Patent Publication Number: US-2021186797-A1

Title: Medical pressure therapy device and components thereof

Description:
FIELD OF THE DISCLOSURE 
     The disclosure relates generally to medical devices for applying pressure therapy. 
     BACKGROUND 
     Many medical conditions can be treated with controlled application of pressure to a patient&#39;s body. Healthcare or emergency medical professionals may apply pulsating pressure to a patient&#39;s body, such as by massage, to increase blood velocity in the region where the pulsating pressure is applied or in neighboring regions. This pressure therapy can provide a number of benefits by increasing peripheral circulation and/or lymphatic circulation, promoting blood flow, effecting redistribution of blood flow and diffusion, promoting healing of tissues (e.g. wound healing and growth of new blood vessels) by increased blood flow, and increasing the flow of substances between vessels and cells through increased diffusion. 
     These effects can be employed as part of a treatment regimen for patients suffering from conditions such as open wounds, chronic ulcers, burns, skin transplants, diabetic ulcers, edema, pain, conditions caused by inactivity, spinal cord injury, lymphedema, atherosclerosis, stroke, heart attack, or cancer. 
     Pressure therapy is also often employed for treating patients suffering from overheating or overcooling, such as heat stroke or hypothermia, in combination with external heating or cooling to help rapidly regulate a patient&#39;s temperature. The pulsating pressure can increase the rate at which temperature changes to the patient&#39;s limb are transferred to the patient&#39;s core, more effectively regulating the patient&#39;s core temperature than if the patient&#39;s limb was heated or cooled without pressure treatment. 
     In other situations, it may similarly be desirable to heat or cool patients for therapeutic purposes. Such situations may be during chemotherapy, before, after or during surgical intervention and where metabolism should be reduced for example during stroke or heart arrest. In other situations, one may want to pre-warm a patient before anesthesia to prevent or reduce hypothermia. 
     In its most basic form, a trained medical professional may apply pressure therapy in the form of a manual massage, but there have been efforts to improve and automate pressure therapy with pressure therapy devices. These devices can apply more precise pressure levels than a massage and can employ both negative pressure and positive pressure against a limb during treatment. 
     However, using pressure therapy devices is relatively new in clinical practice, and beyond the general application of pressure to a portion of a limb, few refinements or advances have been identified. There remains a need for developing new features in pressure therapy devices for increasing blood flow. 
     To apply pressure to a patient&#39;s body, known pressure therapy devices typically establish a controlled pressure environment, such as a pressure chamber, around the region of the user where the pressure is to be controlled. Pressure can then be adjusted within the closed environment of the pressure chamber by the removal or addition of air to the chamber. 
     Where pulsating pressure is to be applied to a patient&#39;s leg, for example, a controlled pressure environment may be established around the patient&#39;s foot and up the calf toward the thigh. This may involve positioning the patient&#39;s leg in a pressure chamber that isolates at least a portion of the leg from the ambient environment. 
     Proper placement of the patient&#39;s limb in a pressure chamber is often difficult, as users needing medical pressure therapy often suffer from limited mobility and flexibility due to old age or other debilitating conditions as recited above. Known pressure systems are also often large and difficult to adjust, while also being complex to operate, requiring the assistance of a trained medical professional to use safely and effectively. 
     During application of negative pressure in known devices, the negative pressure environment created inside of the pressure chamber may draw the patient&#39;s limb deeper into the pressure chamber and against interior edges or surfaces of the device. This can cause pressure points on the patient&#39;s limb, potentially limiting blood circulation through the patient&#39;s limb, and causing contusions, discomfort, necrosis or creating other undesirable impacts. 
     Patients suffering from the conditions listed above also often have fragile skin, which may be damaged unless properly protected from edges and protrusions. If the patient&#39;s limb is drawn into the closed end of the pressure chamber, contact between the patient&#39;s limb and the wall of the pressure chamber may create a contact point of high pressure that can damage to fragile skin. This can impose a particular risk to patients with neuropathy and/or limited skin blood flow. 
     In other devices, a limb may be supported or protected by padding structures, which must be custom-fitted or -shaped to individual users to provide sufficient support and avoid pressure points on the limb. Individual fitting requires additional time, materials, and the assistance of trained technicians. Alternative methods in the prior art may involve constructing a pressure chamber on or to fit a limb, which is similarly expensive and difficult to construct. 
     Sealing of the pressure chamber about a patient&#39;s limb is likewise difficult due to the irregular variations in the anatomy of a user, combined with the need to have a large opening to allow insertion of legs with limited ankle mobility. Prior art methods often require resilient sealing components under high tension, which are often uncomfortable, often require assistance to apply, and may induce pressure points on the skin and be difficult for a user to adjust. 
     From the above, known negative pressure systems are not configured for use by unskilled patients, and may require special fittings, complex components and pressure generators to ensure appropriate levels of pressure are generated and released without damaging the vulnerable limb of a patient. These complex systems are often expensive to manufacture and cost prohibitive for use on a consumer scale. 
     It is a concern that the difficulty of using known pressure therapy devices may discourage patients from receiving needed treatments. There is also a concern that a pressure therapy device may be used incorrectly, with ineffective and/or potentially harmful pressure levels or limb placement, without intervention from a trained technician. 
     It is desired to provide only a few sizes of components for pressure therapy devices, minimizing the need for customization while providing increased support for a patient&#39;s limb and maximizing exposure of the limb to pressure therapy. There is a need for a medical pressure therapy device that permits simple placement and adjustment of a pressure chamber about a limb, including means of sealing and applying pressure therapy to the limb while improving the efficacy of pressure therapy actuated by the device on a limb. 
     It is further desired to provide a pressure therapy device having safety features that ensure the device is simple and safe to operate both in and out of a clinical setting, and that are capable of inexpensive production. 
     Likewise, there is a need for pressure therapy devices capable of more advanced features, that do more than simply apply a negative or positive pressure to a portion of a limb. 
     SUMMARY 
     According to the embodiments described herein, a pressure therapy device is arranged for creating pressure therapy for a user, particularly over a patient&#39;s limb. The pressure therapy device enables the application of pressure to a limb within an enclosed environment, while offering a superiorly comfortable fit, safety features, improved support and simple placement of a limb. 
     Improvements of the pressure therapy device over prior art devices and methods may include novel components comprising a pressure chamber, seals, inflatable padding, and internal positioning mechanisms for supporting a patient&#39;s limb. The pressure therapy device may further be provided with a novel pump unit and valve systems, configured to improve the safety and usability of the device. 
     Indications for the pressure therapy device may include open wounds, diabetic ulcers, conditions caused by inactivity, spinal cord injury, lymphedema, atherosclerosis, heat stroke, hypothermia, stroke, heart attack, bone fractures, inflammation, swelling, tendonitis, muscle damage, or cancer. 
     Various embodiments of the pressure therapy device provide significant improvements over known pressure therapy devices in donning and fitting processes. The donning and fitting processes may be made without measurements and catered to anatomy and physical capabilities of a user. In particular, embodiments according to the current disclosure enable a patient to perform the donning and fitting of the device without assistance. 
     The pressure therapy device is further configured to adapt to the size and shape of an individual patient without intervention from a technician or other professional, such that the device is customized for optimal fit and performance. 
     Embodiments of the disclosure may include pressure chambers with streamlined features, including a large opening and angled neck to facilitate insertion of a limb without flexion of a joint and allow a relaxed position for a limb during use. The bottom surface of the pressure chamber may be made of a molded material and be provided with a flat base with a slanted end. 
     The pressure therapy device may be arranged to be adjustable by a user in a sitting position by providing means for lifting and turning the device from a distance, increasing the ease and comfort of a user during use as compared to known devices. The pressure therapy device may be adapted to cooperate with external support features for holding or repositioning the device in a preferred position. 
     These features reduce weight, size and bulk over known pressure therapy devices and permit donning of the device without requiring excessive exertion or bending and rotation of a limb. 
     According to an embodiment of a pressure therapy device, the pressure therapy device includes a pressure chamber having a first end and a second end, and anterior and posterior exterior surfaces. The first end defines an opening configured to widen from a receiving region into a pressure region adapted for receiving and enclosing a limb. 
     Where prior art devices frequently have a distinct boot shape that narrows at an ankle or lower leg of a user, embodiments of the current disclosure may comprise an oversized opening and interior region. The opening may be configured to be a predetermined size that extends into the receiving region and forms a short “neck” before expanding into the interior of the pressure chamber, such that a limb may be passed through without rotation or bending of the limb, which is often difficult or painful for a user. The foot and lower leg of a user may be introduced through the opening and the neck of the pressure chamber at a 90° angle, without rotation or flexion of an ankle. 
     The anterior and posterior exterior surfaces of the pressure chamber may form a certain angle, such that the distance between the anterior and posterior surfaces increases towards the second end of the pressure chamber at a predetermined rate along a height of the pressure chamber. The arrangement allows the wide opening to expand into a wider area within the chamber without tight angles, particularly in the anterior surface. 
     According to an embodiment of the pressure chamber, the anterior surface may be configured to be straight and to extend at a constant angle from the neck of the opening of the pressure chamber. The straight surface advantageously allows the user to insert a foot and lower leg at a 90° angle without the toes of the user contacting the surface of the pressure chamber, which may be painful or otherwise cause difficulty in donning and doffing of the device. 
