Apparatus for topical negative pressure therapy
Contents
1. 811 2005 0131327 Al 6 2005 Lockwood et al MN 3 2007 WO WO 2008 141470 11 2008 2007 0167927 Al 7 2007 Hunt et al 604 313 2008 0071216 Al 3 2008 Locke et al OTHER PUBLICATIONS 2010 0160878 Al 6 2010 Hunt et al 2013 0150813 AI 6 2013 Gordon et al Info V A C User Manual KCI Dec 2006 in 76 pages International Preliminary Report on Patentability issued on Jun 8 FOREIGN PATENT DOCUMENTS 2010 in International Application No PCT GB2008 051048 in 9 pages WO WO 99 19013 4 1999 WO WO 2004 016313 2 2004 cited by examiner US 8 617 129 B2 Sheet 1 of 9 Dec 31 2013 U S Patent Old US 8 617 129 B2 Sheet 2 of 9 Dec 31 2013 U S Patent U S Patent Dec 31 2013 Sheet 3 of 9 US 8 617 129 B2 FIG 3 US 8 617 129 B2 Sheet 4 of 9 Dec 31 2013 U S Patent U S Patent Dec 31 2013 Sheet 5 of 9 US 8 617 129 B2 US 8 617 129 B2 Sheet 6 of 9 Dec 31 2013 U S Patent FIG 7 U S Patent Dec 31 2013 Sheet 7 of 9 US 8 617 129 B2 LL 2220244 AL 22 10727 gt am y i 5 204 220 288 266 268 300 g SN 260 P EA 2222222 280 292 2884 7 278 U S Patent Dec 31 2013 Sheet 8 of 9 US 8 617 129 B2 446 404 408 416 4g 42 410 FIG 10B U S Patent Dec 31 2013 Sheet 9 o2. The invention is comprised in part of an overall apparatus for the provision of TNP therapy to a patient in almost any environment The apparatus is lightweight may be mains or battery powered by a rechargeable battery pack contained within a device henceforth the term device is used to connote a unit which may contain all of the control power supply power supply recharging electronic indicator means and means for initiating and sustaining aspiration functions to a wound and any further necessary functions of a similar nature When outside the home for example the apparatus may provide for an extended period of operation on battery power and in the home for example the device may be connected to the mains by a charger unit whilst still being used and operated by the patient The overall apparatus of which the present invention is a part may comprise a dressing covering the wound and seal ing at least an open end of an aspiration conduit to a cavity formed over the wound by the dressing an aspiration tube comprising at least one lumen therethrough leading from the wound dressing to a waste material canister for collecting and holding wound exudates waste material prior to disposal and a power control and aspiration initiating and sustaining device associated with the waste canister The dressing covering the wound may be any type of dress ing normally employed with TNP therapy and in very general terms may comprise for
3. understood to be applicable to any other aspect embodiment or example described herein unless incompatible therewith What is claimed is 1 Apparatus for the provision of topical negative pressure therapy to a wound site the apparatus comprising vacuum generating means being operably connected to a dressing at said wound site by aspiration conduit means pressure sensing conduit means in fluid communication with said aspiration conduit means at a junction adjacent said dressing first pressure sensing means between said junction and said vacuum generating means second pressure sensing means operably associated with said pressure sensing conduit means a valve associated with said pressure sensing conduit means diagnostic means in communication with said first and second pressure sensing means and control means in communication with said diagnostic means for controlling pressure in said aspiration and said pressure sensing conduit means wherein the control means is configured to detect a blockage in the aspiration conduit means based on comparison ofa pressure difference between pres sure sensed by the first pressure sensing means and pressure sensed by the second pressure sensing means with a pressure difference threshold open the valve in response to detecting the blockage close the valve if the pressure difference falls to substan tially zero after expiration of a first time interval and activate a blockage alarm if the pressu
4. and canister 204 are also provided with features which prevent the canister and device from exhibiting a mutual wobble when connected together Ribs not shown extending between the canistertop closure member 288 and the inner face 300 of the upstanding flange 260 locate in grooves 302 in the device sidewalls when canister and device are connected The casing 230 also houses all of the electrical equipment and control and power man agement features the functioning of which was described briefly with respect to FIGS 3 and 4 hereinabove The side 20 25 30 35 40 45 50 55 60 65 12 piece 238 is provided with a socket member 298 to receive a charging jack from an external mains powered battery charger both not shown FIG 10A shows a schematic representation of an apparatus 400 according to a first embodiment ofthe present invention The apparatus comprises a vacuum pump 402 connected to a woundsite 404 by an aspirant conduit 408 via a waste canister 409 As shown schematically in FIG 10B the wound site 404 itself comprises a wound per se 406 having one end of the aspirant conduit 408 applied thereto and sealed into a wound cavity 410 formed by and overlying sealing drape film 412 which is sealed around the edges of the wound 406 by an adhesive layer not shown on the film 410 well known in the dressings art to sound skin 414 The aspirant conduit 408 is sealed to the drape 412 at the point 416 at which it
5. may comprise a 1 um hydrophobic liquid filter and a 0 2 um bacteria filter such that all liquid and bacteria is confined to an interior waste collecting volume of the waste canister 22 The exit port 28 of the waste canister 22 mates with an entry suction port 30 of a device unit 32 by means of mutually sealing connector portions 34 36 which engage and seal together automatically when the waste canister 22 is attached to the device unit 32 the waste canister 22 and device unit 32 being held together by catch assemblies 38 40 The device unit 32 comprises an aspirant pump 44 an aspirant pressure monitor 46 and an aspirant flowmeter 48 operably connected together The aspiration path takes the aspirated fluid which in the case of fluid on the exit side of exit port 28 is gaseous through a silencer system 50 and a final filter 52 having an activated charcoal matrix which ensures that no odours escape with the gas exhausted from the device 32 via an exhaust port 54 The filter 52 material also serves as noise reducing material to enhance the effect of the silencer system 50 The device 32 also contains a battery pack 56 to power the apparatus which battery pack also powers the control system 60 which controls a user interface system 62 controlled via a keypad not shown and the aspiration pump 44 via signals from sensors 46 48 A power management system 66 is also provided which controls power from the battery pack 56 the recharging thereof and the
