Orthostatic Hypotension Relief Device

Abstract

Orthostatic hypotension alleviating apparatus includes: a housing including a hole extending through the housing; a carriage disposed within the housing and configured to reciprocate toward and away from the hole along a carriage displacement axis; a mandrel disposed on the carriage and configured to rotate about a mandrel axis; a tether at least partially wound around the mandrel and including a distal end extending through the hole, the tether being arranged such that by pulling the distal end away from the hole to cause the mandrel to rotate about the mandrel axis, the tether can be extended from a retracted configuration to an extended configuration in which the tether is fully extended; a mandrel biasing mechanism connected to the mandrel and configured to apply a biasing torque about the mandrel axis to the mandrel to bias the tether toward the retracted configuration; and, a carriage biasing mechanism disposed within the housing, connected to the carriage, and configured to bias the carriage away from the hole.

Description

Technical Field

[0001] The present invention relates to an orthostatic hypotension alleviating device. More specifically but not exclusively, the present invention relates to an orthostatic hypotension alleviating device that includes a carriage disposed within a housing and having a spindle thereon around which a tether is at least partially wound, the carriage being biased away from the housing by a carriage biasing mechanism, and the tether being biased into a retracted configuration by a spindle biasing mechanism connected to the spindle. Background Art

[0002] In a healthy state, the human body can quickly detect and correct blood pressure changes caused by the transition from a static position (sitting or lying down) to an upright position. Orthostatic hypotension (OH) is a condition that represents a failure of the body's reflex system (autonomic nervous system), resulting in the patient's blood pressure being unable to adjust during postural changes or prolonged quiet standing. This insufficient blood pressure causes a reduction in blood flow to anatomically superior parts of the body such as the head. This can lead to dizziness, lightheadedness, fainting, visual changes, weakness, cognitive impairment, syncope, angina, and stroke. Secondary sequelae are even more concerning, such as falls leading to hospitalization, which are typically associated with debilitating prognoses such as brain injury, fractures, immobility, etc. OH may nominally sound physiologically benign, but due to its prevalence and prognosis, it can have a profound impact on patients.

[0003] Current treatments for OH include non-pharmacological treatments such as avoiding causative medications, increasing hydration, drinking large amounts of water before standing, dietary restrictions, and physical compression garments or physical compression maneuvers. However, these treatments are often not practical, may be complex or uncomfortable, or become ineffective due to poor patient compliance.

[0004] The types of physical compression maneuvers are clinically limited and are generally difficult to perform alone in the patient population with OH without assistance. Performing isometric exercises (e.g., weightlifting before standing) may cause the patient's blood pressure to rise. However, due to the unrelated relationship between blood pressure and the speed and force used by the patient during exercise, this is not recommended. This can lead to large fluctuations in blood pressure, which may exceed the safe treatment window and can result in complications such as stroke or aneurysm rupture. Summary of the Invention

[0005] The present invention seeks to overcome the problems of the prior art.

[0006] Accordingly, the present invention provides an orthostatic hypotension alleviating device, comprising:

[0007] a housing including a hole extending through the housing;

[0008] A bracket, the bracket being arranged within the housing and being configured to reciprocate along a bracket displacement axis towards and away from the hole;

[0009] A mandrel, the mandrel being arranged on the bracket and being configured to rotate about a mandrel axis;

[0010] A tether, the tether being at least partially wound around the mandrel, the tether including a distal end extending through the hole, the tether being arranged such that by pulling the distal end away from the hole to cause the mandrel to rotate about the mandrel axis, the tether can be extended from a retracted configuration to an extended configuration in which the tether is fully extended;

[0011] A mandrel biasing mechanism, the mandrel biasing mechanism being connected to the mandrel and being configured to apply a biasing torque about the mandrel axis to the mandrel to bias the tether towards the retracted configuration; and,

[0012] A bracket biasing mechanism, the bracket biasing mechanism being arranged within the housing, being connected to the bracket, and being configured to bias the bracket away from the hole.

[0013] The instrument according to the present invention employs two biasing mechanisms. This enables a patient to extend the tether with a very small force, thereby reducing the adverse effects of performing isotonic exercise, but once the tether is extended, an isometric exercise is performed against a relatively strong biasing force provided by the bracket biasing mechanism.

[0014] Preferably, the bracket biasing mechanism is connected between the bracket and the housing.

