Compression device, system and method of use

Apparatus and methods for cyclically compressing the limb of a patient to improve blood flow in the limb. In one embodiment, a compression device includes a compressive section sized and shaped for extending around a portion of the limb for applying compressive pressure and a housing operatively connected to the compressive section. The housing includes first and second housing members movable relative to each other between contracted and expanded positions. A non-pneumatic mechanical actuator is provided in the housing for cyclically moving the first and second housing members from their contracted position to their expanded position.

BACKGROUND OF THE INVENTION

This invention relates generally to compression therapy, and more particularly to devices which enhance blood flow to avoid circulation problems, such as deep vein thrombosis (DVT).

Cyclical compression of a body part (e.g., leg) is beneficial to a person who has a blood circulation problem involving poor venous return to the heart. Many devices on the market and in the prior art provide compression by using one or more pneumatic bladders that encircle the leg or other limb(s). The bladders are inflated in a predetermined sequence and to a prescribed pressure at timed intervals. The device that controls the inflation typically employs an air pump or compressor and a number of valves that operate to direct the flow of air to the bladders. Conventional products use a bladder-filled sleeve wrapped around the limb and a tube that connects the bladder(s) to a controller device that resides separately from the patient such as on the footboard of a bed, on the floor, or on a night stand. If the patient must move, the device must be removed. In addition, while the device is on the patient, it is possible that tubes become entangled in the patient's limbs and/or become a nuisance or safety hazard to caregivers and visitors who may be close to the bed.

There is a need, therefore, for an improved compression device.

SUMMARY OF THE INVENTION

In general, a compression device of this invention is used for cyclically compressing the limb of a patient to improve blood flow in the limb. The compression device comprises a compressive section sized and shaped for extending generally circumferentially around a portion of the limb for applying compressive pressure to the limb portion, and a housing operatively connected to the compressive section. The housing includes first and second housing members movable relative to each other between a contracted position in which the housing has a first dimension for relaxing pressure on the limb portion, and an expanded position in which the housing has a second dimension greater than the first dimension for compressing the limb portion. A non-pneumatic mechanical actuator is provided in the housing for cyclically moving the first and second housing members from their contracted position to their expanded position.

In another aspect, this invention is directed to a compression system which includes at least two of the compression devices described above and, in addition, a single integrated control system for controlling the operation of the at least two compressive devices.

In still another aspect, this invention is directed to a method of using a compression device to cyclically compress the limb of a patient to improve blood flow in the limb. The compression device comprises a compressive section sized and shaped for extending generally circumferentially around a portion of the limb for applying compressive pressure to the limb portion, and a housing operatively connected to the compressive section. The housing includes first and second housing members movable relative to each other between a contracted position in which the housing has a first dimension and an expanded position in which the housing has a second dimension greater than the first dimension. The method comprises the steps of first applying the compression device to a limb of a patient such that the compressive section extends circumferentially around a portion of the limb, and then cyclically activating a non-pneumatic mechanical actuator located inside the housing to move the housing members from their contracted position to their expanded position in a series of cycles to cyclically compress the limb.

In another aspect, this invention is directed to a method of using a compression system to cyclically compress portions of a limb of a patient to improve blood flow in the limb. The compression system comprises a compressive unit having zones corresponding to different portions of a limb, and at least two modules each comprising a housing including first and second housing members movable relative to each other between a contracted position in which the housing has a first dimension and an expanded position in which the housing has a second dimension greater than the first dimension. The method comprises the steps of applying the compressive unit to a limb such that the compressive unit extends circumferentially around the limb and the zones of the unit correspond with the limb portions to be cyclically compressed, and operatively connecting the modules to the compressive unit such that the modules are positioned in respective zones of the compressive unit. The housing members are then caused to move cyclically between their expanded and retracted positions for cyclically compressing the limb portions.

In another aspect, a compression device of this invention comprises a compressive section sized and shaped for extending generally circumferentially around a portion of the limb for applying compressive pressure to the limb portion, and a module operatively connected to the compressive section for cyclic expansion and contraction in generally radial directions with respect to the limb portion between a contracted condition in which the module has a first dimension for relaxing pressure on the limb portion, and an expanded condition in which the module has a second dimension greater than the first dimension for compressing the limb portion. The module comprises the combination of at least one pneumatic bladder and at least one non-pneumatic mechanical device. The at least one non-pneumatic mechanical device is operable to apply a force in a generally radial direction with respect to the limb portion for moving the module toward its expanded condition.

In another aspect, this invention is directed to a disposable band for use in a compression therapy to improve blood flow in the limb of a patient. The band comprises a band member adapted to extend circumferentially around a portion of the limb. The band member has opposite ends. A fastening device is provided on the band member for releasable attachment of opposite ends of the band member to secure the band member around the limb portion. A pocket on the band member is sized and shaped for receiving a module cyclically movable between a contracted condition in which the module has a first dimension for relaxing pressure on the limb portion and an expanded position in which the module has a second dimension greater than the first dimension for compressing the limb portion. The module is removable from the pocket whereby on termination of the compression therapy the band can be disposed and the module re-used with a different disposable band.

Corresponding parts are indicated by corresponding reference numbers throughout the several views of the drawing.

DETAILED DESCRIPTION

Referring now toFIGS. 1-3, one embodiment of a compression device of this invention is designated in its entirety by the reference numeral1. As will be explained in detail hereinafter, the device is used for cyclically compressing the limb of a patient to improve blood flow in the limb. By way of example, the limb may be a leg, foot or arm generically indicated at3inFIGS. 1 and 2. In general, the compression device comprises a compressive section, generally designated5, sized and shaped for extending generally circumferentially around a portion of the limb3for applying compressive pressure to the limb portion, the limb and limb portion both being numbered3in the figures. The compression device1also includes a housing, generally designated9, operatively connected to the compressive section5. The housing9includes first and second housing members indicated at15and17, respectively, movable relative to each other between a contracted position in which the housing has a first dimension D1(FIG. 6) for relaxing pressure on the limb portion, and an expanded position in which the housing has a second dimension D2(FIG. 7) greater than D1for compressing the limb portion. An actuator, generally indicated at21inFIG. 4, is provided in the housing9for cyclically moving the first and second housing members between their contracted (FIG. 1) and expanded (FIG. 2) positions.