     The second end of the pressure chamber is closed by a support surface, the support surface having a flat portion and an angled portion at least at a posterior end. The angled portion and the flat portion are adapted to allow angular adjustment and stable placement of the pressure chamber both during insertion of a limb and during operation of the device. 
     When inserting or removing the limb from the pressure chamber, the angled portion may be a heel rest for stabilizing the pressure chamber in an upright position. With the pressure chamber in the upright position, the user may insert the limb without rotation or bending of the limb. The foot and the lower leg of the user may be inserted from a sitting position without rotating the ankle by only raising the leg and extending the knee. 
     Once contact is made by the limb against the lower surface of the pressure chamber, the pressure chamber may rotate forward to lie on the flat portion for a stable, comfortable and consistent treatment position. 
     The support surface may comprise friction enhancing materials on an exterior surface, such as a rubber-like material to prevent the pressure chamber from slipping while in use. 
     The exterior surfaces of the pressure chamber may also be configured to be transparent and may include indicia for proper positioning of a limb, such that a user may have a clear view of the limb as it is positioned. A clear view of the positioning of a limb is beneficial for users suffering from neuropathy, who may lack the ability to feel pressure or touch on a limb and must be able to see the limb floating freely. 
     The anterior exterior surface may include a first locking element arranged to engage an adjustment piece. The adjustment piece may extend toward the first end of the pressure chamber for manipulation by a user and may be detachably fixed to the pressure chamber at a position near the opening to increase leverage. The adjustment piece may comprise a detachable handle and would allow the user increased control of the positioning of the pressure chamber during use. 
     Embodiments of the pressure therapy device may secure and position the limb of the user within the pressure chamber using an inflatable padding and a seal positioned at the first end of the pressure chamber. The first end may include second locking elements for securing the inflatable padding through the opening and in the receiving region of the pressure chamber. 
     The second locking elements may be configured to engage receiving elements on the inflatable padding such that the proper positioning of the inflatable padding is clear and repeatable for the user. 
     The seal may be configured to surround the opening of the pressure chamber and the inflatable padding, and to engage the second locking elements with no additional belts. 
     In an embodiment the inflatable padding may engage the second locking elements on an exterior surface of the first end of the pressure chamber in a predetermined position and extend into the opening and receiving region of the pressure chamber. In an alternative embodiment the inflatable padding may engage the second locking elements on an interior surface of the first end of the pressure chamber. 
     The inflatable padding may be deflated to allow insertion of the limb of the user through the opening of the pressure chamber and may be configured to adopt a shape corresponding to the limb of the user when inflated. In doing so, the inflatable padding may further be adapted to inflate and close the opening of the pressure chamber about the limb. 
     The inflatable padding may be provided with a valve for inflating and deflating with limited intervention by a user. The valve may be a check valve, non-return valve or one-way valve adapted to inflate the inflatable padding in response to a negative pressure in the pressure chamber by drawing air from ambient surroundings into the inflatable padding, and to deflate only when the valve is opened by a user or at a predetermined interval. 
     Using the one-way valve with a negative pressure allows for an automatic inflation of the inflatable padding during operation of the pressure therapy device and has been surprisingly discovered to provide a further massaging effect on the limb of the user during therapy. The massaging effect occurs due to the inflatable padding being closed to ambient pressure, such that following a release of negative pressure in the pressure chamber an overpressure is generated within the inflatable padding. 
     Where the negative pressure draws blood into the limb of the user, the overpressure causes the inflatable padding to slightly squeeze or massage the limb of the user at the same moment as the limb of the user is released from the effects of the negative pressure in the pressure chamber, e.g. as atmospheric pressure is restored. This squeezing or massaging effect helps accelerate the blood pulled into the limb of the user by the negative pressure and increases blood flow through the limb. 
     The dual benefit of negative pressure around the limb combined with positive pressure applied by the inflatable padding is achieved simply by utilizing the existing dynamic between the negative and atmospheric pressure; that is, the introduction of negative pressure causes the inflatable padding automatically to inflate. The massaging effect is achieved without the need to generate a positive pressure in the pressure chamber and allows the pressure therapy device to apply both positive and negative pressure to the limb with no complex pumping systems. 
     The valve of the inflatable padding may be configured as a lever actuated valve opened when the seal is pulled away from a limb of a user, as a timed valve or as a manually actuated valve, such that the user may easily deflate the inflatable padding for removing the limb from the pressure chamber. 
     In an alternative embodiment, the inflatable padding may be configured to communicate with a pump unit, such as with a three-way valve. 
     The thickness of the material of the inflatable padding may be configured such that greater or lesser pressure or overpressure is applied to a limb. Where the material of the inflatable padding is thick or more resilient, the inflatable padding resists expansion, while the reverse is true of a thin or flexible material. 
     In an embodiment, the inflatable padding comprises at least two air chambers such that the limb may be appropriately positioned in the pressure chamber. Using an inflatable padding having only one air chamber fills unevenly, as the air in the padding will redistribute according to the resistance provided by the limb. Where an inflatable padding comprises only one air chamber the padding may not appropriately position the limb but may allow the limb to rest against the side or back of the pressure chamber due to the weight and position of the limb. 
     The inflatable padding may comprise a seamless material, a single mold material, or a material having multiple welds. The inflatable padding may thereby present a smooth interior surface free from protrusions or recessed areas that may cause discomfort, indentations or marks on the skin of a user. 
     The inflatable padding may be made of polyvinyl chloride (PVC) or polyurethane (PUR), and may have a flocked surface. A PUR material is advantageous due to the increased friction provided relative to a PVC or flocked material. The inflatable padding may be provided with different surface types or treatments, such as a sticky surface for better retaining the limb of a user, a smooth surface, or a padded surface for increasing comfort of a user. 
     In some configurations, the inflatable padding may have a uniform length, or may have an anterior length that is shorter than a posterior length, in order to better grip the posterior portion of a limb and to better support the limb at a resting side, for example the posterior side of a leg. The inflatable padding may also extend beyond the opening of the pressure chamber in a proximal direction in order to better grip the limb and protect the limb from the edges of the opening of the pressure chamber. 
     In one embodiment the inflatable padding may have an extension of 5 to 20 mm beyond an upper edge of the pressure chamber to protect the limb from contact with a hard edge of the pressure chamber. 
     The seal of the pressure therapy device is configured to surround the opening of the pressure chamber and the inflatable padding at the first end of the pressure chamber, such that a portion of the user&#39;s limb is enclosed therein. The seal is configured to tightly grip the limb of the user, such that the interior of the pressure chamber may be separated from ambient pressure. 
     The seal may comprise a frustoconical cuff or a cone made of an elastic material having a first and a second end. The first end of the cuff may be adapted to engage with the second locking elements at the first end of the pressure chamber and may have a decreasing diameter as it extends away from the opening to the second end of the cuff. The second end of the cuff may be positioned eccentric to the first end, having a center axis being posterior to a center axis of the first end of the cuff to naturally position the limb in the preferred position without user intervention. 
     Using the frustoconical cuff with the second end eccentric to the first end has been found to advantageously allow the seal to easily and intuitively adapt to the irregular shape of the anatomy of a user. In particular, the described shape of the seal can close small dips or grooves in the anatomy of the user, such as are common on an anterior surface of the lower leg, where the tibia may narrowly protrude from the calf. 
     The surface of the seal may be provided with friction enhancing materials or with a smooth surface for improving sealing to a limb, and to facilitate rolling back and securing the seal about the opening of the pressure chamber during insertion of a limb. The first end of the seal may further be provided with protrusions for securing the seal in an open or rolled position. 
     The seal preferably has a length sufficient to engage the patient&#39;s limb about a predetermined distance, to ensure a good seal and prevent the formation of pressure points. An exterior surface of the seal may be provided with indicia for trimming or cutting, to adjust the length of the seal or the diameter of the second end of the seal. 
     As the seal is configured to tightly grip the limb of the user, the exterior surface of the seal may be provided with a pull tab to facilitate intuitive grasping and opening of the seal by the user. 
     The seal may comprise an elastic material, and may be configured to have a variable thickness, such that the first end of the cuff is thicker than the second end. The thicker material of the first end enables a more secure attachment to the pressure chamber, while the thinner material of the second end facilitates opening and rolling back of the seal by a user. The seal may be manufactured by injection molding, where an injection point comprises the circumference of the second end of the cuff to avoid a single injection point that would be susceptible to tearing after repeated use and an uncomfortable fused seam. 
     A modular component may be added to certain embodiments of the medical pressure therapy device to enable the application of additional treatment options to the limb. Examples of a modular component that may be coupled with the pressure therapy device may include a heating or cooling unit, vibration unit, electrical stimulation unit, etc. The modular component improves the efficacy of the medical pressure therapy device in treating particular conditions, including hypothermia, heat exhaustion, etc., and may be placed in a modular space in the support surface of the pressure chamber. The modular space may be configured to receive a plurality of interchangeable modular components having different functions. 
     In an embodiment of the pressure therapy device, the exterior of the pressure chamber is provided with a stabilizing structure to hold the pressure chamber in a predetermined position, such as to facilitate a seated position for a user. The stabilizing structure may be adjustable to different lengths and may comprise at least one stabilizing piece fixed to the pressure chamber. The at least one stabilizing piece may be curved or straight, and may cooperate with an adjustment mechanism provided on the pressure chamber. 