[0015] Preferably, the bracket biasing mechanism includes at least one bracket biasing spring, the at least one bracket biasing spring extending along an axis substantially parallel to the bracket displacement axis.

[0016] Preferably, the bracket biasing spring has a spring constant k, the value of k being such that: as the pulling force on the tether is increased to the value at which the mandrel first begins to rotate, and then at that value of the pulling force, the bracket biasing spring is partially compressed or partially extended.

[0017] Preferably, the bracket biasing spring has a spring constant k, the value of k being such that: when a pulling force P c is applied to the tether, the tether generates a torque on the mandrel that balances the torque applied to the mandrel by the mandrel biasing mechanism, and the bracket biasing spring is partially compressed or partially extended.

[0018] Preferably, the mandrel biasing mechanism is connected between the mandrel and the bracket.

[0019] Preferably, the mandrel biasing mechanism includes a clockwork spring.

[0020] Preferably, the bracket includes a bracket plate and an inner shell connected to the bracket plate, and the mandrel and the mandrel biasing mechanism are arranged inside the inner shell.

[0021] Preferably, the inner shell is detachably connected to the bracket plate.

[0022] Preferably, the orthostatic hypotension relief device further includes a position detection mechanism for detecting the position of the bracket along the bracket displacement axis.

[0023] Preferably, the position detection mechanism includes a first electrical contact and a second electrical contact arranged inside the outer shell, the first contact being close to the second contact, and the first contact and the second contact being arranged such that: as the bracket moves along the displacement axis, the bracket abuts against the first contact, thereby pushing the first contact into contact with the second contact.

[0024] Preferably, the orthostatic hypotension relief device further includes at least one of an accelerometer, a blood pressure sensor, and a pulse monitor.

[0025] Preferably, the orthostatic hypotension relief device further includes a strap connected to the outer shell for connection to the human body.

[0026] Preferably, the strap is a wrist strap. Description of the Drawings

[0027] The present invention will now be described by way of example only with reference to the accompanying drawings, without any limiting sense, in which:

[0028] Figure 1 A known device for the exercise field is shown;

[0029] Figure 2 A first embodiment of the device according to the present invention is shown;

[0030] Figure 3 Shows Figure 2 the bottom surface of the bracket of the device;

[0031] Figures 4(a) to 4(d) Shows Figure 2 the operation of the device;

[0032] Figure 5 Another embodiment of the device according to the present invention is shown;

[0033] Figure 6 Another embodiment of the device according to the present invention is shown; and,

[0034] Figures 7(a) and 7(b) illustrate another embodiment of the device according to the present invention. Detailed Description

[0035] Figure 1 A known exercise device 1 is shown. The device 1 includes a housing 2 having a hole 3 extending through the housing 2. A collar 4 is attached to the outer side of the housing 2. A spindle (not shown) is disposed within the housing 2 and is free to rotate about a spindle axis. A tether 5 is wound around the spindle and extends through the hole 3.

[0036] In use, a user attaches the collar 4 to one of their feet. The user then grasps the tether 5 and pulls it upwardly out of the housing 2, extending the tether 5 from a retracted configuration to an extended configuration, thereby performing an isokinetic exercise. An adjustable biasing device within the housing 2 biases the tether 5 toward the retracted configuration, thereby controlling the work done by the user in extending the tether 5.

[0037] Although such a device 1 finds application in the field of personal exercise, it is not suitable for use as an orthostatic hypotension alleviation device. In fact, it may be dangerous for a patient to use such a device to alleviate orthostatic hypotension. The exercise performed by the user is an isokinetic exercise (i.e., an exercise involving muscle contraction against resistance at a substantially constant speed). There is no relevant relationship between blood pressure and the speed and force at which the user performs the exercise. This can lead to significant fluctuations in blood pressure, which may exceed the safe treatment window, resulting in complications such as stroke or aneurysm rupture.

[0038] Figure 2 A first embodiment of an orthostatic hypotension alleviation device 10 according to the present invention is shown in schematic form. The device 10 includes a housing 11 defined by a housing wall 12. A hole 13 extends through the housing wall 12. The upper half of the housing 11 is not shown so that the contents of the housing 11 can be seen.

[0039] A carriage 14 including a carriage plate 15 is disposed within the housing 11. The carriage plate 15 is configured to reciprocate toward and away from the hole 13 along a carriage displacement axis 16.