In one embodiment (seeFIGS. 1 and 2), the compressive section5comprises a generally annular band27which encircles the limb3. The band material is preferably soft and non-abrasive to the skin and may include a slipping, non-compliant material at the interface of the band and the patient. Desirably, the material is breathable and may have hydrophilic properties that help to improve patient comfort by creating a dry condition at the skin. (A dry skin condition tends to minimize chafing and abrasion, since the material is less likely to stick to the skin.) By way of example, the band27may be of a non-woven PVC material which is substantially non-stretchable. As shown inFIGS. 1 and 2the band27comprises a band member (also designated27) having opposite ends releasably secured together by means of a fastening device31(e.g., mating hooks and loops, releasable adhesives, snaps, buttons or other mechanisms) to provide circumferential adjustment to enable the band to fit limbs of different sizes. The band member27comprises a single elongate piece of material. Alternatively, the band member27can be formed in multiple pieces. For example, the band member27can comprise a first piece releasably attached to one side of the second housing member17and a second piece releasably attached to an opposite side of the second housing member17. Also, the band member27can be of varying length and width to accommodate limbs of differing sizes and shapes. During use, one compression device1can have a thinner and shorter band member27to fit around the calf, while a second compression device can have a wider and longer band member27to fit around the thigh.

In the illustrated embodiment (FIGS. 1 and 2), the band27includes an interior layer35of material secured to the exterior layer of the band to form an interior pocket39which is sized and shaped for removably receiving the housing9containing the actuator21. The pocket has at least one open end for insertion of the housing into the pocket. A releasable closure such as a closure flap (not shown) can be provided for closing the open end of the pocket39to secure the housing in the pocket until such time as access is needed or desired. The housing9may be releasably secured in place in the pocket39by other means or combinations of means. For example, in one embodiment, an attaching member (not shown) is secured to an inside surface of the pocket39. The attaching member and housing9have mating detent components that securely, but releasably hold the housing in place. In another embodiment, mating hook and loop fasteners on the housing9and on an interior surface of the pocket39or pocket closure (if used) can be used to releasably secure the housing9in the pocket. In yet another embodiment, the housing9is snuggly fitted between semi-rigid holders secured within the pocket, creating a slip fit or interference fit. A release latch can be used to hold the housing9in place for additional sturdiness. After use of the compression device1, the housing9may be removed from the pocket39for re-use with a different (fresh) band. Typically, the band27is discarded after a single use.

A force-distributing device (generally designated45) is interposed between the housing9and the limb3for distributing compressive forces applied by the device1more evenly across the limb. As shown inFIGS. 1 and 2, this device45comprises a cushion49received in the pocket39, the pocket being sized and shaped to hold both the housing9and the device45at a location between the housing9and the limb3of the patient. In the embodiment shown inFIGS. 1 and 2, the cushion49comprises an extruded body of soft resilient rubber-like material having open cells separated by flexible walls51which absorb the compressive forces and distribute them more uniformly over the limb3. The cushion49has an upper surface55which conforms to the bottom (base member15) of the housing9and which extends up on opposite sides of the housing to cradle it, and a lower surface57which is adapted to conform to the convex shape of a limb and which has rounded corner edges to minimize any pinching or abrasion of the skin. In another embodiment, the cushion49comprises a sealed bladder filled with air or other suitable gas. (Various bladder embodiments are described later in this specification.) In yet another embodiment (not shown), the cushion comprises a substantially solid body formed from a pliant gel-like material. Regardless of form, the force-distributing device45may be attached (e.g., adhered or otherwise fastened) to the housing9, or it may be unattached to the housing.

In some embodiments, the compression device may be used without a force-distributing device (e.g., device45). In these embodiments, the pocket39is preferably of a smaller size.

As illustrated inFIGS. 3,4,6and7, the first housing member15comprises a base member (also designated15) having a bottom wall61, opposite upstanding side walls63and opposite upstanding end walls65. In the embodiment shown, the base member15is substantially rectangular, but other shapes can be used without departing from the scope of this invention. The interior space defined by the base member15is divided by a partition67into a first section or compartment69containing the actuator21and a second section or compartment71containing components for controlling the operation of the compression device (more on this later).

The second housing member17comprises a cover member (also designated17) having a substantially planar top wall77generally parallel to the bottom wall61of the base member15, opposite side walls81curving down from the top wall, and opposite end walls83extending down from the top wall. The top, side and end walls of the cover member17may have other shapes.

The base and cover housing members15,17are fabricated from a suitable material, such as a flexible plastic or a rigid plastic having an outer coating of a more resilient material (e.g., an over-molded spongy or rubbery material). The parts may be molded as one-piece parts having a relatively thin-wall construction to reduce expense and weight.

The base and cover members15,17of the housing are adapted to be moved by the actuator21from their stated contracted position to their stated expanded position. In a contracted position, the cover member17is spaced relatively close to the base member15and, in one embodiment, the bottom rim87of the cover member mates with the top rim89of the base member. In its contracted position (FIG. 6), the housing9has the aforesaid dimension D1which is shown as representing the overall height of the housing in its contracted state. In expanded position (FIG. 7), the cover member17of the housing is spaced farther away from the base member15so that the housing has the aforesaid dimension D2representing an increased overall height of the housing (FIG. 2). The specific way in which the housing members15,17are arranged or fit together can vary without departing from the scope of this invention. For example, rather then having abutting rims87,89, the base and cover members15,17may have side walls which telescope relative to one another to provide the necessary dimensional change.

