AU2009100891B4

AU2009100891B4 - Thrombosis Prevention Device

Info

Publication number: AU2009100891B4
Application number: AU2009100891A
Authority: AU
Inventors: Walter Meyer
Original assignee: SMARTSHOP HOME AUTOMATION Pty
Current assignee: SMARTSHOP HOME AUTOMATION Pty Ltd
Priority date: 2008-09-15
Filing date: 2009-09-07
Publication date: 2010-09-30
Anticipated expiration: 2017-09-07
Also published as: AU2009100891A4

Description

INNOVATION SPECIFICATION FOR A PATENT in the name of The Smart Shop Home Automation Pty. Ltd. entitled "THROMBOSIS PREVENTION DEVICE" Filed by: Walter Meyer Unit 8 Oldfield Road Sinnamon Park Brisbane Qld. 4073 Australia P/00/009 1 TITLE Thrombosis Prevention Device FIELD OF THE INVENTION 5 The invention relates to a device to assist in the prevention of thromboses. In particular, although not exclusively, the invention relates to a device which encourages blood flow to assist in the prevention of formation of a thrombosis. 10 BACKGROUND TO THE INVENTION This invention relates to an apparatus for enhancing blood flow through a limb of a subject. In particular, the invention concerns an apparatus 15 for preventing deep vein thrombosis. Deep vein thrombosis (DVT) is characterized by the development of a clot within a deep vein anyvhere in the body but almost exclusively in the veins of the calf or thigh. DVT's are a large source of morbidity, the most common serious complication of DVT being a pulmonary embolism whereby 20 a blood clot breaks free from a vein wall, travels to a lung and blocks an artery.

2 The following factors can promote blood clot formation within a vein: 1. Increased coagulation of the blood (e.g. women on hormones); 2. Increased clotting factor in the blood; 5 3. Damage to a vein wall (e.g. trauma to a leg), whereby coagulation factors are released and a chemical cascade causes clot to form; 4. Stasis of the blood, as happens in dependant limbs where gravity causes decreased blood flow through the veins. Blood 10 clots are known to form most frequently in the legs due to stasis. The circulatory system circulates blood around the body using various mechanisms. The heart pumps blood into the arterial system and this system distributes to every part of the body. Above the heart, gravity plays a role in 15 returning blood to the heart, and below the heart, muscular contractions compress veins to move the blood towards the heart. Directional valves of the veins ensure that blood flow is directional. Small muscle groups move small amounts of blood during each contraction of the leg muscle and this is important as, since vein walls are thin and elastic, too much blood in a vein 20 could cause the vein to distend, to suffer damage and to render the directional valves non-functional.

3 During long periods of muscular inactivity (e.g. when traveling on an aeroplane, car, bus or train, when confined to a wheelchair, or when bed ridden), the risk of blood clot forming in a person increases as there may be little or no venous blood movement within the legs of the person. In addition 5 to stasis, with blood continuing to collect within the leg veins, the directional valves may leak, the veins may distend and suffer darnage and hence release clotting factors which could also initiate clot formation. Compression sleeves for preventing DVT are known. However, although such sleeves decrease the risk of a blood clot forming, the sleeves 10 generally have the disadvantage that they do not decrease the risk to an acceptable level. In particular, those sleeves that compress a large area of muscle at any given time and consequently squeeze large volumes of blood through the veins may have the following disadvantages: 1. During compression of the sleeve, blood may be squeezed back 15 into the veins below the sleeve, thus increasing stasis in, and causing further distension of, the veins below the sleeve. This problem is exacerbated by long sleeve compression times. Large compressed areas and if the veins located beneath the sleeve already contain too much blood. 2. Following compression, the sleeve is relaxed, and the empty veins 20 in the previously compressed muscle refill with blood from below the sleeve, 4 there is no blood flow above the sleeve and thus the blood in the veins above the sleeve lies static until the sleeve is next compressed. 3. If there is any constriction of the veins above the sleeve, such as the veins located in a seated person's thighs, then the large volume of blood 5 may distend and damage those veins. To recapitulate, some of the known compression sleeves have disadvantages in that they aggravate stasis below the sleeve during compression of the muscle, they cause stasis above the sleeve when the sleeve is relaxed, and may distend vein walls and render directional valves of 10 the veins non-functional, thus increasing the risk of blood clot formation. This is also true of those sleeves that have a serious of inflatable chambers which compress areas of a leg sequentially, as the chambers, which envelop a large atea of muscle, do not deflate until all of the chambers have inflated. 15 OBJECT OF THE INVENTION It is therefore an object of the present invention to provide an apparatus for enhancing blood flow through a limb of a subject that minimizes or overcomes at least one of the disadvantages referred to above, or to 20 provide the public with a useful or commercial choice.

