WO2011117618A1

WO2011117618A1 - Positive pressure application

Info

Publication number: WO2011117618A1
Application number: PCT/GB2011/050561
Authority: WO
Inventors: Bryan Greener
Original assignee: Smith and Nephew PLC
Current assignee: Smith and Nephew PLC
Priority date: 2010-03-23
Filing date: 2011-03-22
Publication date: 2011-09-29
Anticipated expiration: 2012-09-23
Also published as: GB201004819D0

Abstract

Apparatus (10) for applying a positive pressure at a target surface (22).

Description

POSITIVE PRESSURE APPLICATION

The present invention relates to an apparatus and method for applying a positive pressure at a target surface. In particular, but not exclusively, the present invention relates to the application of positive pressure locally on a human or animal body.

Certain devices for applying positive pressure to the surface of a body are known. However, many require encapsulation of a part of the body or a circumferential cuff of some sort. For localised application of the positive pressure the circumferential cuff or similar arrangement is applied to mechanically exert positive pressure on the target area. However, positive fluid (liquid or gas) pressure is very difficult to apply locally in the absence of a bracing mechanism. For example, in the case of circumferential cuffs, a circumferential retainer must be used. It is known that in the absence of such a bracing mechanism the fluid pressure works to expand away from an intended site of application leading to a seal failure and thus a loss of the positive pressure.

It is aim of the present invention to at least partly mitigate the above-mentioned problems. It is an aim of certain embodiments of the present invention to provide an apparatus and/or method for applying a positive pressure at a target surface without the need for a bracing mechanism.

It is an aim of certain embodiments of the present invention to facilitate application to a broad range of bodily locations whether internal or external.

It is an aim of certain embodiments of the present invention to provide an apparatus and/or method able to generate a positive pressure at a target site, such as a wound site, without breaking a seal.

According to a first aspect of the present invention there is provided apparatus for applying a positive pressure at a target surface, comprising:

a surface contact member comprising a first surface locatable in contact with a target surface, a further surface spaced apart from the first surface and at least one through orifice extending between the first and further surface; and a spacer member extending from said further surface and defining at least one chamber region; wherein

at least a portion of the surface contact member is located beneath a portion of said chamber region.

According to a second aspect of the second invention there is provided a method for applying a positive pressure at a target surface, comprising the steps of:

locating a first surface of a surface contact member on a target surface;

providing a positive pressure in at least one chamber region defined by a spacer member extending from a further surface of the surface contact member; and

urging a portion of the surface contact member towards the. target surface via the positive pressure in the chamber region.

Certain embodiments of the present invention enable a device to be applied to cover a bodily area having a broad choice of geometry. For example convex and/or concave surfaces can be covered and a positive pressure applied thereto.

Certain embodiments of the present invention provide apparatus which can be secured to a body by a sealing mechanism that provides a substantially fluid-tight seal under positive pressure. The apparatus is provided such that the contained positive pressure does not exert excessive force in a direction that would result in rupture of the sealing mechanism and therefore to pressure loss.

Certain embodiments of the present invention provide at least a portion of an interface surface upon which a contained positive pressure generates a force which is exerted in the direction of the contact surface. As an example this can be achieved by creating a contact interface that extends inside the perimeter of a positive pressure enclosure. The portion which extends inside the positive pressure enclosure experiences a force that is directed towards the contact surface and thus encourages device attachment and seal integrity.

Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates apparatus for applying a positive pressure at a target surface; Figure 2 illustrates a cross sectional view of the apparatus shown in Figure 1;

Figure 3 illustrates an exploded view of apparatus for applying a positive pressure at a target surface;

Figure 4 illustrates a layer of the apparatus shown in Figure 3; Figure 5 illustrates the layer shown in Figure 4; Figure 6 illustrates two of the layers shown in Figure 3; and

Figure 7 illustrates a top view of a portion of the apparatus shown in Figure 3. In the drawings like reference numerals refer to like parts.

Figure 1 illustrates an apparatus which can be utilised to apply a positive pressure at a target surface. Positive pressure describes any pressure exceeding a surrounding pressure such as, for example, an ambient atmospheric pressure. Aptly the positive pressure applied does not exceed 1000 mmHg above ambient atmospheric pressure. Aptly the positive pressure does not exceed 500 mmHg above ambient atmospheric pressure. Aptiy the positive pressure does not exceed 250 mmHg above ambient atmospheric pressure.

