the pressure equalizing zone may extend beyond edges140,160and into the gluteal bases. The illustrated moisture management layer220is confined to the planform of the sacral member, but could be present elsewhere in the occlusion zone, instead of or in addition to being present in the sacral member. In the limit the moisture management layer is present throughout the zone of occlusion.

FIGS. 52-53show the combined moisture management and pressure equalizing layer220used in the strip adhesive configuration (e.g. the configuration ofFIGS. 5-6).FIGS. 54-55show the combined moisture management and pressure equalizing layer220used in the strip/distributed adhesive configuration (e.g. the configuration ofFIGS. 7-8).FIGS. 56-57show the moisture management and pressure equalizing layer220used in a distributed adhesive configuration (e.g. the configuration ofFIGS. 10-11).FIGS. 58-59show the moisture management and pressure equalizing layer220used in the variable strength adhesive configuration (e.g. the configuration ofFIGS. 11-12). In the arrangements ofFIGS. 54-59, the moisture management layer and the pressure equalizing layer both reside in the zone of occlusion and are both transversely between the moisture barrier layer and the adhesive layer or other connective element120which is illustrated as a distributed adhesive200inFIGS. 52-59.

FIGS. 60-64illustrate variations on the planform of the dressing. The planform ofFIG. 60is similar to that ofFIGS. 1, 3A and 4except that edges150,170of the gluteal bases are concave rather than convex from the vantage point of an observer looking in direction D. In addition, the dressing ofFIG. 60includes a tab244which extends inferiorly from the inferior edge132of sacral member130at a location between the gluteal members136,156. Alternatively the tab may be thought of as a feature that defines the inferior edge and projects longitudinally into intermember space180. The tab has a longitudinal dimension LTABwhich is less than the longitudinal dimension LEXTof the gluteal extensions. In particular the tab is sized and shaped so that when the dressing is applied to a care recipient the tab conforms to and nests in the care recipient's intergluteal cleft. This helps ensure a tight seal which, in turn, helps ensure that the occlusive nature of the zone of occlusion is not compromised. The dressing planform ofFIG. 61is linear along the superior edge134of sacral member130. The dressing illustrated inFIG. 62is more irregularly shaped. The dressing illustrated inFIG. 63has straight line borders which meet at right angles. In addition sacral member130is more laterally elongated than is the case in other embodiments previously described. The dressing illustrated inFIG. 64is similar to that ofFIG. 63except at least part of the sacral member has a shape which approximates the shape of a triangle. The triangle has a base246corresponding approximately to the care recipient's sacral base and an apex248. The base is superior of the apex.

In the arrangement ofFIG. 65sacral member130, left gluteal member136and right gluteal member156are individual members rather than being integrated into a single unit. The left and right gluteal members are dimensioned such that gluteal extensions142,162will extend inferiorly of the inferior edge132of the sacral member when the gluteal members are applied to a care recipient such that the gluteal members border the sacral member and the sacral member is longitudinally aligned with the care recipient's sacrum.

Although the dressing has been defined in geometric terms, it can also be described in relation to a target anatomy. In practice the dressing may be sized and proportioned for a target anatomy representative of a selected population for example a 50th percentile United States male, with the understanding that the dressing may prove to be suboptimally sized for other individuals, particularly an individual whose anatomy differs markedly from the target anatomy, for example a 1st or 99th percentile United States male. Alternatively the dressing may be sized and proportioned for an extreme target anatomy such as the 99th (or 1st) percentile anatomy, with the understanding that an oversized (or undersized) dressing may nevertheless work well for at least some range of lower (or higher) percentile individuals.