Referring toFIGS. 4,5A and5B, it will be observed that the base and cover members15,17of the housing9are guided between their contracted and expanded positions by a number of pins95extending down from the rim87of the cover member through guide holes99in the rim89of the base member. (Alternatively, the guide pins can extend up from the base member15through holes in the rim87of the cover member17.) The base and cover members15,17are urged toward their contracted position by springs103surrounding the pins99, each spring reacting at one end against the underside of the rim89of the base member15and at its other end against a stop105on the pin. Other guide and/or spring arrangements can be used. In some embodiments, the springs103are eliminated entirely, since the base and cover members15,17of the housing will move back toward their contracted position automatically as the actuator21moves back to a position corresponding to the contracted position of the housing.

Referring toFIG. 4, the actuator21is shown to be a mechanical actuator contained entirely within the housing9, i.e., within the space defined by the opposing housing members15,17. The actuator21of this particular embodiment is a non-pneumatic actuator, i.e., it does not include any components requiring the use of pressurized air or gas for operation. As illustrated inFIG. 4, the actuator21includes a pair of cam shafts115having cams121mounted at one end thereof, a prime mover comprising a reversible electric motor125(e.g., a small DC motor) having an output shaft127, and a gear train, generally designated131, connecting the output shaft of the motor to the two cam shafts. As shown best inFIGS. 6 and 7, the gear train131comprises a pair of cam gears135rigidly affixed to respective cams121, a directional gear141in mesh with one of the two cam gears135, and a pinion gear145on the output shaft127of the motor125in mesh with the directional gear141and the other of the two cam gears135. Two additional cams121are mounted on the opposite ends of the cam shafts115, such that there are a total of four cams located for engaging the cover member17of the housing9at intervals spaced around the cover member to more evenly distribute the force applied by the actuator21over a greater area of the cover member. The number of cams121used can vary, four being shown for purposes of illustration only. The gears and cams are preferably (but not necessarily) of a suitable plastic for quiet operation.

The arrangement shown inFIG. 4is such that rotation of the motor output shaft127causes the two cam shafts115to rotate in opposite directions. The two cams121on each cam shaft115are shaped and contoured for contact with the bottom surfaces of the curved side walls81of the cover member17(or other downwardly facing surfaces of the cover member) such that rotation of the motor output shaft127in one direction causes the cams121to rotate, e.g., through a partial revolution, to increase the separation between the two housing members15,17against the urging of the springs103to expand the overall dimension of the housing9from D1(FIG. 6) to the larger dimension indicated at D2inFIG. 7. To contract the housing members15,17, the motor125rotates the output shaft127in the reverse (opposite) direction to move the cams121back to their initial (FIG. 6) position. This allows the two housing members to move back toward one another to contract the overall dimension of the housing9from D2to D1. The magnitudes of the distances D1and D2will vary depending on a variety of factors, such as the size and configuration of the base and cover members15,17of the housing, and the “throw” of the cams121as determined by the contour of their cam surfaces and the extent of rotary movement of the cam shafts115. In general, however, the system should be configured such that the housing members15,17expand a distance sufficient to apply the necessary compression to a limb and contract a distance sufficient to relieve such compression.

It will be understood that the actuator21described above is only exemplary and that other actuators can be used for effecting relative movement between the housing members without departing from the scope of this invention. Preferably, the actuator is non-pneumatic so that the compression device is entirely self-contained, i.e., all components for effecting cyclic compression are contained in a single garment which can be applied and removed as a unit from the patient. It is also preferred that the actuator be operable to rapidly expand and contract the housing9in an energy efficient manner.

The compression device1further comprises a control system, generally designated201(seeFIGS. 4 and 4A), for controlling the operation of the device, including an on-off switch205positioned on the base member15of the housing9for convenient access and suitable electronics211located in the second compartment71of the base member15for controlling operation of the motor125. A power source comprising a battery221is also located in the second compartment71for supplying power to the motor125and other electrical components. The battery221can be an off-the-shelf item or custom designed, and it can be disposable or rechargeable. A battery charge indicator225is provided on the base member15of the housing9for indicating the remaining charge (useful life) of the battery221.

FIG. 4Aillustrates the control system201according to an embodiment of the invention. It will be understood that control system201is merely exemplary and that other control circuitry known to those skilled in the art can be used for controlling operation of device1generally and effectuating control of motor125particularly. The control system201desirably includes one or more devices227for indicating (either directly or indirectly) the pressure exerted by the compression device1on the limb3of a patient.

In one embodiment, this indicating device227senses a characteristic indicative of the actual pressure applied to the limb. By way of example, the device227may comprise a suitable circuit for monitoring the amount of current and/or voltage to the electric motor125, which amount is proportional to the actual pressure applied to the limb. Alternatively, the pressure-indicating device may comprise one or more pressure sensors for sensing the pressure in one or more chambers in the cushion49(if a sealed bladder-like cushion is used), the sensed pressure being proportional to the actual pressure applied to the limb. In still another embodiment, the pressure-indicating device227may comprise one or more strain gauges on the band27, the tension in the band being indicative of the actual pressure on the limb. Other devices for indicating the pressure applied to the limb may be used.

Preferably, the control system201also includes a visual indicator231for indicating the operational status of the compression device1. Although various types of visual indicators are contemplated,FIG. 4illustrates an example comprising an array of tri-color lamps235(LED's). The array indicates, among other things, the ON/OFF status of the compression device1, the status of any ongoing adjustment to a system setting (e.g., a pressure setting), the readiness of the actuator21to begin cycling, the status of communication with other compression devices which may be in use (described in more detail later), and an alarm condition. For example, one lamp on (amber) may indicate that the power is on and that one or more setting adjustments are in progress. Two lights on (green) may indicate that the power is on and that all setting adjustments are complete. Three lights on (all green) may indicate that all adjustments are complete and that the compression device is successfully communicating with other compression devices of the system. Three lights on (all red) may indicate an alarm condition. This protocol may vary within the scope of this invention.

