Patent Publication Number: US-2022211576-A1

Title: Devices, systems and methods for treating and preventing venous insufficiency, thrombosis, orthostatic intolerance, and impaired lymphatic drainage

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority pursuant to 35 U.S.C. § 119(e) of U.S. provisional patent application No. 63/134,664, filed 7 Jan. 2021, entitled “DEVICES, SYSTEMS AND METHODS FOR TREATING AND PREVENTING VENOUS INSUFFICIENCY,” which is hereby incorporated by reference herein in its entirety for all purposes. 
    
    
     BACKGROUND 
     I. Introduction 
     The venous network in humans is characteristically a low-pressure system, which necessitates the presence of staggered valves in order to prevent backflow as blood from the lower legs is pumped against gravity and back toward the heart. The calf (gastrocnemius) muscle assists with the pumping action during walking, thereby facilitating venous return, but individuals in career fields that involve prolonged standing are at increased risk of a condition known as venous insufficiency, in which the peripheral vascular system becomes overwhelmed by stagnant blood due to inactivation of the calf pump. Here, superficial veins dilate in order to accommodate the venous congestion that results, which can ultimately lead to painful and unsightly varicose veins. 
     Currently, compression socks and sleeves are available to help combat this issue, but with limited effectiveness. Moreover, the currently available compression socks, sleeves and related apparatuses require frequent replacement due to limited retention of elasticity over time. 
     What is needed are improved apparatuses, wearables and/or medical devices that effectively prevent, mitigate and/or treat venous insufficiency and related/resultant conditions. Such is provided by the presently disclosed subject matter. 
     BRIEF SUMMARY 
     In one embodiment, an apparatus for treating or preventing venous insufficiency, thrombus development, or lymphedema is disclosed. The apparatus includes a sleeve wearable on a limb of a user; an upper bracket and a lower bracket releasably couplable to the limb; an actuator coupled to one of the upper or lower brackets; a shaft coupled to the actuator and the other of the upper or lower brackets; a plurality of cams fixedly coupled to, and longitudinally spaced along, the shaft; and a respective plurality of flexible elements each coupled to one of the plurality of cams and to the sleeve, wherein rotational motion of the actuator about an axis of rotation causes the plurality of cams, via the respective plurality of flexible elements, to induce a peristaltic pressure wave in the limb. 
     Optionally, in some embodiments, each of the plurality of cams in angularly indexed with respect to at least one other of the plurality of cams about the axis of rotation. 
     Optionally, in some embodiments, a first cam of the plurality of cams has a first nose height; and a second cam of the plurality of cams has a second nose height. 
     4 Optionally, in some embodiments, the first nose height is greater than the second nose height. 
     Optionally, in some embodiments, the first cam is adjacent to the second cam along a longitudinal dimension of the shaft. 
     Optionally, in some embodiments, a direction of rotation of the actuator is reversible. 
     Optionally, in some embodiments, a rotation of the actuator in a first direction induces a cranial/proximal pressure wave in the limb. 
     Optionally, in some embodiments, a rotation of the actuator in a second direction opposite the first direction induces a caudal/distal pressure wave in the limb. 
     Optionally, in some embodiments, the sleeve is conformable on the limb. 
     Optionally, in some embodiments, the pressure wave has a magnitude of between about 30 mmHg and 200 mmHg. 
     Optionally, in some embodiments, the pressure wave has a frequency of about 20 to 60 waves per minute. 
     Optionally, in some embodiments, the apparatus induces a second pressure wave in the limb at the same time and different location as the pressure wave. 
     Optionally, in some embodiments, the apparatus includes a power source that powers the actuator. 
     Optionally, in some embodiments, the user is a human susceptible to and/or is suffering from lower extremity varicose veins, thrombosis, venous insufficiency, blood clot formation, orthostatic intolerance, and/or edema. 
     In one embodiment, a method of treating or preventing venous insufficiency, thrombus development, or lymphedema is disclosed. The method includes applying a wearable device to a limb of a user, wherein the wearable device includes a sleeve wearable on a limb of a user; an upper bracket and a lower bracket releasably couplable to the limb; an actuator coupled to one of the upper or lower brackets; a shaft coupled to the actuator and the other of the upper or lower brackets; a plurality of cams fixedly coupled to, and longitudinally spaced along, the shaft; and a respective plurality of flexible elements each coupled to one of the plurality of cams and to the sleeve, wherein rotational motion of the actuator about an axis of rotation causes the plurality of cams, via the respective plurality of flexible elements, to induce a peristaltic pressure wave in the limb. 
     In one embodiment, a wearable device is disclosed. The wearable device includes: a plurality of flexible elements wearable on a limb of a user. Each of the flexible elements circumferentially surrounds at least a portion of the limb and a plurality of actuators each coupled to a respective one of the plurality of flexible elements. Adjacent actuators are configured to sequentially constrict the limb via the respective plurality of flexible elements to induce a peristaltic pressure wave in the limb. 