The positive pressure can be applied to a target surface. A broad range of target surfaces are applicable to certain embodiments of the present invention. For example, inanimate objects or animate surfaces including animal and human bodies. Certain embodiments of the present invention enable a positive pressure to be applied at a localised region of a target surface. That is to say, at any area of a body, whether animate or inanimate, that is less than an entirety of the body.

As illustrated in Figure 1 the apparatus 10 includes a generally circular flange 11 having an upper surface 12 and lower surface 13. The lower surface acts as a contact surface which is Iocatable in contact with a target surface where a positive pressure is to be applied. The flange 11 has a central aperture 14 which enables a positive pressure generated in a chamber 15 inside a dome 6 of the apparatus to be applied underneath the apparatus 10. Figure 2 illustrates a cross sectional view of the apparatus shown in Figure 1 in more detail and illustrates how a domed wall which extends upwardly from the upper surface 12 of the flange region acts as a spacer separating an inlet tube 20 from the flange region 1 .

The tube 20 is connected to a positive pressure source such as a pump, bellows, head of liquid, mechanically powered container or the like. When the pump is energised a positive pressure relative to the surrounding pressure will be generated within the region of the chamber 5. That is to say, the pressure P-i within the chamber will be greater than the ambient pressure P₂.

The apparatus for applying a positive pressure shown in Figure 2 is illustrated as being located over a region of a human body 21 where a wound site 22 is located. As will be understood by those skilled in the art application of a positive pressure in the chamber 15 is, under certain circumstances, known to aid a healing process. In such use an upper/outer surface 23 of the body forms a target surface against which the contact surface 13 of the apparatus is juxtaposed. As illustrated in Figure 2 a portion of the flange 11 undercuts the central domed region 16. That is to say there is part of the flange 11 which acts as a surface contact member that is located beneath a part of the chamber 15. The flange 1 which acts as a surface contact member may thus be thought of as a ring element comprising a body portion surrounding an open centre region, it will be understood that one or more apertures may be formed beneath the domed region which may or may not be centred according to certain other embodiments of the present invention. It will likewise be understood that the flange region may be circular, rectangular, square, hexagonal or octagonal or any other shape. Because a part of the apparatus which contacts the target surface is located beneath the region where a positive pressure is generated and maintained that positive pressure acts to urge the undercut region against the target surface. This helps ensure that a seal is maintained between the apparatus for applying the positive pressure and the target surface. It will be understood that whilst the positive pressure in the chamber 15 may be applied by pumping air into the chamber any fluid, such as any other gas or a liquid, could be utilised to generate the positive pressure. Aptly, the material from which the dome 16 is manufactured is flexible. As the positive pressure is applied the nature of the material is such that the domed region will expand before the seal between the flange and target surface is broken.

By generating a positive pressure in the chamber and having a portion of the apparatus which is in contact with a target surface falling below/within the footprint of that chamber the positive pressure acts to urge the apparatus against the contact surface which overcomes peeling pressures and forces which would otherwise tend to break the seal between the apparatus and the target surface. Aptly the region lying below the chamber which acts as a lip encircles the whole circumference of each and every aperture in the flange.

When the positive pressure apparatus 10 is duly iocated at a target site and then inflated with a positive pressure a substantially leak-free seal is generated between the device and a target surface about the volume of the contained positive pressure. A substantially leak-free seal is taken to mean the containment of a volume of positive pressure with a fluid leak rate below 10 mlmin^"1. Aptly the fluid leak rate is below 1 mlmin^"1. Aptly the fluid leak rate is below 100 mlmin^'1.

Such containment is achieved by applying a device geometry that enables at least a portion of the force generated by the contained positive pressure to act upon the device in the direction of the target contact surface. The portion of the device upon which the positive pressure exerts a force in the direction of the target surface may be continuous or discontinuous. Aptly the portion of the device upon which the positive pressure exerts a force in the direction of the contact surface covers a contact area that exceeds 5% of the area bounded by the positive pressure enclosure provided as the volume contained underneath the dome. Aptly the portion exceeds 10% of the area bounded. Aptly the portion exceeds 30% of the area bounded.