Referring again toFIG. 4A, control system201further comprises a central processing unit (CPU)237, such as a microprocessor or the like for executing computer-implemented instructions in the form of software237aand/or firmware237b. In one embodiment, the CPU237provides control signals to operate the actuator21of compression device1and to carry out a desired compression treatment regimen (as discussed below). The control signals from CPU237may provide distinct compression regimens, depending on the location of compression device1on the patient's limb3(e.g., attached to the calf at position B or the thigh at position C inFIG. 9). As shown inFIG. 4A, control system201communicates with its power source (e.g., battery221) and visual indicator231via interconnection electronics239. The interconnection electronics239send control signals from CPU237to the compression device's prime mover (e.g., motor125) over, for example, electrical or fiber optic lines. In addition, CPU237receives information from pressure-indicating devices227via interconnection electronics239over the same or similar lines. Advantageously, the electronics211of control system201also communicate with sensing elements409(FIG. 11), one or more other compression devices (e.g., modules321inFIG. 9), external communications sources (e.g., RF or IR communications), and the like via electronics239.

Those skilled in the art are familiar with executing software237aand/or firmware237bby CPU237to perform a number of operations, including but not limited to: controlling the operation of motor125, including its output shaft127; communicating with pressure sensing devices227; controlling charge indicator225and/or visual indicator231; communicating with charge indicator225; operating actuator21; and sensing the voltage or current to the motor125to indicate a relaxed state of the device1. As known in the art, a processor such as CPU237may further execute computer-implemented instructions in the form of software237aand/or firmware237bto control voltage or speed of motor125to rotate its output shaft127for increasing the throw of the cams121, thereby increasing D2to increase the pressure during a compression therapy regimen. Once activated, CPU237determines the treatment regimen and begins treating, as described above, by rotating motor125, which in turns adjusts the throw of the cams121for the correct pressure at the device based on its position on the limb (e.g., higher pressure may be desired on the ankle compared to the thigh).

A typical use of the compression device1can be described as follows. Initially, the contracted housing9and force-distributing device45(if used) are inserted in the pocket39of the band27. The band is then applied to a portion of a limb3to be treated, as illustrated for example inFIG. 8. As initially applied, the band27should be in a relatively relaxed state or condition applying little if any compressive force to the limb. After all setting adjustments have been made and the compression device is ready for operation, as indicated by the lamp array235, the control system201operates the actuator21to expand and contract the housing members15,17through a series of cycles, each cycle comprising a compress stage followed by a relax stage.

During the compress stage, the electric motor125is energized to rotate the cam shafts115in a first direction, which causes the two housing members15,17to move away from one another, thereby increasing the overall dimension of the housing from D1. As the housing9expands, the cover member17exerts a force in a direction away from the limb3to tension the band27and the base member15exerts a force in the opposite direction toward the leg. As a result of these forces (indicated at251inFIG. 8), the limb is compressed. The force-distributing device45functions to distribute the compressive pressure more uniformly across the limb. As the cam shafts115continue to rotate, the pressure applied to the limb3increases. To prevent over-pressurization, the control system201monitors the amount of applied pressure, as indicated for example by the amount of current and/or voltage supplied to the electric motor125. When a predetermined compressive pressure is reached, the control system de-energizes the motor to stop further rotation of the cam shafts. During this compression stage, the overall dimension of the housing increases from D1to D2.

After a predetermined compressive pressure is applied to the limb3for a duration of time (compress interval), the control system201operates the motor125to rotate the cam shafts115and cams121thereon in the opposite direction to contract the housing members15,17and thus reduce the overall housing dimension from D2back to D1to relax the pressure on the limb. The relax pressure may range from zero to some pressure greater than zero but less than the compression pressure, as sensed by the current and/or voltage to the motor125or by some other suitable means. The relax pressure (if any) is maintained for a period of time (relax interval) sufficient to allow blood to return to the limb. The length of this time period may be fixed (e.g., sixty seconds) or it may vary depending on when a vascular refill condition is detected. In this regard, there is typically some increase in the circumferential size of the limb as blood returns to the compressed portion of the limb. This increase in size can be used to trigger the start of a new cycle. In one embodiment, the pressure sensing device of the control system201is used to detect the increase in limb size. For additional details regarding detection of a vascular refill condition, reference may be made to U.S. Pat. No. 6,231,532, assigned to Tyco Healthcare Group LP. This patent is incorporated herein by reference for all purposes not inconsistent with this disclosure.

The cycling continues as described above until the motor is de-energized automatically by the control system201or manually by actuating the power switch205. After use, the housing9is removed from the pocket39of the band27for re-use with a fresh band.

During operation of the device1, particularly during initial start-up, the compressive pressure applied by the device may need to be adjusted. The control system201can make any necessary adjustment by varying the “throw” of the cams121until the pressure sensing device of the control system201indicates that the desired compressive pressure is being applied. Thus, to increase the pressure, the control system201simply operates the motor125to rotate its output shaft127through a greater number of degrees to increase the throw of the cams121and thus increase dimension D2of the housing9. To decrease the compressive pressure, the control system201operates the motor125to rotate its output shaft127through a shorter segment of rotation, thereby decreasing the throw of the cams121to decrease dimension D2.

As illustrated inFIG. 9, two or more compression devices (e.g.,1A,1B and1C) can be used simultaneously on the limb or limbs of a patient. By way of example, as will be understood by those skilled in this field, a plurality of compression devices1can be used on the same limb to cyclically compress different portions of the limb in a sequential manner. Alternatively, the compression devices can be applied to different limbs for compressing the limbs alternately or concurrently or in some other synchronized manner. The compression devices1A,1B and1C may operate completely independent of one another, or they may be under the control of a single integrated control system. If an integrated control system is used, it may be similar to the control system201described above for a single compression device but modified to include wireless (e.g., RF) transmitters and receivers and/or other components enabling communication between the multiple compression devices.