     Optionally, in some embodiments, the device is adapted for use in an inflight phase of space travel to mitigate hemodynamic changes related to cephalad fluid shifts caused by exposure to microgravity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified view of wearable devices in place on a user&#39;s a lower leg. 
         FIG. 2A  illustrates an aspect of the subject matter in accordance with one embodiment. 
         FIG. 2B  illustrates an aspect of the subject matter in accordance with one embodiment. 
         FIG. 3A  is an isometric view of an embodiment of a wearable device. 
         FIG. 3B  is an isometric view of the embodiment of the wearable device in  FIG. 3A  worn on an opposing portion of a limb of a user from the wearable device shown in  FIG. 3A . 
         FIG. 3C  is an exploded view of the wearable device of  FIG. 3A . 
         FIG. 3D  is a detailed section view of the wearable device of  FIG. 3A  taken at line  3 D- 3 D. 
         FIG. 4A  is a rear elevation view of an embodiment of a wearable device. 
         FIG. 4B  is a right elevation view of an embodiment of the wearable device of  FIG. 4A . 
         FIG. 5  is an example of a timing diagram of for a pressure wave induced by a wearable device of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     II. Discussion 
     The presently disclosed subject matter now will be described more fully hereinafter, in which some, but not all embodiments of the presently disclosed subject matter are described. Indeed, the presently disclosed subject matter can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. 
     In humans, as well as other warm-blooded and mammalian species, the venous system functions at a characteristically low pressure. The venous network returns blood from distal structures, to include extremities (e.g. feet/legs and hands/arms), to the cardiopulmonary vasculature, to then reenter the arterial system. Due to the nature of this low-pressure system, the presence of staggered, one-way valves is necessary in order to prevent backflow as blood from extremities and limbs, and particularly the lower legs when in a standing position, is pumped against gravity and back toward the heart. At least in humans, the calf (gastrocnemius) muscle in the leg assists with the pumping action during walking and other movements of the legs, thereby facilitating and/or assisting in venous return. However, subjects that are sedentary for extended periods of time, and particularly standing for prolonged periods, e.g., individuals in career fields that involve prolonged standing, are at increased risk of a condition known as venous insufficiency. 
     Venous insufficiency occurs in subjects when the peripheral vascular system becomes overwhelmed by stagnant blood due to inactivation of the calf pump, i.e., during prolonged standing or other inactivity resulting in reduced blood flow from the extremities. In such instances, superficial veins dilate in order to accommodate the venous congestion that results, which can ultimately lead to painful and unsightly varicose veins. 
     Definitions 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the presently disclosed subject matter. 
     While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. 
     All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one skilled in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. 
     In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. 
     Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims. 
     Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “a cell” includes a plurality of such cells, and so forth. 
     Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. 
     Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter. 
     As used herein, the term “about,” when referring to a value or to an amount of a composition, mass, weight, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions. 
     The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim. 
     As used herein, the phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole. 
     As used herein, the phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. 
     With respect to the terms “comprising”, “consisting of”, and “consisting essentially of”, where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms. 
     As used herein, the term “and/or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D. 
     Overview of Presently Disclosed Subject Matter 
     In some embodiments, provided herein are apparatuses and/or devices for treating and/or preventing venous insufficiency, wherein the apparatuses and/or devices are configured to be worn by or applied to a subject, wherein the apparatuses and/or devices are configured to apply a peristaltic movement and/or peristaltic pressure to an affected region or area of the subject, wherein the apparatuses and/or devices comprise a soft robotic system capable of producing a peristaltic movement and/or peristaltic pressure within the apparatuses and/or devices. In some embodiments, peristaltic movement can be cranial/proximal for some applications (e.g., terrestrial/venous/lymphatic), and caudal/distal for other applications (e.g., spaceflight use). In some aspects, the soft robotic system capable of producing a peristaltic movement and/or peristaltic pressure within the apparatus and/or device comprises one or more synthetic muscle fibers, optionally wherein the one or more synthetic muscle fibers are configured to be activated concentrically by electrical impulse to mimic natural peristaltic movement. 
     In some aspects, the apparatuses and/or devices comprise a sleeve or foldable sheet of material, wherein the sleeve or foldable sheet of material comprises the soft robotic system capable of producing a peristaltic movement and/or peristaltic pressure within the apparatuses and/or devices. In some aspects, the sleeve can include an inner layer and an outer layer, wherein the inner layer comprises the soft robotic system, wherein the outer layer comprises a fabric material, wherein the sleeve is configured to be wearable over an appendage or limb of a subject. The soft robotic system of the inner layer can in some aspects comprise synthetic muscle fibers configured to be activated concentrically by electrical impulse to cause a natural peristaltic movement in an axial direction of the sleeve. 
