CN87106548A - Apparatus and method for anti-blood column formation - Google Patents

Abstract

Translated fromChinese

一种防止卧床不起病人腿部发生静脉血栓形成的预防措施包括将一种具有两个绕枢轴摆动的主体部分(3与4)的装置依次装到病人的脚(11)与小腿下部(10)，这装置有动力驱动装置(14)将该两主体部分连接起来摆动以实现病人足踝的强制背屈及被动的松驰来通过病人腿内(肌肉)的腔隙间压力促进静脉血液流通。

A prophylaxis against venous thrombosis in the legs of a bedridden patient involves attaching a device having two pivoting body parts (3 and 4) sequentially to the patient's foot (11) and lower leg ( 10), this device has a power drive device (14) that connects the two main parts to swing to realize the forced dorsiflexion and passive relaxation of the patient's ankle to promote venous blood through the interstitial pressure in the patient's leg (muscle) circulation.

Description

Device and method for preventing blood column formation

The present invention relates to a device and method for preventing venous thrombosis by mechanical means.

Preventing bedridden patients from developing venous thrombosis is a significant problem. Some surgical procedures, including lower limb orthopedic surgery, are found, for example, in hospitals with an abnormally high incidence of postoperative venous thromboembolism, i.e., venous thrombosis or pulmonary embolism. Several preventive measures are currently employed, including basic prevention using drugs or physical methods. The latter employs a newer pneumatic device comprised of multiple circumferential bands that are strapped to the patient's calf and thigh. One is a shank segment with four surrounding air chambers and a thigh segment with two. By applying pneumatic pressure, the two sections of the air chamber expand sequentially from the ankle, thereby facilitating blood flow to the deep venous system. The girdle is tested to be continuously used on a patient after an operation, and the incidence rate of deep venous thrombosis is reduced. This method is found to have both physical and pharmacological effects, without the risk of bleeding and virtually without side effects. Although compressed air is often supplied to operating rooms and intensive care units, it is rarely supplied to general wards, and certainly not at home.

The primary object of the present invention is to provide a mechanical anti-thrombotic device that is effective and operable upon attachment of a readily available power source.

The present invention provides an anti-thrombotic device for fitting to a patient's lower leg to cause repeated compression of the lower leg muscles to assist in deep venous circulation, the device comprising a first body member, means for fitting the body member to the lower part of the patient's lower leg, a second body member pivotally connected to the first body member for engaging the patient's foot, a drive link disposed between the first and second body members for actuating a swinging movement about the patient's ankle axis, and power means incorporated in the first body member for actuating the drive link.

The invention has the effect that the ratio of the pressure between deep posterior lacunae in the shank muscle in the fully passive dorsiflexion state and the fully passive plantar flexion state of the ankle is about 9: 1 on average, and the pressure change caused by repeated ankle movement realizes proper deep venous circulation to prevent thrombosis.

Accordingly, the present invention also provides a method of preventing venous thrombosis in the legs of a bedridden patient, comprising the steps of attaching to the lower part of the patient's foot and lower leg a device having two hinged body members with a rocking drive means therebetween, and forcibly effecting repetitive plantar flexion and dorsiflexion movements of the patient's ankle to effect pressure fluctuations in the patient's leg (muscle) compartment to promote blood flow in the leg.

The invention will be described in more detail by means of preferred embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a device of the present invention attached to a user's foot;

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1;

FIG. 3 is a perspective view of the drive means inside the device;

fig. 4 is a block schematic diagram of an electronic control device thereof.

Referring to figures 1 and 2, the device of the invention comprises anupper body portion 3 connected to alower body portion 4 by opposed pairs ofbrackets 5 and 6, each integral with itsbody portion 3 and 4, each pair being interconnected at itsdistal end 7 and 8 by a pivot pin. Theportions 3 and 4 are both channel-shaped shells of thermoplastic material which are contoured to enclose at least part of thelower leg 10 and foot 11 (figure 1) of the user. Theupper body portion 3 is preferably provided with a resilient backing (not shown) therein. Thecounter bracket 6 extends laterally from thebase 17 of theupper body portion 3 and thecounter bracket 5 is upstanding from the lower body portion. The location and length of thebrackets 5 and 6 are such that the location of eachpivot pin 9 corresponds approximately to the centre of the ankle of the user. Thestraps 12 securely fasten theupper body portion 3 to the user'slower leg 10. Andstraps 13 secure thelower body portion 4 to thefoot 11. Thestraps 12 and 13 may include velcro-type fastening devices.

It will thus be seen that rotation of thelower body portion 4 about thepivot pin 9 moves thefoot 11 between the passive dorsiflexed and plantar flexed positions, so that thefoot 11 can be swung between these positions by an external medium, by means of a drive link 14 (figure 2) secured to theheel 15 of thelower body portion 4 and actuated by adrive means 16 housed within the housing of theupper body portion 3. The drive means 16 shown in fig. 3 may comprise anelectric motor 17 connected to thedrive link 14 by arotatable drive shaft 18. Thedrive shaft 18 is journalled at itsdistal end 20 rotatably in abearing 19 and is provided with a threaded intermediate portion 21. An internally threadedfollower 22 is threadedly connected to the threaded portion 21 of theshaft 18 and is restrained against rotation by thedrive link 14 and is only axially movable along theshaft 18 in response to rotation of theshaft 18. The direction of axial movement of thefollower 22 is determined by the direction of rotation of theshaft 18. Thedrive link 14 preferably comprises asheet metal element 24 displaceable within theupper body portion 3 along aslot 25, one end of which is provided with ayoke 23 which surrounds thefollower 22 and the other end of which is provided with amounting bracket 26 for attachment to theheel portion 15 of thelower body portion 4 of the device. Thefollower 22 is connected to theyoke 23 by apin 27 displaceable along aslot 28 in the yoke so that thedrive link 14 has a certain degree of linear movement relative to thefollower 22 required for the swinging movement of the twobody parts 3 and 4.

