AU2004298287B2

AU2004298287B2 - Fluid delivery device

Info

Publication number: AU2004298287B2
Application number: AU2004298287A
Authority: AU
Inventors: Philip Stuart Esnouf
Original assignee: Chimden Medical Pty Ltd
Current assignee: Chimden Medical Pty Ltd
Priority date: 2003-12-16
Filing date: 2004-12-16
Publication date: 2010-09-16
Anticipated expiration: 2024-12-16
Also published as: AU2004298287A1

Description

WO 2005/058394 PCT/AU2004/001771 FLUID DELIVERY DEVICE FIELD OF THE INVENTION 5 The present invention relates to a fluid delivery device. In particular, the invention relates to a local anaesthetic fluid delivery device for slow delivery of local anaesthetic fluid to a patient while the device is attached to the patient. BACKGROUND OF THE INVENTION 10 After a patient undergoes surgery, it is sometimes desirable to supply an amount of local anaesthetic to the patient at the site where the surgery was performed, in order to treat pain. A convenient way of administering such local anaesthetic is to allow the patient to carry an anaesthetic fluid delivery device which is arranged to allow release of the local 15 anaesthetic fluid to the patient surgery site over a period of time. One such local anaesthetic fluid delivery device is sold under the name "Pain Buster" made by I-Flow Corporation. The Pain Buster device is a 270 ml capacity device with a spherical balloon designed to be placed in a cloth pouch which can be tied around 20 the patient's waist. Disadvantages associated with this device include that it does not affix securely to the patient and can result in tangled tubing. Because of its size, it can introduce a relatively large volume of anaesthetic liquid to the treatment site, but this also results in it being cumbersome in size and weight. 25 A similar product, called "Pain Pump" made by Stryker Corporation includes a spring-driven rigid pump that is also placed in a pouch in a similar fashion to the Pain Buster product. The Pain Pump is an even bigger device, being about 5 inches in diameter and 8 inches long, resulting in even more cumbersome size and weight characteristics. 30 C :RPonbDCCDER\262017_ LDOC.5MI/2011 -2 It is desired to provide a device which addresses or ameliorates one or more disadvantages associated with prior art fluid delivery devices. The reference to any prior art in this specification is not, and should not be taken 5 as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia. SUMMARY OF THE INVENTION 10 According to the present invention there is provided a local anaesthetic delivery device for supplying local anaesthetic to a patient, the device including: anaesthetic supply means; an outlet line which is supplied with local anaesthetic from said supply means; a housing within which the anaesthetic supply means is located; 15 means for adhering the housing to a patient; and wherein the anaesthetic supply means includes a resilient reservoir in the form of a generally hollow cylindrical body when unexpanded, and having an inlet and an outlet at ends of the cylindrical body, the arrangement being such that a charge of local anaesthetic can be introduced into the reservoir through said inlet to resiliently expand the cylindrical 20 body radially and said outlet line is connected to said outlet of the reservoir, so that the local anaesthetic is, in use, pressurised by the radially expanded resilient reservoir and the local anaesthetic is delivered to said outlet line; and wherein the outlet line includes a length of flow restricting line which terminates in a coupling which enables coupling to a catheter whereby the effective rate of delivery of 25 local anaesthetic to the catheter is determined by the radial expansion of the resilient reservoir and the flow restricting line. The invention also provides a method of delivering local anaesthetic to a patient having a catheter including the steps of: 30 introducing a charge of local anaesthetic to anaesthetic supply means located in a housing; wherein the anaesthetic supply means includes a resilient reservoir in the form of a generally hollow cylindrical body when unexpanded, and having an inlet and an outlet at C:\NRPVnbliDCCDERU62017SI.DOC-25M21O -3 ends of the cylindrical body, the arrangement being such that the charge of local anaesthetic introduced into the reservoir through said inlet resiliently expands the cylindrical body radially and an outlet line is connected to said outlet of the reservoir, so that the local anaesthetic is pressurised by the radially expanded resilient reservoir and the 5 local anaesthetic is delivered to said outlet line; adhering the housing to the skin of the patient near the catheter; and coupling an outlet line of the supply means to said catheter. Preferably, the fluid delivery device is lightweight and the housing is mostly 10 formed of lightweight plastic. Preferably, the fluid delivery means includes an inflatable fluid reservoir which, when inflated with fluid, such as local anaesthetic fluid, applies pressure to the fluid so as to cause it to flow along a fluid delivery line to the patient. Preferably, the fluid delivery line includes a flow restriction between the inflatable 15 reservoir and the patient site for limiting the rate of flow of fluid to the patient along the fluid delivery line. Preferably, a filter is included in the fluid delivery line between the inflatable fluid reservoir and the flow restriction. Preferably, the housing is roughly dome shaped in cross-section on a side facing 20 away from the patient when the housing is adhered to the patient. Preferably, the underside of the housing is relatively planar but of a flexible material to accommodate adhesion to non-planar areas of the patient's skin. Preferably, the housing includes a semi cylindrical reinforcing member within an outer wall of the housing for providing increased shape stability to the dome shape of the housing. Preferably, a raised area is provided on 25 an outer portion of the domed area of the housing for affixing a label thereto. Preferably, the fluid delivery device has an inlet port at one end thereof and the inlet port is in fluid connection with the inflatable reservoir via a one-way valve operative such that fluid is only allowed to pass from the inlet port to the inflatable fluid reservoir. 