WO2008152544A1

WO2008152544A1 - System and method for reducing the risk of deep vein thrombosis

Info

Publication number: WO2008152544A1
Application number: PCT/IB2008/052213
Authority: WO
Inventors: Wilhelmus J. J. Stut; Ronaldus M. Aarts
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2007-06-12
Filing date: 2008-06-05
Publication date: 2008-12-18

Abstract

Airline passengers that travel long distance may suffer from limited blood circulation in the lower leg, which increases the risk of deep vein thrombosis. Active voluntary contraction of the calf muscle is an essential factor in the circulatory system, and reduces the risk of deep vein thrombosis. A system (100) is described that enables aircraft passengers to control their personal in-flight entertainment system by lifting the ankles, the balls of the foot, or an entire foot. Thanks to these movements the passenger voluntarily contracts and stretches the calf muscle, and thereby reduces the risk of deep vein thrombosis during long flights.

Description

System and method for reducing the risk of deep vein thrombosis

BACKGROUND OF THE INVENTION

Technical field

The present invention relates to a system, method and a computer program for reducing the risk of deep vein thrombosis.

DESCRIPTION OF RELATED ART

Airline passengers that travel long distance may suffer from limited blood circulation in the lower leg. This increases the risk of deep vein thrombosis (DVT). Active voluntary contraction of the calf muscle is an essential factor in the circulatory system. Failure to exercise the calf muscles for prolonged periods may result in limited or poor blood circulation in the lower leg and increase the risk of DVT. An association between long distance travel and increased risk of DVT has been established.

Airlines recommend a number of lower leg exercises as a DVT preventative measure. In the future such exercises will even become more relevant since new aircrafts will allow for non-stop flights that last 18 hours or more. Furthermore, as the profitability of an airline depends on selling enough seats to enough customers at sufficient prices to ensure an adequate return on capital investment and operating costs, airlines will continue to place as many seats as possible in a cabin, thereby limiting the amount of space per passenger.

Today, some in-flight entertainment systems or magazines recommend a number of exercises that prevent limited blood circulation and DVT. However, passengers must entirely rely on their own motivation and/or discipline to do those exercises. As a result, passengers still have an increased risk of limited blood circulation and DVT.

US 2006/0085047 Al discloses a method for reducing the incidence of Deep Vein Thrombosis and Pulmonary Embolism by the application of Neuromuscular Electrical Stimulation (NMES) of the plantar muscle. Electrodes that deliver the electric pulses generated by the NMES device are placed at the bottom of the foot. However, electrical stimulation methods have drawbacks. For example, positioning the electrodes on the calf muscle or the sole of the foot can be problematic. The difference in size and shape of people's calf muscles or feet requires fitting cuffs or adjusting sole plate size to ensure accurate placement of the electrodes. Often these electrodes present cuffs or bands shift or slide down the leg with use. Electrodes applied to the soles of the feet also shift or become dislodged. One irritating problem is the removal of the electrode from the calf when the hair on the leg becomes bound to the sticky electrode. Another difficulty with calf stimulators is that the fatty tissue layer has a relatively high resistance to electric current. This fatty surface layer, between the electrode and the muscle beneath, requires higher current settings for stimulation adequate to contract the muscle. These higher current settings, especially with obese patients, can cause significant discomfort to the skin area around the electrode. Additionally, for calf muscle stimulation, a relatively high current setting is required to cause contraction. Again, higher current pulses are more likely to cause sensations that the user finds unpleasant, especially when administered over a long period.

It is therefore an object of the invention to provide an improved system and method for reducing the risk of deep vein thrombosis.

SUMMARY OF THE INVENTION

This and other objects of the invention are achieved by a system according to claim 1, a method according to claim 12 and a computer program according to claim 13. Favorable embodiments are defined by the dependent claims 2-11 and 14-15.

According to an aspect of the invention a system is provided for reducing the risk of deep vein thrombosis comprising a user interface for stimulating active voluntary movement of a calf muscle by the user. The active voluntary movement consists of lifting the heels and the balls of the foot or the entire foot, because hereby the user voluntarily contracts and stretches the calf muscle. In this way, the calf muscle is stimulated in a more effective way than by moving the foot to the left and the right or backward and forward, which is done with a so called foot mouse. Active voluntary contraction of the calf muscle is an essential factor in the circulatory system, and prevents limited blood circulation and DVT during long periods of sitting still, for example during long flights. With the system according to the present invention it is avoided that the user does not perform the movements due to forgetfulness. In it simplest form the system is adapted to provide the user at regular intervals with instructions related to the active voluntary movement of the calf muscle by means of the user interface. In this way, the user is regularly reminded of the need to do the exercises. Alternatively, the system is adapted to provide the user with instructions related to the active voluntary movement of the calf muscle by means of the user interface only in case that no general motion of the user has been detected for a predetermined period of time. A wireless accelerometer mounted at e.g. the ankles can be used for detecting such general motion of the user. In this way, it is avoided that a user is unnecessarily reminded of the exercises, for example in case that he has just made a walk.