Referring again toFIGS. 1-2 and 3Cthe dressing may be sized and proportioned according to the criteria set forth in table 1 below. In the table, WS, ITis the lateral dimension of the intermember space180taken at a longitudinal position corresponding to the longitudinal position of the ITs of a target anatomy when the dressing is applied to the anatomy with its superior edge134approximately longitudinally aligned with the sacral base of the anatomy. LGMis the longitudinal dimension of the left and right gluteal members:

TABLE 1dimensionvalueWS, ITless than distance WITbetween left and right ischialtuberosity of the target anatomy.LGMgreater than or equal to a longitudinal distance LL5S1-ITfrom the ischial tuberosity to the L5/S1 interface of thetarget anatomy.
The distance WS, ITin the table ensures that gluteal extensions142,162are wide enough that their inner edges144,164are closer to the care recipient's saggital plane PSAGthan the ITs are. As a result the gluteal extensions will extend laterally far enough toward the saggital plane to overlie the ITs. The distance LGMensures that the dressing extends longitudinally far enough to provide protection to the care recipient's sacral region and to the region susceptible to pressure ulcers in the vicinity of the ITs.

Referring additionally toFIGS. 66-67, according to another set of criteria the gluteal extensions are sized so that when the dressing is applied to a care recipient having a target anatomy with the superior edge134of sacral member130approximately longitudinally aligned with the care recipient's sacral base, the left and right gluteal extensions overlie respective left and right threat-susceptible regions TSL, TSRof the target anatomy. The left threat-susceptible region TSLis a region bounded by the intersection260L, when the target anatomy is in a seated posture, of the care recipient's skin S and a left notional cone262L having a vertex264L at the care recipient's left ischeal tuberosity ITLand an opening angle α of about 90 degrees. The right threat-susceptible region TSRis a region bounded by the intersection260R, when the target anatomy is in a seated posture, of the care recipient's skin S and a right notional cone262R whose vertex is at the care recipient's right ischeal tuberosity ITRand which has an opening angle α of about 90 degrees.

Referring toFIG. 68, according to another set of criteria the dressing is configured for a target adult care recipient according to the criteria set forth in table 2 below:

TABLE 2Dimension:Value:gluteal membersufficiently long to extend longitudinally from thelongitudinal lengthsacral base to the ischeal tuberosity.LGMgluteal memberlaterally narrow enough that when each glutealintermembermember is approximately laterally centered on adistance WS,ITcorresponding gluteus maximus of the care recipient,inner edges 144, 164 of the gluteal members are, ata longitudinal position corresponding to thelongitudinal position of the ITs, at least as laterallyclose to the saggital plane as the correspondingischeal tuberosities are.

Referring toFIG. 69, according to another set of criteria the dressing is configured for a representative adult care recipient according to the criteria set forth in table 3 below:

TABLE 3Dimension:Value:longitudinal length LEXTsufficiently long to extend longitudinallyof the left and rightfrom the lateral middle “B” of the superiorgluteal extensionsedge of the respective left or right gluteusmaximus to the ischeal tuberosity.gluteal memberlaterally narrow enough that when each glutealintermembermember is approximately laterally centered ondistance WS,ITa corresponding gluteus maximus of the carerecipient, inner edges 144, 164 of the glutealmembers are, at a longitudinal positioncorresponding to the longitudinal positionof the ITs, at least as laterally close to thesaggital plane as the correspondingischeal tuberosities are.

In yet another embodiment the preventive dressing includes a moisture barrier layer110and a connective element120on the recipient side of the dressing. As in the previously described embodiments the connective element is arranged to provide a zone of occlusion Z. The moisture barrier layer includes a sacral member130and a left gluteal member136. The left gluteal member has a left base138which borders a left side of the sacral member and a left extension142which extends longitudinally inferior of the left base. The moisture barrier layer also includes a right gluteal member156. The right gluteal member has a right base158which borders a right side of the sacral member and a right extension162which extends longitudinally inferior of the right base. The sacral member is shaped and dimensioned to overlie the sacrum of a target care recipient. The gluteal members are shaped and dimensioned to overlie the gluteus maximus muscles of the care recipient and to extend longitudinally inferiorly at least as far as the ischeal tuberosities of the care recipient when the dressing is applied to the care recipient with the sacral member approximately laterally and longitudinally aligned with the care recipient's sacrum. The dressing may also include a tab244which extends inferiorly from an inferior edge of the sacral member at a location between the gluteal members. The tab is sized and shaped to conform to the intergluteal cleft of the care recipient.