     In other embodiments the stabilizing structure may be separate from the pressure chamber and may be configured to adjust to the position of the pressure chamber and hold the pressure chamber in place, such as with a bean bag, sling or inflated pillow. 
     The pressure chamber may include a positioning mechanism inside the pressure chamber, for indicating and supporting the proper positioning of a limb. The positioning mechanism may be configured to provide support to an arch of a foot, without contacting the heel and ball of a foot. 
     Using the positioning mechanism has been shown to increase usability of the pressure therapy device, by facilitating consistent and correct positioning of the limb within the pressure chamber, and surprisingly achieves a further massaging effect during negative pressure cycles to force blood from the vascular bed under the foot. The positioning mechanism may be configured to contact the limb of the user only at a particular point, such as in the arch of the foot, to avoid wounds commonly found on the heel or pad of the foot. 
     In an alternative embodiment, the positioning mechanism may be configured to extend from the pressure chamber in a releasable configuration, such that when contacted by the limb of the user, the mechanism is moved away from the limb to prevent the mechanism from contacting the limb after positioning the limb is complete. Using the releasable positioning mechanism allows for consistent placement of the limb, while leaving the limb hanging freely within the pressure chamber. In another embodiment the positioning mechanism may collapse in response to a negative pressure. 
     Such a free hanging configuration may be advantageous where a wound is present on the bottom of the limb of the user. 
     According to an embodiment of the pressure therapy device, the pressure chamber is connected to the pump unit for providing a non-atmospheric pressure within the pressure chamber. The pump unit may provide an alternating pressure, such that a first period of non-atmospheric pressure is followed by a second period of non-atmospheric or atmospheric pressure. Additional embodiments and description are provided in U.S. Pat. No. 7,833,179, issued Nov. 16, 2010; U.S. Pat. No. 7,833,180, issued Nov. 16, 2010; U.S. Pat. No. 8,021,314, issued Sep. 20, 2011; U.S. Pat. No. 8,361,001, issued Jan. 29, 2013; U.S. Pat. No. 8,821,422, issued Sep. 2, 2014; and U.S. Pat. No. 8,657,864, issued Feb. 25, 2014, which are incorporated herein by reference. 
     The pump unit may include a first valve system configured to operate as a one-way valve with a safety release feature. The first valve system may include a chamfered washer for closing a tube or line. The chamfered washer may comprise through holes and be placed against an elastic covering configured to fit the tube and close the through holes of the chamfered washer. 
     The chamfered washer and the elastic covering define a central opening, providing communication between a pressure region side and an atmosphere or pump side of the tube or the valve. A sealing unit, such as a ball, is configured to fit to the dimensions of the central opening and seal the first valve system closed. Due to the chamfered edge and the elastic covering the sealing unit can be engineered with a high tolerance while still preventing leaks. 
     At a predetermined pressure level, the sealing unit may be moved from the central opening to allow communication to atmospheric pressure, preventing the interior pressure from reaching unsafe levels. In the first valve system, the mass of the sealing unit and the dimensions of the central opening calibrate the first valve system to a predetermined pressure range and prevent misuse or injury from high pressures. 
     The chamfered washer may define additional openings not defined by the elastic covering. In this configuration the elastic covering acts as a one-way valve, opening the additional openings or through holes to allow air to be removed from the pressure region side during operation of the pump and sealing the negative pressure of the pressure region side when the pump is idle. The additional openings are closed by the elastic covering under a negative pressure and opening under a positive overpressure. 
     The elasticity of the elastic covering may be configured to calibrate the first valve system to a predetermined pressure range. The elastic covering may also be pre-stretched to prevent the covering from moving or stretching into the central opening or the additional holes. 
     In an embodiment the first valve system may include a leverage arm, configured to displace the sealing unit at a predetermined time or in response to a predetermined event, to control the application and release of non-atmospheric pressure. In an embodiment, the leverage arm may be adapted to displace the sealing unit upon activation of the pump unit, such that the pump unit may remove air from the pressure region side, and to release the sealing unit on deactivation of the pump unit, such that the opening is sealed. 
     The first valve system or the pressure chamber may also be provided with a permanent opening or leak valve. The leak valve is configured to provide a small opening to atmospheric pressure, such that the pressure within the chamber is slowly adjusted back to atmospheric levels when the pump unit is not operating. Using the leak valve helps prevent misuse, such as unsafe pressure levels and/or pressure levels maintained for unsafe periods of time. 
     A similar leak hole may be provided in the inflatable padding and covered with tape for sealing the hole, such that the user may remove the tape and empty the inflatable padding if the valve of the inflatable padding fails. 
     The pump unit may include a piston configured to generate a non-atmospheric pressure. The piston may include elastic extensions or wings to increase engineering tolerance and reduce friction between the piston and a cylinder. The wings may also be configured with a predetermined elasticity, such that the wings fold inwards in response to a predetermined pressure and preventing the generation of unsafe pressure levels. 
     The pressure therapy device may include a control unit, including a processor and a memory, for operating the pump unit. The control unit may include sensors provided in the pressure chamber or other components, or on the limb of the user, for monitoring and recording the results of treatment. The control unit may be programmed by the user or by a medical professional, and be provided with software for ensuring compliance with a personalized treatment regimen. 
     In an embodiment, the control unit may be configured to receive programming from a removable memory, such as a flash drive, or to receive programming or communicate wirelessly. In this way a medical professional may access and update the information stored by the control unit. 
     The pressure therapy device may be provided as a kit including a combination of a pressure chamber, inflatable padding, pump unit, control unit and/or seal. The pressure therapy device may be configured to the needs and anatomy of a particular user by a technician or by the user due to the advantageous configurations of each part. 
     A method of using the pressure therapy device may comprise inserting the limb of the user through the opening of the pressure chamber, such that the pressure chamber, the seal and the inflatable padding surround the limb. Upon insertion of the limb, the inflatable padding may be in a deflated state and the seal may be in a retracted or rolled position, such there is space for the limb to pass through the opening of the pressure chamber without rotation of the limb. 
     Inserting the limb may further include rotating the position of the pressure chamber such that the pressure chamber is in an upright position on the flat portion of the lower surface when the limb is inserted. The limb may then contact the positioning mechanism within the pressure chamber and the pressure chamber may rotate to lie on the flat portion of the lower surface. 
     The seal may then be extended or unrolled to fit against the limb of the user and cover the opening of the pressure chamber and the inflatable padding therein. 
     Upon activation of the pump unit, the pump unit draws air from the pressure chamber through a conduit in the pressure chamber. In response to the negative pressure, the inflatable padding inflates through the valve and secures the limb in the opening of the pressure chamber, away from the edges and interior surfaces of the pressure chamber. The negative pressure likewise pulls the seal against the limb of the user and separates the interior of the pressure chamber from atmospheric pressure. 
     The negative pressure is applied to the limb in a pulsating fashion, while the inflatable padding remains inflated and applies a positive massaging effect on the limb during an over pressure period. 
     These and other features, aspects, and advantages of the present disclosure will become better understood regarding the following description, appended claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a pressure therapy device. 
         FIG. 2  shows a perspective view of the pressure chamber with and without an inflatable padding. 
         FIG. 3  shows a perspective view of the pressure therapy device with a seal in an extended and retracted position. 
         FIG. 4  shows a perspective view of a pressure therapy device configured with an adjustment piece and the method of donning and doffing. 
         FIG. 5  shows a perspective view of the adjustment of a seal about a limb of a patient. 
         FIG. 6  shows a perspective view of a pressure therapy device with a stabilizing structure. 
         FIG. 7  is a plan view of a piston of a pump unit according to an embodiment. 
         FIG. 8  is a plan view of a first valve system of a pump unit. 
         FIG. 9  is a plan view of a first valve system of a pump unit having a leverage arm. 
         FIG. 10  is a perspective view of an image of a pressure therapy device with a stabilizing structure. 
         FIG. 11  shows a perspective view of a seal for use with a pressure therapy device according to the current invention. 
         FIG. 12  shows a side perspective view of the seal of  FIG. 11 . 
         FIG. 13  shows a top perspective view of the seal according to  FIG. 11 . 
         FIG. 14  shows a zoomed perspective view of at least one second locking element on an interior of the pressure chamber. 
         FIG. 15  shows a plan view of an example of holes corresponding to the at least one second locking element. 
         FIG. 16  shows a plan view of a positioning mechanism having a collapsible configuration. 
         FIG. 17  shows a perspective view of a pressure chamber having a positioning mechanism. 
         FIG. 18  shows a side perspective view of a pressure chamber having a positioning mechanism. 
         FIG. 19  shows a zoomed perspective view of a portion of a piston having an elastic wing according to another embodiment. 
         FIG. 20  shows a side-by-side plan view of a valve in an open and closed configuration. 
         FIG. 21  shows a side perspective view of a pressure chamber having a lever actuated valve mechanism. 
         FIG. 22  shows a side perspective view of a pressure chamber having a timer valve mechanism. 
         FIG. 23  is a side-by-side detail view of a timer valve mechanism including a spring and rotational damper in an actuated state. 
         FIG. 24  is a perspective view of a pressure chamber system including a plurality of components. 
         FIG. 25  is a bottom perspective view of a pressure chamber having different angled portions at a posterior and anterior side. 
         FIG. 26  is a side view of a pressure chamber moved from an upright position to lie on a lower surface by a limb of a user. 
         FIG. 27  is a perspective view of an inflatable padding. 
         FIG. 28  is a perspective view of a positioning mechanism. 
     