In the example ofFIG. 9, a first compression device1A is secured around the ankle for applying a first compressive pressure (e.g., 45 mmHg); a second compression device1B is secured around the calf for applying a second compressive pressure (e.g., 40 mmHg); and a third compression device1C is secured around the lower thigh of a patient for applying a third compressive pressure (e.g., 30 mmHg). The devices1A,1B, and1C can be physically interconnected, color-coded, or otherwise identified to indicate where they are to be placed and/or the different compressive pressures they will apply. The integrated control system operates the devices sequentially through a series of cycles, each of which includes a compress stage followed by a relax stage.

During the compress stage of an exemplary cycle, expansion of the ankle compression device1A is started at time T1=0 seconds, for example, to apply the first compressive pressure; expansion of the calf compression device1B is started at time T2=2.5 seconds, for example, to apply the second compressive pressure; and expansion of the thigh compression device1C is started at time T3=5.5 seconds, for example, to apply the third compressive pressure. Each compression device continues to expand until the proper pressure is reached, as sensed by the sensing device incorporated into the control system201of the compression device. Further expansion of the compression device is then stopped. There may be some overlap of the times during which the compression devices expand, but in general the compression applied by the devices should occur in a progressive manner to move the blood in the limb in a direction toward the heart.

After the compress stage has ended (e.g., at a cycle time of T4=11 seconds), any further expansion of the compression devices1A,1B,1C is stopped, and the devices are contracted simultaneously to relax or release the pressure on respective portions of the limb. The relax stage preferably continues for an interval of time sufficient to allow blood to return to the limb, as discussed above. A new cycle begins after the relax stage of the previous cycle has ended (e.g., at time T5=71 seconds). The cycles continue to repeat until the compression devices are shut off, which may occur automatically via the control system or by manual operation.

FIG. 10shows another embodiment of a compression system of this invention, generally indicated at301. The system includes two or more compression devices, three such devices303,305,307being illustrated. The compression devices are similar to the compression device1described above except that the compressive sections are integrated into a single compressive unit309sized and shaped for extending generally circumferentially around a limb such as a leg. As used herein, the term “integrated” means any configuration where the compressive sections are physically connected to one another. By way of example, the unit309may comprise an elongate panel sized to encircle the limb and to be releasably secured in place by an appropriate number of fasteners along adjacent edges of the panel to form a sleeve around the limb. The compressive unit309may have other configurations. Pockets315are provided on the unit309for removably receiving respective “modules”321of the compression devices303,305,307. Each such module321includes a housing9, an actuator21and, preferably, a force-distributing device45, the construction and operation of which are described above. These modules321operate to apply compressive pressure to different portions of the limb. The modules321may be removably attached or otherwise removably connected to the unit309by means other than pockets.

In use, the compressive unit309is applied to the limb and the modules321are operatively connected to the unit, as by placing the modules in respective pockets of the unit. The modules are then operated to compress respective portions of the limb in a sequential manner, i.e., in a direction toward the heart. This direction is important so as not to cause injury to the patient. After the treatment has ended, the modules321are removed from respective compressive sections of the unit309. The unit309is then typically discarded. The modules can be re-used with a different unit309holding multiple modules, or with one or more bands each holding only one module. Because the modules321can be positioned at different locations with respect to a limb during re-use, it is desirable to have an integrated control system which senses the location of the modules with respect to the limb, and which coordinates the operation of the modules after they have been placed in position so that proper sequential and gradient compression of the limb is achieved. Preferably, the coordination of these modules should not interfere with the operation of other modules applied to a different limb of the same patient or with the operation of other modules on a limb or limbs or a different patient.

FIG. 11illustrates an exemplary integrated control system, generally designated401, for controlling the operation of two or more modules321when they are placed on the compressive unit309. In this embodiment, the compressive unit309has three compressive sections or zones CZ1, CZ2and CZ3corresponding to different locations on the limb (e.g., ankle, calf and lower thigh), but it will be understood that the number of zones can vary. Each zone comprises a module sensing area405at a location where a module321is to be placed on the unit309. This location may correspond to the location of a pocket (e.g., like pocket39) or other means for operatively and removably connecting the module to the unit309. The integrated control system401comprises location sensing devices on the unit309and on the modules321(FIG. 10), for sensing the zone (e.g., CZ1, CZ2or CZ3) in which each module is located when the modules are positioned on the compressive unit309. In one embodiment, these location sensing devices comprise small sensing elements409in the module sensing areas405and cooperating sensing elements (not shown) on the modules321. By way of example, these sensing elements409can be magnetic elements secured to the unit309for actuating magnet sensing elements on the modules to open or close circuits of the control system401. Alternatively, the sensing elements409can be optical elements on the unit309(e.g., areas of different colors or optical patterns) and optical sensing elements on the modules321for optically sensing, either reflectively or absorptively, the optical elements on the unit309. Alternatively, the sensing elements409can be electrical contacts on the unit309which mate with electrical contacts on the modules321when the modules are placed in position on the unit309. Other sensing elements can be used without departing from the scope of this invention.

The integrated control system401also includes means for providing communication between the modules321. For example, as shown inFIG. 11, electrical or fiber-optic lines421may be embedded or otherwise secured to the unit. When positioned on the unit309, the modules releasably connect with these lines421in a suitable manner (e.g., via quick-connect connectors) to provide the communication necessary for providing control information to and from the modules. InFIG. 11, the first (lower) and second (middle) sensing areas405are connected by a single pair of communication lines; the second and third (upper) sensing areas405are connected by two pairs of communication lines. Other line configurations are possible. Alternatively, communication between the modules may be by wireless RF or IR. Through the use of frequency coded communication transmission, close proximity and/or suitable shielding, the RF or IR communication signal is preferably directed only to the modules321on the unit309and not to other modules on different limbs or other patients. By means of this communication, the control system401is able to coordinate the operation of the modules321, e.g., the pressure applied by each module to a respective limb portion, the timing of each compression cycle, and the detection, indication and/or correction of various parameters or errors (e.g., pressure, timing).