30 The inlet port may include a female luer fitting for engaging with a male luer fitting of a syringe, whereby the anaesthetic fluid can be injected into the inflatable fluid reservoir, thereby inflating the reservoir with the anaesthetic fluid. Thus an amount of local C:\NRPonblDCCDER\620173.DOC-25Sf8/20 -4 anaesthetic fluid can be stored in the inflatable reservoir over a period of time, for example in the order of 24 hours, and the fluid delivery device will slowly deliver the local anaesthetic fluid to the patient site during that time. 5 Preferably, the fluid delivery device has a relatively large adhesive area on its underside, including wings extending to either side to increase the surface area to which the adhesive is applied. Preferably, the direct attachment is to the patient's skin proximate a patient fluid 10 delivery site. Preferably, the means for affixing includes at least part of the means for housing and includes, or is adapted to cooperate with, an adhesive or adhesion means. Preferably, the means for affixing affixes the means for housing to a patient's skin. 15 Preferred features described above in relation to one embodiment may also be applicable to any other described embodiments in any combination or singular application of such features. 20 Advantageously, fluid delivery devices according to embodiments of the present invention are light and may be easily affixed to patients by means of an adhesive underside surface. The amount of local anaesthetic fluid held in the fluid reservoir is generally less than the amount held by prior art devices, thus reducing the weight carried by the fluid delivery device. Further, as the components of the device are all relatively cheap to 25 purchase or manufacture, the device has a significantly lower manufacturing cost than prior art devices. Further advantageously, the fluid reservoir, in the form of an inflatable balloon or bladder, is formed of a flexible polyisoprene material, rather than latex. While latex would 30 normally be an ideal material for an inflatable bladder of the kind contemplated, a number of patients are allergic to latex and therefore the choice of an alternative material, such as C:RPonblCC\DER\262017_ I.DOC-25A/082010 -5 polyisoprene, is desirable. Advantageously, because of the secure attachment of the present fluid delivery device to the patient's skin, the device can be better fixed in place, with less chance of the 5 fluid delivery line becoming entangled or the fluid delivery device being dislodged or getting in the way when the patient moves. Advantageously, the dome form of the device helps to prevent or reduce external pressure being applied to the fluid reservoir if, for 10 WO 2005/058394 PCT/AU2004/001771 -6 example, the patient should inadvertently contact the outside of the domed outer wall of the device. The device of the invention can be made with inexpensive material so that it is a 5 single use or disposable device. Preferably further, the device is lightweight and compact so that it can be discretely worn under the clothing of a patient. 10 Preferably, the device has a housing which has a length in the range from 120 to 180mm and preferably about 160mm, a width in the range from 60 to 100mm and preferably 80mm and a height in the range from 20 to 50mm and preferably 35mm. Preferably further, the weight of the device (without local anaesthetic) is in the range from 25 to 50gms and preferably about 35gms. 15 Further features of embodiments of the invention are hereinafter de scribed, by way of example only, with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS 20 Figure 1 is a plan view of a fluid delivery device according to an embodiment of the invention; Figure 2 is a longitudinal cross section through the device; Figure 3 is a transverse cross-sectional view through the device; 25 Figure 4 is an enlarged view of part of the device; Figure 5 is a cross-sectional view along the line 5-5; Figure 6 shows the device with the fluid reservoir inflated; Figure 7 shows an attachment for altering the delivery rate from the device. and Figure 8 is a schematic view showing deployment of the device on a patient. 30 WO 2005/058394 PCT/AU2004/001771 -7 DETAILED DESCRIPTION OF THE PREFERRED EMBOI)IMENTS The device 2 illustrated in the drawings is for delivery of local anaesthetic to a patient 3 at a controlled rate. The device includes an inflatable reservoir 4 which as best 5 seen in Figures 4 and 5 includes a central cylindrical portion 8 and smaller diameter end portions 10 and 12. The end portion 12 is received within a threaded socket 14 of a female luer connector 16. The luer connector may include a one-way valve (not shown) which permits fluid to pass from an inlet port 18 to the interior of the reservoir 4 but not in the reverse direction. The other end portion 12 is connected to an outlet line 20. In the 10 illustrated arrangement, the end of the reservoir 4 is a snug fit on the outer diameter of the line 20 and is retained in position by means of a retaining band 22. The outlet line 20 is connected to a micro filter 30 of known type for filtering out any solid materials in the fluid delivered from the reservoir. The filter 30 is then connected 15 to a flow restricting line 32 which terminates in a male luer connector 34. The male luer connector 34 can be connected to a female luer connector 36 or to a cap (not shown). The reservoir 4 is located within a protective housing 38 which includes a base wall 40 which is generally cruciform in shape and having rounded ends. The housing can be 20 regarded as a lightweight flexible pouch which enables it to be directly adhered to the skin of the patient 3 whilst not causing significant discomfort. The housing 38 also includes a top wall 42 which is generally complementary in shape to the base but is domed so as to accommodate the reservoir 4. The top wall 42 is formed with a peripheral flange 44 enabling it to be glued or bonded to the base wall 40. As best seen in Figure 2, the top wall 25 42 is formed with an inlet formation 46 to permit the female luer connector to pass therethrough. The top wall 42 is formed with an outlet formation 48 which permits the outlet line 20 to pass therethrough. There is a relatively loose fit between the outlet line 20 and the outlet formation 48. The luer connector 16 is glued to the formation 46 to hold it in place. This holds the reservoir 4 in place within the housing 38. The housing 38 also 30 includes a stiffening sleeve 50 which is generally semi-cylindrical and located adjacent to the top wall 42 as shown in Figures 2 and 3.