    
    
     The drawing figures are not drawn to scale, but instead are drawn to provide a better understanding of the components, and are not intended to be limiting in scope, but to provide exemplary illustrations. 
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     A better understanding of different embodiments of the disclosure may be had from the following description read with the accompanying drawings in which like reference characters refer to like elements. 
     While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments are in the drawings and described below. It should be understood, however, there is no intention to limit the disclosure to the specific embodiments disclosed, but on the contrary, the disclosure covers all modifications, alternative constructions, combinations, and equivalents falling within the spirit and scope of the disclosure. 
     It will be understood that, unless a term is expressly defined in this disclosure to possess a described meaning, there is no intent to limit the meaning of such term, either expressly or indirectly, beyond its plain or ordinary meaning. 
     Numerous pressure therapy device embodiments and components for use therewith are described herein, with particular focus given to devices and components directed to a limb. The limb can be any part of a human or animal body that can be easily introduced into the device. A limb can comprise an arm or leg, a portion of an arm or leg (e.g. a forearm, hand, lower leg, or foot), or more than one of such parts of the body. While the pressure therapy device is described within the context of a preferred embodiment directed to a lower leg and foot, many features described herein may be extended to pressure therapy devices and components that secure other limbs and body parts. 
     The pressure therapy device embodiments and components for use therewith may be dimensioned to accommodate different types, shapes and sizes of human joints and appendages. In addition, embodiments may be modified to orient principal forces exerted by pressure systems of the embodiments at any desirable location. Embodiments may further be modified to secure the device onto a limb at any desirable location. 
     For explanatory purposes, each pressure therapy device embodiment or component thereof described herein may be divided into sections denoted by general anatomical terms for the human body. Such anatomical terms are provided to distinguish various elements of the device embodiments from one another, but which are not to be considered to limit the scope of the disclosure. 
     Each of these terms is used in reference to a human leg, by way of example, which is divided in similar sections with a proximal-distal plane. The terms “proximal” and “distal” generally refer to locations of the device that correspond to the location of leg relative to the point of attachment of the leg to the body. The terms “upper” and “lower” may be used in combination with “proximal” and “distal” to connote gradations in location of “proximal” and “distal.” 
     The embodiments of the pressure therapy device can also be considered to fall within “anterior” and “posterior” sections of an anterior-posterior plane. The anterior-posterior plane generally corresponds to the coronal or frontal plane of a human limb which lies along the central longitudinal axis of a body. A posterior side or element is therefore behind this anterior-posterior plane, whereas an anterior side or element is in front of the anterior-posterior plane. 
     The terms “inwardly” or “inner” commonly used herein to distinguish the side of the device that may be specifically adjacent to the limb of the user of the device. Contrariwise, the term “outwardly” or “outer” are used to denote the side of the device that is opposite to the inwardly side. 
     According to the embodiments of the current disclosure, pressure therapy devices are disclosed having advantageous configurations of pressure chambers, seals, inflatable paddings, positioning mechanisms, pump units and the like. It is an advantage of these embodiments that the pressure therapy devices are easy to maneuver onto a limb, simple and safe to operate even by an untrained user, and comfortable to use while improving efficacy of pressure therapy actuated by the device. 
       FIG. 1  illustrates an embodiment of a pressure therapy device  100  having a pressure chamber  110  with first and second ends  112 ,  114  and anterior and posterior surfaces  116 ,  118 . The anterior surface  116  may be provided with a first locking element  126  and the second end  114  defines an opening  120  to a receiving region  122  inside the pressure chamber  110  that widens into a pressure region  124  in the distal direction. 
     The pressure region  124  of the pressure chamber  110  may communicate with a pump unit  190  with a conduit  188  at a posterior side  118  of the pressure chamber  110 . Embodiments of the pressure therapy device  100  are not limited to a particular location for the conduit  188 , as long as the conduit  188  is in communication with the pressure region  124 . 
     The pump unit  190  may be any suitable device for generating a non-atmospheric pressure within the pressure region  124 , such as a vacuum pump. In a preferred embodiment the pump unit  190  is provided with additional safety and efficiency features such as a piston  200  for generating non-atmospheric pressure and a first valve system  210  for opening and closing the pressure chamber  110  from communication with ambient atmospheric pressure. 
     An inflatable padding  140  secures to the opening  120  of the pressure chamber  110  and extends through the opening  120  and into the receiving region  122 . The inflatable padding  140  is secured to the pressure chamber  110  by at least one second locking element  136 , as shown in  FIGS. 2 and 14 . The at least one second locking element  136  may be provided on the interior or exterior of the pressure chamber  110  and comprises a hook or extension for passing through a corresponding hole in the inflatable padding  140 , such that the inflatable padding  140  may include an extension overlapping the exterior surfaces  116 ,  118  of the pressure chamber  110  before extending through the opening  120  and into the receiving region  122 . The at least one second locking element  136  may have a total height of 1.5 mm and include a widened top, or knob, having a height of 0.5 mm. 
     A portion of the inflatable padding  140  provided with the hole corresponding to the at least one second locking element  136  may be reinforced with an increased material thickness in order to better secure to the pressure chamber  110  and to provide an audible confirmation, or snap, indicating proper attachment. The increased material thickness may be provided by a plastic or fabric band, such as a hostaphan band  240 , fixed to or incorporated into the inflatable padding  140 . In one embodiment, the portion of the inflatable padding  140  has a thickness of 0.35 mm. The hole may be configured with a shape corresponding to the second locking elements  136 , as demonstrated by the examples in  FIG. 15 . 
     The inflatable padding  140  may comprise a stretchable or non-stretchable material such as a thin polyurethane or PVC having a thickness of under about 1 mm, and may include padded felt or a friction enhancing surface. The inflatable padding  140  may be created in a single mold or in two welds to reduce the presence of seams that may create pressure points or leave marks on the limb of the user. The inflatable padding  140  may be provided with multiple chambers, such that portions of the inflatable padding  140  inflate separately about the limb of a user. 
     In an embodiment, the inflatable padding  140  may be formed of an inner sheet and an outer sheet, such as TPU sheets, that each form a cylinder. The ends of the sheets are then welded together to form an air chamber therein. A band  240  and knobs  242  may also be incorporated or affixed thereon, as illustrated in  FIG. 27 . The band  240  and the knobs  242  allow the user to secure the inflatable padding  140  to the pressure chamber  110  only in the correct configuration, and to remove the inflatable padding  140  for cleaning or replacement. 
     In the depicted embodiment of  FIG. 1  the inflatable padding  140  is inflated to grip the limb of a user and narrow the opening  120  to sealable dimensions. The inflatable padding  140  enables the use of an exceptionally wide opening  120  and facilitates placement of limbs having different sizes without requiring excessive rotation or bending of the limb and while still enabling an effective sealing of the pressure chamber  110 . The inflatable padding  140  is configured to inflate and adjust the dimensions of the opening  120  to the anatomy of a user and compress about a limb. 
     The inflatable padding  140  may be configured to have a greater distal extension along a posterior side of the limb of a user than along an anterior side, as wounds are often more prevalent on the anterior side of the limb. The reduced distal extension on the anterior side in relation to the posterior side also allows a user to adjust the limb during treatment, increasing the comfort of a user. The distal extension is preferably limited such that the distal portion of the limb is free from contact with the inflatable padding, as wounds are often more prevalent on a distal portion of a limb (e.g. the heel and ball of a foot). This arrangement allows the inflatable padding  140  to effectively guide and support the limb of the user without putting undue pressure on sensitive or vulnerable areas. 
     In an embodiment the inflatable padding  140  may provide additional support and protection to the limb by extending beyond the pressure chamber  110  in a proximal direction up to 20 mm. The inflatable padding  140  may be configured to have a varying length, such that the distal extension of the inflatable padding  140  is shorter on an anterior side than on a posterior side, in order to better grip the back side of a limb while exposing more of the limb to the pressure within the pressure region  124 . The inflatable padding  140  may also be provided with striped friction materials in order to better grip a limb. 