6. paths employed in the control system for control of the aspirant pump and other features of the apparatus A key purpose ofthe TNP system is to apply negative pressure wound therapy This is accom plished via the pressure control system which includes the pump and a pump control system The pump applies negative pressure the pressure control system gives feedback on the pressure at the pump head to the control system the pump control varies the pump speed based on the difference between the target pressure and the actual pressure at the pump head In order to improve accuracy of pump speed and hence provide smoother and more accurate application ofthe negative pressure at a wound site the pump is controlled by an auxiliary control system The pump is from time to time allowed to free wheel during its duty cycle by turning off the voltage applied to it The spinning motor causes a back electro motive force or BEMF to be generated This BEMF can be monitored and can be used to provide an accurate measure of pump speed The speed can thus be adjusted more accurately than can prior art pump systems In some embodiments of apparatus actual pressure at a wound site may not be measured but the difference between a measured pressure at the pump and the wound pressure is minimised by the use of large filters and large bore tubes wherever practical If the pressure control measures that the pressure at the pump head is greater than a target p
7. power requirements of the aspirant pump 44 and other electrically operated components An electrical connector 68 is provided to receive a power input jack 70 from a SELV power supply 72 connected to a mains supply 74 when the user of the apparatus or the apparatus itself is adjacent a convenient mains power socket FIG 2 shows a similar schematic representation to FIG 1 but shows the fluid paths in more detail The wound exudate is aspirated from the wound site dressing 14 via the conduit 12 the two connector portions 18 20 and the conduit 24 into the waste canister 22 The waste canister 22 comprises a relatively large volume 80 in the region of 500 ml into which exudate from the wound is drawn by the aspiration system at an entry port 82 The fluid 84 drawn into the canister volume 80 is a mixture of both air drawn into the dressing 14 via the semi permeable adhesive sealing drape not shown and liq uid 86 in the form of wound exudates The volume 80 within the canister is also at a lowered pressure and the gaseous element 88 of the aspirated fluids is exhausted from the can ister volume 80 via the filters 26 and the waste canister exhaust exit port 28 as bacteria free gas From the exit port 28 of the waste canister to the final exhaust port 54 the fluid is gaseous only FIG 3 shows a schematic diagram showing only the device portion of the apparatus and the power paths in the device of 20 25 30 40 45 55 65 10
8. 264 there around sealingly engages with a cylindrical tube portion 266 formed around an exhaust exit port 268 in the waste canister The spigot 214 of the device is not rigidly fixed to the device casing but is allowed to float or move in its location features in the casing to permit the spigot 214 and seal 264 to move to form the best seal with the bore of the cylindrical tube portion 266 on connection of the waste canister to the device unit The waste canister 204 in FIG 9 is shown in an upright orientation much as it would be when worn by a user Thus any exudate 270 would be in the bottom of the internal volume of waste receptacle portion 272 An aspiration conduit 274 is perma nently affixed to an entry port spigot 278 defining an entry port 280 to receive fluid aspirated from a wound not shown via the conduit 274 Filter members 282 comprising a 0 2 um filter and 284 comprising a 1 um filter are located by a filter retainer moulding 286 adjacent a top closure member or bulkhead 288 the filter members preventing any liquid or bacteria from being drawn out ofthe exhaust exit port 268 into the pump and aspiration path through to an exhaust and filter unit 290 which is connected to a casing outlet moulding at 291 via an exhaust tube not shown in casing side piece 236 The side pieces 236 238 are provided with recesses 292 having support pins 294 therein to locate a carrying strap not shown for use by the patient The side pieces 230
9. In particular the carry case may be provided with a bottom opening flap to permit the waste canister to be changed without complete removal of the apparatus form the carry case The carry case may be provided with an aperture covered by a displaceable flap to enable user access to a keypad for varying the therapy applied by the apparatus According to a second aspect ofthe present invention there is provided a method for the topical negative pressure treat ment ofa wound site using the apparatus of the first aspect the method comprising the steps of providing vacuum generat ing means for generating a negative pressure at said wound US 8 617 129 B2 7 site said vacuum generating means being operably connected to a dressing at said wound site by aspiration conduit means providing pressure sensing conduit means in fluid communi cation with said aspiration conduit means at a junction adja cent said dressing providing first pressure sensing means between said junction and said vacuum generating means providing second pressure sensing means operably associ ated with said pressure sensing conduit means providing diagnostic means in communication with said first and sec ond pressure sensing means and providing control means in communication with said diagnostic means for controlling pressure in said aspiration and said pressure sensing conduit means sensing pressures at said first and second pressure sensor means and triggering an app
10. al ribs within the chamber formed to prevent the inner surfaces of the two opposing walls from contacting each other and so closing the chamber within to exudate fluid flow The ribs holding the walls apart under vacuum conditions to permit continuous fluid flow there through The dual lumen portion may provide one portion for aspi rated exudate fluid flow therethrough towards a waste canister whilst the second lumen may for example be provided for the purpose of admitting an air bleed into the system prefer ably close to the dressing so as to ensure continuous aspirant fluid flow under all conditions The flattened shaped exudate collecting portion may be formed in other shapes and constructions according to the requirements of a particular wound formation According to a fourth aspect of the present invention there is provided an adapter for use in topical negative pressure therapy the adapter comprising a connecting spigot potion having a fluid flow inlet conduit therethrough a body portion wherein the inlet conduit communicates with two fluid flow passages the body portion also including means for receiving two fluid flow lumens both fluid flow lumens being in fluid communication with each other in the body portion The adapter may be used to connect to a single lumen aspirant conduit exiting a sealed wound cavity under a dress ing drape during TNP therapy one lumen in the adapter being for aspiration of wound exudate to an asso