WO 2005/058394 PCT/AU2004/001771 -8 The cruciform shape of the base wall 40 defines two lateral wings 54 and 56, the ends of which are generally rounded, as shown in Figure 1. The underside surface of the wings 54 and 56 and the part of the base wall 40 therebetween are provided with a layer 58 5 of adhesive. The adhesive layer 58 is covered by a removable backing strip 60. In use of the device, the backing strip 60 can be removed so that the adhesive layer 58 can be used to adhere the housing 38 to the skin of a patient adjacent to the site 61 where the local anaesthetic is to be delivered, as shown in Figure 8. Alternatively, the housing 38 can be adhered to a dressing which may be present near a surgical site rather than directly to the 10 skin of the patient. The adhesive is preferably a hypoallergenic medical grade adhesive such as product code 467MP made by 3M. The surface area of the adhesive layer is preferably in the range from 80 to 150sq cm and most preferably about 115sq cm in order to provide secure adhesion to the patient's skin. The wings 54 and 56 preferably extend from about 30 to 100mm and more preferably about 40mm laterally from the outer 15 periphery of the flange 44. This enables the flaps to be used to secure delivery lines beneath them and the patient's skin, as will be described below. In the preferred form of the invention, the housing 38 is formed from clear flexible polyvinylchloride which is relatively soft to touch and is comfortable for the patient. The 20 PVC materials can be glued together using a cyclohexanone adhesive. Alternatively, the PVC components can be ultrasonically welded. The domed shape of the top wall 42 and the inlet and outlet formations 46 and 48 can be moulded by vacuum forming an initially flat sheet of PVC. The sheet of PVC which is used to form the top wall preferably has an initial thickness of say 0.6mm. The base wall 40 is preferably die cut from a flat sheet of 25 PVC having a thickness of say 0.25mm. The stiffening sleeve 50 is preferably formed from a relatively stiff plastics material. It has been found that acrylic sheet having a thickness of 0.2mm is preferred. The stiffening sheet 50 is initially flat and is held in the hemi-cylindrical shape as shown in Figure 3 by elastic forces. Edges of the stiffening sleeve 50 butt against the upper side of the base wall 40. The stiffening sleeve 50 helps to 30 maintain the domed shape of the top wall 42.

