Patent Application
20120065561
The present disclosure relates generally to circulatory conditions such as chronic venous insufficiency (CVI), deep vein thrombosis (DVT), and lymphedema, and more specifically to devices that apply compressive pressure on extremities for the treatment, prevention, and diagnosis of CVI, DVT, lymphedema, and related circulatory conditions.
A variety of circulatory conditions exist in which compressive pressure, typically intermittent compressive pressure, is applied to the extremities of a patient in order to improve the flow of some fluid in the patient's body. Three such circulatory conditions are deep vein thrombosis, chronic venous insufficiency, and lymphedema. With regard to deep vein thrombosis, which is also referred to more generally as venous thrombosis, current estimates are that in the United States alone about two million people develop deep vein thrombosis each year, and over 600,000 of those people are hospitalized because of the condition. Deep vein thrombosis is known to be associated with the risk of developing a pulmonary embolism, which is a blockage of the main artery of the lung resulting from clot that has traveled from elsewhere in body, and in this case from the thrombus or clot associated with the deep vein thrombosis. Pulmonary embolisms are the third most common cause of death in the United States so prevention and early diagnosis of deep vein thrombosis that can lead to pulmonary embolisms are of great importance in reducing the number of related deaths.
Chronic venous insufficiency is a condition in which the veins of a patient's body cannot pump enough oxygen-poor blood back to the patient's heart. Chronic venous insufficiency of the lower extremities is a condition caused by abnormalities of vein walls and of valves within these veins, leading to the obstruction or reflux of blood flow in the veins. The term “lower extremities” as used herein includes the hip region, thigh region, calf region, ankle, and the foot of a patient, and the term “extremities” includes the lower extremities plus the arms of the patient. Lymphedema is a similar condition that occurs when the lymphatic system of a patient is not able to clear fluid from the interstitial tissues of the body and return it to the bloodstream via the system's lymphatic vessels and lymph nodes. With chronic venous insufficiency and lymphedema poor flow of blood and other bodily fluids, respectively, in the extremities may cause chronic swelling, inflammation, ulcerations and pain that contribute to other medical problems. These problems, along with deep vein thrombosis, may arise in surgical patients and are increasingly common in otherwise healthy people having occupations that require sitting for long periods of time as part of their work, or as a result of frequent travel.
Current solutions for treating venous thrombosis involve applying intermittent compression to extremities. A pneumatically inflatable device is placed around the extremity to apply the desired compression, with these pneumatic devices being tethered to an external unit including an electric motor or pump and to an air or other gaseous source. As a result, the devices are bulky and awkward, often having exposed wires and tubing that make the devices prone to misuse, nonuse, and making them difficult to maneuver and thus not portable. Traditional methods of diagnosing venous thrombosis include various forms of impedance plethysmography, in which changes in venous blood volume and pressure (and by extension changes in volume and pressure in the limbs) during an arterial pulse cycle are compared to known baseline measurements, as will be understood by those skilled in the art.
Chronic venous insufficiency treatment is aimed at alleviating symptoms and, whenever possible, at correcting the underlying abnormality. For chronic venous insufficiency, graduated compression is the cornerstone of modern treatment. Properly fitted compression stockings provide compression starting at the patient's ankle, with the pressure gradually decreasing at more proximal levels of the leg (i.e., as you move up the leg towards the hip region). The compression is sufficient to restore normal venous flow patterns in many or even most patients with superficial venous reflux, and to improve venous flow in patients with severe deep venous incompetence.
Lymphedema can occur in a variety of different scenarios. It can be inherited and can also arise after lymph nodes are removed and as a result of radiation therapy, both of which typically occur during cancer diagnosis and treatment. As with deep vein thrombosis and chronic venous insufficiency, compression garments are also utilized in the treatment of lymphedema. Compression bandaging restores shape to the limb and/or affected area, reduces skin changes such as ulcerations, supports overstretched skin, and softens subcutaneous tissues. Pneumatic compression devices are also widely used in the treatment of lymphedema.
Whether the condition is deep vein thrombosis, chronic venous insufficiency, or lymphedema, current compression devices, including both inelastic compression devices like compression stockings and bandages as well as pneumatic compression devices that apply dynamic compression, are not well suited to portability. These devices also are many times difficult for patients to independently operate or utilize. Application of inelastic compression devices many times requires a trained healthcare professional to properly apply the compression bandages, and the same is true regarding the fitting and use of pneumatic compression devices. This lack of portability and difficulty of independent patient use reduces patient utilization of such compression devices, even where utilization would benefit the patient.
There is a need for improved compression devices for the treatment, prevention, and diagnosis of conditions such as deep vein thrombosis, chronic venous insufficiency, and lymphedema, with the compression device being portable, comfortable for patients to wear, and allowing easier patient operability of the device.
One embodiment described in the present invention is directed to a compression device for applying compression to an extremity of a mammal. The compression device includes a cuff adapted to be placed around and secured to the extremity. A control and tensioning unit is attached to the cuff and is operable to control a tension of the cuff to thereby control the compression applied to the extremity. The cuff may further include a bladder system, in which case the compression device further includes a hydraulic pump that is operable to transfer fluid within the bladder system to control the compression applied to the extremity.
In the present description, certain details are set forth in conjunction with the described embodiments of the present invention to provide a sufficient understanding of the invention. One skilled in the art will appreciate, however, that the invention may be practiced without these particular details. Furthermore, one skilled in the art will appreciate that the example embodiments described below do not limit the scope of the present invention, and will also understand that various modifications, equivalents, and combinations of the disclosed embodiments and components of such embodiments are within the scope of the present invention. Alternative embodiments including fewer than all the components or steps of any of the respective described embodiments may also be within the scope of the present invention although not expressly described in detail below. Finally, the operation of well-known components and/or processes has not been shown or described in detail below to avoid unnecessarily obscuring the present invention.