     In some aspects, the inner layer and outer layer are separable, optionally wherein the inner layer and outer layer are attached and/or integrated. The inner layer can optionally comprise a silicone material, wherein the outer layer can optionally comprise a cotton or neoprene material. The sleeve can comprise any dimension suitable for application to a limb of a subject, optionally wherein the sleeve has a circumference of about 10 cm to about 60 cm (or about 10 cm, 20 cm, 30 cm, 40 cm, 50 cm or 60 cm) optionally wherein the sleeve has a length of about 10 cm to about 60 cm (or about 10 cm, 20 cm, 30 cm, 40 cm, 50 cm or 60 cm), optionally wherein the sleeve has a thickness of about 5 mm to about 1.5 cm (or about 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 1 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.4 cm or 1.5 cm). In some embodiments, the apparatus and/or device is configured to be wearable by a subject, optionally wherein the apparatus and/or device is configured to be placed on and/or over a limb, a leg or an arm of a subject, or otherwise applied to an affected area of the subject. 
     In some embodiments, apparatuses and/or devices are configured to apply a peristaltic movement or peristaltic pressure to an affected region or area of the subject, wherein a force applied to the affected region or area ranges from about 30 mmHg to about 200 mmHg. Additionally, in some aspects, the peristaltic movement or peristaltic pressure is applied at a frequency of about 20 to about 60 contractions per minute. 
     In some aspects, the apparatuses and/or devices further comprise a power source, optionally wherein the power source is a battery, optionally wherein the battery is rechargeable. 
     The apparatuses and/or devices can further comprise a computer, optionally wherein one or more functions of the apparatus and/or device are controlled by a processor of the computer, further comprising a computer readable medium having stored thereon computer executable instructions executable by the processor. 
     Provided herein are methods of treating and/or preventing venous insufficiency, the methods comprising applying the apparatuses and/or devices to a subject in need of treatment, wherein the subject is a human subject, optionally wherein the subject is susceptible to and/or is suffering from lower extremity varicose veins and/or edema. In such methods the apparatuses and/or devices are applied to one or more limbs or extremities of the subject, wherein the apparatuses and/or devices are controlled to apply peristaltic movement and/or peristaltic pressure to an affected region or area of the subject. 
     Detailed Description of Devices, Apparatuses and Methods to Prevent and/or Treat Venous Insufficiency 
     Provided herein are wearable apparatuses and/or devices configured to be placed on and/or over a limb, e.g. leg, arm, etc., of a subject, or otherwise applied to an affected area of a subject, where the apparatus and/or device is configured to apply a peristaltic movement or peristaltic pressure to an affected region. In some embodiments, such apparatuses and/or devices can comprise a sleeve or foldable sheet of synthetic muscle fibers that can be activated concentrically by electrical impulse to mimic natural peristaltic movement. See, e.g.,  FIGS. 1, 2A, and 2B . 
     The disclosed apparatuses and/or devices can comprise synthetic muscle or synthetic muscle fibers, including for example hydraulically amplified electrostatic actuators or other soft robotics that couple electrostatic and hydraulic forces to achieve diverse modes of actuation, to facilitate a natural peristaltic movement or pressure within the apparatus or device. Such synthetic muscle can be arranged within or integrated throughout the apparatus, including for example in a tube or sleeve structure that when activated concentrically via electrical impulse produces or mimics a natural peristaltic movement. In some embodiments, the disclose apparatuses and/or devices can include multiple layers of material/components, such as for example an inner layer (or inner sleeve or sheath) of synthetic muscle fibers surrounded by an outer layer (or outer sleeve or sheath) of material to support and/or maintain the orientation of the inner layer. Alternatively, and/or in addition, in some embodiments the synthetic muscle fibers can be integrated into and/or amongst other fibers or materials to form a composite layer that provides a sheet or sleeve of material with actuatable soft robotic capability to produce a peristaltic pressure. In some aspects, such materials, including the inner sleeve, outer sleeve, composite, etc., can include, but are not limited to cotton, polyester, neoprene, and blends thereof. 
     Such an apparatus and/or device, at least in applications for the leg, lower leg and/or calf area of the leg, can help to facilitate venous return by applying sequential external forces that propel blood from the lower leg back to the heart ( FIGS. 1 and 2A /B). This alleviates gravity-induced pressure and can both prevent and treat venous insufficiency. 
     In some embodiments, the disclosed apparatus and/or device can be designed to be wearable by the user such that the user&#39;s mobility and/or day-today activities are not significantly affected by the device. In some aspects, the device and/or apparatus can be powered by a small, USB-rechargeable battery, and can be fully Bluetooth-capable and operable through a mobile application. To facilitate ease of use the device can be operable without being plugged into an electrical outlet, although in some aspects it can be configured to be used while plugged into an outlet. Such wearable designs can also be configured to be slim-fit such that they can be worn under clothing and outer wear. 