     A seal  150  secures to the pressure chamber  110 , surrounding the opening  120  and extending beyond the pressure chamber  110  in a proximal direction. The seal  150  may be secured by means of the at least one second locking element  136  or with friction, such as friction against the limb. The seal  150  may be provided with a narrow opening  155  (shown in  FIG. 12 ) to assist with securing and positioning of the seal  150 . The seal  150  may comprise an elastic material with enhanced frictional properties, such that the seal  150  fits tightly about the limb of a user. 
     The seal  150  may comprise heat pressed silicone, thermoplastic elastomer (TPE), or TBE having a thickness of about 1-2 mm. The seal  150  may be configured with a material having a hardness within the range of 0-15 shore A, more preferably about 5 shore A, such that the material affixes firmly about the limb of a user without leaving indentations or marks. 
     As shown in  FIGS. 3 and 11 , the seal  150  may have a frustoconical shape including a proximal end  152  and a distal end  154 . The proximal end  152  may have a center axis that is eccentric to a center axis of the distal end  154 , such that a limb is positioned more in a posterior portion P of the opening  120 , as shown in  FIG. 12 . 
     When secured about the limb of a user, a pull tab  157  may be configured to extend along the distal length of the seal  150  to enable a user to grip and open the seal  150  about the limb. The proximal end  152  of the seal  150  may be rolled back in a distal direction to widen an opening of the seal  150  for placement or removal of a limb. Protrusions  156  may be positioned on the distal end  154  to frictionally retain the seal  150  in a rolled position such that a user does not have to hold the seal  150  back during placement of a limb. This feature enables the use of the pressure therapy device  100  by individuals that do not have sufficient strength, dexterity, or mobility to manipulate a seal while also maneuvering a limb or the pressure chamber  110 . 
     In one embodiment the seal  150  may have a variable thickness, such that the distal end  154  securing to the pressure chamber  110  has a greater thickness, for example 2 mm, than the proximal end  152 , for example 1 mm. The increased thickness of the distal end  154  ensures a more secure attachment to the pressure chamber  110 , while the reduced thickness of the proximal end  152  enables easier adjustment and positioning of the seal  150  by a user (such as by simply rolling or unrolling the seal  150 ) and greater comfort against the user&#39;s limb. 
     After placement of a limb, the seal  150  may be rolled in a proximal direction to surround a limb and seal the pressure chamber  110  from ambient pressure, as shown in FIG.  5 . The seal  150  preferably has a length sufficient to contact a limb over a predetermined length to provide a strong pressure seal. In an embodiment of the pressure therapy device  100  the seal  150  may be interchangeable with different sizes to fit the anatomy of different users or limbs. The seal  150  may be provided with trimming indicia  158 , such that the seal  150  may be cut to the dimensions of a user. 
     In an embodiment the inflatable padding  140  may provide additional support and protection to the limb by extending beyond the pressure chamber  110  in a proximal direction up to 20 mm. 
     As depicted in  FIGS. 1-2 and 6 , the pressure chamber  110  may comprise a support surface  130  at the second end  114 . The support surface  130  may comprise a flat bottom portion  132  and angled portions  134  and may be molded as a separate part fixed to the pressure chamber  110 . The flat bottom portion  132  allows the pressure chamber  110  to remain stable in a predetermined position such that a user may be seated comfortably during use of the pressure therapy device  100 . The angled portions  134  may be present at the anterior and posterior surfaces  116 ,  118  such that the pressure chamber  110  can be stably positioned in a tilted position. The angled portions  134  may be curved, such that the pressure chamber  110  may be easily rotated, or may be flat to provide stability in a predetermined position. 
     According to the embodiment of  FIG. 25 , a posterior angled portion  135  is flat while an anterior angled portion  133  is curved. 
     As shown in  FIG. 26 , the pressure chamber  110  may be positioned to rest on the posterior angled portion  135  in an upright position, where the angled portion may be used as a heel rest for stabilizing the pressure chamber in the upright position, such that a user may insert the limb into the pressure chamber without rotation or bending of the limb. The foot and the lower leg of the user may be inserted from a sitting position without rotating the ankle by only raising the leg and extending the knee. The limb may then contact the positioning mechanism  172  within the pressure chamber  110  and the pressure chamber  110  may rotate to lie on the flat portion of the lower surface  130 . 
     The support surface  130  may comprise a modular space  180  for receiving one or more modular components. In one embodiment the modular components may be interchangeable and may include a vibration component, heating component, cooling component, etc. 
     As shown in  FIG. 4 , an adjustment piece  128  may engage the first locking element  126  to allow manipulation of the pressure chamber  110  from a distance, for example from a seated position. The pressure chamber  110  may then be lifted or rotated to allow passage of a limb through the opening  120  without requiring any bending or rotation of the limb. 
     A positioning mechanism  172  may indicate to a user the correct positioning of a limb within the pressure chamber  110 , such that the limb rests comfortably without contacting walls or surfaces of the pressure chamber  110 . Together with the rolled back seal  150 , the adjustment piece  128 , a third locking element and corresponding receiving element  138 , the positioning mechanism  172  allows for easy and accurate placement of a limb within the pressure chamber  110 . 
     The positioning mechanism  172  is preferably positioned in the pressure chamber  110  such that contact is avoided with sensitive regions of the limb of a user. As shown in  FIG. 28 , the positioning mechanism  172  may be provided with receiving elements  175 , such as grooves for locking to the bottom surface  130  of the pressure chamber. The bottom surface  130  of the pressure chamber  110  may have corresponding protrusions or locking elements. In one embodiment, the positioning mechanism  172  is provided with a plurality of receiving elements  175  corresponding to a plurality of protrusions on the bottom surface  130  of the pressure chamber, such that the positioning mechanism  172  may be adjustable and may be secured to the pressure chamber in many positions. The positioning mechanism  172  may be fixed to the bottom surface  130  of the pressure chamber  110 . 
     In an embodiment, the positioning mechanism  172  may have a shape corresponding to the arch of a foot, as shown in  FIGS. 17, 18 and 28 , and may provide slight positive pressure massage to the foot which increases comfort and blood flow for a user. In one example, the medial and lateral sides of the positioning mechanism may have different heights and angles, for more comfortably securing the limb of the user in a preferred position. The positioning mechanism  172  may be provided with a hollow space, such as for adapting the flexibility of the positioning mechanism under the limb and/or for receiving a moisture removing element  174 . The moisture removing element  174  may include a silica packet, for example. 
     In an embodiment, the positioning mechanism  172  may also provide a slight pressure during negative pressure cycles to force blood from the vascular bed under the foot up towards the heart. During oscillating pressure cycles, a slight massaging effect will be experienced under the foot. 
     The positioning mechanism  172  may be configured with a predetermined shape, such as a narrow arch having a predetermined height, designed to avoid pressure under the toes, front foot and heel where ulcers often are located. Any residual suction of the limb not compensated by the inflatable padding  140  would only cause the foot to flex upward (toes upward), while the heel would move slightly downward without touching the bottom of the pressure chamber  110 . 
     To provide the described massaging effect without allowing the limb to contact the bottom of the pressure chamber  110 , a positioning mechanism  170  may comprise a slightly elastic arch, such as having a height of 7 to 10 cm. The positioning mechanism may comprise a polyurethane or other slightly elastic material that is strong enough to prevent the limb of the user from collapsing the positioning mechanism and contacting the pressure chamber, while also slightly elastic to increase the massaging effect on the limb and provide a comfortable rest. The positioning mechanism may have a hardness of 30-50 shore A, more particularly 45 shore A. 
     The positioning mechanism  172  may be retractable, such that after contact with a limb the positioning mechanism  172  collapses or is withdrawn to ensure the limb is freely positioned within the chamber, as shown in  FIG. 16 . In another embodiment, the positioning mechanism  172  may be configured to provide support to the limb of a user throughout operation of the pressure therapy device  100 . 