11. ale mating face 218 which engages with a co operating peripheral female formation 220 on an upper edge of the waste canister 204 see FIGS 8 and 9 On each side of the device 202 clips 222 hinged to the canister 204 have an engaging finger not shown which co operates with formations in recesses 226 in the body of the device unit From FIG 7 it may be seen that the casing 230 of the device unit is of largely clamshell construction comprising front and back mouldings 232 234 respectively and left hand and right hand side inserts 236 238 Inside the casing 230 is a central chassis 240 which is fastened to an internal moulded structural member 242 and which chassis acts as a mounting for the electrical circuitry and components and also retains the battery pack 246 and aspiration pump unit 248 Various tubing items 250 252 254 connect the pump unit 248 and suction entry port 216 to a final gaseous exhaust via a filter 290 FIG 8 shows a partially sectioned side elevation of the apparatus 200 the partial section being around the junction between the device unit 202 and the waste canister 204 a cross section of which is shown at FIG 9 Theses views show the rebated edge 218 of the male formation on the device unit co operating with the female portion 220 defined by an upstanding flange 260 around the top face 262 of the waste canister 204 When the waste canister is joined to the device unit the spigot 214 which has an O ring seal
12. at home or at work subject to the availability of an easily portable and maintain able TNP therapy apparatus It is desirable to be able to differentiate between and to measure separately the pressures being applied immediately adjacent a vacuum pump connected to TNP apparatus and a dressing and the actual pressure being applied at or adjacent a wound dressing itself This is because the pressure reduc tion being applied by a vacuum pump may not necessarily be that pressure which actually exists at the wound dressing For example an aspirant tube may be kinked or otherwise blocked perhaps by aspirated fluids and although a pressure measured by a sensor adjacent the pump may indicate that a desired pressure is being applied the actual pressure at the wound site may be very different GB A 2 307 180 describes a portable TNP therapy unit which may be carried by a patient clipped to belt or harness The portable TNP apparatus described permits the measure ment of pressure applied at the wound site and also that pressure generated by a vacuum pump However the means of conveying the respective pressures is by a multi Iumen tube which is complex and expensive to produce and which also requires a made to fit connector and dressing in order to connect the multi Iumen tube to a wound Furthermore the apparatus applies a vacuum to the dressing via the waste canister therefore the waste canister itself is a complex and expensive moulding needing
13. az United States Patent Hartwell US008617129B2 US 8 617 129 B2 Dec 31 2013 10 Patent No 45 Date of Patent 54 APPARATUS FOR TOPICAL NEGATIVE PRESSURE THERAPY 75 Inventor Edward Hartwell York GB 73 Assignee Smith amp Nephew PLC London GB Notice Subject to any disclaimer the term of this J y patent is extended or adjusted under 35 U S C 154 b by 572 days 21 Appl No 12 746 499 22 PCT Filed Nov 11 2008 86 PCT No 371 c 1 2 4 Date PCT GB2008 051048 Sep 24 2010 87 Pub No WO2009 071926 PCT Pub Date Jun 11 2009 65 Prior Publication Data US 2010 0280422 Al Nov 4 2010 30 Foreign Application Priority Data Dec 6 2007 0723876 9 51 Int CI A61M 1 00 52 U S Cl hd rat nr entes 604 313 58 Field of Classification Search USPC entr ttt 604 304 313 319 540 See application file for complete search history 2006 01 56 References Cited U S PATENT DOCUMENTS 3 276 472 A 3 750 704 A 10 1966 Jinkens et al 8 1973 Burke et al 4 735 606 A 4 1988 Davison 4 936 834 A 6 1990 Beck et al 5 207 641 A 5 1993 Allton 5 370 610 A 12 1994 Reynolds 6 142 982 A 11 2000 Hunt et al 7 316 672 Bl 1 2008 Hunt et al 7 553 306 Bl 6 2009 Hunt et al Continued FOREIGN PATENT DOCUMENTS GB 2 307 180 5 1997 WO WO 92 12369 7 1992 Continued OTHER PUBLICATIONS Inter
14. ciated waste can 20 25 30 35 40 45 50 55 60 65 8 ister and the second lumen being for admitting an air bleed into the system preferably close to the dressing so as to ensure continuous aspiration of fluid from the wound cavity BRIEF DESCRIPTION OF THE DRAWINGS Inorderthat the present invention may be more fully under stood examples will now be described by way of illustration only with reference to the accompanying drawings of which FIG 1 shows a generalised schematic block diagram show ing a general view of an apparatus and the constituent appa ratus features thereof FIG 2 shows a similar generalised schematic block dia gram to FIG 1 and showing fluid paths therein FIG 3 shows a generalised schematic block diagram simi larto FIG 1 butofa device unitonly and showing power paths for the various power consuming producing features of the apparatus FIG 4 shows a similar generalised schematic block dia gram to FIG 3 ofthe device unit and showing control system data paths for controlling the various functions and compo nents of the apparatus FIG 5 shows a perspective view of an apparatus FIG 6 shows a perspective view of an assembled device unit of the apparatus of FIG 5 FIG 7 shows an exploded view ofthe device unit of FIG 6 FIG 8 shows a partially sectioned side elevation view through the interface between a waste canister and device unit of the apparatus FIG 9 shows a c
15. en portion 454 at a junction portion 480 where the single lumen 482 of the portion 454 is divided The end portion 462 of the dual Iumen conduit 456 may then be connected to an aspirant conduit to the vacuum pump device by say lumen 458 and Iumen 460 may be connected to a pressure sensing conduit having a pressure sensor and valve as in FIG 10A for example thus bringing the aspirant conduit and pressure sensing conduit in fluid communication by the lumens 458 and 460 Referring now to FIG 12 where FIG 12A shows an axial cross section through a flow splitting connector device 500 and a portion of dual lumen conduit 512 attached thereto FIG 12B shows a similar cross section but at 90 to that of FIG 12A and FIG 12C which shows across section through the dual lumen conduit 512 at 12C 12C of FIG 12A In effect the flow splitting connector 500 may replace the T piece 422 of FIG 10A The connector 500 comprises an inlet con duit portion 502 having a spigot 504 and shoulder 506 to prevent unwanted detachment from a single lumen drain con duit exiting a wound dressing as at 416 of FIG 10B The inlet 20 25 30 35 40 45 50 55 60 65 14 conduit portion 502 becomes enlarged 507 within a body portion 508 and terminates at a socket portion 510 dimen sioned and shaped to receive a dual lumen conduit 512 The dual lumen conduit 512 has two conduits a large conduit 514 which forms the aspirant conduit to whic
16. example a semi permeable flex ible self adhesive drape material as is known in the dressings art to cover the wound and seal with surrounding sound tissue to create a sealed cavity or void over the wound There may aptly be a porous barrier and support member in the cavity between the wound bed and the covering material to enable an even vacuum distribution to be achieved over the area of the wound The porous barrier and support member being for example a gauze a foam an inflatable bag or known wound contact type material resistant to crushing under the levels of vacuum created and which permits transfer of wound exu dates across the wound area to the aspiration conduit sealed to the flexible cover drape over the wound The aspiration conduit means may be a plain flexible tube for example having a single lumen therethrough and made from a plastics material compatible with raw tissue for example A portion of the tube sited within the sealed cavity over the wound may have a structure to enable continued aspiration and evacuation of wound exudates without becom ing constricted or blocked even at the higher levels of the negative pressure range envisaged Where an aspiration con duit having a single lumen is combined into the dressing to aspirate the wound the pressure sensing conduit may be connected in fluid communication with the aspiration conduit at a junction adjacent the dressing by means of a hollow or Y piece f
