VENOUS THROMBOEMBOLISM PREVENTION FOOTWEAR

Abstract

The invention provides an apparatus and method for the prevention of VTE and related conditions to promote blood flow in a foot, the apparatus including: at least two inflatable bladders (20, 21) adapted to be disposed in use under the foot; and one or more pumps (31, 32) configured to repeatedly inflate and deflate the bladders with a fluid, applying compressive force to the foot in use.

Claims

1. An apparatus for the prevention of VTE and related conditions to promote blood flow in a foot, the apparatus comprising: at least two inflatable bladders adapted to be disposed in use under the foot; and one or more pumps configured to repeatedly inflate and deflate the bladders with a fluid, applying compressive force to the foot in use.

2. The apparatus of claim 1, wherein the at least two inflatable bladders comprise a first inflatable bladder adapted to be disposed in use beneath a forefoot of the foot, and a second inflatable bladder adapted to be disposed in use beneath a midfoot of the foot.

3. The apparatus of claim 1, wherein the fluid is atmospheric air.

4. The apparatus of claim 1, further comprising a microcontroller configured to provide the repeated inflation and deflation of the bladders.

5. The apparatus of claim 2, wherein the repeated inflation and deflation of the bladders is configured to provide a compressive wave from the forefoot to the midfoot.

6. The apparatus of claim 5, wherein the repeated inflation and deflation of the bladders comprises cycles, each cycle comprising an inflation of the first inflatable bladder, followed by inflation of the second inflatable bladder, followed by deflation of the first and the second inflatable bladders.

7. The apparatus of any one of claim 1, wherein the at least two inflatable bladders are within a cavity in a sole of a shoe.

8. The apparatus of claim 1, wherein the at least two inflatable bladders are in an insert that is insertable above a sole of a shoe.

9. A method of preventing VTE and related conditions by promoting blood flow in a foot, the method comprising the steps of: providing at least two inflatable bladders adapted to be disposed in use under the foot; providing one or more pumps; and configuring the one or more pumps to repeatedly inflate and deflate the bladders with a fluid, applying compressive force to the foot in use.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] FIG. 1 is a semitransparent plan view of a shoe comprising an apparatus according to an embodiment of the invention;

[0042] FIG. 2 is a perspective view of a sole of the shoe of FIG. 1 showing cavities accommodating elements of the apparatus of the embodiment of FIG. 1;

[0043] FIG. 3 is a diagram of inflatable bladders according to the embodiment of FIG. 1; and

[0044] FIG. 4 is a functional diagram of components of the apparatus of the embodiment of FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

[0045] An embodiment of the current invention will now be described.

[0046] Referring first to FIG. 1, a semitransparent plan view is provided of an embodiment of the invention. Shoe 1 is defined by sole perimeter stitching 2 affixing leather or fabric upper 3 including tongue 4, and shoelace 5. Control elements of apparatus of the invention are positioned in the sole of the shoe within a cavity defined by dotted line 6 comprising a rectangular cavity and a channel.

[0047] Referring now to FIG. 2, a perspective view shows sole 10 composed of a block of EVA, defining sole upper surface 15, perimeter 11, control box rectangular cavity defined by recessed floor 13 about 20 millimetres below sole upper surface 15, and control box rectangular cavity perimeter 12 of dimensions approximately 120 by 45 millimetres. Leading from perimeter 12 is a channel 14 of width approximately 6 millimetres and depth of approximately 6 millimetres for accommodating of a first inflation tube for connecting with a first inflatable bladder positioned under a forefoot of the wearer, as described in more detail below.

[0048] Referring now to FIG. 3, the inflatable bladders of the embodiment are shown, from below. The inflatable bladders are constructed from a double layer of polyurethane thermoplastic elastomer (TPU-70), sealed around perimeters by heat seal lines such as 22, 23, 24, 25 and incorporating annular pneumatic tube attachment elements 26, 27 comprising annular projections of outside diameter 5 mm and inside diameter 3 mm adapted for attaching and securing to correspondingly sized first and second inflation tubes of plastic by friction fit. First inflatable bladder 21 is defined by perimeter elements 24, 25 and attachment element 27, and is shaped and positioned to inflate beneath a forefoot of the wearer, at the base of the toes. Attachment element 27 is positioned to correspond with an end of channel 14 engaging with first inflation tube. Second inflatable bladder 20 is defined by perimeter elements 22, 23 and attachment elements 26, and is shaped and positioned to inflate beneath a midfoot of the wearer at the arch. Attachment element 26 is positioned to correspond with and protect into an aperture in a top of the control box when positioned in rectangular cavity defined by perimeter 12, to attach to a shorter second inflation tube disposed within the control box.

[0049] Referring now to FIG. 4, a functional diagram of the components of the apparatus is shown. The diagram is not to scale and is drawn for explanatory clarity. Pneumatic lines are depicted by heavy solid black lines such as 40, 40a, 41, 41a, and the direction of inflation and deflation air is depicted by hollow arrows.