     Preferably, the limb may be positioned in the pressure chamber  110  without contacting the pressure chamber  110 , as shown in  FIG. 6 . The wide opening  120  and short “neck” or receiving region  122  combine to facilitate entry of the limb, such that the pressure chamber  110  may be manipulated to “thread” onto the limb of the user by advantageous use of the adjustment piece  128  and the angled portion  134  of the support surface until the limb contacts the positioning mechanism  172 . Positioning a limb in this way enables the user to position the limb without requiring significant exertion or difficulty, and ensures a greater portion of the limb is exposed to pressure therapy while preventing pressure points or skin damage. 
     In one example according to  FIG. 4 , the pressure chamber  110  may be configured to have a shape similar to a boot for receiving a foot. In contrast to a regular boot the pressure chamber  110  has streamlined features, including a wide opening, a short neck, and a sloped anterior portion. The pressure chamber  110  can be advantageously threaded over the foot of a user without flexion or rotation of an ankle or other joint, which may be difficult or painful for a user. 
     The pressure chamber  110  may be configured to be assembled or closed about a limb. While a pressure chamber  110  configured to be assembled or closed about a limb provides the same advantage of limited flexion or rotation of a limb, the implementation is more difficult and manufacturing and sealing the pressure chamber  110  are more complex. It is preferred to use a pressure chamber  110  having the preferred wide opening  120  and short receiving region  122  for insertion of a limb. 
     A stabilizing structure  170  may extend from the pressure chamber  110  to position the pressure chamber  110  and support the limb in a particular position, for example a resting position. The stabilizing structure  170  may support the limb of a user in a reclined position, to provide comfort during use or may assist the user in initial positioning of the limb within the pressure chamber  110 . Preferably, the stabilizing structure  170  is adjustable to different lengths and positions. 
     While shown in  FIGS. 6 and 10  as a single straight piece, the stabilizing structure  170  may be curved, may include multiple pieces, may be split in a fish tail configuration and may be retractable within or separable from the pressure chamber  110 . In an embodiment the stabilizing structure  170  may comprise a least one elastic bow extending from the pressure chamber  110 , and may further be adjustable to different positions or curvature. The stabilizing structure  170  facilitates use and positioning of the pressure therapy device  100  by a user, and assists in avoiding pressure points or discomfort by helping the pressure therapy device  100  to be properly supported. 
     As shown in  FIG. 24 , the pressure chamber  110  may be provided with a stabilizing structure  170 , positioning mechanism  172  and adjustment piece  128 . 
     As shown in  FIG. 1 , the pressure chamber  110  is configured such that the anterior and posterior  116 ,  118  sides of the pressure chamber  110  extend at a predetermined angle for providing a wide opening  120 . The anterior side  116  of the pressure chamber  110  may be configured to be predominantly straight, to facilitate the passage of a limb through the opening  120  and the receiving space without bending or rotating a limb. In certain embodiments, the posterior side  118  of the pressure chamber  110  may be extended beyond the extension of the anterior side  116 . 
     The pressure region of the pressure chamber  110  may communicate with a pump unit  190  with a conduit  188  at a posterior side  118  of the pressure chamber. Embodiments of the device are not limited to a particular location for the conduit  188 , as long as the conduit is in communication with the pressure region  124 . 
     As shown in  FIGS. 7 and 19 , the piston  200  of the pump unit  190  may include wings  202  for contacting a cylinder  204 . As the piston  200  is moved within the cylinder  204 , non-atmospheric pressure is generated within the pressure chamber  110 . The wings  202  reduce the friction between the piston  200  and the cylinder  204 , such that the resistance of the cylinder  204  to the movement of the piston  200  is reduced, thereby reducing the mechanical requirement for moving the piston  200  to generate non-atmospheric pressure. 
     Because the piston  200  is not in direct contact with the cylinder  204 , engineering tolerance is increased and the piston  200  and/or the cylinder may be manufactured by injection molding, which requires a slightly conical shape to allow removal of the molded part from a mold, rather than as a “perfect” cylinder shape. Sides of the molded part may have an inclination angle of 0.2 degrees, forming a slightly conical shape. 
     Prior art methods for creating a piston  200  without the described wings  202  typically require more precise components and more expensive materials, such as metals. The use of the injected molded parts according to the current disclosure allow the piston  200  and/or the cylinder  204  to be each produced as a single injection molded part, resulting in a reduction in the cost of materials and the required precision in manufacturing. This is particularly advantageous because of the cost of producing components that require precise conformity; by using wings  202 , the tolerance for components of different sizes is increased, which simplifies the costs and complications of the manufacturing process, reducing the cost of the piston  200  and cylinder  204 . 
     In an embodiment the wings  202  may comprise an elastic material to adjust to the dimensions of the piston  200  and cylinder  204 . Using elastic wings  202  allows the piston  200  to adjust to varying dimensions of the cylinder  204 . The adjustable nature of the piston  200  and elastic wings  202  allows for manufacturing low cost cylinders  204 , particularly molded cylinders where a first end of the cylinder may have a diameter that is larger than a second end. In one embodiment, the first end of the cylinder  204  may form an angle of up to three degrees with the second end. The elastic wings  202  are configured to have a length and elasticity sufficient to seal the cylinder  204  along its entire length. 
     Referring to  FIG. 8 , a first valve system  210  is depicted for opening and closing communication between the pressure region  124  and ambient atmospheric pressure. The first valve system  210  may include an enclosed passage  212  that communicates with the pressure region  124  and ambient atmospheric pressure. As depicted, the passage  212  may include an elastic covering  216  on an ambient atmospheric pressure side and a chamfered washer  214  on a pressure region side, the elastic covering  216  and the chamfered washer  214  together defining a central opening  218  wider at the chamfered washer  214  than at the elastic covering  216 . A sealing unit  220  is placed within the passage  212  on the pressure region side of the chamfered washer  214 . 
     According to an embodiment, the sealing unit  220  may include a ball having dimensions configured to close the central opening  218  by contact with the chamfered washer  214  and the elastic covering  216 . Because the elastic covering  216  contacts the sealing unit  220 , the engineering tolerance for the sealing unit  220  is increased and the sealing of the central opening  218  is improved. 
     When generating a negative pressure within the pressure region  124 , the sealing unit  220  keeps central opening  218  closed until a predetermined pressure is reached that lifts the sealing unit  220  from the central opening  218  and allows communication between the pressure region  124  and ambient atmospheric pressure. The pressure region  124  may be configured with a maximum safe pressure by adjustment of the mass of the sealing unit  220 , elasticity of the elastic covering  216 , and the dimensions of the central opening  218 . In a preferred embodiment the sealing unit  220  is removed from the central opening  218  at a pressure of 60 to 150 mmHg, more particularly 60 to 75 mmHg. 
     The chamfered washer  214  may include additional openings  215  positioned at the sides of the chamfered washer  214  to open the elastic covering  216  in response to an overpressure. The first valve system  210  operates as a safety valve. 
     The elastic covering  216  may be pre-stretched and fixed in the passage  212  by means of the chamfered washer  214  and the walls of the passage  212 . As depicted in  FIG. 8 , the elastic covering  216  is fixed in place and cannot move or be pulled through the central opening  218  in response to a negative pressure. 
     As shown in  FIG. 9 , the first valve system  210  may include a leverage arm  222  configured to displace the sealing unit  220  at a predetermined time or in response to a predetermined pressure. When the leverage arm  222  displaces the sealing unit  220  the pressure chamber  110  is in communication with ambient pressure, and the interior pressure of the pressure chamber may adjust to ambient pressure. 
     A preferred method of use for the pressure therapy device  100  is for pressure therapy to the limb of a user. Pressure therapy may include the application of a pulsating pressure or repeated, alternating introduction of two or more different pressures during consecutive time periods. In one example, a pulsating pressure can comprise the alternating introduction of an applied pressure and release of the applied pressure to return to approximately atmospheric pressure. The applied pressure can be a positive pressure or a negative pressure. In embodiments using a negative pressure, the period during which the negative pressure is introduced and is present is the negative pressure period. Likewise, in systems utilizing a positive pressure, the period during which the positive pressure is introduced and is present is the positive pressure period. In each case, the period during which the applied pressure is released, and atmospheric pressure is returned and is present is the atmospheric pressure period. 