17. f 9 US 8 617 129 B2 464 474 452 478 P d 468 470 474 472 m 472 478 474 466 FIG 11C FIG 11B 482 480 458 460 FIG 11D FIG 12B e i 516 512 514 FIG 126 US 8 617 129 B2 1 APPARATUS FOR TOPICAL NEGATIVE PRESSURE THERAPY CROSS REFERENCE TO RELATED APPLICATIONS This application is a U S National Phase of the PCT Inter national Application No PCT GB2008 051048 filed on Nov 11 2008 designating the U S and published on Jun 11 2009 as WO 2009 071926 which claims priority to Great Britain Patent Application No 0723876 9 filed on Dec 6 2007 The disclosure of both prior applications is incorporated by refer ence in their entirety and should be considered a part of this specification BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to apparatus and a method for the application of topical negative pressure TNP therapy to wounds In particular but not exclusively the present inven tion relates to the control and monitoring of reduced pressure at a wound site 2 Background of the Invention There is much prior art available relating to the provision of apparatus and methods of use thereof for the application of TNP therapy to wounds together with other therapeutic pro cesses intended to enhance the effects of the TNP therapy Examples of such prior art include those listed and briefly described below TNP therapy assists in the closure and healing of wounds b
18. h a vacuum source not shown is attached and through which a wound cavity is aspirated to remove exudate to a waste receptacle not shown and a smaller lumen 516 which may be connected to a second pressure sensor not shown In essence the lumen 514 is the aspirant conduit and corresponds to lumen 408 in FIG 10A the lumen 516 is the pressure sensing conduit and corresponds to lumen 424 in FIG 10A and the region 507 where the inlet conduit becomes enlarged is the point where the aspirant conduit 514 and the pressure sensing conduit 516 are in fluid communication with each other and corresponds to the T piece 420 of FIG 10A Throughout the description and claims of this specifica tion the words comprise and contain and variations of the words for example comprising and comprises means including but not limited to and is not intended to and does not exclude other moieties additives components integers or steps Throughout the description and claims of this specifica tion 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
19. h pressure sensor means will be substantially atmospheric or close thereto at which point the control sys tem in response to information stored in the memory thereof will close the valve and normal operation of the apparatus will be resumed Where there is a leak of ambient air into the system due for example to an inadequately applied dressing drape then the pressures sensed by the two sensor means will be approximately equal and in which case the control system will not open the valve but information in the control system memory related for example to the rate of pumping of the vacuum pump and the rate of attaining a required vacuum level being lower than specified may trigger an alarm that the dressing integrity may need checking for example The valve may preferably be provided with a microbial filter to ensure that bacteria cannot either enter the device or be expelled to atmosphere In view of the fact that the device unit contains the majority of the intrinsic equipment cost therein ideally it will also be able to survive impact tolerate cleaning in order to be reus able by other patients In terms of pressure capability the aspiration means may be able to apply a maximum pressure drop of at least 200 mmHg to a wound site dressing The apparatus is capable of maintaining a predetermined negative pressure even under conditions where there is a small leak of air into the system and a high exudate flow The pressure control system
20. his happens the control system may open the valve to atmo sphere If for example there is a kink in the aspiration con duit effectively stopping flow in the aspirant conduit then the first pressure sensing means will continue to read a pressure equal to a preset pressure for the vacuum pump to achieve whereas the second pressure sensing means will show atmo spheric pressure The control system may issue an appropri ate alarm to check the condition of the aspirant conduit means Alternatively if the aspirant conduit means is not blocked due to a kink for example it may be blocked due to the waste canister being full and unable to accept any more wound exudate fluid in which case the control system will issue an alarm to the need to replace the waste canister and or check the aspirant conduit In the event that the aspirant conduit is blocked merely due to aspirated wound exudate then opening of the valve will admit air into the system and enable the vacuum pump to aspirate the exudate into the waste canister and so clear the aspirant conduit In this latter case on opening the valve the pressure sensed by the first pressure 20 25 30 35 40 45 50 55 60 65 6 sensor mean swill initially be that of the vacuum level set by the user or clinician and that sensed by the second pressure sensor will be atmospheric However after a short time the vacuum pump will clear the aspirant conduit and the pressure sensed by bot
21. luid flow path 9 The apparatus according to claim 8 further comprising a leakage alarm configured to indicate a leakage in the fluid flow path wherein the controller is configured to activate the leakage alarm in response to determining that the pressure difference satisfies a leakage threshold 10 The apparatus according to claim 9 wherein the leak age threshold is substantially zero 11 The apparatus according to claim 8 wherein the con troller is further configured to open the valve in response to determining that the pressure difference satisfies the first pressure difference threshold wherein opening the valve allows a flow of air into the pressure sensing lumen 12 The apparatus according to claim 11 wherein the valve is configured to clear a blockage in the aspiration lumen when the valve has been opened 13 The apparatus according to claim 1 wherein the junc tion comprises one of a T piece or Y piece 14 The apparatus according to claim 8 wherein the junc tion comprises one of a T piece or Y piece ke
22. may prevent the minimum pressure achieved from exceeding for example 200 mmHg so as not to cause undue patient discomfort The pressure required may be set by the user at a number of discreet levels such as 50 75 100 125 150 175 mmHg for example depending upon the needs of the wound in question and the advice of a clinician Thus suitable pressure ranges in use may be from 25 to 80 mmHg 50 to 76 mmHg or 50 to 75 mmHg as examples The control system may also advantageously be able to maintain the set pressure within a tolerance band of 10 mmHg ofthe set point for 95 ofthe time the apparatus is operating given that leakage and exuda tion rates are within expected or normal levels Aptly the control system may trigger alarm means such as a flashing light buzzer or any other suitable means when various abnormal conditions apply such as for example pressure outside set value by a large amount due to a gross leak of air into system duty on the aspiration pump too high due to a relatively smaller leakage of air into the system pressure differential between wound site and pump is too high due for example to a blockage or waste canister full The apparatus of the present invention may be provided with a carry case and suitable support means such as a shoul der strap or harness for example The carry case may be adaptedto conform to the shape ofthe apparatus comprised in the joined together device and waste canister