     The disclosed apparatuses and/or devices can be configured to apply sufficient pressure to modulate venous and lymphatic flow, while also being comfortable to the user. They can be configured to be easy to apply and remove, e.g., through the use of elastic and stretchable materials, and/or through the use of various fasteners, e.g., hook and loop closures, snaps, buttons, zippers and the like. Such apparatuses and/or devices can be designed to be reasonably quiet, i.e., low decibels, such that use of the device does not disturb the user or others nearby. Moreover, it can be Bluetooth-enabled and can be controlled by a device and/or mobile application. 
     In some embodiments, and by way of example, the disclosed apparatuses and/or devices can include one or more of the following specifications: 
     Materials
         Silicone and other proprietary compounds   Covered in a thin, removable cotton sleeve       

     Dimensions
         Circumference: 40 cm at its widest point   Length: 32 cm   Thickness: 2 mm (1.5 cm for small charging pack)       

     Pumping Action
         Force Applied: 30 mmHg to 200 mmHg (controllable within app)   Frequency: 20 to 60 contractions per minute (controllable within app)       

     Charging Mechanism
         USB-rechargeable battery       

     Additional specifications and examples, including materials, dimensions and the like, are provided herein. 
     The subject matter disclosed herein can be implemented in software in combination with hardware and/or firmware. For example, the subject matter described herein can be implemented in software executed by a processor. In one exemplary implementation, the subject matter described herein can be implemented using a computer readable medium having stored thereon computer executable instructions that when executed by a processor of a computer control the computer to perform steps. Exemplary computer readable mediums suitable for implementing the subject matter described herein include non-transitory devices, such as disk memory devices, chip memory devices, programmable logic devices, and application-specific integrated circuits. In addition, a computer readable medium that implements the subject matter described herein can be located on a single device or computing platform or can be distributed across multiple devices or computing platforms. 
     With reference to  FIG. 1 , an example of a wearable device  100  is shown worn by a user  102 . A wearable device  100  is shown on each of the user&#39;s calves  106 . While the wearable device  100  shown for example may be adapted to be worn on the calves  106 , other embodiments, of wearable device  100  may be adapted to be worn on other extremities  104 , such as a thigh, or upper or lower arm. The dimensions (e.g., circumference, length, thickness) of the wearable device may be adapted for use different limbs and/or different parts of limbs. In one example, a wearable device adapted for use on an upper arm may have a length of about 20 cm and/or circumference of about 25 cm to 30 cm. In another example, a wearable device adapted for use on a lower arm may have a length of about 20 cm to 25 cm and a circumference of about 15 cm to 30 cm. In another example, a wearable device adapted for use on a thigh of a user may have a length of about 30 cm and a circumference of about 40 cm to 60 cm. In another example, a length of a device adapted to be used for an upper and lower arm may have a length of about 40 cm to 60 cm. In another example, a length of a device adapted to be used for an upper and lower arm may have a length of about 60 cm to 80 cm. A number and spacing of flexible elements may be similarly adapted for use with different limbs or portions of limbs. With reference to  FIGS. 2A and 2B  an example of a peristaltic pressure wave  108  induced by a wearable device  100  is shown. In the example shown, the pressure wave  108  is a cranial/proximal pressure wave  108  (e.g., a wave that tends to move fluid toward the heart of the user  102 ). As shown for example, the pressure wave  108  begins low on the user&#39;s calf  106 , constricting a portion of the calf  106 . The pressure wave  108  travels up the calf  106  as the wearable device  100  progressively constricts the calf  106  further up toward the user&#39;s heart, while releasing the lower portions of the calf  106 . The pressure wave  108  may reset once it reaches an end (e.g., top or bottom) of the wearable device  100 . For example, when the  108  reaches the top of the pressure wave  108 , a new pressure wave  108  may be initiated by the wearable device  100  at the lower end of the calf  106 . In some embodiments, multiple pressure waves  108  may travel along the wearable device  100  at the same time. A wearable device  100  may be configured to apply either a cranial/proximal pressure wave  108  or a caudal/distal pressure wave  108 , depending on the user&#39;s preference or therapeutic needs. In some embodiments, the direction of a pressure wave  108  can be changed between cranial/proximal and caudal/distal by changing a setting or configuration of the wearable device  100 . 
     With reference to  FIG. 3A - FIG. 3D , an example of a wearable device  300  is shown. The wearable device  300  includes an upper cuff  314  and a lower cuff  316 . The upper cuff  314  and the lower cuff  316  are adapted to releasably attach the wearable device  300  to a limb of a user  102 , such as to the calf  106 . The wearable device  300  includes a sleeve  322  that at least partially surrounds the limb of the user  102  between the upper cuff  314  and lower cuff  316 . An upper bracket  312  and lower bracket  318  are attached to the respective upper cuff  314  and lower cuff  316 . The upper bracket  312  is further coupled to an actuator  310 . The lower bracket  318  is coupled to a shaft  306  that extends between an output of the actuator  310  and the lower bracket  318 . The shaft  306  may be coupled to the output  328  of the actuator  310 . One or more cams  304  are coupled to the shaft  306 . Each of the cams  304  has a groove that receives a flexible element  302 . The flexible element  302  extends around the calf  106 , and its respective cam  304 . The flexible elements  302  may be received in or coupled to the sleeve  322 . In some embodiments, the  300  may include an actuator, shaft, and plurality of cams on opposite sides of the same limb, as shown for example in phantom lines in  FIG. 3A  [drafter is updating to show]. 