Themotor 17 can be reversed by electronic control, to be described later, and the range of oscillation of themain portion 4 with respect to themain portion 3 can be determined by the movement of a set ofmicro-switches 29 corresponding to acam 30 carried by theyoke 23. Thedrive shaft 18 is split into two pieces and interconnected by a shock absorbing spacer 31 to minimize the impact the patient's muscle response applies to themotor 17. The electronic control means are mounted on a printedcircuit board 32 located in theupper body portion 3 of the device.

Therefore, when themotor 17 is energized, thedriving link 14 reciprocates to repeatedly force the user'sfoot 11 to dorsiflex. The device can be used in all places of a hospital and even for home care, because it is driven by the common commercial power. As a result, deep venous circulation can be maintained in the lower leg of the patient, avoiding the development of venous thrombosis. In at least some cases, the patient is fitted with a single device on both legs. It will be appreciated that alternating, simultaneous or other related operations may require mutual timing. Preferably, the operation of each device is provided with a pause in the rest position, with the timing, speed and extent of oscillation of thecontrol body portions 3 and 4. Typically, the oscillation period of the apparatus of the present invention is about one minute and the pause lasts about one minute.

Fig. 4 shows a block diagram of the electronics controlling themotor 17. This circuit is based on a dedicated microprocessor device for adapting the operation to the vast majority of patients. The circuit includes amotor drive circuit 33 connected to amicroprocessor 35 and aposition feedback sensor 34. Thesensor 34 is able to detect the current position of the patient'sfoot 11 relative to a central or "rest" position, which allows the device to be positioned prior to patient fitting and, if appropriate, synchronized with a controller (not shown) attached to the other foot.

Theprogram switch 36 can vary the stroke and speed of movement in both directions relative to the rest position. This position is normally preset at a standard level, but allows for changes to accommodate the needs and comfort of each patient.

In most post-operative applications, a patient needs to have one device on both feet. To avoid causing discomfort to the patient, the two devices are synchronized. The two devices may be operated in the same motion, i.e. both feet move in the same direction and at the same speed, or in opposite phase, with one foot moving upwards and the other downwards. This control is taken from thesynchronization interface 38. This arrangement requires anexternal power supply 37 to allow for proper isolation and related regulations.

Detection is provided to determine stall and failure of themotor 17. The patient is also provided with exercise control measures to allow the patient to take a short break when they feel uncomfortable. Such control may be limited or restricted by the caregiver, as desired. A control switch 39 may be mounted on one end of the upper body portion, but is preferably cabled out to a location easily accessible to the patient. The control circuit uses low power CMOS devices as much as possible to reduce power consumption and to combat external interference.

Although a preferred embodiment has been described in the preceding section, it should be understood that other forms, modifications and improvements are possible within the scope of the invention.

Claims (10)

1. An anti-thrombosis device for fitting to a patient's lower leg to cause repeated compression of the lower leg muscles to assist deep venous circulation, the device comprising a first body member, means for fitting the body member to the lower part of the patient's lower leg, a second body member pivotally connected to the first body member for engaging the patient's foot, a drive link disposed between the first and second body members for actuating a swinging movement centred on the patient's ankle axis, and power means incorporated in the first body member for actuating the drive link.

2. An antithrombotic device as defined in claim 1, wherein the second body member has a heel portion for partially encircling the patient's heel, and the drive link is connected to the heel portion.

3. An antithrombotic device as claimed in claim 1 or 2, wherein the motive means is a reversible motor, the drive linkage being actuated by rotation of the drive shaft.

4. An antithrombotic device as set forth in claim 3 wherein the drive shaft has a threaded portion and a threaded follower engages the portion to drive the drive link and impart linear motion to the drive link by rotation of the drive shaft.

5. An anti-thrombotic device according to any one of the preceding claims, further comprising an electronic circuit controlling the application of power to the motive means and including means for selecting the specification of the oscillatory movement of the body member.

6. An antithrombotic device as defined in claim 5, wherein the electronic circuit further comprises means for synchronizing the oscillatory movement of the one device with the oscillatory movement of the other device in a predetermined manner when the device is attached to each leg of the patient.

7. A method for preventing venous thrombosis in the lower leg of a bedridden patient, characterised in that it comprises attaching to the foot and lower part of the lower leg of the patient a device having two hinged body members with a rocking drive means therebetween, and effecting forcibly repetitive movements in plantar flexion and dorsiflexion of the ankle of the patient to effect pressure fluctuations in the patient's leg (muscle) compartment to promote blood flow in the leg.

8. A method according to claim 7, wherein the repetitive movement has a pause in rest after each cycle of the patient's foot movement which forces dorsiflexion and plantar flexion of the patient's ankle.

9. A method according to claim 7 or 8, wherein the repetitive movement is controlled to be synchronised in a predetermined manner with the repetitive movement of another device attached to the patient's other foot having two articulated body members with a swing drive therebetween.

10. A method according to claim 8, wherein the patient's foot movement cycle takes one minute and the pause lasts one minute.

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