23. national Search Report from PCT GB2008 051048 mailed Oct 2 2009 in 7 pages Continued Primary Examiner Melanie Hand 74 Attorney Agent or Firm Knobbe Martens Olson amp Bear LLP 57 ABSTRACT Apparatus and a method for the provision of topical negative pressure therapy to a wound site are described the apparatus comprising vacuum generating means for generating a nega tive pressure at said wound site said vacuum generating means being operably connected to a dressing at said wound site by aspiration conduit means pressure sensing conduit means in fluid communication with said aspiration conduit means at a junction adjacent said dressing first pressure sensing means between said junction and said vacuum gen erating means second pressure sensing means operably asso ciated with said pressure sensing conduit means diagnostic means in communication with said first and second pressure sensing means and control means in communication with said diagnostic means for controlling pressure in said aspira tion and said pressure sensing conduit means 14 Claims 9 Drawing Sheets US 8 617 129 B2 Page 2 56 References Cited WO 0 2004 037334 5 2004 WO WO 2005 046760 5 2005 U S PATENT DOCUMENTS WO WO 2005 046761 5 2005 WO WO 2005 046762 5 2005 7 670 323 B2 3 2010 Hunt et al WO WO 2005 061025 7 2005 7 758 555 B2 7 2010 Kelch et al WO WO 2005 105180 11 2005 7811269 B2 10 2010 Boynton et al WO MOSES 32007
24. nister full condition and may also provide means for cessation of aspiration when the canister reaches the full condition The canister may be provided with filters to prevent the exhaust of liquids and odours therefrom and also to prevent the expulsion of bacteria into the atmosphere Such filters may comprise a plurality of filters in series Examples of suitable filters may comprise hydrophobic filters of 0 2 um pore size for example in respect of sealing the canister against bacteria expulsion and 1 um against liquid expulsion Aptly the filters may be sited at an upper portion of the waste canister in normal use that is when the apparatus is being used or carried by a patient the filters are in an upper position and separated from the exudate liquid in the waste canister by gravity Furthermore such an orientation keeps the waste canister outlet or exhaust exit port remote from the exudate surface Aptly the waste canister may be filled with an absorbent gel such as ISOLYSEL trade mark for example as an added safeguard against leakage ofthe canister when full and being changed and disposed of Added advantages of a gel matrix within the exudate storing volume of the waste canister are that it prevents excessive movement such as slopping ofthe liquid minimises bacterial growth and minimises odours The waste canister may also be provided with suitable means to prevent leakage thereof both when detached from the device unit and als
25. nt to the wound dressing the junction configured to fluidically connect the aspiration lumen and the pressure sensing lumen a first pressure sensor positioned along the aspiration lumen between the junction and the negative pressure source a second pressure sensor positioned along the pressure sensing lumen a valve in fluid communication with the pressure sensing lumen and a controller configured to based on signals received from the first and second pressure sensors perform at least one of detect a blockage in the aspiration lumen clear 20 25 30 35 16 the blockage in the aspiration lumen and detect a leak age in a fluid flow path wherein the fluid flow path comprises the wound dressing the negative pressure source the aspiration lumen and the pressure sensing lumen wherein the controller is further configured to detect the blockage in the aspiration lumen based on comparison of a pressure difference between pressure sensed by the first pressure sensor and pressure sensed by the second pressure sensor with a pressure differ ence threshold open the valve in response to detecting the blockage close the valve if the pressure difference falls to substan tially zero after expiration of a first time interval and activate a blockage alarm if the pressure difference does not fall to substantially zero after expiration of a sec ond time interval the blockage alarm configured to indicate a blockage in the f
26. o when the aspiration conduit is detached from the wound site dressing The canister may have suitable means to prevent emptying by a user without tools or damage to the canister such that a US 8 617 129 B2 5 full or otherwise end of life canister may only be disposed of with waste fluid still contained The device and waste canister may have mutually comple mentary means for connecting a device unit to a waste can ister whereby the aspiration means in the device unit auto matically connects to an evacuation port on the waste canister such that there is a continuous aspiration path from the wound site dressing to an exhaust port on the device Aptly the exhaust port from the fluid path through the apparatus is provided with filter means to prevent offensive odours from being ejected into the atmosphere In general terms the device unit comprises an aspirant pump means for monitoring pressure applied by the aspirant pump the first pressure sensing means a flowmeter to moni tor fluid flow through the aspirant pump a control system which controls the aspirant pump in response to signals from sensors such as the pressure monitoring means and the flow meter for example and which control system also controls a power management system with regard to an on board battery pack and the charging thereof and lastly a user interface system whereby various functions of the device such as pres sure level set point for example may be adjus
27. on and cleansing of the wound however it further includes the important additional step of providing heating means to control the temperature of that beneficial material being returned to the wound site dressing so that it is at an optimum temperature for example to have the most effica cious therapeutic effect on the wound In our co pending International patent application WO 2005 105180 apparatus and a method for the aspiration irri gation and or cleansing of wounds are described Again in very general terms this document describes similar apparatus to the two previously mentioned documents hereinabove but 0 30 40 45 55 2 with the additional step of providing means forthe supply and application of physiologically active agents to the wound site dressing to promote wound healing The content of the above references is included herein by reference However the above apparatus and methods are generally only applicable to a patient when hospitalised as the appara tus is complex needing people having specialist knowledge in how to operate and maintain the apparatus and also rela tively heavy and bulky not being adapted for easy mobility outside of a hospital environment by a patient for example Some patients having relatively less severe wounds which do not require continuous hospitalisation for example but whom nevertheless would benefit from the prolonged appli cation of TNP therapy could be treated