The device may be constructed of any suitable material. For some target surfaces where contact is made which have predetermined shape characteristics (for example inanimate objects) the device may be manufactured from a very rigid and strong material having a predetermined lower surface cross section to mate with the specific target surface. Aptly the device is constructed in a manner and of a material that allows sufficient conformational flexibility to facilitate secure attachment to any location of a target object where attachment is desired. When the target surface concerned is a human body, the device is aptly constructed of a material that has a force constant of less than 500 Nm^'1. Aptly less than 100 Nm^"1. Such properties can conveniently be achieved by applying silicone or polyurethane-based elastomeric materials in the device construction. Attachment to the site of application can be achieved by any suitable means. Aptly an adhesive layer is included on a lower surface 13 of the flange. Alternatively an inherently adhesive material can be utilised to manufacture at least the flange region 12 of the apparatus. For application to the human body the adhesive is preferably one that does not create trauma on removal. Such adhesives include those based upon silicone elastomers. Peel force from intact skin is preferably less than 100 gfcnrf¹. Aptly less than 50 gfcm^"1. In the case where an adhesive layer is applied to an underside of the device adhesive coat weight is preferably greater than 50 gm^'2. Aptly greater than 100 gm^"2. Aptly greater than 200 gm^'2. Aptly the adhesive coat weight should not exceed 600 gm^'2

Aptly the geometry of the device is such that it can expand to contain a volume of positive pressure at the site of application. It is preferably that expansion occurs predominantly in the portion of the apparatus that is not in contact with the site of application. To achieve this advantageous, but not essential, expansion the portion of the device not in contact with the site of application is constructed in such a manner as to allow expansion under positive pressure without generating significant distortion in the portion of the device in contact with the target surface. This can be achieved in a variety of ways.

Figure 3 illustrates an alternative way in which positive pressure can be applied at a target surface. As shown in Figure 3 which illustrates an exploded view, a laminate including three sheets can be used as apparatus for applying a positive pressure at a target site. This provides a low profile alternative to the apparatus illustrated in Figures 1 and 2. A target surface contact layer 30 which includes multiple apertures is used. The apertures may be formed either as perforations formed in a film layer or as holes in a welded knitted layer or in any other way. This contact layer has a lower surface 31 which will contact a target surface where a positive pressure is to be applied. The contact layer has an upper surface 32 and against this a spacer layer 33 is provided. The spacer layer 33 is illustrated in more detail in Figure 4 and Figure 5. As illustrated in Figure 4 and Figure 5 the spacer layer is manufactured as a sheet having rectangular holes 40 perforated therethrough. Other shape holes can of course be used. The holes 40 are through hoies. As illustrated in Figure 5 the perforated holes can be formed in rows and columns in an aligned arrangement or alternatively, according to certain other embodiments, the holes may be randomly formed or made in predetermined different patterns. The thickness d of the sheet is such that each hole 40 is surrounded by a side wall. In the embodiment shown in Figures 4 and 5 the holes 40 are rectangular in shape and have a first elongate side wall 51 and a second elongate side wall 52 spaced apart from and parallel to the first side wall. A first shorter end wall 53 is parallel to and spaced apart from a further short end wall 54. The holes 40 in the spacer sheet each act in a similar manner to the chamber 15 described with respect to Figures 1 and 2. The materia! of the sheet forms a wall around each hole thus enclosing the hole.

Referring again to Figure 3 the spacer layer 33 is covered with a fluid-impermeable top film 34. This includes a centrally positioned aperture 35 which may be secured to a tube leading to a pump or other positive pressure source. The aperture may of course be located off centre and might comprise multiple openings.

Figure 6 illustrates the spacer layer 33 secured above the target surface contact layer 30. As illustrated in Figure 6 the through holes in the contact layer 30 are smaller and are on a smaller pitch than the holes 40 in the spacer layer. The two layers are secured together via an adhesive or welding or any other suitable securement. As illustrated in Figure 6 one, two or more holes 60 in the surface contact layer 30 lead into each hole 40 in the spacer layer. The material 61 which is the bulk material of the surface contact layer underlies the holes 40 in the spacer layer and the remaining material 55 of the spacer layer. Figure 7 illustrates a top view looking down on the spacer layer which covers the contact surface layer 30. Each hole 40 in the spacer layer overlies at least one aperture 60 in the surface contact layer 30.