It will be observed from the foregoing that the integrated control system401performs two functions. First, it senses the location of each module321with respect to the compression zone in which it is placed. Second, based on this sensed location, the system coordinates the operation of the modules321to achieve the desired sequential and gradient compression of the limb.

According to aspects of the invention, the integrated control system401cooperates with control system201, such as shown inFIG. 4A, which may be part of each of the modules321. In this instance, CPU237communicates via interconnection electronics239over one or more of the lines421. The software239aexecuted by CPU237may be modular such that control system201is capable of controlling operation of module321in any one of the sensing areas405. In this embodiment, the CPU239is responsive to communications via line421and/or sensing elements409for identifying the relative position of the associated module321and providing control signals as a function of the identified position. Each control system201associated with one of the modules321operates independently to effectuate a compression regimen in one location on compression unit309, but its operation is coordinated with that of the control systems201associated with other modules321. As described above, the control signals from each CPU237may provide distinct compression regimens, depending on the location of compression device1on the patient's limb3(e.g., attached to the calf at position B or the thigh at position C inFIG. 9). For example, when control system201identifies one or more compression devices1A,1B or1C attached to the patient's limb3, as inFIG. 9, software237acauses the control systems201to place their associated modules321in a standby mode until the user activates one of the modules. Once activated, CPU237executes software237ato determine the treatment regimen for the respective position of the associated module321and begins treatment.

In an alternative embodiment, one control system201functions as a master controller for controlling operation of all of the modules321connected thereto. In another alternative embodiment, the control system201associated with one module321is responsive to the control system associated with another module321as a function of the relative positions of the modules on the patient's limb3. In yet another alternative embodiment, the integrated control system401comprises the control systems201associated with the compression devices1of modules321operating cooperatively.

FIG. 12illustrates an alternate embodiment of a compression device of this invention, generally designated501. This device is substantially the same as the compression device1of the previous embodiment and corresponding parts are identified by the same reference numbers. In this embodiment, the force-distributing device comprises one or more bladders505(only one being shown) filled with air or other suitable gas. The combination of the bladder(s)505, housing9and actuator21form a module509received (e.g., removably received) in the pocket39of the compressive section5. As described below, the module509is adapted for cyclic expansion and contraction in opposite generally radial directions511with respect to the limb portion3between a contracted condition (FIG. 12) in which the module has a first dimension551for relaxing pressure on the limb portion, and an expanded condition (FIG. 12A) in which the module has a second dimension553greater than the first dimension for compressing the limb portion.

The bladder505provides additional pressure and size adjustment when compressive treatment is provided to the patient. The bladder505is a sensing bladder for sensing a characteristic of compression therapy on a patient. The bladder505has a sensing device521in communication with the contents of the bladder for sensing, for example, the pressure of the contents of the bladder, and for outputting a signal indicative of that characteristic to the control system201. Placing the sensor in-situ with the bladder medium provides for greater accuracy and control of the compression afforded during treatment. The bladder pressure directly impacts blood flow, in that, a lower pressure distributes less force from the mechanical device to the patient limbs, and likewise a higher pressure distributes a greater amount of the force from the mechanical device to the patient's limb. The ability to adjust the bladder pressure with precision allows the patient to tailor treatment to their comfort level. A patient wearing the device can adjust the nominal pressure, independent of computer instruction operating a therapy regime, as described below in the operation of the device. Other sensing devices for sensing other characteristics of the compression therapy are contemplated. For example, the sensor may be a sensor, in a thin layer composite, between the bladder and the leg for sensing a condition of the patient (e.g., temperature, pulse, blood flow, oxygen level).

The bladder has a pneumatic port513and a suitable valve mechanism (not shown) for inflation of the bladder by a pump515. InFIG. 12, this pump515is integral with the compression device501and is mounted inside or adjacent the base member15of the housing9for communication with the port513. Preferably, the pump515is a small pneumatic pump, such as a miniature battery-operated air compressor, which consumes a relatively small amount of power. The power is provided by the battery221or a separate power source in the housing9. Alternatively, the pump used to inflate the bladder can be non-integral with the compression device501. By way of example, the pump can be a hand pump manually operated by the patient or caregiver. A suitable transducer521(e.g., pressure sensor) is provided for sensing pressure of the air (or other gas) in the bladder505. The bladder505can be sized to minimize the distance (e.g., D2minus D1inFIGS. 6 and 7) by which the housing parts15,17must expand and contract to effect the necessary cyclic compression. As a result, the size of various components of the actuator21(e.g., motor125, cams121, gears135,141,145) can be decreased to reduce cost.

In use, one or more of the compression devices501are applied to the limb3to be treated, as described in the previous embodiments. A nominal pressure is maintained in the bladder(s)505to provide for therapy adjustment, to provide a static baseline pressure, and to distribute the compressive forces applied by the compression device501evenly about the surface of the leg or limb of a patient. The transducer521provides feedback to the controller (e.g., CPU237inFIG. 4a) for application of proper therapy to the limb. The pressure in the bladder(s)505is maintained by the pump515. If desired, a pressure relief valve or passively activated check valve (not shown) can be installed to maintain the pressure in the bladder(s)505at a pressure no greater than a predetermined pressure.

In operation, the compression device501cyclically compresses both the limb and the bladder(s)505. This action is monitored by the transducer521which provides feedback to the controller to monitor and adjust the tension in band27. Preferably, the aforementioned small nominal pressure is maintained in the bladder505during the relax stage of each compression cycle. This pressure is much less than in prior art systems, such as found in U.S. Pat. No. 4,253,449 (Arians et al.) owned by Tyco Healthcare Group LP.