5 DISCLOSURE OF THE INVENTION 5 In one form, although it need not be the only or indeed the broadest form, the invention resides in a device for prevention of thrombosis, said device comprising; a compression member able to apply a force to a limb of a person's body; a rotatable shaft mounted for rotation, the rotatable shaft connected to 10 the compression member; a drive unit connected to the rotatable shaft to rotate the rotatable shaft; wherein rotation of the rotatable shaft causes movement of the compression member. 15 Preferably, the rotatable shaft is threaded and the compression member is connected to the rotatable shaft by a threaded portion. The invention may further comprise a disengaging device to disengage the rotatable shaft from the drive unit. The invention may further comprise a returning device to return the compression member from a 20 finishing position to a starting position.

6 Additionally, the invention may further comprise a fastener to fasten the device against the limb of a person's body. The invention may further comprise a housing, to contain and protect the device, wherein the housing adjacent the compression member is 5 flexible. The invention may further comprise an electronic timing control circuit for changing speed and frequency of operation. According to a further aspect of the invention there is provided a device for prevention of thrombosis, said device comprising; 10 a compression member of varying thickness along its length for distributing a compressive force to a limb of a person's body, said compression member being stationary relative to the limb in use; an actuator arranged to apply a compressive force to the compression member along a predetermined line of travel; and 15 a drive unit arranged to move the actuator member along the predetermined line of travel. Preferably the device includes at least one sensor to detect the actuator reaching a finish point along said line of travel. In a preferred embodiment the device includes a returning means to 20 return the actuator from the finish point.

7 Preferably the compression member is shaped to apply the compressive force in response to the actuator travelling toward the finish point along said line of travel and to cease to apply the compressive force in response to the actuator travelling away from the finish point along said line 5 of travel. Further features of the present invention will become apparent from the following detailed description. 10 BRIEF DESCRIPTION OF THE DRAWINGS To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect preferred embodiments of the invention will be described by way of example only with reference to the 15 accompanying drawings, wherein: FIG. 1 shows vertical section view of an embodiment of the invention; FIG. 2 shows a top section view of a further embodiment of the invention; FIG. 3 shows an internal view of a further embodiment of the 20 invention; 8 FIG. 4 shows an external view of a further embodiment of the invention; FIG. 5 shows a further external view of a further embodiment of the invention; FIG. 6 shows an application of an embodiment of the 5 invention; FIG. 7 shows a cross sectional view of FIG. 6 FIG. 8 shows another embodiment of the invention 10 DETAILED DESCRIPTION OF THE INVENTION The device of the invention is a lightweight, self-contained device, which may be easily used in locations such as a plane, a hospital or in the home. The device applies a compressive force against a person's limb, 15 without restricting blood flow either above or below the device. FIG. I shows vertical section view of an embodiment of the invention. The device 10 includes a compression member 20, a compression actuator 21, a rotatable threaded shaft 40, a drive unit 50, a housing 60, a returning device 7A and a disengaging device 80. The compression member 20 is 20 shaped like a wedge and compressed by actuation member 21. In a particularly preferred embodiment of the invention the actuation member 21 9 is a curved rod. The actuation member 21 may be fitted with moveable parts, such as rollers, to reduce friction between the actuation member 21 and compression member 20. The compression member 20 may be stiff, but have the ability to be deformed to a shape to conform to a person's limb. In 5 another embodiment the compression member 20 may be slightly flexible, so as to flex to conform to a person's limb, whilst still being sufficiently rigid to impart a compressive force onto a person's limb. The actuation member 21 is connected to an attachment portion 30, which may be integrally formed with the actuation member 21, or may be a 10 separate part, such as a nut. Preferably, the attachment portion 30 is internally threaded. A rotatable shaft 40 is attached to the actuation member 21 via the attachment portion 30. Preferably, the rotatable shaft 40 is threaded to correspond to the attachment portion 30. 15 A drive unit 50 is connected to the rotatable shaft 40 via the disengaging device in the form of a clutch unit 80. The drive unit 50 may be in the form of a motor gearbox or may be driven by hand. The motor may be powered by a battery, or connected to an external power supply or may be solar powered. The drive unit 50 may also be located externally to the device 20 10. There may be various connectors, such as cogs, between the drive unit 50, the clutch member and rotatable shaft 40, as is well known in the field.