Although the anatomically based criteria set forth above have, in some cases, been presented separately from the geometric criteria, they do not necessarily conflict with each other. Therefore a designer may find it useful to choose design criteria from among the separately enumerated criteria.

FIG. 70shows a preventive dressing assembly270which comprises a dressing100and an exciter280. The dressing of the dressing assembly, like the dressings already described, has a moisture barrier layer110with a recipient side, an environmental side, a superior edge134, an inferior edge defined by gluteal extension inferior edges148,168, a perimeter P, and a connective element, such as an adhesive, on the recipient side of the moisture barrier layer.

Unlike the dressings already described the dressing100of the dressing assembly270also includes an array of electrodes. The electrode array includes a left inferior electrode280L, a left intermediate electrode282L, a right inferior electrode280R, and a right intermediate electrode282R. The intermediate electrodes are superior of the inferior electrodes. In the illustrated embodiment the electrodes are positioned relative to each other within dressing perimeter P so that the left electrodes overlie the left gluteus maximus of a care recipient and the right electrodes overlie the right gluteus maximus of the care recipient when the dressing is applied to the care recipient with sacral member130overlying the care recipient's sacrum. In the illustrated embodiment the intermediate electrodes282are longitudinally aligned with sacral member130, and the inferior electrodes280are positioned near the termini148,168of the gluteal extensions, for example inferior of a laterally extending centerlines CGEof the gluteal members but nevertheless not where they would be inferior of the inferior edge of the gluteus maximus of the care recipient.

The dressing assembly also includes an exciter290connected to the electrodes by wires292. The illustrated exciter is connected to an AC power source294such as a conventional outlet. Alternatively, power source294may be an RF power source or a near field power source. The exciter is adapted to selectively apply an intermittent excitation to specific electrodes, for example a left excitation to only the left electrodes, a right excitation to only the right electrodes, concurrent excitation to both the left electrodes and the right electrodes, and excitation to longitudinally aligned electrodes for example to the left and right intermediate electrodes. An example excitation is the application of a voltage difference across two electrodes.

In the illustrated embodiment the left intermediate electrode282L is laterally aligned with the left gluteal member136and the right intermediate electrode282R is laterally aligned with the right gluteal member156. The left inferior electrode280L is on the left gluteal extension142longitudinally inferior of the left intermediate electrode, and the right inferior electrode280R is on the right gluteal extension162inferior of the right intermediate electrode. Referring additionally toFIG. 71, exciter290is capable of selectively applying an excitation in each excitation mode set forth in table 4 below. A lightning bolt symbol inFIG. 71indicates which electrodes are companions of each other for each mode of excitation. Plus and minus signs next to the electrode symbols show voltage polarity (plus for higher voltage; minus for lower voltage) for each companion pair.

The dressing is sized and the electrodes are positioned so that when the dressing is applied to a care recipient having a target anatomy with each gluteal member approximately laterally centered on a corresponding gluteus maximus of the care recipient, and the sacral member approximately laterally and longitudinally aligned with the sacrum of the care recipient, the excitation stimulates one or more muscles of the care recipient as set forth in table 5 below and inFIG. 71.

Modes D1 and D2 are the same except for the voltage polarity. In mode D1 electrical current flows through the gluteal muscle tissue between left intermediate electrode282L and left inferior electrode280L thereby stimulating the left gluteus maximus of the care recipient. Similarly, electrical current flows through the gluteal muscle tissue between right intermediate electrode182R and right inferior electrode280R thereby stimulating the right gluteus maximus. The excitation causes the muscle to contract which makes the tissue less susceptible to deep tissue injury. Because the voltage at both intermediate electrodes is the higher voltage, there is no noteworthy current flow laterally between the left and right intermediate electrodes.