Also note that in the present description when there is more than one of the same component, such as the compression devices 102a, 102b of
The compression system 100 further includes a remote control unit 106 that communicates with control units 108a and 108b contained in the compression devices 102a and 102b, respectively. Although the embodiment of
Through the control units 108a, 108b or remote control unit 106 the user can turn the compression devices 102 ON and OFF and can also control various operating parameters of the compression devices, such as setting desired pressure, displacement, and elasticity characteristics of each device. Additional operating parameters that the user can control through the control units 108a, 108b and remote control unit 106 include setting desired intermittent, cyclic, or other controlled compression profiles for the compression devices 102. A compression profile defines the pressure that the compression device 102 applies to the patient extremity (i.e., calf of the patient 104 in the example of
The remote control unit 106 or control units 108a, 108b may also be utilized to control the overall independent or coordinated operation of the individual compression devices 102 and additional compression devices (not shown in
The user can also utilize the remote control unit 106 to place the compression devices 102 in a diagnostic mode of operation in which the compression devices apply appropriate compression profiles to establish baseline vital signs for the patient 104 and determine required physiological characteristics of the patient. In the diagnostic mode of operation, each of the compression devices 102 applies the appropriate compression profiles and gathers patient data corresponding to these applied profiles. A computer system 116 receives this patient data gathered by the compression devices 102, either directly from the compression devices or via the remote control unit 106 as is the case illustrated in
A physician (not shown in
The compression system 100 allows the compression devices 102 to gather patient data and this data to be supplied to the computer system 116 for use by others. In some embodiments, caregivers can review usage data and physiological data transmitted by the compression devices 102 to the computer system 116. Using this data, the caregiver may then utilize the computer system 116 to provide new therapy sequences for treatment of the patient 104 to the compression devices 102 over the communications link 118. The wireless remote control unit 106 allows the patient 104 to control the compression devices 102 without touching the device. In some embodiments, the remote control unit 106 allows the patient 104 to enter commands in response to menu on an operator interface (not shown) of the remote control unit 106.
In other embodiments, the remote control unit 106 is operable to transmit commands to the compression devices 102 in response to simply tapping of the remote control unit, with the remote control unit including one or more inertial sensors to detect the motion of the unit. Such an embodiment could be particularly helpful where the patient 104 has limited mobility, and in cases where multiple compression devices 102 are utilized so that the patent need not individually program each compression device.
In the embodiment of
The cuff 200b includes the same components 202a-210a and 214a as does the cuff 200a so like components for the cuff 200b have been given the same reference numbers as the corresponding components for the cuff 200a along with the letter reference “b.” A control unit 212b couples to cuff 200b and operates in the same way as described for control unit 212a. Note that the control units 212a and 212b correspond to the control unit 108a or 108b of
Referring to
As previously mentioned, the embodiment of the compression device 102 illustrated in
In the compression device 102, the control unit 211 can control the pump 208 in the cuffs 200 in a variety of different ways. The pump 208 in a given cuff 200 can be actuated to pulse synchronously with the pumps in other cuffs, or the pumps can be actuated asynchronously, or sequentially such as where a series of cuffs are worn on a patient's legs and cuffs 200 are sequentially activated from bottom to top to remove unwanted fluid build-up in the patient's legs. The pumps 208 in respective cuffs 200 can also be actuated intermittently or the pumps in multiple cuffs actuated concurrently in accordance with programmed courses of therapy, or in accordance with programmed responses to input from the patient 104, or from caregivers or from feedback provided by sensors and valve systems (not shown) contained in the compression devices 102.
In some embodiments, compression cycling can be timed with sensor inputs of vital signs of the patient 104 such as heart rate, breathing rate, respiratory rates, venous flow, blood pressure and activity levels. Embodiments of the compression devices 102 are portable, low cost, and the device or portions thereof, such as the outer sleeve 216 and all components of the cuff 200 except for the control unit 211, can even be disposable. The compression device 102 also provide self-contained operation such that no exposed tubes or wires are required in connection with use of the device. Such self-contained compression devices 102 include rechargeable or disposable batteries in some embodiments that allow the devices to be worn at all times by the patient 104, even when walking and sleeping, and during immersion in water and during inclement weather, for many hours each day over an extended number of day. The operation of the compression devices 102 may also be very quiet, allowing the patient 104 to more comfortably wear the devices without distraction. The compression devices 102 can also be used to provide massage to the extremities of the patient 102 even when sequential compression is medically unnecessary. The improved portability, length of operation, and comfort, should increase the willingness of the patient 104 to use the compression devices 102 for longer therapeutic periods, thereby improving the likelihood of a favorable outcome from the treatment.
To increase the radial pressure applied by the membranes 206, the pump 208 is controlled to pump fluid from the reservoir 214 into the manifold 302 and from the manifold through the orifices 300 and into the membranes 206. When fluid is pumped into the membranes 206, the membranes expand and apply pressure in the direction indicated by the arrow 304, which is termed a “radial” direction or pressure given that when the cuffs 200 is wrapped around the calf of the patient 104 this pressure is applied inward towards the center of the calf. Conversely, in order to lower the radial pressure applied by the membranes 206, the pumped 208 is controlled to pump fluid from the manifold 302 into the fluid reservoir 214. As fluid is removed from the manifold 302 the fluid contained in the membranes 206 flows through the orifices 300 and into the manifold, reducing the radial pressure applied by the membranes.