Just before the compress stage of each cycle begins, the pneumatic port513of the bladder505is closed by a suitable valve mechanism (not shown) or other means to capture the small nominal pressure in the bladder. As the base and cover members15,17of the housing9expand, the tension in the band27and the pressure in the bladder505increase proportionally. The pressure transducer521monitors this change in pressure and the peak pressure value is fed into a feedback algorithm executed in one of the software and/or firmware modules237a,237bofFIG. 4a. The algorithm functions to compare the peak pressure value to a predetermined (selected) peak value or set point corresponding to the desired maximum pressure to be applied to the limb during the compress stage of each cycle. If the sensed peak pressure is higher than the predetermined set point, then the nominal pressure in the bladder505is adjusted downward by venting an appropriate amount of air (or other gas) from the bladder. Conversely, if the sensed peak pressure is lower than the predetermined set point, then the nominal pressure in the bladder505is adjusted upward by delivering additional air (or other gas) to the bladder(s). This adjustment process continues for subsequent cycles until the sensed peak pressure value substantially matches the predetermined maximum pressure set point.

In the case of an edematous patient, the level of swelling in a limb or limbs can change over time. An advantage of this compression device501is that the pressure in the bladder(s)505, as sensed by the pressure transducer521, can be adjusted to reduce or increase the volume contained within the compressive band27in a manner which is inversely proportional to the amount of edema change. For example, if the compression device501is set to apply a predetermined compressive pressure of 45 mmHg during the compress interval, but the pressure transducer521senses a bladder pressure of 50 mmHg due to increased edema, the control system201will automatically reduce the pressure in the bladder(s)505to compensate for the increased swelling. As a result, blood flow to the swollen limb is not unduly restricted.

The compression device501using one or more bladders505is also capable of measuring vascular refill time (VRT). VRT measurement is an air plethysmographic technique that determines when the veins of a limb have substantially completely refilled with blood after the compression stage of a compression cycle. See, for example, the VRT measurement described in U.S. Pat. No. 6,231,532 to Watson et al., the entire content of which is incorporated by reference herein. This VRT technique is used to minimize the amount of time that blood remains stagnant in the veins.

In general, a VRT measurement is made during the relax stage of the compression cycle in which the compressive device501first reaches its compressive pressure set point. Thereafter, measurements are taken at selected intervals (e.g., every 30 minutes). The measurement process it initiated at T=Tstartwhen the sensed pressure in the bladder decreases to a predetermined level (e.g., 5-7 mmHg), indicating the end of the compress stage and the start of the relax stage of the cycle. As blood returns to the limb3, the limb expands and causes the pressure in the bladder(s)505to increase. This pressure increase is sensed over time by the transducer521. In one example, the bladder pressure is sampled at one-second intervals and the pressure is monitored by using a moving or “rolling” 10-second window of time in which the oldest sample value is dropped from the window and a new sample value is added every second. When the difference between the first and last sample values in the window decreases to a predetermined value (e.g., about 0.3 mmHg), indicating that the refill curve has reached its plateau and that refill is substantially complete, the measurement process is terminated at T=Tend. The vascular refill time is then determined (Tendminus Tstart) and, if necessary, an appropriate adjustment to the relax interval of the compression cycle is then made.

For example, in one embodiment the “default” relax interval is 60 seconds. If the measured VRT is greater than 60 seconds, then the relax interval remains at 60 seconds. If the measured VRT is between 20 and 60 seconds, the relax interval is re-set to the measured VRT. If the measured VRT is less than 20 seconds, then the relax interval is re-set to a minimum time of 20 seconds, for example. The minimum relax interval (e.g., 20 seconds) should be sufficient to insure that the limb has substantially refilled with blood before initiation of the compress stage of the next cycle. The minimum relax interval may also be established by adding a predetermined safety factor (e.g., 5 seconds) to the measured VRT.

Under certain circumstances, the VRT measurement may be disregarded. For example, such circumstances might include a situation where the standard deviation of the pressure values in the sample window exceed a predetermined maximum standard deviation, indicating that the VRT measurement is erroneous; or a situation where the sensed pressure in the bladder(s)505falls below a predetermined minimum value (e.g., 2 mmHg) during the measurement process, indicating a possible leak in the system; or a situation where the sensed pressure in the bladder(s)505exceeds a predetermined value (e.g., 20 mmHg) during the measurement process. In such situations the VRT measurement is disregarded, and the relax interval of the prior cycle continues to be used.

As explained in regard to the first embodiment, more than one compression device501can be used to sequentially compress different portions of the same limb (e.g., one leg) or different limbs (e.g., two legs). If more than one device501is used, the VRT is determined separately for each limb portion being compressed. Preferably, the longest of the measured vascular refill times is then used as the new relax interval for all of the compression devices. The VRT measurements for the compression devices are made (i.e., started and stopped) independent of one another. Preferably, however, any adjustment to the relax interval of the compression devices is not made until after the VRT measurements have been completed for all devices.

As an enhanced safety feature, the control system201of the compression system501may provide an audible and/or visual error alarm for one or more of the following error conditions: high pressure error, including a sensed pressure greater than a set maximum pressure; low pressure error, including a sensed pressure less than a set minimum pressure (e.g., also detecting the absence of bands or sleeves); system pressure error, including a pressure sensed during a compress stage and/or relax stage of a compression cycle outside of desired parameters; valve error; software error; pump error; vent and deflation error; battery error; and temperature error, including temperatures detected outside of specified environmental conditions. (The compression device501can be modified to include one or more temperature sensors to provide the latter feature.) An alarm system of the type described advantageously enhances the safety of the patient during vascular therapy. In the event of an alarm condition, it is contemplated that the visual indicator231or other means may flash error signals, sound a continuous alarm, or otherwise indicate an alarm situation. Further, the control system201may be responsive to an alarm condition to deflate the bladder(s)505and cease further operation of the compression device501.