[0040] Figure 3 The underside of the carriage 14 and a portion of the housing wall 12 are shown. The underside of the carriage 14 includes a tongue 17. A corresponding groove 18 is disposed in the housing wall 12. In use, the tongue 17 is disposed within the groove 18, thereby constraining the carriage 14 to move along the carriage displacement axis 16.

[0041] Return Figure 2 , the device 10 further includes a spindle 19 disposed on the carriage plate 15. The spindle 19 is free to rotate about a spindle axis 20 which, in this embodiment, is substantially perpendicular to the carriage displacement axis 16.

[0042] The tether 21 is partially wound around the mandrel 19. The proximal end 22 of the tether 21 is connected to the mandrel 19. As shown, the distal end 23 of the tether 21 extends through the hole 13 in the housing wall 12. In Figure 2 it, the tether 21 is shown in a retracted configuration, with most of the tether 21 wound around the mandrel 19 and only the distal end 23 of the tether 21 extending through the hole 13 in the housing 11. By pulling the distal end 23 of the tether 21 away from the hole 13, the mandrel 19 rotates, thus extending the tether 21 into an extended configuration in which the tether 21 is no longer wound around the mandrel 19, and thus further pulling on the tether 21 will not cause any further rotation of the mandrel 19. This will be explained in more detail below.

[0043] A mandrel biasing mechanism 24 is connected between the mandrel 19 and the carriage 14. In the present embodiment, the mandrel biasing mechanism 24 is a wound spring 24. For clarity, only the two ends of the wound spring 24 are shown. The mandrel biasing mechanism 24 is configured to apply a torque about the mandrel axis 20 to the mandrel 19, thereby biasing the tether 21 towards the retracted configuration. If the tether 21 is to be partially extended and then released, the torque applied by the mandrel biasing mechanism 24 to the mandrel 19 will cause the mandrel 19 to rotate, thus retracting the tether 21 until it reaches the retracted configuration.

[0044] The instrument 10 further includes a carriage biasing mechanism 25 disposed between the carriage 14 and the housing 11. The carriage biasing mechanism 25 is configured to bias the carriage 14 away from the hole 13. In this embodiment, the carriage biasing mechanism 25 includes a carriage biasing spring 25 having a spring constant K and extending along an axis generally parallel to the carriage displacement axis 16.

[0045] FIG. 4(a) shows the instrument 10 schematically from above with the tether 21 in the retracted configuration. Again, for clarity, only the ends of the wound spring 24 are shown. In addition, only a portion of the housing wall 12 adjacent the hole 13 is shown. In use, the patient holds the housing 11 in one hand and the distal end of the tether 21 in the other hand. Alternatively, since the instrument 10 is relatively compact, it can be attached to the wrist by means of a wrist strap attached to the housing 11, thus allowing single-handed operation. The patient then begins to pull on the distal end 23 of the tether 21. The force initially applied by the patient is small. This pulling force creates a tension in the tether 21 which in turn creates a torque about the mandrel axis 20 on the mandrel 19. This torque is less than the torque applied by the wound spring 24 about the mandrel axis 20 in the opposite direction, so the mandrel 19 does not rotate. However, the tension causes a small degree of compression of the carriage biasing spring 25, thus causing the carriage 14 to shift slightly along the carriage displacement axis 16 towards the hole 13, as shown in FIG. 4(b).

[0046] The patient then increases the pulling force on the tether 21 to the value P c . At this time, the torque applied to the mandrel 19 about the mandrel axis 20 balances the torque applied to the mandrel 19 by the mandrel biasing mechanism 24 in the opposite direction.

[0047] The patient then increases the pulling force on the tether 21 to exceed P c . The torque generated by the tether 21 on the mandrel 19 then exceeds the torque generated by the clockwork spring 24 in the opposite direction. Accordingly, the mandrel 19 begins to rotate, and by maintaining this pulling force, the patient can extend the tether 21 from the retracted configuration to the extended configuration as shown in Fig. 4(c). In the extended configuration, the tether 21 is completely unwound from the mandrel 19, so the mandrel 19 does not rotate further.

[0048] The torque applied to the mandrel 19 by the clockwork spring 24 is relatively small. Accordingly, the tether 21 can be pulled by the patient from the housing 11 from the retracted configuration to the extended configuration without difficulty. Although the patient is performing an isokinetic movement at this time, the forces involved are small and do not cause any significant increase in the patient's blood pressure.