     Embodiments discussed herein are discussed referring to a negative applied pressure. Usually negative pressure systems can be readily substituted with positive pressure systems by inverting pump and valve operations or by other adjustments apparent to one of ordinary skill in the art. One should appreciate that any discussion of negative pressure systems, unless otherwise indicated, likewise applies to positive pressure systems. In such case, the term “negative pressure” as used herein should be interchanged with the term “positive pressure” and pressure values should likewise be substituted. The disclosure should not be construed to exclude devices and methods using a positive pressure rather than a negative pressure. 
     In some embodiments, multiple, consecutive, alternating negative pressure periods and atmospheric pressure periods are applied to a limb within a pressure chamber without removing the limb from the chamber. The negative and atmospheric pressure periods can be of the same or a different duration. In some embodiments, the negative pressure periods and atmospheric pressure periods can be selected according to known methods, such as those described in commonly owned U.S. Patent Application Publication No. 2005/0027218, published Feb. 3, 2005, which is herein incorporated by reference. 
     In some embodiments the negative pressure period is between 1 second and 20 seconds in duration and the atmospheric pressure period is between 2 seconds and 15 seconds in duration. Further, in some embodiments, the negative pressure period is between 5 seconds and 15 seconds in duration and the atmospheric pressure period is between 5 seconds and 10 seconds in duration. And in some preferred embodiments, the negative pressure period is approximately 10 seconds in duration and the atmospheric pressure period is approximately 7 seconds in duration. 
     The pressure applied within the pressure chamber can be fixed or selected at the point of use. Embodiments of devices and methods according to the present disclosure provide for applying a negative pressure of −150 mmHg or less, more particularly −80 mmHg (−10.7 kPa) or less. Corresponding pressure chambers are configured to withstand negative pressures of at least −80 mmHg (−10.7 kPa), and preferably considerably more. In some embodiments, the negative pressure can be −60 mmHg (−8.0 kPa) or less. Some embodiments utilize a negative pressure of approximately −40 mmHg (−5.3 kPa). The preferred negative pressures have been selected to reduce complications that might arise from applying higher negative pressures. In some embodiments, a negative pressure has been selected to encourage local vasodilation in the surface of the limb while minimizing the risk of possible complications. Pulsating the negative pressure has been found to encourage blood flow and a pulsating negative pressure of 0 to −40 mmHg (0 to −5.3 kPa) is preferably generated in the pressure chamber. 
     According to an embodiment of the device in  FIGS. 20 and 27 , the inflatable padding  140  is configured with a valve  192  to provide communication with ambient atmospheric pressure, preferably a one-way valve or a check valve. The valve  192  may be positioned to extend through a side of the pressure chamber  110  in fixation nobs  242  surrounding openings in the inflatable seal and extending through openings in the pressure chamber  110 . 
     In such an embodiment the inflatable padding  140  is inflated by applying negative pressure within the pressure chamber  110 , and does not require the use of any additional vacuum or pressure generating mechanism. Advantageously, when the inflatable padding  140  is provided with a valve  192 , the inflatable padding  140  will inflate in response to the negative pressure and fix the limb in a predetermined position within the pressure chamber  110 . Where the inflatable padding  140  is provided with multiple chambers, each chamber is provided with a valve or a three-way valve is provided for independent inflation and deflation. 
     The leverage arm  222  may be positioned to displace the sealing unit  220  during the atmospheric pressure period and to retract during the negative pressure period. According to an embodiment of the pressure therapy device  100  the leverage arm  222  may be secured to a motor of the pump unit  190 , such that the torque of the motor moves the leverage arm  222  away from the central opening  218  when the motor is activated for driving the piston  200  and generating a non-atmospheric pressure, and displaces the sealing unit  220  only when the motor is not in use. 
     At the conclusion of a negative pressure period and during an atmospheric pressure period within the pressure chamber  110 , the inflatable padding  140  may provide an overpressure against the limb of the user. The overpressure results from the changing pressure within the pressure chamber  110  that the inflatable padding  140  cannot adjust to due to the closure of the valve  192 . The overpressure against the limb of a user may cause the application of positive pressure against the limb of a user of about 10 mmHg during the atmospheric pressure period, further increasing blood flow through the limb of the user by direct mechanical force. 
     The inflatable padding  140  may be configured with material of a greater or lesser thickness to adjust and control the magnitude of overpressure applied to the limb. The inflatable padding  140  may have a variable thickness, to distribute pressure or overpressure unevenly to the limb. A higher thickness area may be arranged to contact areas needing less pressure or compression, whereas a thinner thickness area may be arranged to contact areas needing more pressure. The thicknesses may also be arranged based on needed heat transfer characteristics or comfort needs. 
     When in use, the inflatable padding  140  is inflated during a negative pressure period and secures the limb of the user within the pressure chamber  110 . To make it possible for the user to remove the limb after use, the inflatable padding  140  is adapted to be deflated to release the pressure created during the negative pressure periods of the pressure therapy device  100 . 
     To deflate the inflatable padding  140 , and enlarge the opening  120  of the pressure chamber  110  for insertion or removal of the limb of a user, the valve  192  may comprise a lever actuated valve  194 , a timer valve  196 , or a manually actuated valve (not shown). According to  FIG. 21 , the lever actuated valve  194  may be provided on the exterior of the pressure chamber  110  such that the seal  150  in a rolled back position actuates the lever and opens the valve  192 . When the seal  150  is rolled onto the limb of a user, the valve  192  resumes a closed position, and can be inflated in response to the negative pressure. According to  FIG. 22 , a timer valve  196  may be provided on the exterior of the pressure chamber  110 , such that a user may actuate the valve by depressing a switch  198 . 
     As shown in  FIG. 23 , the switch  198  actuates the valve  192  in a depressed position but is connected to a spring  206  and a rotational damper  208 , such that the switch  198  slowly returns to its original position and closes the valve  192 . The spring  206  and the rotational damper  208  can be configured to actuate the valve  192  for a predetermined amount of time, such that the predetermined amount of time will deflate the inflatable padding  140  and remove the limb of a user. In a manually actuated valve, a button may be provided that the user may depress to actuate the valve  192 . The valve remains open only for the period that the user depresses the button. In embodiments having for example the three-way valve, the valve  192  may also be connected to the pump unit  190  for deflating the inflatable padding  140  in a rapid manner. 
     By providing a medical pressure therapy device according to the embodiments of the disclosure, the problems of pressure therapy devices being difficult to customize for individual users, limited in pressure therapy techniques, difficult to don for users of limited dexterity or strength, uncomfortable due to pressure points and contact between the pressure chamber and wounds or sores on the limb of a user, and dangerous due to the buildup of unhealthy levels or durations of non-atmospheric pressure are addressed. The pressure therapy device of the disclosure advantageously allows for a user to intuitively and accurately don the device without the aid of a clinician. The device, thanks to the operation of the seal and the inflatable pads, conforms to the user&#39;s dimensions and prevents the device from contacting wounds on the surface of the user&#39;s limb. The device further has unique valve arrangements that automatically mitigate harmful levels or durations of pressure, while providing an advantageous distribution of negative pressure about the limb and an intermittent massaging effect. 
     Case studies have been employed to demonstrate the efficacy of the pressure therapy device according to the current disclosure and have yielded positive initial outcomes. 
     In one such study, the effect of varying pressure levels on the limb of the user was analyzed by employing the pressure therapy device of the current disclosure to treat a sample population of 16 individuals suffering from peripheral arterial disease. Over 90 percent of the sample population in the study suffered from mild claudication and were categorized as stage II of the fontaine stages for chronic limb ischemia. 
     Pairwise comparisons of the impact of pressure levels −10 mmHg, −20 mmHg, −40 mmHg and −60 mmHg on flow and laser Doppler flux measurements of the leg and foot were performed, and demonstrated a statistically significant increase in flow and Doppler flux, as shown in Table I below. 
     