[0050] Control box 70 is shown as a dotted line and is sized to fit within perimeter 12 of sole 10, and a rectangular memory foam spacer shaped to correspond with perimeter 12 placed above control box 70. Bladders 20, 21 are disposed above as described above. In relation to second inflation bladder 20, second inflation tube 41a in reality is short and inside control box 20, with attachment elements 26 projecting into an aperture in a lid of control box 20 as described above. A layer of padded fabric as an insole is then disposed above bladders 20, 21.

[0051] Two other elements project from control box 70 and are not specifically depicted in the diagrams FIG. 1-3. These are isolation switch 61 and USB charging port 51. Isolation switch 61 is an on off switch for isolating and connecting lithium ion rechargeable battery 60. USB charging port 51 enables recharging of rechargeable battery 60 and may also facilitate communication with BLE controller 50 for programming or user interaction, in addition to the Bluetooth communication channel. USB charging port 51 is connectable by the wearer to a USB charging cable conveniently able to be connected to airline seat electronic device USB charging sockets or mobile phone chargers. Isolation switch 61 and USB charging port 51 are typically provided on the end of a cable leading from control box 70 and along shoe upper 3 to a convenient location on the shoe sufficiently elevated to be substantially protected from water ingress caused by walking on wet ground, and operable by the wearer while wearing shoe 1.

[0052] Bluetooth low-energy (BLE) controller 50 (obtainable as an off-the-shelf item) contains a programmed microprocessor and input output components and is the primary controller of the system. BLE controller 50 controls management of lithium ion rechargeable battery 60 (3.7 volt, 1600 mAh), including charging through USB charging port 51. User controls for the system are provided by Bluetooth communication with BLE controller 50 through an app operable from a smartphone or tablet device. BLE controller also measures pressure in pneumatic lines 40, 41 through pressure transducers 44, 45 and actuates pumps 31, 32 and solenoid release valves 33, 34 through motor controller 30 (obtainable as an off-the-shelf item). First pump 32 pressurises first inflation line 40 through inflation tube 40a to inflate first bladder 21. First pump 32 is stopped when pressure transducer 44 reaches a desired inflation pressure. Pressure transducer 44 Solenoid valve 42 controlled by solenoid 33 is normally closed and when solenoid 33 is energised, air escapes from and depressurises first inflation line 40, deflating first bladder 21. Similarly, second pump 31 pressurises second inflation line 41 through inflation tube 41a to inflate second bladder 20. Second pump 31 is stopped when pressure transducer 45 reaches a desired inflation pressure. Solenoid valve 43 controlled by solenoid 34 is normally closed and when solenoid 34 is energised, air escapes from and depressurises second inflation line 41, deflating second bladder 22.

[0053] The system through BLE controller 50 is programmed to provide a repeated inflation and deflation of first inflation bladder 21 and second inflation bladder 20. The repeated inflation and deflation is co-ordinated to provide a wave of compression from the forefoot through the midfoot, enhancing venous return from the foot compared with single arch inflation bladders.

[0054] An example of the coordination cycle is as follows. At the start of the cycle, first inflation bladder 21 is inflated to 130 mmHg. Three seconds later, second inflation bladder 20 is also inflated to 130 mmHg, creating a wave of compression from the forefoot to the midfoot. After a further three seconds following full inflation, both first and second inflation bladders 20, 21 are deflated. The cycle is repeated at an interval of 40 seconds.

[0055] It has been found that when fully charged, the system can operate continuously for eight hours or more.

[0056] It is advantageous to program system to sense when the wearer stands up and starts walking, whereby the first and second inflation bladders 21, 20 are deflated and the cycle paused. This may be detected by an accelerometer chip, or by increase or fluctuation in pressure sensed by pressure transducers 44, 45.

[0057] It is believed that the provision of two inflation bladders preferably operable in sequence, particularly with a forefoot inflation bladder inflated before the midfoot function bladder, improved venous return is enabled. Furthermore, fitting the controls and other components inside a sole of the shoe enables an unobtrusive system which is suitable for in-flight use.

[0058] The following results were obtained in an experiment on a human subject using above embodiment of the invention:

TABLE-US-00001 Shoe in operation Foot at (average of 5 rest readings) Peak blood velocity 7.6 18.3 cm/s Mean blood velocity 1.6 8.0 cm/s Volume flow ml/min 68.3 327

[0059] Persons skilled in the art will also appreciate that many variations may be made to the invention without departing from the scope of the invention, which is determined from the broadest scope and claims.

[0060] For example, while the embodiment described utilises atmospheric air as the inflation fluid, a liquid could also be used in devices suitably designed to contain the fluid in reservoir when deflated.

[0061] Further, while the embodiment described utilises space within a sole of a shoe, other embodiments are envisaged involving an insert which may be inserted inside a shoe on top of the sole. In such an insert embodiment, the isolation switch and USB power terminal may be provided in the insert and operable when the wearer removes the insert.

[0062] Further still, while the embodiment described describes the first inflation bladder disposed beneath the forefoot and a second inflation bladder disposed beneath the midfoot, timed for inflation in a sequence of forefoot before midfoot, other locations of the at least two inflation bladders and different timing coordinations thereof are within the broadest scope of the invention.

[0063] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word comprise or variations such as comprises or comprising is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Further, any method steps recited in the claims are not necessarily intended to be performed temporally in the sequence written, or to be performed without pause once started, unless the context requires it.

[0064] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.