28. or example Alternatively to a plain single lumen conduit the dressing over the wound site may be provided with a purpose made drain aspirant conduit portion sealed to a dressing sealing film or drape and which is connected to the vacuum aspirant conduit and to the pressure sensing conduit means outside the dressing boundary In this regard the drain aspirant conduit portion may have a first portion resistant to being occluded or closed up due to the pressure applied thereto by the outer atmospheric pressure bearing down upon the drain portion via the sealing drape or film The drain aspirant conduit portion may also have an aspirant conduit portion having two lumens therethrough in the portion which exits the dressing Such drain aspirant conduit portions for incorporation into a dress 20 25 30 35 40 45 50 55 60 65 4 ing are available commercially and of low cost One of the lumens may be connected to the aspiration conduit vacuum generating means and first pressure sensing means and the second lumen to the pressure sensing conduit means and the second pressure sensing means Thus the junction between the aspiration conduit means and the pressure sensing conduit means may be provided inside the dressing in the drain aspirant conduit portion It is envisaged that the negative pressure range for the apparatus embodying the present invention may be between about 50 mmHg and 200 mmHg note that these pressures a
29. passes therethrough by for example pinching the self adhesive drape film around the conduit The wound may or may not have a filler 418 of some kind therein as is known in the TNP therapy art The conduit 408 is divided into two portions by a piece 420 inserted close to the dressing drape 412 see FIG 10B and having the branch portion 422 connected to a pressure sensing conduit 424 Aspirant conduit 408 is pro vided with a first pressure sensor 426 and conduit 424 is provided with a second pressure sensor 430 Pressure sensing conduit 424 is further provided with a valve 432 which may be an electrically operated solenoid valve for example and connected to a logic system 434 which is part of the control system 60 and user interface 62 see FIGS 1 to 4 and accom panying description When the valve 432 is closed the con duit 424 is also closed constituting a blind branch of the aspirant conduit 408 and when the valve 432 is open the conduit 424 is effectively open to the atmosphere The valve 432 is provided with a microbial filter not shown to prevent bacteria from contaminating the device and or being expelled to atmosphere The pump 402 is connected to logic 436 in the control system to run the pump in response to settings pro vided by the user or a clinician by a user operated device 440 such as a keypad not shown to set a desired pressure for example Logic 442 in software is also provided to control the operation of the
30. re difference does not fall to substantially zero after expiration of a sec ond time interval the blockage alarm configured to indicate the blockage in the aspiration conduit means US 8 617 129 B2 15 2 The apparatus according to claim 1 wherein said valve enables said pressure sensing conduit to be opened to atmo sphere under controlled conditions 3 The apparatus according to claim 1 wherein said second pressure sensing means is situated between said junction and said valve 4 The apparatus according to claim 1 wherein said first pressure sensing means is situated between said vacuum gen erating means and said junction 5 The apparatus according to claim 1 wherein said junc tion is situated adjacent a dressing over said wound site 6 The apparatus according to claim 1 wherein said junc tion is situated within a dressing over said wound site 7 The apparatus according to claim 6 wherein said aspi ration conduit means and said pressure sensing conduit means are connected to a portion of a drain aspirant conduit having dual lumens exiting said dressing 8 Apparatus for the provision of topical negative pressure therapy to a wound site the apparatus comprising a wound dressing configured to cover and seal the wound site an aspiration lumen a pressure sensing lumen a negative pressure source configured to provide negative pressure to the wound dressing via the aspiration lumen a junction positioned adjace
31. re relative to normal ambient atmospheric pressure thus 200 mmHg would be about 560 mmHg in practical terms Aptly the pressure range may be between about 75 mmHg and 150 mmHg Alternatively a pressure range of up to 75 mmHg up to 80 mmHg or over 80 mmHg can be used Also aptly a pressure range of below 75 mmHg could be used Alternatively a pressure range of over 100 mmHg could be used or over 150 mmHg The aspiration conduit at its distal end remote from the dressing may be attached to the waste canister at an inlet port or connector The device containing the means for initiating and sustaining aspiration of the wound dressing may be situ ated between the dressing and waste canister however in a preferred embodiment of the apparatus embodying the present invention the device may aspirate the wound dress ing via the canister thus the waste canister may preferably be sited between the wound dressing and device The aspiration conduit at the waste material canister end may preferably be bonded to the waste canister to prevent inadvertent detachment when being caught on an obstruction for example The canister may be a plastics material moulding or a composite unit comprising a plurality of separate mouldings The canister may aptly be translucent or transparent in order to visually determine the extent of filling with exudates How ever the canister and device may in some embodiments pro vide automatic warning of imminent ca
32. ressure closer to atmospheric pressure for a period of time the device sends an alarm and displays a message alerting the user to a potential problem such as a leak In addition to pressure control a separate flow control sys tem can be provided A flow meter may be positioned after the pump and is used to detect when a canister is full or the tube has become blocked If the flow falls below a certain thresh old the device sounds an alarm and displays a message alert ing a user to the potential blockage or full canister Referring now to FIGS 5 to 9 which show various views and cross sections of a preferred embodiment of apparatus 200 embodying the present invention The preferred embodi ment is of generally oval shape in plan and comprises a device unit 202 and a waste canister 204 connected together by catch arrangements 206 The device unit 202 has a liquid crystal display LCD 208 which gives text based feedback on the wound therapy being applied and a membrane keypad 210 US 8 617 129 B2 11 the LCD being visible through the membrane of the keypad to enable a user to adjust or set the therapy to be applied to the wound not shown The device has a lower generally trans verse face 212 in the centre of which is a spigot 214 which forms the suction entry port 216 to which the aspiration means to be described below are connected within the device unit The lower edge of the device unit is provided with a rebated peripheral m