       
         
           
               
               
               
             
               
                 TABLE I 
               
             
            
               
                   
               
               
                   
                 Flow 
                 Laser Doppler Flux 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Sample 1 
                   
                   
                 Std. 
                   
                 Adjusted 
                   
                   
                 Std. 
                   
                 Adjusted 
               
               
                 vs 
                 Test 
                 Std. 
                 Test 
                 P- 
                 p-value 
                 Test 
                 Std. 
                 Test 
                 P- 
                 p-value 
               
               
                 Sample 2 * 
                 Statistic 
                 Error 
                 Statistic 
                 value 
                 # 
                 Statistic 
                 Error 
                 Statistic 
                 value 
                 # 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 vs −10 
                 −0.38 
                 0.56 
                 −0.67 
                 0.50 
                 1.00 
                 −0.56 
                 0.56 
                 −1.01 
                 0.31 
                 1.00 
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 0 vs −20 
                 −1.31 
                 0.56 
                 −2.35 
                 0.02 
                 0.19 
                 −1.06 
                 0.56 
                 −1.90 
                 0.06 
                 0.57 
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 0 vs −40 
                 −2.56 
                 0.56 
                 −4.58 
                 &lt;0.01 
                 &lt;0.01 
                 −2.25 
                 0.56 
                 −4.03 
                 &lt;0.01 
                 &lt;0.01 
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 0 vs −60 
                 −3.25 
                 0.56 
                 −5.81 
                 &lt;0.01 
                 &lt;0.01 
                 −2.38 
                 0.56 
                 −4.25 
                 &lt;0.01 
                 &lt;0.01 
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −10 
                 −0.94 
                 0.56 
                 −1.67 
                 0.09 
                 0.94 
                 −0.50 
                 0.56 
                 −0.89 
                 0.37 
                 1.00 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −20 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −10 
                 −2.19 
                 0.56 
                 −3.91 
                 &lt;0.01 
                 &lt;0.01 
                 −1.69 
                 0.56 
                 −3.02 
                 &lt;0.01 
                 0.03 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −40 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −10 
                 −2.88 
                 0.56 
                 −5.14 
                 &lt;0.01 
                 &lt;0.01 
                 −1,81 
                 0.56 
                 −3.24 
                 0.01 
                 0.01 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −60 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −20 
                 −1.25 
                 0.56 
                 −2.24 
                 0.03 
                 0.25 
                 −1.19 
                 0.56 
                 −2.12 
                 0.03 
                 0.34 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −40 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −20 
                 −1.94 
                 0.56 
                 −3.47 
                 &lt;0.01 
                 &lt;0.01 
                 −1.31 
                 0.56 
                 −2.35 
                 0.02 
                 0.19 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −60 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −40 
                 −0.69 
                 0.56 
                 −1.23 
                 0.22 
                 1.00 
                 −0.13 
                 0.56 
                 −0.22 
                 0.82 
                 1.00 
               
               
                 mmHg vs 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 −60 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 mmHg 
               
               
                   
               
            
           
         
       
     
     As demonstrated, embodiments of the pressure therapy device utilizing a negative pressure of approximately −40 mmHg (−5.3 kPa) shows a significant improvement in blood flow through the limb of patients suffering from peripheral arterial disease, and can thereby improve healing. 
     An additional study has reviewed the effect of the pressure therapy device of the current disclosure on individuals suffering from critical lower limb ischaemia. These individuals suffer numerous symptoms, including chronic pain and open wounds or ulcers on the lower limbs. In particular, individuals who were not suitable for or who had elected not to undergo a revascularization procedure, i.e. angioplasty, vascular bypass or other surgical intervention, were selected for treatment. 
     Initial data from the study show that chronic wounds tend to deteriorate when no revascularisation options are available with 5/7 of the original wounds in the standard care group increasing in size by an average of 275% (SD 514%) and two new wounds developing. When the pressure therapy device of the current disclosure was used, wound healing was observed in 6/9 wounds present at the start of treatment, with an average decrease in wound size of 19% (SD 78%). 
     Alongside changes in wound size, changes in the care and management of the wounds were also seen. The number times of dressing were changed per week to manage the wounds in the control group increased from 1.67 to 3.67 on average, while a reduction from 2.75 to 1.75 times per week was observed in the group treated with the pressure therapy device of the current disclosure. As each wound dressing requires both a physical cost per dressing and a specialist vascular nurse or podiatrist to assist this indicates a potential cost saving advantage for the pressure therapy device of the current disclosure over prior art methods. 
     Foot pain was recorded for participants on a Visual Analogue Scale in which 0 represents no pain and 100 represents the worst pain imaginable. Foot pain increased slightly in the control group from 46 to 58 but was shown to decrease in the group treated with the pressure therapy device of the current disclosure from 48.75 to 45.25. Pain management with medication was also shown to differ between the two groups with a reduction of opioid pain medication in the treatment group versus the control group. 
     The case studies above clearly demonstrate the advantages of treatment using the pressure therapy device of the current disclosure, including increased wound healing, reduction in treatment costs, decrease in pain, and a decrease in the need for opioid use. No similar advantages appear to have been accomplished in the prior art. 
     As is readily apparent from the foregoing discussion, it is understood that the size, number, configuration and location of the medical pressure therapy device and the components thereof can be adjusted so many different users having different sized joints and body parts may benefit from the present design with no custom manufacturing and design. It is also understood that the arrangement of the inflatable pads, seals, positioning mechanisms, and other components can be alternated from those shown, as advantageous for users of different dimensions and pathologies. 
     It is to be understood that not necessarily all objects or advantages may be achieved under any embodiment of the disclosure. Those skilled in the art will recognize that the embodiments may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as taught or suggested herein. 
     The skilled artisan will recognize the interchangeability of various disclosed features. Besides the variations described herein, other known equivalents for each feature can be mixed and matched by one of ordinary skill in this art to construct an orthopedic device under principles of the present disclosure. 
     Although the medical pressure therapy device is disclosed in certain exemplary embodiments and examples, it therefore will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the pressure therapy device and obvious modifications and equivalents thereof. It is intended that the present medical pressure therapy device herein disclosed should not be limited by the disclosed embodiments described above.