The impermeable top layer is secured to the spacer layer at least around a periphery thereof. Aptly further discontinuous connections are made between the spacer layer and the top layer. This helps allow transmission of positive pressure. By connecting the aperture in the top layer to a positive pressure source positive pressure can be established in each hole 40 in the spacer layer. This positive pressure is communicated to the target surface, such as a wound site, through the holes 60 in the contact surface layer 30. Thus positive pressure can be applied to a target surface below the contact surface layer 30.

As previously described with respect to Figures 1 and 2, because a part of the apparatus which contacts the target surface is located beneath a region where a positive pressure is generated and maintained, that positive pressure acts to urge the material lying below the footprint of the region against the target surface. This helps ensure that a seal is maintained between the low profile apparatus and the target surface.

It will be appreciated that certain embodiments of the present invention have a broad range of uses. Aptly certain embodiments can be used for fluid flow stasis. Aptly certain embodiments of the present invention can be used for haemostasis or exude flow stasis.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires, in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. Apparatus for applying a positive pressure at a target surface, comprising:

a surface contact member comprising a first surface !ocatable in contact with a target surface, a further surface spaced apart from the first surface and at least one through orifice extending between the first and further surface; and

a spacer member extending from said further surface and defining at least one chamber region; wherein

2. The apparatus as claimed in claim 1 , further comprising:

the surface contact member comprises a ring element comprising a body portion surrounding an open centre region.

3. The apparatus as claimed in claim 2 wherein the ring element is circular or rectangular or square or hexagonal or octagonal shaped.

4. The apparatus as claimed claim 2 or claim 3, further comprising:

the spacer member comprises a wall member extending away from the further surface of the ring element around the whole length of the body portion of the ring element, said wall member forming an enclosure around and over the open centre region. 5. The apparatus as claimed in claim 4, further comprising:

an inlet in the wall member for applying positive pressure to the chamber region defined between the enclosure.

6. The apparatus as claimed in claim 1, further comprising:

the surface contact member comprises a first sheet comprising a plurality of through holes.

7. The apparatus as claimed in claim 6 wherein the first sheet comprises a perforated film sheet.

8. The apparatus as claimed in claim 6 or claim 7, further comprising: the spacer element comprises a further sheet comprising a plurality of through holes,

9. The apparatus as claimed in claim 8 wherein the further sheet comprises a perforated film sheet. 0. The apparatus as claimed in any one of claims 8 or 9 wherein each through hole in the further sheet defines a chamber region therein. 11. The apparatus as claimed in any one of claim 8 to 10 wherein the first and further sheets are secured together.

12. The apparatus as claimed in claim 1 wherein the first and further sheets are welded or adhered together.

13. The apparatus as claimed in claim 8, further comprising:

the pitch of holes in the first sheet is different from the pitch of holes in the further sheet, holes in the first sheet being smaller and/or more closely spaced apart than the holes in the further sheet.

14. The apparatus as claimed in any one of claims 6 to 13, further comprising:

a cover sheet extending over the spacer element and comprising an inlet for applying positive pressure. 15. A method for applying a positive pressure at a target surface, comprising the steps of:

locating a first surface of a surface contact member on a target surface;

urging a portion of the surface contact member towards the target surface via the positive pressure in the chamber region.

16. The method as claimed in claim 15, further comprising the steps of:

preventing generation of a peeling force between the surface contact member and the target surface. 17, The method as claimed in claim 15, further comprising the steps of:

providing a plurality of chamber regions via a corresponding plurality of through holes in a sheet comprising said spacer member. 18. The method as claimed in claim 15, further comprising the steps of:

providing a chamber region via a wall member extending from a ring element comprising said surface contact member, said wall member forming an enclosure around and over an open centre region of the ring element. 19. Apparatus constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

20. A method substantially as hereinbefore described with reference to the accompanying drawings.