[0049] Once the tether 21 is in the extended configuration, the patient further increases the pulling force. With the mandrel 19 no longer rotating, this increase in pulling force causes the carriage biasing spring 25 to compress, as shown in Fig. 4(d). The carriage biasing spring 25 is a relatively rigid spring (i.e., having a high spring constant), so a relatively large increase in pulling force is required to produce any substantial compression of the carriage biasing spring 25.

[0050] Once the patient has pulled the tether 21 with the desired pulling force (typically in the range of 20 - 100 N), the patient then holds the tether 21 stationary against the biasing force of the carriage biasing spring 25, thus performing an isometric movement (i.e., a force is applied but the muscle is not lengthened or shortened). The isometric movement produces a controlled increase in the patient's blood pressure. Once the tether 21 has been held by the patient against the biasing force of the carriage biasing spring 25 for the desired period of time, the patient then releases the tether 21, and the tether 21 retracts to the retracted configuration by the clockwork spring 24.

[0051] Generally speaking, the carriage biasing spring 25 has a spring constant k. The value of k is such that when the pulling force P cWhen a force is applied to the tether 21 to create the following torque on the mandrel 19, where the torque is used to balance the torque applied to the mandrel 19 by the mandrel biasing mechanism 24. In other words, as the tension in the tether 21 increases to the value at which the mandrel 19 first begins to rotate, then at that tension value, the carriage biasing spring 25 is partially compressed. If the spring constant is too small, the carriage biasing spring 25 will be fully compressed before the mandrel 19 begins to rotate. Then, after the tether 21 has reached the extended configuration, the patient will not be able to perform subsequent controlled isometric exercises by further compressing the carriage biasing spring 25.

[0052] Figure 5 Shown is an alternative embodiment of the orthostatic hypotension alleviation device 10 according to the present invention. In this embodiment, the carriage biasing spring 25 is located on the side of the carriage 14 opposite the aperture 13, and in this embodiment, the carriage biasing spring 25 is extended rather than compressed by the user during operation. Similarly, the spring constant of the carriage biasing spring 25 and the torque provided by the clockwork spring 24 are selected such that when the tether 21 moves from the retracted configuration to the extended configuration, the carriage biasing spring 25 is only partially extended, and in this embodiment, end stops 26 are used to prevent the carriage biasing spring 25 from extending beyond the fully extended position and becoming plastically deformed.

[0053] In Figure 2 's embodiment, when the tether 21 is in the retracted configuration and there is no tension in the tether 21, the carriage biasing spring 25 is in an intermediate position, i.e., neither extended nor compressed. In an alternative embodiment of the present invention, when the device 10 is in this state, the carriage biasing spring 25 is partially compressed, thereby pushing the carriage 14 as far away from the aperture 13 as possible. The operation of this embodiment is the same as Figure 2 's operation, except that when the tether 21 is pulled, the carriage 14 does not move towards the aperture 13 until the tether 21 reaches the extended configuration and the tension has increased beyond the force exerted on the carriage 14 by the carriage biasing spring 25.

[0054] Figure 6 Another embodiment of the device 10 according to the present invention is shown. In this embodiment, the carriage 14 further includes an inner housing 27 connected to the carriage plate 15. The mandrel 19 and the mandrel biasing mechanism 24 are disposed within the inner housing 27. The mandrel biasing mechanism 24 extends between the mandrel 19 and the inner housing 27. Preferably, the inner housing 27 is removably connected to the carriage plate 15 such that the inner housing 27, the mandrel 19, the tether 21, and the mandrel biasing mechanism 24 can be removed and replaced as a single unit when needed.

[0055] As referenced Figures 4(a) to 4(d)As explained, once the tether 21 reaches the extended configuration, the patient increases the pulling force, which causes compression of the carriage biasing spring 25 and causes the carriage 14 to move towards the aperture 13. Thus, the position of the carriage 14 is a function of the pulling force, in other words, a function of the tension in the tether 21. It is generally desirable for the patient to apply only a predetermined pulling force, and in particular not to exceed this predetermined pulling force, as this may have undesirable side effects on the patient or the device 10. As shown in the schematic diagram of FIG. 7(a), FIG. 7(a) is a vertical cross-sectional shape of another embodiment of the device 10 according to the present invention. This embodiment further includes a position detection mechanism 28 for determining the position of the carriage 14. The position detection mechanism 28 includes first and second electrical contacts 29 disposed within the housing 11, the first contact 29 being spaced apart from but close to the second contact 29.