In mode D2 electrical current flows longitudinally between left intermediate electrode282L and left inferior electrode280L by way of the left gluteal muscle tissue thereby stimulating the left gluteus maximus. Electrical current flows longitudinally between right intermediate electrode282R and right inferior electrode280R by way of the right gluteal muscle tissue thereby stimulating the right gluteus maximus. In addition, the voltage difference between the left and right intermediate electrodes is expected to cause current to flow laterally between the left gluteus medius and the right gluteus medius thereby stimulating the gluteus medius muscles. The lateral current flow is expected to be relatively weak in comparison to the longitudinal current flow because the gluteus maximus muscles lie transversely between the intermediate electrodes and the gluteus medius muscles. The electrodes are therefore not optimally positioned to cause lateral current flow.

In mode E electrical current flows between the left and right intermediate electrodes thereby stimulating the left and right gluteus medius muscles. As with mode D2 the electrodes are not optimally positioned to stimulate the gluteus medius, however the stimulation is expected to be less weak than that of mode D2.

The foregoing describes a four electrode embodiment.FIGS. 72-73shows a six electrode embodiment. In the diagrams ofFIG. 73a horizontal line schematically signifies the superior edge of the gluteus maximus and therefore distinguishes between the electrodes that are superior of and inferior of the superior edge of the gluteus maximus. The six electrode embodiment includes a left superior electrode284L longitudinally superior of left intermediate electrode282L and a right superior electrode284R longitudinally superior of the right intermediate electrode282R. In the illustrated embodiment the electrodes are positioned relative to each other within dressing perimeter P, so that the left and right superior electrodes overlie the left and right gluteus medius muscles of a care recipient when the dressing is applied to the care recipient with sacral member130overlying the care recipient's sacrum. In the illustrated embodiment the superior electrodes284are longitudinally aligned with sacral member130, and the inferior electrodes280are positioned near the termini of the gluteal extensions, for example inferior of laterally extending centerlines CGEof the gluteal members but nevertheless not where they would be inferior of the edge of the gluteus maximus of the care recipient.

The dressing assembly also includes an exciter290connected to the electrodes by wires292. The illustrated exciter is connected to an AC power source294such as a conventional outlet. Alternatively, power source294may be an RF power source or a near field power source. The exciter is adapted to selectively apply an excitation to specific electrodes, for example a left excitation to only the left electrodes, a right excitation to only the right electrodes, concurrent excitation to both the left electrodes and the right electrodes, and excitation to longitudinally aligned electrodes for example to the left and right superior electrodes. An example excitation is the application of a voltage difference across two electrodes.

In the illustrated embodiment the left superior electrode284L is laterally aligned with left gluteal member136and the right superior electrode284R is laterally aligned with the right gluteal member156. The left inferior electrode280L is on the left gluteal extension142longitudinally inferior of the left intermediate electrode282L, and the right inferior electrode280R is on the right gluteal extension162longitudinally inferior of the right intermediate electrode. Exciter290is capable of selectively applying an excitation in each excitation mode set forth in table 7 below. A lightning bolt symbol inFIG. 73indicates which electrodes are companions of each other for each mode of excitation. Plus and minus signs next to the electrode symbols show voltage polarity (plus for higher voltage; minus for lower voltage) for each companion pair.

The dressing is sized and the electrodes are positioned so that when the dressing is applied to a care recipient having a target anatomy with each gluteal member approximately laterally centered on a corresponding gluteus maximus of the care recipient, and the sacral member approximately laterally and longitudinally aligned with the sacrum of the care recipient, the excitation stimulates one or more muscles of the care recipient as set forth in table 8 below and inFIG. 73.