In one embodiment of the cuff 200, the fluid reservoir 214 includes a pressure-sensitive bellows (not shown in
In the embodiment of
In the embodiments of the cuff 700 illustrated in
In operation, the control units 814a and 814b operate to control the other compression devices 804, 806 and 810 to apply in overall desired compression profile each of the patient's legs 802a and 802b. The user may initiate operation of the compression devices 804-810 to apply the desired compression profile using the display 816 and control unit 814 in the compression devices 808. Once activated to implement the desired compression profile, the control unit 814 in each compression device 808 provides control signals to the other compression devices 804, 806 and 810 to control the cuffs in each of those compression devices to apply the desired compression profile. In response to these control signals, the cuffs in each of the compression devices 804-810 apply the desired compression profile to that portion of the patient's leg 802. For example, where the cuffs in the compression devices 804-810 correspond to the cuff 200 in
Although the compression system 800 is described as including only a single control unit 814a in the compression device 808a for the left leg 802a, and the same for control unit 814b in compression device 808b for the right leg 802b, in other embodiments the cuff in each compression device 804-810 includes a separate control unit 814, but only one of the control units coordinates overall the control of all the cuffs. In this embodiment, appropriate wires 812 connect the master control unit 814 in compression device 808 to the control units in the other compression devices 804, 806, and 810. In this embodiment, as an alternative to the wires 812 the control units 814 in each of the compression devices 804, 806 and 810 could wirelessly communicate with the master control unit 814 in compression device 808. Power transmission signaling for the control units 814 in compression devices 804, 806 and 810 in such an embodiment may be achieved with inductive coupling devices, as will be appreciated by those skilled in the art. Also in this embodiment, the master control unit 814 in compression devices 808 can alter operation of the various cuffs based on sensor system data or valve system data monitored by the control units in the cuffs in compression devices 804, 806 and 810.
In the compression system 800, the master control unit 814 in compression devices 808 coordinates the operation of the cuffs in the other compression devices 804, 806 and 810 to achieve desired compression profiles to meet therapeutic or diagnostic patient needs. Operation of the compression system 800 can be initiated by the patient via the master control units 814 in compression devices 808, and can also be initiated by a physician using a remote user interface, such as the computer system 116
In operation, the control and tensioning unit 902 controls the circumferential displacement 906 of the compression band 904 to thereby apply a desired compression profile to the extremity 908 of the patient, as will be now explained in more detail below with reference to
Once the compression device 900 is placed on the extremity 908 of the patient, the process proceeds to step 914 and the control and tensioning unit 902 is activated. When activated, the control and tensioning unit 902 operates to control the circumferential displacement of the compression band 904 so that an applied pressure PAPP applied by the band to the extremity 908 increase towards a desired initial pressure PINIT. In doing so the specific manner in which the control and tensioning unit 902 controls the circumferential displacement to increase the applied pressure PAPP may vary, as will be appreciated by those skilled in the art. For example, the control and tensioning unit 902 stepwise increases the circumferential displacement as a function of time in one embodiment and linearly increases the circumferential displacement as a function of time in another embodiment.
From step 914, the process goes to step 916 and determines whether the applied pressure PAPP applied by the compression band 904 to the extremity 908 has reached the desired initial pressure PINT. As long as this is not the case, meaning the determination in step 916 negative, the process goes back to step 914 and the control and tensioning unit 902 continues increasing the circumferential displacement so that the applied pressure PAPP continues increasing towards the desired initial pressure PINIT. When the applied pressure PAPP has reached the desired initial pressure PINIT, the determination in step 916 is positive. The control and tensioning unit 902 then maintains the circumference of the compression band 904 at the corresponding value and the process proceeds to step 918 and determines whether to continue or terminate operation in response to patient or user input. For example, a user such as a physician may wish to reposition the compression device 900 on the extremity 908 of the patient or the patient may wish to remove the compression device in order to take a bath or go swimming.
When the determination in step 918 is positive, meaning that for whatever reason either a user or the patient wishes to terminate use of the compression device 900, the process goes to step 920 and the control and tensioning the 902 releases the compression band 904. Release of the compression band 904 allows the circumference of the band to increase due to outward pressure from the extremity 908 on the band. The applied pressure PAPP accordingly decreases, allowing the compression device 900 to be removed from or repositioned on the extremity 908 of the patient. The process then goes to step 922 and terminates.
When the determination in step 918 is negative, operation of the compression device 900 is to continue in the process proceeds to step 924 and monitors the applied pressure PAPP applied to the extremity 908 of the patient. This monitoring includes sensing or detecting the value of the applied pressure PAPP, and would typically include sampling through appropriate electronic circuitry electrical signals indicating the value of the applied pressure PAPP that the compression band 904 is applying to the extremity 908 of the ambulatory patient. Where the compression device 900 is placed around a lower extremity 908 of the patient, the applied pressure PAPP will vary due to contraction and release of the patient's muscles in the extremity while moving. Thus, the control and tensioning unit 902 maintains the circumference of the compression band 904 at a constant value and this results in a variable pressure being applied to the extremity 908 of the ambulatory patient. In step 924 the control and tensioning unit 902 samples and stores the values of this variable pressure over time.
From step 924 the process then proceeds to step 926 and utilizes groups of the stored values to determine a moving average of the applied pressure PAPP the compression band 904 applies to the extremity 908 of the patient, with this moving average pressure being designated PMAVG. One skilled in the art will understand the concept of a moving average and thus the details of this operation will not be described. Briefly, a subset consisting of a defined number of samples of the applied pressure PAPP is utilized to generate a given value for the moving average pressure PMAVG, with new samples being included in the calculation of the moving average pressure as they are acquired and as each new sample is included in the group the oldest PAPP sample is removed.
The process then proceeds from step 926 to step 928 and determines whether the moving average pressure PMAVG is less than a minimum pressure PMIN. The minimum pressure PMIN to ensure that the compression profile corresponding to the applied pressure PAPP as desired characteristics for proper treatment of the patient. For example, when the compression device 900 is being utilized to treat chronic venous insufficiency (CVI), as the circumference of the compression band 904 is maintained, constant fluid in the extremity 908 of the patient is removed due to the corresponding applied pressure PAPP. This applied pressure PAPP will ideally decrease over time as the fluid is removed. Thus, to continue removing additional fluid from the extremity, and to physically maintain the compression band 904 in position on the extremity 908, the moving average pressure PMAVG of the applied pressure PAPP is maintained above a minimum pressure PMIN.