According to an embodiment the system is adapted to provide feedback to the user on performed movements on the basis of sensed movements of at least one foot. In its simplest form this feedback is a simple message indicating to the user if the exercises were performed correctly and/or long enough.

However, in a preferred embodiment, the feedback is provided by controlling a functionality of the system. The controlled functionality may be one or more of the position of an object on a screen, a channel being watched and an audio volume level. In this way the user is provided with an even stronger trigger to do the exercises. The sensors necessary for sensing the movements of the user may be either an integral part of the system or an external accessory that is coupled to the system.

According to a preferred embodiment there are at least four sensors arranged as a 2x2 sensor matrix for sensing the lifting of the heels and the balls of both feet. In this way, all the relevant movements for stretching and contracting the calf muscle can be detected. Preferably, the sensors are simple pressure sensors sensing the pressure on the floor exercised by the respective parts of the feet.

The system may be a personal entertainment system in an airplane, because airplane passengers that travel long distances may suffer from limited blood circulation in the lower leg, which increases the risk of deep vein thrombosis. However, the system according to the invention can also be applied to other situations where people are not able to use the calf muscles naturally, such as in the case of bus passengers, or people with a profession that leads to little movement, such as certain office workers.

According to a further aspect of the invention a method is provided for reducing the risk of deep vein thrombosis comprising the step of stimulating active voluntary movement of a calf muscle by the user by means of a user interface.

Preferably, the method according to the invention is implemented by means of a computer program.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and its numerous objects and advantages will become more apparent to those skilled in the art by reference to the following drawings, in conjunction with the accompanying specification, in which:

Figure 1 shows a block diagram of an exemplary embodiment of the invention.

Figures 2-6 show some examples how to control the position of an object on a screen according to an exemplary embodiment of the invention.

Throughout the figures like reference numerals refer to like elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring now to figure 1, an exemplary embodiment of the system according to the invention will be described. The system 100 is a personal entertainment system for use in an airplane. It comprises a controller 110 consisting of a processor 120 and its associated memory 130. The processor 120 is coupled to a user interface 140. The user interface 140 is preferably a display but it may also be a head set. The system may also comprise communication means (not shown) to communicate with a server in the airplane for receiving data of a movie, etc.

The aircraft passengers use their legs, ankles, and feet to control their personal in-flight entertainment system. More precisely, this system is controlled by lifting the ankles, the balls of the foot, or the entire foot. In this way the passenger can control e.g. the position of an object (such as a cursor or an actor) on the screen, the movie channel being watched, the audio volume level, etc.

By lifting the ankles and the balls of the foot the passenger voluntarily contracts and stretches the calf muscle. Active voluntary contraction of the calf muscle is an essential factor in the circulatory system, and prevents limited blood circulation and DVT during long distance flights, as explained in more detail in "An Investigation of Recommended Lower Leg Exercises for Induced Calf Muscle Activity" K.J. O'Donovan, T. Bajd, PA. Grace, D.T. O'Keeffe, and G.M. Lyons, Proceeding of the 24th IASTED international conference on Biomedical Engineering - 2006.

The system detects which part(s) of which feet have been lifted by means of sensors 150. These sensors can be placed at the floor before the passenger's seat and/or in the shoe soles of the passenger. In a simple form the system only needs four sensors, capable of measuring pressure applied thereto, in the form of a 2x2 sensor matrix, but it is also possible to use more sensors.

The figures 2-6 show some examples how to control the position of an object using a 2x2 sensor matrix. Only figure 2 shows the shoes of the passenger. A white area indicates that the corresponding foot part or leg has been lifted and the sensor does not measure pressure. A grey area indicates that the corresponding foot part or leg is on the floor and the sensor measures pressure. The arrows indicate the resulting direction of the object controlled.

In figure 2 the passenger keeps both feet on the floor. As a result all 4 areas measure pressure, and the object does not move. In figure 3 the passenger lifts both heels. As a result only the 2 upper areas measure pressure, and the object moves up. In figure 4 the passenger lifts the left leg. As a result only the 2 right areas measure pressure, and the object moves to the right. In figure 5 the passenger lifts both foot balls. As a result only the 2 lower areas measure pressure, and the object moves down. In figure 6, the passenger lifts his left heel. As a result the lower left area does not measure pressure and the remaining three areas measure pressure, and the object moves to the upper right.