Modes D1 and D2 are the same except for the voltage polarity. In mode D1 electrical current flows between the left intermediate electrode282L and the left inferior electrode280L by way of the left gluteus maximus thereby stimulating the left gluteus maximus. Similarly, electrical current flows from right intermediate electrode282R to the right inferior electrode280R by way of the right gluteus maximus thereby stimulating the right gluteus maximus. The excitation causes the gluteus maximus muscles to contract which makes the tissue less susceptible to deep tissue injury. Because the voltage at both intermediate electrodes is the higher voltage, there is no noteworthy current flow laterally between the left and right intermediate electrodes.

In mode D2 electrical current flows through the left gluteus maximus between left intermediate electrode282L and left inferior electrode280L thereby stimulating the left gluteus maximus. Electrical current flows through the right gluteus maximus between the right intermediate electrode282R and the right inferior electrode280R thereby stimulating the right gluteus maximus. In addition, the voltage difference between the left and right intermediate electrodes is expected to cause current to flow laterally between the left gluteus medius and the right gluteus medius thereby stimulating the gluteus medius muscles. The lateral current flow is expected to be relatively weak in comparison to the longitudinal current flow because the gluteus maximus muscles lie transversely between the intermediate electrodes and the gluteus medius muscles. The electrodes are therefore not optimally positioned to cause lateral current flow.

In mode E electrical current flows between the left and right superior electrodes thereby stimulating the left and right gluteus medius muscles.

In yet another set of embodiments the electrode arrangements and electrode excitation patterns are as already described in connection withFIGS. 70-73, however other elements of the dressing do not cooperate to provide a zone of occlusion. Referring toFIGS. 74-75, a dressing100A includes an external layer110A which is analogous to moisture barrier layer110as previously described but which does not prevent moisture transfer from the environment to the portion of the care recipient's skin covered by the dressing. In addition, connective element120A (illustrated as a spatially distributed adhesive200A) is an adhesive element which also does not protect against moisture ingress. As a result, the region of the care recipient's anatomy covered by the dressing is a zone of coverage ZCrather than a zone of occlusion Z. In such an embodiment the dressing serves as an electrode host which is configured to place the electrodes at the desired location on the anatomy of the care recipient, but does not protect against moisture ingress into the area covered by the dressing (i.e. into zone ZC). This is indicated by the solid arrows which penetrate transversely through external layer110A and connective element120A and which also penetrate longitudinally and laterally into connective element120A.FIG. 74shows the four electrode variant already described in connection withFIGS. 70-71, however dressing100A can also accommodate the six electrode variant ofFIGS. 72-73.

FIGS. 76-77show an embodiment similar to that ofFIGS. 74-75but in which the connective element120A is illustrated as an adhesive strip190A. Moisture transfer is indicated by the solid arrows which penetrate transversely through external layer110A and which also penetrate longitudinally and laterally through adhesive strip190A. Once again the dressing serves as an electrode host which is configured to place the electrodes at the desired location on the anatomy of the care recipient but which does not protect against moisture ingress transversely across external layer110A or laterally and longitudinally through adhesive strip190A.

FIGS. 78-79show an embodiment similar to that ofFIGS. 76-77but in which the connective element120is a an adhesive strip190which blocks moisture transfer laterally and longitudinally into zone ZC. Moisture can nevertheless enter zone ZCby way of external layer110A. This is indicated by the solid arrows which penetrate transversely through external layer110A and by the laterally and longitudinally directed solid arrows which terminate without crossing adhesive strip190. Once again the dressing serves as an electrode host which is configured to place the electrodes at the desired location on the anatomy of the care recipient but which does not protect against moisture ingress transversely across external layer110A.

The variations in planform, such as those ofFIGS. 60-65, apply equally to the non-occlusive embodiments just described. In addition a pressure equalizing layer such as layer220described in connection withFIGS. 43-50may also be incorporated.

Although this disclosure refers to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the subject matter set forth in the accompanying claims.