WO 2005/058394 PCT/AU2004/001771 -9 The reservoir 4 is preferably formed from flexible polyisoprene material and may be say 60mm long and having an outside diameter in the range from say 6.3 to 10.5mm. The wall thickness is approximately 2mm. When the device is to be used, a syringe 62, preferably having a male luer connector on its end, can be coupled to the female luer 5 connector 16. The syringe 62 is used to fill the reservoir 4 with local anaesthetic and the pressure of the anaesthetic inflates the reservoir to an inflated position as shown in Figure 6. Normally the reservoir will hold about 120mls of local anaesthetic when fully inflated. Once the reservoir 4 has been inflated, the syringe 62 can be disconnected and the resilient pressure applied by the inflated reservoir 4 will force the local anaesthetic through the 10 outlet line 20, through the filter 30 and into the flow restricting line 32 so that the system is flushed with anaesthetic in readiness for use. At this point, the cap 36 can be placed in the connector 34 so that the device remains primed with anaesthetic or alternatively it can be directly deployed at a site 61 on a patient. 15 The reservoir is preferably injection moulded from polyisoprene. It contains no latex and is therefore suitable for use with patients who may be allergic to latex. The reservoir 4 preferably complies with US FDA and International Pharmacoepia requirements including requirements for ISO 10993-5. The fluid reservoir is highly elastic and behaves like a resilient bladder. Its initial volume is expanded from a relaxed state of 20 about 7 to 10ml to an expanded state of 120ml. The elastic properties of the reservoir 4 exert the pressure on the local anaesthetic and this property in conjunction with the flow restricting line 32 is a particularly simple and effective way of delivering a relatively constant supply of anaesthetic to the patient. After inflation of the reservoir, the internal pressure of the anaesthetic will be about 8.5 to 9 psi and this pressure will remain 25 substantially constant as the anaesthetic is dispensed and the elastic extension of the reservoir becomes less. It has been found that there is little variation in pressure until about the last 5% of the anaesthetic remains in the reservoir after which there will be a rise in pressure and a brief increase in delivery rate. It will be appreciated that the technique is low cost and does not involve the use of any pump or motor or other form of power input 30 to the device other than the initial energy which is expended when the syringe 62 is used to inflate the reservoir 4.

WO 2005/058394 PCT/AU2004/001771 -10 If the flow restricting line 32 or other flow controlling device were not present, the rate of flow of local anaesthetic from the inflated reservoir 4 would be non-linear and generally proportional to the extent of expansion of the reservoir. The provision of the 5 flow restricting line 32, however, ensures a generally uniform rate of delivery of anaesthetic to the patient, notwithstanding the variation in pressure applied by the reservoir 4. This is because the flow restricting line 32 has a very fine bore and the pressure drop therein is substantial compared with pressure drops in other parts of the device and hence the flow rate is more or less constant. It is preferred that the flow restricting line 32 is 10 formed of PVC microbore tubing having a nominal internal diameter of about 0.1 mm and nominal outside diameter of 2 mm. It is preferred for flow restricting line 32 to be about 95 mm in length, which allows an anaesthetic fluid flow of about 5 ml per hour. Generally speaking, the flow rate is inversely proportional to the length of the flow restricting line 32. If a lower flow rate is required an additional flow restricting line 64 can be provided, as 15 seen in Figure 7. In this arrangement the additional flow restricting line 64 has the same length as the line 32 so that when connected in series the flow delivery rate will be reduced from about 5ml per hour to about 2.5ml per hour. The additional flow restricting line 64 can be provided with a female luer coupling 65 at one end and a male luer coupling 66 at the other. 20 Figure 8 shows the device 2 deployed on the patient 3. In this drawing, the reservoir 4 has been filled with local anaesthetic. The backing strip 60 has been removed so that the adhesive layer 58 can be applied directly to the skin of the patient. It will also be seen that part of the line 20 and/or flow restricting line 32 can be located under one or 25 other of the wings 54 or 56 in order to prevent fouling of these components. The male luer connector 34 can then be connected to a female luer mounted on the end of a catheter 68 which enters the skin of the patient beneath an adhesive bandage 70, as shown. It will be appreciated by those skilled in the art that the device of the invention is 30 simple and inexpensive to make which makes it suitable as a single use product. It is also WO 2005/058394 PCT/AU2004/001771 - 11 convenient and comfortable for the patient 3 when compared to the bulky rigid structures of the prior art. Preferably, the device has a housing which has a length in the range from 120 to 5 180mm and preferably about 160mm, a width in the range from 60 to 100mm and preferably 80mm and a height in the range from 20 to 50mm and preferably 35mm. Preferably further, the weight of the device (without local anaesthetic) is in the range from 25 to 50gms and preferably about 35gms. Accordingly, the device is compact and lightweight and so it can be discretely worn by a patient beneath the patient's clothes. 10 Also, the wings 54 and 56 have sufficient lateral extent so that the outlet line 20 and/or the flow restricting lines 32 and 64 can be fastened between one or both wings 54, 56 and the patient's skin adjacent to the site where the catheter 68 is located and this minirnises the possibility of the lines being caught and torn away from the patient if these lines were external to the patient's clothing as they are in the prior art devices. 15 It will be appreciated by those skilled in the art that the compact, lightweight device of the invention having a pouch like housing with a flat base provided with adhesive material constitutes a significant advantage over prior art devices. 20 Whilst the primary use of the device of the invention is for delivery of local anaesthetic, it is possible that the same or a similar device could be used for delivering local anaesthetic together with other medical agents or alternatively other medical agents not necessarily including local anaesthetic. 25 Many modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A local anaesthetic delivery device for supplying local anaesthetic to a patient, the device including: 5 anaesthetic supply means; an outlet line which is supplied with local anaesthetic from said supply means; a housing within which the anaesthetic supply means is located; means for adhering the housing to a patient; and wherein the anaesthetic supply means includes a resilient reservoir in the form of a 10 generally hollow cylindrical body when unexpanded, and having an inlet and an outlet at ends of the cylindrical body, the arrangement being such that a charge of local anaesthetic can be introduced into the reservoir through said inlet to resiliently expand the cylindrical body radially and said outlet line is connected to said outlet of the reservoir, so that the local anaesthetic is, in use, pressurised by the radially expanded resilient reservoir and the 15 local anaesthetic is delivered to said outlet line; and wherein the outlet line includes a length of flow restricting line which terminates in a coupling which enables coupling to a catheter whereby the effective rate of delivery of local anaesthetic to the catheter is determined by the radial expansion of the resilient reservoir and the flow restricting line. 20