[0056] When the patient increases the pulling force on the tether 21, the carriage 14 moves towards the first electrical contact 29 and then abuts against the first electrical contact 29. As the patient further increases the pulling force, the carriage 14 moves closer to the aperture 13, causing the first electrical contact 29 to bend towards the second electrical contact 29. When the pulling force applied by the patient reaches the predetermined pulling force, the first electrical contact 29 abuts against the second electrical contact 29, as shown in FIG. 7(b). The device is designed such that the tension in the tether 21 is typically in the range of 20 - 100 N at this time. The circuit 30 is connected to the first and second electrical contacts 29 and is configured to generate an alarm such as a sound or light when the two contacts 29 touch. The patient can simply pull the tether 21 with increasing force until the alarm appears and then hold the tether 21 in that position, thereby performing the required isometric exercise.

[0057] The circuit 30 can provide additional functions. The circuit 30 can include a timer that can generate a second alarm once the patient has performed the isometric exercise for a desired amount of time. The timer can be programmable. The circuit 30 can further store data such as the time of exercise and the duration of the exercise, and this data can be downloaded for subsequent analysis.

[0058] In another embodiment of the present invention, the device 10 further includes a blood pressure monitor and a pulse rate monitor. If the patient's blood pressure exceeds a safe level during exercise, the blood pressure monitor is adapted to issue an alarm. Similarly, if the patient's pulse rate exceeds a safe level during exercise, the pulse rate monitor is adapted to issue an alarm. Both monitors can be configured to store data for subsequent analysis. The device 10 can further include an accelerometer to measure the movement of the device 10 during use.

Claims

1. An orthostatic hypotension alleviation device, comprising: a housing, the housing including a hole extending through the housing; a carriage, the carriage being disposed within the housing and being configured to reciprocally shift toward and away from the hole along a carriage shift axis; a mandrel, the mandrel being disposed on the carriage and being configured to rotate about a mandrel axis; a tether, the tether being at least partially wound around the mandrel, the tether including a distal end extending through the hole, the tether being arranged such that by pulling the distal end away from the hole to cause the mandrel to rotate about the mandrel axis, the tether can be extended from a retracted configuration to an extended configuration, in which the tether is fully extended; a mandrel biasing mechanism, the mandrel biasing mechanism being connected to the mandrel and being configured to apply a biasing torque to the mandrel about the mandrel axis to bias the tether toward the retracted configuration; and, a carriage biasing mechanism, the carriage biasing mechanism being disposed within the housing, being connected to the carriage, and being configured to bias the carriage away from the hole; the carriage biasing mechanism being connected between the carriage and the housing; the carriage biasing mechanism including at least one carriage biasing spring, the at least one carriage biasing spring extending along an axis substantially parallel to the carriage shift axis; wherein the carriage biasing spring has a spring constant k, the value of k being such that: as the tension on the tether is increased to the value at which the mandrel first begins to rotate, and then at that value of the tension, the carriage biasing spring is partially compressed or partially extended.

2. The orthostatic hypotension alleviation device according to claim 1, wherein the mandrel biasing mechanism is connected between the mandrel and the carriage.

3. The orthostatic hypotension alleviation device according to claim 1, wherein the mandrel biasing mechanism includes a wound spring.

4. The orthostatic hypotension alleviation device according to claim 1, wherein the carriage includes a carriage plate and an inner housing connected to the carriage plate, the mandrel and the mandrel biasing mechanism being disposed within the inner housing.

5. The orthostatic hypotension alleviation device according to claim 4, wherein the inner housing is detachably connected to the carriage plate.

6. The orthostatic hypotension alleviation device according to claim 1, further comprising a position detection mechanism for detecting the position of the carriage along the carriage shift axis.

7. The orthostatic hypotension alleviation device according to claim 6, wherein the position detection mechanism includes a first electrical contact and a second electrical contact disposed inside the housing, the first electrical contact being close to the second electrical contact, the first electrical contact and the second electrical contact being arranged such that: as the carriage moves along the shift axis, the carriage abuts the first electrical contact, thereby pushing the first electrical contact into contact with the second electrical contact.

8. The orthostatic hypotension alleviation device according to claim 1, further comprising at least one of an accelerometer, a blood pressure sensor, and a pulse monitor.

9. The orthostatic hypotension alleviating device according to claim 1, further comprising a band connected to the housing for connection to a human body.

10. The orthostatic hypotension alleviating device according to claim 9, wherein the band is a wristband.

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