When the determination in step 928 is positive this means that the moving average pressure PMAVG has dropped below the desired minimum pressure PMIN. The control and tensioning unit 902 then controls the circumferential displacement of the compression band 904 to increase the applied pressure PAPP. Accordingly, the process goes to step 930 and the control and tensioning unit 902 increases the circumferential displacement of the compression band 904, meaning that the control and tensioning unit reduces the circumference of or tightens the compression band around the extremity 908. In the present description increasing or decreasing circumferential displacement are utilized relative to an initial position or circumference of the compression band 904. The circumferential displacement is said to be increasing when the circumference of the compression band 904 is decreasing to tighten the band around the extremity 908. Conversely, the circumferential displacement is said to be decreasing when the circumference of the compression band 904 is increasing.
Once the control and tensioning unit 902 has increased the circumferential displacement of the compression band 904 in step 930, the process goes to step 932 and determines whether the applied pressure PAPP equals a new desired pressure PNEW. The new pressure PNEW could, for example, be the initial pressure PINIT that was initially developed by the compression band 904 in step 916. When the determination in step 932 is negative the applied pressure PAPP has not yet reached the desired new pressure PNEW, and so the process returns to step 930 and the control and tensioning unit 902 increases the circumferential displacement of the compression band 904 to thereby increase the applied pressure PAPP. The process continues executing steps 930 and 932 until the determination in step 932 is positive, meaning that the applied pressure PAPP has reached the desired new pressure PAPP. At this point, the process goes from step 932 back to step 918 and executes as previously described for this step and the following steps 920-928.
Returning now to step 928, when the determination in step 928 is negative this means that the moving average pressure PMAVG is not less than the desired minimum pressure PMIN. Accordingly, the operation of the compression device 900 is satisfactory at this point in that the moving average of the applied pressure PAPP (i.e., the PMAVG pressure) being applied by the compression band 904 is above the minimum pressure PMIN. From step 928, the process goes to step 934 and determines whether the moving average pressure PMAVG has exceeded a threshold maximum pressure PMAX.
The compression device 900 performs this determination in step 934 primarily to ensure safety of the patient. For example, if the patient has chronic venous insufficiency and the compression profile being applied by the compression device 900 does not result in fluid being gradually removed from that portion of the patient's extremity 908 over which the compression device is placed then the applied pressure PAPP could increase to unsafe levels. For example, if the compression device 900 is operating at a given circumference of the compression band 904 and fluid within the patient's extremity 908 flows back into that portion of the extremity over which the compression device is placed then the applied pressure PAPP will increase, perhaps to an unsafe level. Accordingly, the process performs this check on the moving average pressure PMAVG exceeding the threshold maximum pressure PMAX in step 934.
When the determination in step 934 is negative, the moving average pressure PMAVG does not exceed the threshold maximum pressure PMAX meaning that the compression device 900 is operating properly within prescribed thresholds for the moving average pressure PMAVG. Accordingly, if the determination in step 934 is negative the process goes back to step 918 and executes as previously described for this step and the following steps 920-928. If, however, the determination in step 934 is positive then this means the moving average pressure PMAVG has exceeded the threshold maximum pressure PMAX and the process goes to step 936 in which the control and tensioning unit 902 decreases the circumferential displacement of the compression band 904. As previously mentioned, decreasing the circumferential displacement means that the circumference of the compression band 904 is increased, loosening the band around the patient's extremity 908 and thereby lowering the applied pressure PAPP.
From step 936 the process then goes to step 938 and determines whether the applied pressure PAPP has been decreased to a desired new pressure PNEW. Note, the new pressure PNEW in step 938 need not have the same value as the new pressure in step 932. When the determination in step 938 is positive, the applied pressure PAPP equals the desired new pressure PNEW the process goes back to step 918 and executes as previously described for this step and the following steps 920-934. When the determination in step 938 is negative, the process goes back to step 936 and the control and tensioning unit 902 decreases the circumferential displacement to further lower the applied pressure PAPP. The process then goes back to step 928 and once again determines whether the applied pressure PAPP is less than the new pressure PNEW. The process continues executing steps 936 and 938 until the determination in step 938 is positive and the process then returns to step 918.
In one embodiment, the control and tensioning unit 902 also monitors the overall circumferential displacement of the compression band 904 and terminates operation when the circumferential displacement exceeds some maximum threshold value. For example, a physician or other user may desire that even if operation of the compression device 900 is otherwise proceeding properly the circumference of the compression band 904 should not fall below some minimum value. Thus, the control and tensioning unit 902 monitors the overall increase in the circumferential displacement of the compression band 904 and terminates or otherwise adjusts operation of the compression device 900 when the increase in the circumferential displacement exceeds some maximum value.