2. A device as claimed in claim I wherein the housing is in the form of a flexible pouch.

3. A device as claimed in claim I or 2 wherein the housing is formed from sheet 25 plastics material.

4. A device as claimed in claim 1, 2 or 3 wherein the housing is formed from clear PVC. C:\NRPonbl\DCC\DER\2620178..DOC-25/082OI1 - 13 5. A device as claimed in any one of claims 1 to 4 wherein the housing has a flat base wall and a domed top wall and wherein said means for adhering is a layer of adhesive material located on exterior surface of said base wall.

5

6. A device as claimed in any one of claims I to 5 wherein the housing is lightweight and compact.

7. A device as claimed in claim 6 wherein the housing has a length in the range 120 to 180mm, a width in the range 60 to 100mm, and a height in the range 20 to 5 0mm. 10

8. A device as claimed in claim 7 wherein the housing has a length of about 160mm, a width of about 80mm and a height of about 35mm.

9. A device as claimed in claim 6, 7 or 8 wherein the device without anaesthetic has a 15 weight in the range from 25 to 50gms.

10. A device as claimed in claim 9 wherein the device has a weight of about 35gms.

11. A device as claimed in claim 5 including wings which extend laterally from said 20 base wall and wherein adhesive material is located on undersides of said wings.

12. A device as claimed in claim 11 wherein the total surface area of adhesive material on the base and the wings is in the range from 80 to 150sq cm. 25

13. A device as claimed in claim 11 wherein said total surface area is about 115 sq cm.

14. A device as claimed in any one of claims 11 to 13 wherein the wings project laterally from said base wall by about 30 to 100mm to thereby enable at least part or parts of said outlet line to be fastened between the wings and the patient's skin. 30 C:\RPonb\DCCDER\62017_.- DDC-25SM/2010 -14

15. A device as claimed in claim 14 wherein the wings project laterally from said base wall by about 40mm.

16. A device as claimed in claim I wherein the reservoir is formed from flexible 5 polyisoprene.

17. A device as claimed in claim I wherein the inlet to the reservoir includes a luer connector at one end of the cylindrical body, said connector being accessible from the exterior of the housing. 10

18. A device as claimed in claim 17 wherein at least part of said connector is exterior to the housing.

19. A method of delivering local anaesthetic to a patient having a catheter including the 15 steps of: introducing a charge of local anaesthetic to anaesthetic supply means located in a housing; wherein the anaesthetic supply means includes a resilient reservoir in the form of a generally hollow cylindrical body when unexpanded, and having an inlet and an outlet at 20 ends of the cylindrical body, the arrangement being such that the charge of local anaesthetic introduced into the reservoir through said inlet resiliently expands the cylindrical body radially and an outlet line is connected to said outlet of the reservoir, so that the local anaesthetic is pressurised by the radially expanded resilient reservoir and the local anaesthetic is delivered to said outlet line; 25 adhering the housing to the skin of the patient near the catheter; and coupling an outlet line of the supply means to said catheter.

20. A local anaesthetic delivery device or a method of delivering local anaesthetic to a patient substantially as hereinbefore described with reference to the accompanying 30 drawings.