     As previously discussed, the wearable device  300  may include a portable power supply such as a battery to power the actuator  310 . In some embodiments, the wearable device  300  may be powered by a corded power supply. As shown for example in  FIG. 3B , more than one wearable device  300  may be worn on different parts of the user&#39;s limb. For example, as shown in  FIGS. 3A and 3B , one wearable device  300  may be worn on one side of a user&#39;s limb and another wearable device  300  may be worn on an opposing side of a user&#39;s limb. The use of more than one wearable device  300  may be suitable to achieve additional compression of the user&#39;s limb compared to the use of one device. 
     The upper cuff  314  and the lower cuff  316  may be releasably couplable to the limb of a user  102 . For example, the upper cuff  314  and/or lower cuff  316  may include hook and loop fasteners, elastic, buckles, clasps, or other fasteners suitable to releasably couple the wearable device  300  to the limb of a user  102 . In many embodiments, the upper cuff  314  and the lower cuff  316  may include a soft fabric layer or cover such that the wearable device  300  may be comfortably worn by the user. 
     The sleeve  322  may be formed of a thin woven or non-woven fabric material or membrane. The sleeve  322  may in many embodiments, have an elastic property such that the sleeve  322  conforms to the shape of the user&#39;s limb and may automatically adapt to many different user&#39;s with limbs of varying lengths and circumferences automatically. The sleeve  322  may include hems or other passages through which the flexible elements  302  may be received. 
     The upper bracket  312  and lower bracket  318  are adapted to receive the actuator  310  and the shaft  306 . Although the actuator  310  is shown coupled to the upper bracket  312  and the lower end of the shaft  306  coupled to the lower bracket  318 , the arrangement may be swapped in other embodiments. The upper bracket  312  and lower bracket  318  offset the shaft  306  and the cams  304  from the limb of the user  102  such that the cams  304  can be rotated around the rotational axis of the shaft  306  by the actuator  310  without interfering with the user&#39;s limb. The upper bracket  312  may have an aperture  334  formed therein and adapted to receive (such as fixedly receive) a portion of the actuator  310 . Similarly, the lower bracket  318  may have an aperture  338  formed therein and adapted to rotationally support the shaft  306  (e.g., via a bearing, bushing, or the like) with respect thereto. For example, the cap  330  may include a bearing formed therewith that enables relative rotation between the lower bracket  318  and the shaft  306 . 
     The actuator  310  is a rotary actuator suitable to rotate the shaft  306  relative to the upper bracket  312  and the lower bracket  318 . In many embodiments, the actuator  310  includes a motor  324  and a transmission  326  (such as a gear reducer) that adapts torque and/or speed of the raw output of the motor  324  to values suitable to rotate the shaft  306  and cams cam  304  with respect to the limb of the user  102 . The transmission  326  includes an output  328  that couples to the shaft  306  via a coupler  308 . In some embodiments, the actuator  310  is a pneumatic or hydraulic actuator. 
     The shaft  306  includes a long, thin body with a cross section adapted to be received in apertures aperture  332  formed in the cams  304  and/or spacers  320 . The cross section of the shaft  306  and that of the apertures  332  are such that the cams  304  and spacers  320  do not rotate with respect to the shaft  306 . Rather the shaft  306  drives rotation of the cams  304  and spacers  320 . In the embodiment shown in  FIG. 3A-3D , the shaft  306  has a square cross section. The apertures  332  are similarly square. In other embodiments, the shaft may have other cross-sections, such as round, oval, triangular, hexagonal, or may have flats or other features formed thereon and suitable to fixedly couple the cams  304  and/or spacers  320  to the shaft  306 . The cams  304 , shaft  306 , output  328 , and the spacers  320  have a common axis of rotation  344 . The cams  304  include a nose  340  and a heel  342 , as shown for example with respect to the cam  304   a . Each of the cams cam  304  may be fixed in place longitudinally along the length of the shaft  306  by an adjacent spacer  320  affixed to the shaft. In some embodiments, the spacers  320  may be optional. 