In the graphs of
From the time interval from time t0 to time t1 the control and tensioning unit 902 holds the circumference of the compression band 904 constant at initial circumference CINIT, as seen in
During the time interval from t0 to t1 as the applied pressure PAPP varies as shown in
As seen
Notice that in
At the time t1 the moving average pressure PMAVG reaches the minimum pressure threshold PMIN, corresponding to a positive determination in step 928 of
A second time interval from the time t1 until a time t2 demonstrates similar operation of the compression device 900. Once again at the end of this time interval, namely at the time t2, the moving average compression PMAVG reaches the minimum pressure threshold PMIN and the control and tensioning unit 902 increases the circumferential displacement to thereby decrease the circumference C of the compression band 904 to the circumference C2 as illustrated in
A third time interval from the time t2 until a time t3 is also illustrated in
The non-ambulatory process illustrated in
In response to the second circumference C2 of the compression band 904, the compression band applies a new desired pressure PDES that is greater than the initial pressure PINIT as seen in
As was previously described for the compression devices 102 of
The control and tensioning unit 1002 includes a drive mechanism 1400 that is operable to retain the end portion of the slip compression band 1004 within the control and tensioning unit and to drive the end portion to either the left or right as illustrated by the arrows 1402 in
In operation, the control and tensioning unit 1002 operates to drive the end portion of the slip compression band 1004 to the left or to the right as illustrated by the arrow 1402. In this way, the control and tensioning unit 1002 controls the tension of the slip compression band 1004 and thereby compression applied by the slip compression band and integrally attached fluid-filled outer sleeve 1006 to the patient extremity around which the compression device 1000 is placed. Fluid cells 1404 in the fluid-filled outer sleeve 1006 in combination with the slip compression band 1004 form a hydrostatic compression system that functions to provide evenly distributed pressure to the patient extremity. The fluid-filled outer sleeve 1006 and fluid cells 1404 distribute the pressure from high pressure points that could otherwise result to imperfections on the extremity around which the device 100 is placed, making the device more comfortable and applying more uniform pressure to the extremity. Note the specific arrangement of the fluid-filled cells 1404 on the fluid-filled outer sleeve 1006 can vary in other embodiments of the compression device 1000. This is also true of the specific arrangement of the membranes 206 in the embodiments of
The control and tensioning unit 1002 can sense a variety of different patient parameters and implement a variety of different control algorithms responsive to the sensed parameters, as previously mentioned with regard to the compression devices 102, 804-810, and 900. For example, the control and tensioning unit 1002 can monitor ambulatory state of the patient and adjust the applied compression profile accordingly. When the patient is walking, for example, the control and tensioning unit 1002 may stop applying a given compression profile to the patients extremity and when the patient is immobile, such as when the patient is sleeping, the control and tensioning unit may reactivate and apply the desired compression profile.
The control and tensioning unit 1002 can also sense pressure, force and temperature of the patient extremity, with temperature possibly being sensed by sensing the temperature of the liquid contained in the fluid cells of the fluid-filled outer sleeve 1006. Temperature could be modulated according to certain control algorithms being implemented by the control and tensioning unit 1002, such as through a Peltier heat transfer system. In addition, the control and tensioning unit 1002 can measure other patient parameters such as leg circumference of the patient, and utilize this measured parameter accordingly. For example, the control and tensioning unit 1002 could monitor leg circumference changes from a given point in time, such as when the patient initially puts on the compression device 1000. The control and tensioning unit 1002 could then take a variety of different actions utilizing the measured leg circumference changes. For example, the control and tensioning unit 1002 could adjust the displacement of the slip compression band to the left or to the right as indicated by arrows 1402 in order to maintain a constant pressure applied to the patient extremity. As an added safety feature, the control and tensioning unit 1002 could limit further displacement once a previously programmed minimum circumference was reached.
The control tensioning unit 1002 further includes a nonvolatile memory 1508 for use by the microprocessor 1500 to store data and also to store firmware for execution by the microprocessor and controlling the overall operation of the control and tensioning unit. Other types of memory, such as volatile memory like DRAM, could also be contained in the control and tensioning unit 1002. The control and tensioning unit 1002 further includes power components for supplying electrical power to the other components in the control and tensioning unit. In the embodiment of
The control and tensioning unit 1002 further includes a DC-to-DC conversion circuit 1516 that receives power from either the battery 1510 or power supply 1512 and converts the received power to required voltage and current levels to drive other components contained in the control and tensioning unit 1002. In the embodiment of
The control and tensioning unit 1002 further includes a number of different types of sensors, including pressure sensors 1528 for sensing various pressures that may be of interest during operation of the compression device containing the control and tensioning unit. For example, the pressure sensors 1528 could sense the pressure applied by the compression device to the patient extremity and the microprocessor 1500 could, for example, control the device so that a constant pressure or circumference is maintained, or a targeted pressure versus time profile is followed. Another pressure sensor 1528 may be used to measure localized pressure in certain zones of the fluid-filled outer sleeve 1006. This measurement could be used to for more sensitive readings, such as to detect heart rate, and could serve as a redundant measurement for the applied radial pressure for added safety. An analog-to-digital converter 1530 digitizes the signals from the pressure sensors 1528 for use by the microprocessor 1500. The control and tensioning unit 1002 may also include a force sensor 1538 or load cell to measure the force applied to slip compression band 1004, and the signals from the sensors are once again digitized by the analog-to-digital converter 1530 for use by to the microprocessor 1500 in controlling the operation of the compression device. The force measurement on the slip compression band 1004 correlates to the average radial pressure applied to the limb, therefore microprocessor 1500 can perform this real-time calculation for use in the system elsewhere. The control and tensioning unit 1002 may also include a displacement sensor 1540 or encoder to measure the circumference and/or change in circumference of slip compression band 1004, and the signals from the sensors are once again digitized by the analog-to-digital converter 1530 for use by to the microprocessor 1500 in controlling the operation of the compression device. As a safety measure, the measurement of circumference and/or change in circumference will allow the device to terminate application of treatment in cases where displacement thresholds are reached, as potentially defined by a medical professional. The control and tensioning unit 1002 may also include flow rate sensors 1532 and the signals from the sensors are once again digitized by the analog-to-digital converter 1530 for use by to the microprocessor 1500 in controlling the operation of the compression device. The control and tensioning unit 1002 may also include inertial sensors 1534, such as accelerometers and/or gyroscopes that sense movement of the patient and these signals are once again digitized by the analog-to-digital converter 1530 for use by the microprocessor 1500. Ambulatory state of the patient may be sensed through the inertial sensors 1534, as previously mentioned above, and utilized by the microprocessor 1500 to take appropriate action, such as controlling the compression device to apply a suitable compression profile when the inertial sensors 1534 indicate that the patient is sleeping. Finally, the control and tensioning unit 1002 may also include thermal sensors 1542 that measure limb temperatures or other system temperatures. These signals are once again digitized by the analog-to-digital converter 1530 for use by the microprocessor 1500. The control and tensioning unit 1002 further includes data interface and wireless communications circuitry 1536 for communicating with other control units, remote controls units, and/or computer systems (e.g. computer system 116 of
The control and tensioning unit 1002, in conjunction with the various sensors and the various embodiments of compression devices described, allows a wide array of programmable operational modes and physical characteristics of the system. Given the ability to perform closed-loop control of force and displacement, the system can be programmed to respond with a wide range of effective stiffnesses. For example, the device can behave in an inelastic (highly stiff) mode, whereby applied pressures and force do not cause any displacement. In another case, it may be desirable for the system to behave in an elastic manner with a target spring constant. In this case, the closed loop control system allows displacement in proportion to the applied load according to the target spring constant. In yet another case, a constant pressure may be required. In this case the control system adjusts the displacement in real-time to maintain the target applied pressure, no matter what perturbations are put into the system. Finally, it may be desirable to execute controlled pressure cycling according to defined pressure versus time profile. In this case the system drives displacement using inputs of applied pressure and time to follow the target profile.