33. ressure sensed by pressure sensor 430 is to fall or rise to ambient atmospheric pressure and for both to US 8 617 129 B2 13 stay at these pressures for a predetermined time set in the control system memory the control system will issue an alarm relating the need to check that the aspirant conduit is not physically constricted in some way or that the waste canister may be full and needs changing or replacing Alter natively on opening the valve 432 should the pressure indi cated by sensor 430 fall or rise to ambient atmospheric pressure and after a predetermined time interval set in the control system memory the pressure indicated by sensor 426 also reach approximate parity with that indicated by 430 the valve 432 will close and the vacuum pump continue to aspi rate the wound site 404 In this latter case the aspirant conduit is likely to have been blocked by exudate fluid and merely needing clearing with the aid of an air bleed provided by the pressure sensing conduit 424 being open to atmosphere Referring now to FIGS 11A to 11D which show a purpose made drain aspirant conduit 450 for use in place of the plain conduit 408 shown in FIG 10 FIG 11A shows a perspective view of a complete drain aspirant conduit FIG 11B shows a cross section through an exudate fluid collecting part FIG 11C shows a longitudinal cross section through the exudate fluid collecting portion and FIG 11D shows a cross sectional view at a junction of
34. ropriate alarm when pres sure levels sensed by said sensor means lie outside of a preset pressure differential stored in memory means in said control system Desirably said method also includes the optional provision of valve means associated with the pressure sensing conduit means said valve being controlled by said control system to open and close said pressure sensing conduit means to atmo spheric pressure According to a third aspect of the present invention there is provided a drainage conduit member for use in topical nega tive pressure therapy the drainage conduit member compris ing an exudate collecting portion having a plurality of exudate aspiration flow apertures therein the exudate collecting potion being contained in use beneath a wound covering and sealing dressing drape an aspirant conduit portion having a single lumen therethrough in fluid communication with the exudate collecting portion and a dual lumen portion having both lumens in fluid communication with the single lumen aspirant conduit portion The exudate collecting portion may comprise a flattened shape having two opposing walls each having exudate flow apertures therein for collecting wound exudate the two opposing walls may be joined by side pieces thereby forming a chamber in the flattened portion which chamber being in fluid flow communication with one end of the single lumen aspirant conduit portion The opposing wall portions may be provided with intern
35. ross section through a waste canister ofthe apparatus of FIGS 5 to 8 FIGS 10A and 10B show a schematic drawing of a first embodiment of the present invention and part of a control system related to the operation of vacuum pump means and a control valve and a schematic cross section of a wound site respectively FIGS 11A to 11D which show various views and cross sections of a purpose made drain aspirant conduit for incor poration with a wound dressing and for use with apparatus according to the present invention and FIGS 12 to 12C which show an embodiment of a flow splitting device for installation in an aspirant conduit DETAILED DESCRIPTION OF SOME EXEMPLIFYING EMBODIMENTS Referring now to FIGS 1 to 4 of the drawings and where the same or similar features are denoted by common refer ence numerals FIG 1 shows a generalised schematic view of an apparatus 10 of a portable topical negative pressure TNP system It will be understood that embodiments of the present invention are generally applicable to use in such a TNP system Briefly negative pressure wound therapy assists in the closure and healing of many forms of hard to heal wounds by reducing tissue oedema encouraging blood flow and granular tissue formation removing excess exudate and may reduce bacte rial load and therefore infection In addition the therapy allows for less disturbance of a wound leading to more rapid healing The TNP system is detailed fur
36. single and dual lumen portions of the conduit The drain aspirant conduit 450 is flexible and com prises a drain portion 452 for collecting exudate fluids from the wound cavity 410 see FIG 10B a plain portion 454 preferably of length less than 300 mm and more preferably of length less than 100 mm having a single lumen therethrough and a connection portion 456 comprising an aspirant conduit portion having two lumens 458 460 therethrough and which part 456 lies outside of the dressing drape 412 so as to be able to be handled and manipulated by a clinician for example The drain portion 452 comprises a flattened outer shape hav ing two opposing walls 464 466 joined by curved wall por tions 468 470 The wall portions 464 466 have on their inner surface longitudinally extending ribs 472 which prevent the soft flexible material walls from being closed together against each other by the effects of atmospheric pressure existing outside of the dressing in which the drain aspirant conduit is installed as in FIG 10B The ribs maintain longi tudinal passages 474 even when the ends ofthe ribs 472 touch theinner surface ofthe opposing walls The walls 468 470 are provided with a plurality of holes 478 which permit exudate fluid to be sucked into and flow along the passages 474 towards the centrally positioned plain conduit portion 454 Wound exudate fluid flows along the conduit portion 454 to the dual lumen portion 456 which joins the single lum
37. ted including stopping and starting of the apparatus by a user The device unit may contain all of the above features within a single unified casing In the present invention the device may also include the second pressure sensor connected to the pressure sensing conduit means and the diagnostic means The diagnostic means may be comprised in the control system to receive signals from the first and second pressure sensors and in response to software in the control system operate various functions depending upon the signals received The pressure sensing conduit may be connected to a valve which when closed effectively forms with pressure sensing conduit a closed branch of the aspiration conduit and in which branch the second pressure sensing means is located Depending upon the signals received by the control system from the first and second pressure sensing means the control system may open the valve effectively to expose the pressure sensing conduit to atmospheric pressure The response in pressures sensed by the first and second pressure sensor means may be related to software in the control system and trigger appropriate alarms depending on the pressure responses For example the control system may be provided with software which recognises when the difference in pres sure between the aspirant conduit and the pressure sensing conduit as sensed by the first and second pressure sensing means reaches or exceeds a predetermined level When t