     As shown for example in  FIGS. 3A and 3B, and 3C  the cams  304  may be angularly indexed about the shaft  306  with respect to one another. For example, the nose  340  of the cam  304   a  may be oriented in 6 o&#39;clock position when viewed from above. With the shaft  306  in the same position, the cam  304   b  may be disposed in a 3 o&#39;clock position. The cam  304   c  may be disposed in a 12 o&#39;clock position. The cam  304   d  may be disposed in a 9 o&#39;clock position. The cam  304   e  may be disposed in a 6 o&#39;clock position. The cam  304   f  may be disposed in a 3 o&#39;clock position. In other examples, the cams  304  may be disposed at a number of angles with respect to one another in increments of one degree or less or up to 180 degrees. In some embodiments, the respective angles of the cams  304  with respect to one another may be automatically varied while in use such as by a variable cam device, swashplate or the like. 
     With particular reference to  FIG. 3D , certain details of the wearable device  300  are discussed. As shown for example in  FIG. 3D  with respect to the cam  304   a , the nose  340  is disposed a nose height  346  away from an axis of rotation  344  of the shaft  306  and cam  304   a . Similarly, the heel  342  is disposed a heel height  348  away from the axis of rotation  344 . Typically, the nose height  346  is greater than the heel height  348 . As shown for example with respect to the cam  304   b , the cams  304  may have a base width  350  evenly distributed about the axis of rotation  344 . The flexible elements  302  are disposed in grooves  336  formed in each of the cams  304 . As each cam rotates about the axis of rotation  344  the flexible elements  302  apply pressure to the limb of the user  102  by compressing the portion of the limb adjacent to the flexible element  302  with respect to the wearable device  300 . The flexible elements flexible element  302  may have an elastic property (e.g., may stretch along the longitudinal axis thereof) or may be relatively inelastic. An elastic flexible element  302  may apply less force to the limb than an inelastic flexible element. In some examples, a flexible element  302  may be a cord, string, cable, chain, rubber band, bungee cord, or the like. 
     The nose height  346 , heel height  348 , base width  350 , spacing and/or number of cams  304  along the shaft may be varied as desired. For example, the cam  304   a  may have a larger nose height  346  than the other cams. The cams  304   b , cam  304   d , cam  304   e , and cam  304   f  may have similar nose heights  346  and heel heights  348  as one another. The cam  304   c  may have smaller nose height  346  and heel height  348  than the other cams  304 . Different nose heights  346  and heel heights  348  may be used to apply relatively more or less pressure to the limb. For example, the cam  304   a  with its relatively large nose height  346  may apply more pressure to the limb than the other cams with smaller nose heights  346 . It may be beneficial to apply varying pressure to the limb at different points due to the tenderness of the tissue at a particular point, the size of the limb at a particular point, or the need to apply greater pressure to achieve the desired peristaltic effect. 
     By varying the nose height  346 , heel height  348 , base width  350 , spacing and/or number of cams  304  along the shaft, any number and type of pressure waves  108  may be realized. As the shaft  306  is rotated by the actuator  310 , each cam in turn reaches a point during a revolution where its nose  340  is at a furthest point from the user&#39;s limb during a revolution of the cam (bottom dead center) where the flexible element  302  is pulled against the limb by the nose  340  applying pressure to the limb, as shown for example with the cam  304   a  in  FIG. 3A . Similarly, each cam reaches a point during a revolution where its nose  340  is closest to the limb of the user  102  (top dead center) where the tension in the flexible element  302  is relatively less than at bottom dead center, thereby releasing the pressure on the limb. The angular indexing of the cams with respect to one another causes the peristaltic pressure wave  108  to move up or down the limb. The speed of the pressure wave  108  may be varied by varying the speed of the motor  324 . The direction of the pressure wave  108  may be reversed by reversing the direction of rotation of the motor  324 . 
     For example, the wearable device  300  generates a cranial/proximal pressure wave  108  when the motor  324  is rotated clockwise when viewed from above. In fact, the wearable device  300  generates two simultaneous pressure waves  108  when configured as shown with point of highest pressure of one pressure wave  108  being applied by the cam  304   a  and the point of highest pressure of the second wave being applied by the cam  304   e . Beginning as shown in  FIG. 3A , the cam  304   a  and the cam  304   e  are at bottom dead center, applying the most pressure to the limb. As the shaft  306  is rotated clockwise when viewed from above, cam  304   b , cam  304   c , and cam  304   d  each pass through their respective bottom dead center positions and apply pressure to the limb vie the respective flexible element  302   b , flexible element  302   c , and flexible element  302   d . Thus, the wearable device  300  applies one or more cranial/proximal pressure waves  108  to the limb. To apply a caudal/distal pressure wave  108 , the direction of rotation of the motor  324  may be reversed (e.g., counterclockwise when viewed from above). 
     Thus, the wearable device  300  may be easily adapted to a wide variety of body types, limbs (e.g., upper arm, lower arm, calf, foot, or thigh) and may be adapted to provide either cranial/proximal or caudal/distal peristaltic pressure waves  108 . The wearable device  300  may include features, elements, and/or benefits of any other wearable device disclosed herein. 