Once the self-test of step 1602 has successfully completed, indicating the compression device is fully functional, the cycle process goes to step 1604 and the desired compression profile to be applied by the compression device is loaded. From step 1604, the cycle process proceeds to step 1606 in which the control and tensioning unit 1002 measures the pressure being applied to the patient extremity by the compression device. The cycle process then goes to step 1608 and determines whether a desired peak pressure has been achieved. When the determination in step 1608 is negative, the cycle process goes to step 1610 and the pump is activated to increase the applied pressure. Note that although the process of
From step 1610, the cycle process goes back to step 1606 and measures the applied pressure, and then goes to step 1608 and determines whether the measured pressure has reached desired peak pressure. The cycle process continues executing steps 1608, 1610 and 1606 until the determination in step 1608 is positive, indicating the desired peak pressure has been achieved. When the determination in step 1608 is positive, the cycle process proceeds to step 1612 and “dwells” at the desired peak pressure for a desired dwell time. During this dwell time the desired peak pressure is maintained and thus the control and tension unit 1002 is said to “dwell” at this desired peak pressure.
From step 1612 the process goes to step 1614 and determines whether a set dwell time has expired. When this determination is negative, the process returns to step 1612 and continues to maintain or dwell at the desired peak pressure. The process then goes back to step 1614 and once again determines whether the dwell time has expired. The cycle process continues executing steps 1612 and 1614 until the determination in step 1614 is positive, meaning that dwell time has been reached. When the determination in step 1614 is positive, the process goes to step 1616 and once again measures the pressure applied by the compression device. From step 1616 the process goes to step 1618 and determines whether a baseline pressure has been achieved. When the determination in step 1618 is negative, cycle process goes to step 1620 and the pressure applied by the compression device is “bled” such that the applied pressure is lowered. The cycle process then goes back to step 1616 and the applied pressure is once again measured. The cycle process then returns to step 1618 and determines whether the desired baseline pressure has been achieved. The cycle process continues executing steps 1616 and 1618 until the desired baseline pressure, which is lower than the peak pressure, is achieved.
When the determination in step 1618 is positive, meaning that the desired baseline pressure has been achieved, the cycle process goes to step 1622 and maintains or dwells that the baseline pressure. From step 1620 the cycle process goes to step 1624 and determines whether a set dwell time has been achieved. As long as the determination in step 1624 is negative, the cycle process repeats steps 1622 in step 1624 to thereby dwell at the desired baseline pressure. Once the determination in step 1624 is positive, indicating that the pressure applied by the compression device has been maintained at the desired baseline pressure for the desired dwell time, the cycle process goes to step 1626 and determines whether the desired number of cycles have been executed.
When the determination in step 1626 is negative, the process goes back to step 1606 and once again executes steps 16061608 and 1610 to increase the pressure applied by the compression device to the desired the pressure. The process then once again execute step 1612 and 1614 to maintain the applied pressure at the desired peak pressure for the desired dwell time and then once again goes to step 1616, 16181620 to reduce the pressure to the desired baseline pressure. The process then once again goes to step 1622 in 1624 and maintains or dwells at the desired baseline pressure for the desired dwell time. At this point the process once again determines the steps 1626 and determines whether to the desired number of cycles has been executed. Cycle process continues executing in this manner until the desired number of cycles has been executed, at which point the determination in step 1626 is positive in the cycle process proceeds to step 1628 and terminates.
A graph at the bottom of
The middle diagram in
Finally, the lower diagram in
Compression devices according to embodiments of the present invention are worn over or wrapped or placed around the portion of the body of interest. In operation, these compression devices assert a massaging or squeezing effect on the body. The above embodiments have been described as being used on humans but may be used on other mammals as well, and may be used on the upper arms, forearms, wrists, hands, thighs, calves, ankles and feet, and combinations thereof. If used on other mammals, such as smaller or larger animals, the compression devices device may be easily scaled to operate both on large and small animals and can be used on extremities or on larger portions of the animal's body.
The compression devices may utilized in a wide variety of different application, such in treating, diagnosing and preventing circulatory disorders. The compression devices can be worn by surgical patients, during and after surgery, for example. Another application is for people who spend substantial parts of most days lying down, or by the bedridden. In another application the compression devices may be worn by persons who spend substantial parts of the day immobile or substantially immobile, such as persons who sit for long periods of time in work, travel or leisure activities. The compression devices may function to shut OFF or enter a low power standby mode during extended periods of activity of the user, allowing more comfortable use by more active individuals. In some applications the compression devices may be worn by persons simply seeking the massage capabilities of the compression device.