38. the apparatus embodying the present invention Power is pro vided mainly by the battery pack 56 when the user is outside their home or workplace for example however power may also be provided by an external mains 74 supplied charging unit 72 which when connected to the device 32 by the socket 68 is capable of both operating the device and recharging the battery pack 56 simultaneously The power management sys tem 66 is included so as to be able to control power of the TNP system The TNP system is a rechargeable battery powered system but is capable of being run directly from mains elec tricity as will be described hereinafter more fully with respect to the further figures If disconnected from the mains the battery has enough stored charge for approximately 8 hours of use in normal conditions It will be appreciated that batteries having other associated life times between recharge can be utilised For example batteries providing less than 8 hours or greater than 8 hours can be used When connected to the mains the device will run offthe mains power and will simul taneously recharge the battery if depleted from portable use The exact rate of battery recharge will depend on the load on the TNP system For example if the wound is very large or there is a significant leak battery recharge will take longer than if the wound is small and well sealed FIG 4 shows the device 32 part of the apparatus embody ing the present invention and the data
39. ther hereinafter but in summary includes a portable body including a canister and a device with the device capable of providing an extended period of continuous therapy within at least a one year life span The system is connected to a patient via a length of tubing with an end ofthe tubing operably secured to a wound dressing on the patient US 8 617 129 B2 9 More particularly as shown in FIG 1 the apparatus com prises an aspiration conduit 12 operably and an outer surface thereof at one end sealingly attached to a dressing 14 The dressing 14 will not be further described here other than to say that it is formed in a known manner from well know materials to those skilled in the dressings art to create a sealed cavity over and around a wound to be treated by TNP therapy with the apparatus of the present invention The aspiration conduit has an in line connector 16 comprising connector portions 18 20 intermediate its length between the dressing 14 anda waste canister 22 The aspiration conduit between the connector portion 20 and the canister 22 is denoted by a different refer ence numeral 24 although the fluid path through conduit portions 12 and 24 to the waste canister is continuous The connector portions 18 20 join conduit portions 12 24 in a leak free but disconnectable manner The waste canister 22 is provided with filters 26 which prevent the escape via an exit port 28 of liquid and bacteria from the waste canister The filters
40. to separate the various functions of the lumens in the multi lumen tube and provide for the necessary routing thereof SUMMARY OF SOME EXEMPLIFYING EMBODIMENTS It is an aim of the present invention to at least partly miti gate the above mentioned problems in measuring pressures in known portable TNP apparatus It is an aim of embodiments of the present invention to provide portable TNP apparatus where pressures at different locations in the overall apparatus to dressing system may be easily and economically measured According to a first aspect of the present invention there is provided apparatus for the provision of topical negative pres sure therapy to a wound site the apparatus comprising vacuum generating means for generating a negative pressure at said wound site said vacuum generating means being oper ably connected to a dressing at said wound site by aspiration conduit means pressure sensing conduit means in fluid com munication with said aspiration conduit means at a junction adjacent said dressing first pressure sensing means between said junction and said vacuum generating means second pressure sensing means operably associated with said pres sure sensing conduit means diagnostic means in communi cation with said first and second pressure sensing means and US 8 617 129 B2 3 control means in communication with said diagnostic means for controlling pressure in said aspiration and said pressure sensing conduit means
41. valve 432 in response to signals 443 in relation to pressure data from a diagnostic portion 444 ofthe control system 60 which signals are themselves provided in response to pressure data signals 446 448 from the pressure sensors 426 430 respectively In operation a user or clinician sets a pressure which it is desired to achieve at the wound cavity 410 by use of the user interface device 440 at which point the pump 402 is started by the logic software 436 The pump applies a vacuum to the wound cavity 410 via the aspirant conduit 408 Initially the pressures sensed by the sensors 426 430 will be approxi mately equal However as aspiration of the wound cavity proceeds and wound exudate is drawn up the conduit 408 there will be growing pressure differential between the pres sure sensed by the sensor 426 adjacent the pump 402 and that sensed by the sensor 430 adjacent the dressing wound site 404 This is normal as there must be a pressure differential between the pump 402 and the dressing wound site 404 for exudate fluid to travel up the conduit 408 into the waste canister 409 However when the pressure differential between sensors 426 430 reaches or exceeds a level stored in the memory of the diagnostic portion 444 of control system 60 the valve 432 is opened to atmosphere or ambient pressure by logic soft ware 442 As discussed hereinabove if the response of the pressure sensor 426 is to remain at the user set pumping pressure and that p
42. y reducing tissue oedema encouraging blood flow and granulation of tissue removing excess exudates and may reduce bacterial load and thus infection to the wound Fur thermore TNP therapy permits less outside disturbance of the wound and promotes more rapid healing In our co pending International patent application WO 2004 037334 apparatus a wound dressing and a method for aspirating irrigating and cleansing wounds are described In very general terms this invention describes the treatment of a wound by the application of topical negative pressure TNP therapy for aspirating the wound together with the further provision of additional fluid for irrigating and or cleansing the wound which fluid comprising both wound exudates and irrigation fluid is then drawn off by the aspiration means and circulated through means for separating the beneficial mate rials therein from deleterious materials The materials which are beneficial to wound healing are recirculated through the wound dressing and those materials deleterious to wound healing are discarded to a waste collection bag or vessel In our co pending International patent application WO 2005 04670 apparatus a wound dressing and a method for cleansing a wound using aspiration irrigation and cleansing wounds are described Again in very general terms the invention described in this document utilises similar appara tus to that in WO 2004 037334 with regard to the aspiration irrigati
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