     In some embodiments, the wearable device  300  may include a drum with a continuous surface in place of the plurality of cams. The drum may be profiled to generate a continuously variable pressure wave  108  along the limb. 
     With respect to  FIGS. 4A and 4B , a wearable device  400  is shown. The wearable device  400  may have any or all of the benefits of other wearable devices disclosed herein. The wearable device  400  uses one or more artificial tendons  402  the wrap around the limb of the user  102 . The artificial tendons  402  are coupled to respective actuators  404  that can selectively tighten the tendon around the limb. In some embodiments, the actuator  404  is a clutch mechanism described for example in Collins et al. “Reducing the energy cost of human walking using an unpowered exoskeleton,” Nature Research Letter (2015) which is incorporated herein by reference. Similarly, to the wearable device  300 , the wearable device  400  can successively activate each actuator  404   a -actuator  404   f  to generate one or more peristaltic pressure waves  108  that travel up or down the limb of the user. The artificial tendons  402  and/or actuators  404  may be received in or coupled to a sleeve that can be easily donned and doffed by the user  102 . 
     In some embodiments, a wearable device disclosed herein may use an actuator that includes a shape memory alloy (e.g., Nitinol) that contracts or expands on heating or cooling). In some embodiments, a wearable device disclosed herein may include a hydraulically-amplified, self-healing, electrostatic actuator for example as disclosed in U.S. Pat. No. 10,995,779. 
       FIG. 5  shows an example of a timing diagram for an example wearable device of the present disclosure, such as the devices  100 ,  300 , or  400 . As shown in  FIG. 5 , any of the wearable devices disclosed herein may apply a force to the limb of a user in the range of about 0 mmHg to about 200 mmHg. In some embodiments, a wearable device disclosed herein may apply a force to a limb of a user in the range of about 0 mmHg to about 30 mmHg. The frequency of contractions may be about 20 to 60 contractions per minute. In some embodiments, the pressure induced in the limb for four cams  304   a - 304   d  is shown in  FIG. 5 . As can be seen in  FIG. 5 , the successive peaks and troughs of the pressure from the cams causes the peristaltic movement of the pressure wave  108  along the limb of a user thereby moving fluid (lymph, blood, etc.) in a desired direction (e.g., cranial/proximal or caudal/distal). 
     The calf (gastrocnemius) muscle assists with the pumping action during walking, thereby facilitating venous return, but individuals in career fields that involve prolonged standing or sitting (e.g., doctors, factory workers, office workers, etc.) are at increased risk of a condition known as venous insufficiency, in which the peripheral vascular system becomes overwhelmed by stagnant blood due to inactivation of the calf pump and inability of the passive venous system to return blood to the body&#39;s core. The wearable devices disclosed herein may be suitable to treat or prevent venous insufficiency, painful and potentially deadly thrombus, blot clots, lymphatic congestion, lymphedema, and/or adema. For example, the wearable devices, at least in applications for the leg, lower leg and/or calf area of the leg, can help to facilitate the return of blood and other bodily fluids (e.g., lymph or interstitial fluid) by applying sequential external forces that propel fluid from the lower leg back to the heart ( FIGS. 1 and 2A /B). The devices and apparatuses are configured to be used on any subject in any environment or occupational scenario where there is a need for the prevention and/or treatment of lower extremity varicose veins, thrombus, and edema, or where a massage device would prove effective. Standing on your feet or sitting for long periods of time can cause thrombus formation, lymphedema, and venous insufficiency as a result of chronic pooling of blood and/or lymph at the feet. Venous insufficiency, in turn, can lead to spider veins and, ultimately, unsightly varicose veins in the lower legs. The current practice of wearing compression socks has limited utility and effectiveness. Surgeons, physicians, nurses, technicians, and others who spend long periods of time standing are at risk of varicose veins or other serious health conditions that may arise like thrombus development or lymphedema. Additionally, spending hours at a time sitting at a desk, which is routine for many working professionals and students, can increase risk of developing venous insufficiency, thrombus or lymphedema. The devices of the present disclosure also move other bodily fluids such as interstitial and lymph fluid toward the center of the body and prevent pooling or clotting. 
     In applications such as, but not limited to, space exploration, the devices of the present application may treat or prevent orthostatic intolerance by mitigating the risk of postural hypotension (low blood pressure) upon transitioning between two environments with different gravitational forces. For example, following space travel in the weightless environment, hemodynamic changes that often arise during/after landing on another planetary surface can lead to refractory postural hypotension, or orthostatic intolerance. The wearable devices described herein may serve to address these and other, related needs. Further, the wearable devices described herein have pertinent applications in the inflight phase of space travel, during which the body is exposed to microgravity (weightlessness). Hemodynamic changes related to the cephalad fluid shifts observed in this setting may be controlled/mitigated by application of the present wearable device, but with reversal of the peristaltic pumping direction, such that dynamic pressure is applied in the caudal/distal direction. Conditions such as spaceflight-associated neuro-ocular syndrome (SANS) and other, similar physiologic effects of exposure to the spaceflight environment may be controlled and/or mitigated with the application of an embodiment of any wearable device disclosed herein. 