10 A housing 60 is used to house the compression member 20, the actuation member 21, the attachment portion 30, rotatable shaft 40 and the drive unit 50. The case 60 encloses the outer portion of the device 10 and the flexible cover 62 encloses the area of the device 10 which contacts the 5 person's limb. The case 60 is made of a material that is flexible to fit to the shape of the person's limb, yet is sufficiently rigid to protect the device 10. The flexible cover 62 is made of a thin flexible material such that the action of the compression member 20 deforms the flexible cover 62 and compresses the person's limb in the vicinity of the actuation member 21. The flexible 10 cover 62 may be removable, such that it may be removed and laundered, or may be made of a material designed for a single use. The flexible cover 62 and the compression member 20 may be molded as one component attached to case 10. A returning device 70 is connected to the actuation member 21 or the 15 attachment portion 30, in a preferred form of the invention. The returning device 70 may be in the form of a spring or a second drive unit. In one embodiment of the invention, the returning device 70 is in the form of a clockwork spring at an end of the rotatable shaft 40. As the rotatable shaft 40 rotates, the clockwork spring tightens. 20 In another preferred form of the invention, a disengaging clutch 80 is present which acts to disengage the rotatable shaft 40 from the drive unit 50.

11 The disengaging device 80 may be in the form of at least one solenoid. The solenoid 80 may be activated when the attachment portion 30 reaches the top of the rotatable shaft 40, for example by a reed switch 81or similar device. The solenoid 80 acts to disengage the rotatable shaft 40 from the 5 drive unit 50, thus allowing free rotation of the rotatable shaft 40 as the returning device 70 acts to return the compression actuation member 21 to a starting position. The actuation member 21 returns to the starting position without putting pressure on the person's limb. In another embodiment, the solenoid 80 acts to impel the actuation 10 member 21 towards the person's limb during movement of the compression member 20 from the starting position to a finishing position. When the attachment portion 30 reaches the top of the rotatable shaft 40, the solenoid 80 is deactivated and the rotatable shaft 40 and compression member 20 retract from the person's limb. 15 FIG. 2 shows a horizontal section view of a further embodiment of the invention. In FIG.2,it can be seen that the compression member 20 is shaped to more easily conform to the shape of a person's limb. A fastening device 90 may fasten the device 10 to a person's limb. The fastening device 90 may be in the form of bars, as shown in FIG . 2, for 20 the attachment of straps joined by hook and loop tape, a buckle, press studs or the like. The fastening device 90 may consist of more than one strap, for 12 example, one strap at each end of the device 10. Preferably, the fastening device 90 has some elasticity for the person's comfort and to ensure contact of the majority of the length of the compression member 20 with a person's limb. 5 FIG. 3 shows an internal view of a further embodiment of the invention. In this embodiment, the actuation member 21 comprises rollers 21. The rollers 21 reduce the friction between the cover 22 attached to compression member 2A. The rollers 21 may be exchangeable with rollers of differing sizes. A change to the diameter of the rollers will alter the 10 pressure applied by compression member 20 and the person's limb. In this embodiment, the drive unit 50 is powered by two batteries 51 . FIG. 4 shows an external view of a further embodiment of the Invention. The position of the actuation member 21 and the rotatable shaft 40 are shown in dashed outline. In this embodiment, the device 10 is provided 15 with two bars 90 for the attachment of straps, hook and loop tape and the like to fasten the device 10 to a person's limb. The device 10 should be attached to the person's limb such that the bottom 140 is towards the extremity of the limb and the top 150 is towards the person's body. FIG. 5 shows a further external view of a further embodiment of the 20 invention. In this embodiment, a control panel 130 forms an integral part of the device 10. Hook and loop tape 90 is attached to bars on the device 10, 13 for fastening the device to a person's limb. This allows for quick and easy adjustment of the fastener 90 to suit all sizes of limb. FIG. 6 shows an application of an embodiment of the invention. In this embodiment the device 10 is attached to a person's upper calf 100. 5 FIG. 7 shows a cross sectional view of FIG. 6, showing a cross section of the device 10 and a person's upper calf 100. The device 10 is positioned such that leg veins 101 and 102 may be compressed by the compression member 20, shown in dashed outline. Referring again to Figure 1, in operation of a preferred embodiment of 10 the device 10, the drive unit 50 is activated to rotate the rotatable shaft 40 and thus move the actuation member 21 from a starting position 110 to a finishing position 120. The compression member 20 massages the person's limb 100 and assists the circulation of the blood therein. When the actuation member 21 reaches the finishing position 120, it activates a switch 81 that 15 disconnects power to the drive unit 50. The returning device 70 is then caused to activate and rotate the rotatable shaft 40 in the opposite direction to return the actuation member 21 to the starting position 110. Once the compression member 21 returns to the starting position 110, the rotatable shaft 40 reengages with the drive unit 50. 