As described with reference to the above described embodiments, the compression devices can include cuffs that are wrapped around a portion of the body requiring treatment and these cuffs typically include fastening mechanisms for tightening and securing the device around the body before use and quick release means for safety reasons. Examples of such mechanisms include without limitation hook and loop fasteners, snap fasteners, straps with tightening devices, spring locks and other adjustable fastener assemblies. In other embodiments, the device may be conformed to envelope an extremity with a specific configuration, such as the hand or ankle. In yet other embodiments, the size or shape of the device can be customized to an individual's body such that no manual adjustments are necessary once the device is placed around the body. In still further embodiments, latching or tensioning devices are employed so that the device can be simply adjusted with a minimum of steps. In some embodiments, the compression device can take the form of a single-piece cuff or sleeve that is slipped onto an extremity. The cuff can include contour aids for aligning the cuff on the extremity of interest, and include aids to align the cuff to focus constriction on the centerline of the calf or on other locations on the body. The cuff may also be configured to focus localized compressive pressure on such areas of interest.
In many embodiments, the compression device can be used in connection with a fabric sleeve or wrap, such as the protective outer sleeve 216 of
In some embodiments, the compression device includes a cuff having a bladder system, such as the bladder system 204a in the embodiment of
In embodiments of the present invention that include a pump, such as the pump 208 of
The pump 208 or pumps in any of the described embodiments may be mechanical, electrical or electromechanical in nature, and may be powered by batteries to improve portability of the device. The pump is used to achieve appropriate pressures in the device to result in application of compressive stress to the areas of interest. The pump is typically capable of rapid cycling and rapid filling rates. In addition, the pump may be removable and replaceable in the event the pump fails or in the event other compression device components fail. In some embodiments, the pump includes an electroactive polymer that functions as the pump actuator. The term “electroactive polymers” generally describes piezoelectric materials that mechanically deform with a high strain output under low voltage electrical input or stimuli. The mechanical deformation is precise such that highly controlled incremental changes in deformation can be achieved. In addition, the electroactive materials are lightweight, resilient and silent in operation. Therefore, pumps comprising electroactive polymers are quiet in operation and can be configured to work substantially without noise. The use of electroactive polymers also reduces the size of the pump due the materials higher power density and their use reduces or eliminates the need for gear reduction designs or separate force pressure transducers. The use of electroactive polymers allows the pump to be cost efficient.
The compression devices can include failsafe mechanisms such as integral vacuum relief valves and two-way flow control valves to improve the safety of the devices. In some embodiments the cuff, such as cuff 200 of
In some embodiments the cuff, such as cuff 200 of
In some embodiments of compression devices according to the present invention, the control unit, such as control unit 212 of
The control unit may have a user interface that allows a user or caregiver to control the device by entering appropriate input through tactile interfaces. In many cases, the user interface comprises a user display that reports the status or operation mode of the device upon request. The user interface may also in some cases display information regarding the battery usage of the device, the usage of the device in comparison to target usage, and any error or fault codes for the device. Faults include without limitation power faults, sensor faults, and memory faults. In such cases the user interface and display should be configured to be readable to the user when the device is worn.
The control unit typically includes a microprocessor that controls the actuation of pumps or other drive mechanisms and controls the compression device power circuitry. The microprocessor may includes a digital signal processor, and may control power circuitry, electrical charging circuitry, and safe-operation circuitry such as ground fault interruption and arc fault protection circuitry. Such circuitry together with the pump, power supply as applicable and power conversion circuitry can be separately enclosed in a scaled enclosure. The microprocessor includes logic circuitry that processes and uses sensory data from the sensors and any user input to control operation of the device. The microprocessor also controls actuation of the pumps in accordance with a programmed compression profile such as a therapy sequence or profile, or in accordance with calibration or deep vein thrombosis detection sequences, for example. The microprocessor can also be utilized to calibrate, analyze and store the baseline measured characteristics and vital signs for individual users and patients. The control unit may also comprise a device for storage of data, such as, without limitation, a patient's measured physiological characteristics, calibration information, and use metrics. Non-volatile FLASH memory devices may be used for such storage. The control unit may also include a wireless interface, wireless data transmitter and/or receiver that can be used to exchange data with other control modules or other remote interfaces. Examples of such interfaces include user remote controls, computers, personal digital assistants or wireless telephones or smart phones. Of course the control unit may also include ports, such as universal serial bus (USB) ports, for wired external connections to such interfaces for data exchange or download.
The control unit may also include inductive power coupling devices and may also provide real-time measurements of pressure, fluid flow rates, temperature and motion that can be recorded and displayed either on a user interface on the control unit or on a remote computer through wired or wireless means. The control unit may be responsive to real-time input from the user or caregiver including turning the device on and off or placing the device into sleep or idle modes, changing pulsing or compression cycle frequency or changing pulsing or compression cycles from synchronous to asynchronous between different cuffs or devices as described further below. Thus the microprocessor of the control unit can be programmed to respond to sensor feedback in either closed loop or open loop feedback processing. In some cases, the control unit regulates and controls pressure within the bladder system through active control of the pump and active monitoring and measuring of the pressure within the bladder system using sensor feedback and measurements while in other cases the control unit is configured to estimate fluid flow volume using hydraulic pump input voltage, pressure, incompressible fluid temperature, and time-related measurements.
One application of the above-described embodiments is use in treating patients with venous thrombosis by attaching an apparatus of the disclosure to an extremity of the patient. The pump of a compression device placed around the extremity is the actuated to supply the necessary pressure or vacuum to cause the expansion of membranes or chambers or to cause the contraction of bellows elements, as applicable. Pump actuation coordinated with valve operations continue until a target pressure is achieved, as measured by pressure sensors located in the bladder system or by pressure sensors located on the bladder system adjacent to the extremity. The valves between the reservoir and the membranes may be open during this period until the membranes arc filled with fluid to a target pressure which is measured and recorded. The target pressure can be maintained by valve closure, pump modulation, or a combination of these approaches. Pump modulation operates in a closed-loop control manner through continuous monitoring the pressure level with the bladder system, and adjusting the pump output to maintain the target level. Techniques for pump modulation and regulation such as pulse width modulation or continuous voltage input adjustments and other techniques are known to those skilled in the art.