FIG. 13illustrates a third embodiment of a compression device of this invention, generally designated601. This embodiment is similar to the previous embodiment501in that it comprises a compressive section607adapted to extend around a portion609of a limb, at least one pneumatic bladder615, and a non-pneumatic mechanical device, generally designated619. The bladder(s)615and mechanical device619combine to form a module621which is received (e.g., removably received) in a pocket623on the compressive section607. The module621may be operatively connected to the compressive section607in other ways. As described below, the module621is adapted for cyclic expansion and contraction in opposite generally radial directions624with respect to the limb portion609between a contracted condition (FIG. 13) in which the module has a first dimension651for relaxing pressure on the limb portion, and an expanded condition (FIG. 13A) in which the module has a second dimension653greater than the first dimension651for compressing the limb portion.

In one embodiment, the compressive section607comprises a band member635having opposite ends which are releasably connected by a suitable fastening device637(e.g., similar to31in the first embodiment) to form an annular band around the limb. The compressive section607may have other configurations.

The mechanical device619is non-pneumatic in the sense that it does not include pneumatic components requiring or involving the use of pressurized air or other gas. In the embodiment ofFIG. 13, the device619includes an inner platen625seated on the bladder615, an opposing outer platen627, and one or more springs631between the platens urging the platens away from one another. The springs631of the mechanical device619generate a force tending to move the outer platen627in a direction away from the limb to expand the module621and thereby tension (tighten) the band member635around the limb. In this embodiment, the limb is cyclically compressed by varying the pressure in the bladder(s)615to expand and contract the bladder. The pressure may be varied by cycling the operation of a small pneumatic pump641, such as a miniature battery-operated compressor mounted on or adjacent the inner platen625. The pump641communicates with a pneumatic port645on the bladder(s). A pressure sensor (not shown) monitors the pressure in the bladder(s)615. A pressure relief valve or passively activated check valve (not shown) can be installed to maintain the pressure in the bladder(s)615at a pressure no greater than a predetermined pressure.

In operation, the pump641inflates the bladder(s)615which causes the module621to expand to compress the limb portion609to a predetermined pressure during a compress stage of the compression cycle. The pump641deflates the bladder(s)615to a predetermined pressure after an appropriate compress interval has ended. This causes the module621to contract for relieving the pressure on the limb during the relax stage of the compression cycle. As indicated at624inFIG. 13, the module621expands and contracts in opposing generally radial (not circumferential) directions relative to the limb portion609.

FIG. 14illustrates a fourth embodiment of a compression device of this invention, generally designated701. This embodiment is similar to the compression device501previously described in that it comprises a compressive section707adapted to extend around a portion709of a limb, at least one pneumatic bladder715, and a non-pneumatic mechanical device, generally designated719. The bladder(s)715and mechanical device719combine to form a module721which is received (e.g., removably received) in a pocket723on the compressive section707. The module721may be operatively connected to the compressive section707in other ways. As described below, the module721is adapted for cyclic expansion and contraction in opposite generally radial directions724with respect to the limb portion709between a contracted condition in which the module has a first dimension761for relaxing pressure on the limb portion, and an expanded condition (FIG. 14A) in which the module has a second dimension763greater than the first dimension for compressing the limb portion.

In one embodiment, the compressive section707comprises a band member735having opposite ends which are releasably connected by a suitable fastening device737(e.g., similar to31in the first embodiment) to form an annular band around the limb. The compressive section707may have other configurations.

The bladder(s)715is positioned between the limb portion709and the mechanical device719. The bladder(s) has a pneumatic port725for inflation and deflation of the bladder, as by a hand pump manually operated by the patient or caregiver.

The mechanical device719is non-pneumatic in the sense that it does not include pneumatic components requiring or involving the use of pressurized air or other gas. In the embodiment ofFIG. 14, the device719includes a housing comprising a base housing member727seated on the bladder715, an opposing cover housing member729, and an actuator731inside the housing for moving the housing members toward and away from one another, as described in regard to compression device501. In the illustrated embodiment, the actuator731comprises one or more cams741movable between a first position (shown in solid lines inFIG. 14) in which the housing members727,729are relatively closely spaced in a contracted position or condition, and a second position (shown in phantom lines inFIG. 14) in which the members727,729are spaced farther apart in an expanded position or condition. The cam741is rotated between its first and second positions by a prime mover (e.g., a small DC motor, not shown) having an output747which is connected to the cam741by a gear train751or other suitable means. The cam(s)741, prime mover and gear train751are located inside the base housing member727, similar to the compression devices1,501described above. The “throw” of the cam(s)741may be adjustable, as described previously. Alternatively, it may be non-adjustable to reduce cost. A pressure sensor (not shown) monitors the pressure in the bladder(s)715. Alternatively, to reduce cost, a pressure relief valve or passively activated check valve (not shown) can be installed to maintain the pressure in the bladder(s)715at a pressure no greater than a predetermined pressure.

To operate the compression device701, the bladder(s)715is inflated to a suitable pressure using the pneumatic port725. The actuator731is then energized to move the base and cover members727,729toward and away from one another to expand and contract the module721to conduct successive compression cycles on the limb portion709. As indicated at724inFIG. 14, the module721expands and contracts in opposite generally radial (not circumferential) directions relative to the limb portion709. During this operation, the pressure in the bladder(s)715can be adjusted, if necessary.

In at least some of the bladder embodiments described above, the cost of the compression device can be reduced to a point where the entire device can be discarded after a single use. A disposable device has several benefits. First, it is more hygienic for the patient population. Further, the cost of reprocessing the device or components of the device is eliminated. Also, due to the reduced size and weight of the various components, the device is more portable. The bladder embodiments described above are, for the most part, “self-contained”, meaning that all components of the compression apparatus and the control are located on the garment worn by the patient.