The movement of an object on the screen continues until the feet are placed in another position. In order to stimulate that passengers contract their muscles for a longer period of time, the movement of the object may be slowed down on purpose. In order to obtain the functionality described herein above, the processor 120 executes instructions of a computer program stored in the memory 130.

Any other convention than the one described herein above may be used for the relationship between the movement of the feet and the movement of the object. For example, the system can also be designed such that if the heels are lifted, the object moves down, when the left foot is lifted the object moves left, etc.

It is also possible to control other settings of the entertainment system 100 than the position of an object. For example, the movie channel being watched may be increased by one (comparable to the functionality of the "channel up" button on a remote control) by lifting the right foot and decreased by one (comparable to the functionality of the "channel down" button on a remote control) by lifting the left foot. The volume may be increased by lifting both foot balls and decreased by lifting both heels, etc.

The passenger may bring his own sensors, or they may be provided by the airline. When using sensors at the floor, these may be integrated in the floor, or be merely part of a small sensor mat that is placed on the floor. The passenger can be further motivated by receiving a reward, such as frequent flyer points or a free drink, when the passenger has made a certain number of movements with his feet/legs. This may attract more passengers, and may be beneficial for the airline's image. In the embodiment described here, the sensors are suitable for detecting pressure. However, any other sensor types may be used suitable for sensing the lifting of the heel, the foot ball and the whole foot.

Simpler systems to prevent DVT could be contemplated than the embodiment described herein above, for example a system giving just at regular intervals recommendations to move, say every 15 minutes. This can be done on the screen built in the chair, the headphones, a built-in buzzer in the headset, a vibrator in the chair, or a vibrator on the ankles. Alternatively, in order to avoid unnecessary recommendations a wireless accelerometer mounted at e.g. the ankles of the passenger can detect general motion and only if there is lack of motion a recommendation to move can be given to the passenger. The main application of the system is for airline passengers that travel long distances. They may suffer from limited blood circulation in the lower leg and increase the risk of deep vein thrombosis. However, the system can also be applied to other situations were people may not be able to use the calf muscles naturally, such as bus passengers, or people with a profession that leads to little movement, for example certain office workers. The invention can be resumed as follows: Airline passengers that travel long distance may suffer from limited blood circulation in the lower leg, which increases the risk of deep vein thrombosis. Active voluntary contraction of the calf muscle is an essential factor in the circulatory system, and reduces the risk of deep vein thrombosis. A system is described that enables aircraft passengers to control their personal in-flight entertainment system by lifting the ankles, the balls of the foot, or an entire foot. Thanks to these movements the passenger voluntarily contracts and stretches the calf muscle, and thereby reduces the risk of deep vein thrombosis during long flights.

As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications.

Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed, but is instead defined by the following claims. Any reference signs in the claims shall not be construed as limiting the scope thereof.

Claims

CLAIMS:

1. System (100) for reducing the risk of deep vein thrombosis comprising a user interface (140) for stimulating active voluntary movement of a calf muscle by the user.

2. System (100) for reducing the risk of deep vein thrombosis according to claim 1 , being adapted to provide the user at regular intervals with instructions related to the active voluntary movement of the calf muscle by means of the user interface (140).

3. System (100) for reducing the risk of deep vein thrombosis according to claim 1, being adapted to provide the user with instructions related to the active voluntary movement of the calf muscle by means of the user interface (140) only in case that no relevant movement of the user has been detected for a predetermined period of time.

4. System (100) for reducing the risk of deep vein thrombosis according to claim 1 , being adapted to provide feedback to the user on performed movements on the basis of sensed movements of at least one foot.

5. System (100) according to claim 4, being adapted to provide the feedback by controlling a functionality of the system.

6. System (100) according to claim 5, wherein the controlled functionality is one or more of the position of an object on a screen, a channel being watched and an audio volume level.

7. System (100) according to claim 4, wherein the sensed movements are: lifting a heel of the foot and/or lifting a ball of the foot and/or lifting the whole foot.

8. System (100) according to claim 4, comprising sensing means (150) for sensing the movements.

9. System (100) according to claim 8, comprising at least four sensors arranged as a 2x2 sensor matrix for sensing the lifting of the heels and the balls of both feet.

10. System (100) according to claim 8, wherein the sensing means (150) are adapted for measuring pressure.

11. System (100) according to claim 1 being a personal entertainment system.

12. Method for reducing the risk of deep vein thrombosis comprising the step of stimulating active voluntary movement of a calf muscle by the user by means of a user interface (140).

13. A computer program comprising computer program code means adapted to perform the steps of claim 12, when said program is run on a computer.

14. A computer program as claimed in claim 13 embodied on a computer readable medium.

15. A carrier medium carrying the computer program of claim 13.