20 The compression member 20, applies a compressive force to the person's limb. The compressive force moves from the starting position 110 14 to the finishing position 120 as the actuator member 21 moves therebetween. Once the actuation member 21 arrives at the finishing position 120, i.e. the maximum pressure position, the actuation member 21 is disengaged by disengaging device 80. No compression will be applied to the person's limb 5 as the actuator member 21 returns back from the finishing position to the starting position by virtue of the shape of the compression member. Thus compression occurs in one direction only. Preferably, the device 10 is fastened to a person's limb such that compression will occur from the extremity of the limb towards the heart, as 10 this is direction of blood flow through veins. Thus blood flow through the veins will be encouraged. FIG.8 shows another embodiment of the invention. In this embodiment the drive unit 50 is connected to a running clutch 51. The running clutch 51 is connected to the rotatable shaft 40 via a rotatable shaft gear 41. The running 15 clutch 51 is also connected to a rotatable cam shaft 180 via a rotatable cam shaft gear 181. The rotatable shaft 40 may move in a horizontal direction, yet is biased towards the rotatable cam shaft 180. The rotatable cam shaft 180 supports a cam 160 and a return spring 20 170. The cam 160 is connected to the rotatable cam shaft 180 such that a large portion 161 extends on one side of the rotatable cam shaft 180 and a 15 small portion 162 extends on the other side. The shape of the cam 160 may be elliptical or other shapes as are well known in the art. The cam 160 is located such that a portion of the cam 160 is in contact with the rotatable shaft 40. 5 The return spring 170 acts upon the rotatable shaft 40 to bias it towards the rotatable cam shaft 180. In operation of this embodiment, the drive unit 50 operates the running clutch 51, which in turn acts upon the rotatable shaft gear 41 and the rotatable cam shaft gear 181 to rotate the rotatable shaft 40 and the rotatable 10 cam shaft 180. The sizing of the rotatable shaft gear 41 and the rotatable cam shaft gear 181 are such that the rotatable cam shaft 180 turns through 180 in the same time frame that the rotatable shaft 40 makes a sufficient number of rotations to move the compression member 20 from a starting position 110 to a finishing position 120 or vice versa. 1s Whilst the large portion of the cam 161 is in contact with the rotatable shaft 40, the rotatable shaft 40 is impelled in an outward direction with respect to the device 10. When the device 10 is in contact with a person's limb, the compression member 20 applies pressure to the person's limb when the rotatable shaft 40 is impelled outwardly. 20 When the rotation of the rotatable cam shaft 180 rotates the cam 160 such that the small portion of the cam 162 is in contact with the rotatable 16 shaft 40, the biasing action of the return spring 170 allows the rotatable shaft 40 to retract towards the rotatable cam shaft 180. When the device 10 is in contact with a person's limb, the compression member 20 does not apply pressure to the person's limb when the rotatable shaft 40 is retracted. 5 Whilst the rotatable shaft 40 is in the retracted position, the compression member 20 is returned to the starting position 110 as previously discussed. Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific 10 collection of features, Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention. For example, the size and shape of the compression member 20, and correspondingly the device, may be varied. The device 10 may be compact for use on airplanes, or sized to accommodate a full leg for 15 post-operative patients. It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims

1. A device for prevention of thrombosis, said device comprising; a compression member of varying thickness along its length for distributing a compressive force to a limb of a person's body, said compression member being 5 stationary relative to the limb in use; an actuator arranged to apply a compressive force to the compression member along a predetermined line of travel; and a drive unit arranged to move the actuator member along the predetermined line of travel. 10

2. A device according to any one of the preceding claims including at least one sensor to detect the actuator reaching a finish point along said line of travel.

3. A device according to claim 1, including returning means to return the actuator from the finish point. 15

4. A device according to any one of the preceding claims, wherein the compression member is shaped to apply the compressive force in response to the actuator travelling toward the finish point along said line of travel and to cease to apply the compressive force in response to the actuator travelling away from the finish point along said line of travel. 20

5. A device for prevention of thrombosis substantially as described herein with reference to any one of Figures 1 to 5, 7 and 8.