     Unlike existing products, e.g., compression socks/sleeves, presently disclosed apparatuses and devices do not stretch over time and wear out, and therefore provide a long-term solution. Unlike bulky sequential compression devices used in hospital settings, which are large, noisy (typically pneumatic) machines that prevent users from being ambulatory while using the sequential compression device, the wearable devices of the present disclosure can be worn by users in their normal activities (e.g., walking, sitting, running, standing, etc.) Existing devices, like sequential compression devices, do not induce peristaltic waves but rather bulk-compress a large portion or all of a limb and then release it. Furthermore, such existing devices do not circumferentially surround a limb and move fluid in a desired direction as with devices of the present disclosure. 
     Applications and Uses 
     Provided herein are wearable apparatuses and/or devices for treating venous insufficiency in a variety of settings and applications, and/or for providing massage therapy. The devices and apparatuses are configured to be used on any subject in any environment or occupational scenario where there is a need for the prevention and/or treatment of lower extremity varicose veins and edema, or where a massage device would prove effective. Standing on your feet for long periods of time can cause venous insufficiency as a result of chronic pooling of blood at the feet. This, in turn, can lead to spider veins and, ultimately, unsightly varicose veins in the lower legs. The current practice of wearing compression socks has limited utility and effectiveness. 
     By way of example and not limitation, professionals in the medical field are in need of such devices and apparatuses, particularly during a pandemic where long hours are required. Surgeons, physicians, nurses, technicians, and others who spend long periods of time standing are at risk of varicose veins. 
     Additionally, spending hours at a time sitting at a desk, which is routine for many working professionals and students, can increase risk of developing venous insufficiency. Likewise for truck drivers, transport pilots, and others who spend a lot of time sitting. 
     As another example, the disclosed devices and apparatuses can be configured for applications for bedridden/post-operative/Intensive Care Unit (ICU) patients, where venous return and blood clot prevention are critical. 
     As another example, the disclosed devices and apparatuses can be configured for use by high-performance jet pilots. The device can be configured with a specific contraction pattern that can replace the current pneumatic G-suit and help to prevent G-induced loss of consciousness on maneuvering. 
     As another example, the disclosed devices and apparatuses can be configured for applications in space flight and use by astronauts. Astronauts often suffer from the exact opposite problem from that described above: venous return is highly effective in microgravity, and both blood and extravascular fluid tend to stagnate in the head, neck, and upper torso, causing a litany of problems affecting vision, olfaction, and overall cardiopulmonary function. Such an application can help decrease the fluid shifts seen following adaptation to the spaceflight environment. More particularly, a modified version of the disclosed device and apparatus can be configured to pump in the opposite direction, toward the feet, to reduce headward fluid shifts and associated harmful physiologic processes by reversing pump direction and decreasing venous return during space flight. 
     As a final non-limiting example the disclosed devices and apparatuses can be used by athletes to reduce workout recovery time and maximize training value by enhancing post-workout blood flow, including by providing massage therapy. 
     Taken together, in some embodiments, peristaltic movement can be cranial/proximal for some applications (e.g., terrestrial/venous/lymphatic), and caudal/distal for other applications (e.g., spaceflight use). In some embodiments, the disclosed devices can be configured such that a user or practitioner can select between cranial/proximal and caudal/distal peristaltic movement. 
     In addition to treating venous insufficiency, some embodiments of the disclosed devices and apparatuses can be configured to fit the upper extremity and may provide a tremendously effective mechanism for reducing lymphedema associated arm swelling after surgical treatments for conditions such as breast cancer: by propelling lymph flow back toward the torso, lymphatic congestion can be eliminated. 
     These and other applications, as would be appreciated by one of ordinary skill in the art, are provided, particularly where there is a need to treat and/or prevent venous insufficiency, lymphedema release, blood clot relief, extravascular fluids, i.e. lymph and the like. 
     Advantages of the Presently Disclosed Apparatuses and Devices 
     The presently disclosed apparatuses and devices make up for absent gastrocnemius contraction by applying pressure in peristaltic waves to keep blood from pooling in extremities and appendages, including for example the lower legs. Unlike existing products, e.g., compression socks/sleeves, presently disclosed apparatuses and devices do not stretch over time and wear out, and therefor provide a long-term solution. Additionally, the presently disclosed apparatuses and devices are easy to use, hassle-free, and consumer friendly, even in strict environments such as medical facilities, operating rooms, etc. Moreover, the presently disclosed apparatuses and devices can in some embodiments be reasonably quiet and/or inaudible such that during use the devices do not cause a distraction or otherwise interfere with the user and others around the user. 
     It will be understood that various details of the presently disclosed subject matter may be changed without departing from the scope of the presently disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.