After the target pressure is maintained for a determined amount of time the fluid or vacuum is released and returned to the reservoir as applicable, as described with reference to the embodiment of
Other embodiments include methods of characterizing stiffness characteristics of a portion of the body around which a compression device is placed. The compression device can utilize a single bladder system which is actuated concurrently with the sensors such that a separate reference bladder system is not required. The pump of the compression device is actuated to supply the necessary pressure or vacuum to cause the expansion of membranes, or to cause the contraction of bellows elements as applicable. The pump is operated until a first, higher target pressure is achieved, as measured by pressure sensors located in the bladder system or by pressure sensors located on the bladder system adjacent to the extremity. The time required to reach the first, higher target pressure is measured and recorded. During this time period, the pressure exerted by the bladder system, as well as the pump voltage, incremental volumetric displacement and fluid temperature, are repeatedly measured, along with a precise time record of each measurement, until the target pressure is reached. After the target pressure is reached, pump actuation ceases and the bladder system is allowed to return to a second, lower target or baseline pressure through powered or passive “backfeed” through the pump and fluid control valves, if used. The time required to reach the lower target pressure is measured and recorded. During this second time period the pressure exerted by the bladder system, as well as the pump voltage, incremental volumetric displacement and fluid temperature, are repeatedly measured until the second, lower target pressure is reached, after which the valves may be moved into closed positions or pump modulation is enabled. The pressures, volumetric displacements and times are recorded in data storage components of the device or exported to an external memory. The data is used to quantify a stiffness characteristic that can be described as the relationship between the data and applied pressure, which is analogous to an applied force as a function of volumetric displacement analogous to radial displacement of the device by the body. With sufficient measurements a baseline physiological stiffness characteristic may be determined. In a similar manner other stiffness characteristics can be determined by quantifying the relationship between applied pressure and applied pump voltage, device output pressure, fluid temperature, or time, for example. Compression cycles may be repeated to accumulate sufficient data to quantify the standard deviation of the stiffness characteristics to establish baseline stiffness characteristics, or to accumulate sufficient data to distinguish between normal “variation” in the stiffness characteristics from statistically significant physiological changes in the subject. The data collected can also be used to chart or visualize flow rates and pressures, or other measurements, over the cycles or over time periods.
Further embodiments are directed to methods of detecting fluid flow changes in the body that may indicate the presence of deep vein thrombosis. One embodiment includes determining baseline stiffness characteristics as described herein and repeating the compression cycling and measurement of stiffness characteristics to compare the characteristics against the baseline data. The measurements can be taken at both higher and lower fluid flow rates to establish fill rate dependency in the baseline extremity stiffness characteristics at each rate. Changes in the stiffness characteristics beyond the baseline stiffness characteristics or the normal distribution of repeated baseline stiffness characteristic measurements signal the potential development of deep vein thrombosis and indicate a need for further investigation, diagnoses or treatment.
Other embodiments are directed to methods of detecting fluid flow changes in the body that may indicate the presence of deep vein thrombosis through the use of two or more bladder systems. In such cases one of the bladders systems and pumps is placed proximate to the heart of the patient and the other is placed distal to the heart around an extremity. The distal pump is actuated to supply the necessary displacement pressure or vacuum to cause the expansion of membranes or chambers or to cause the contraction of bellows elements, as applicable. Pump actuation continues until a first higher target pressure is achieved as measured by pressure sensors located in the bladder system, or by pressure sensors located on the bladder system adjacent to the extremity. The higher pressure in the distal pump is accomplished through coordinated valve actuation or pump modulation as previously described herein. The pressure in the bladders system is increased to cause constriction in the patient's extremity and hypertension in the patient's deep veins. The proximate pump is also actuated to supply the necessary displacement force or vacuum pressure to cause the expansion of membranes or chambers or to cause the contraction of bellows elements, as applicable. Proximate pump actuation continues until a second lower target pressure is achieved as measured by pressure sensors located in the bladder system or by pressure sensors located on the bladder system adjacent to the extremity. The target pressure in the proximate bladder is a lower reference pressure that supports venous flow feedback measurements. Maintenance of the lower target pressure in the proximate pump is accomplished through coordinated valve actuation or pump modulation as previously described herein. When the target pressures are reached the distal pump ceases actuation and the distal bladder system is commanded to release fluid or vacuum pressure. The extremity will swell as the distally accumulated fluid flows towards the proximate bladder system. The proximate bladder system will experience a transient increase in pressure from the extremity after which the proximate bladder system is then released and the reduction of vacuum pressure until the second lower pressure is achieved through powered or passive back feed. The time required to reach the lower target pressure in the proximate cuff again is measured and recorded. Throughout the entire process the pressure exerted by the distal bladder system as well as the pump voltage and fluid temperature are repeatedly measured until the second lower target pressure is reached. Associated time records and pump modulation parameters can also be recorded, as applicable. The data are recorded in storage components of the device or exported to an external memory. The data can be used to chart flow rates and pressure over cycle time periods. Repeated compression cycling and measurement of stiffness characteristics collects data to be used creating a baseline profile and data collected in subsequent cycles is compared to the baseline stiffness characteristics. Changes in the stiffness characteristics signal the potential development of deep vein thrombosis and indicate a need for further investigation, diagnoses or treatment.
Further embodiments are directed to methods to collect stiffness characteristics from different extremities such as both calves of a patient. Changes in these characteristics between the extremities may indicate the development of deep vein thrombosis in one of the legs and indicate a need for further investigation, diagnoses or treatment. These embodiments may be practiced with compression devices that employ interconnected chambers or contractible bellows in lieu of bladder systems. The methods may also be practiced with a combination of interconnected chambers and contractible bellows and bladder systems in the cuffs of the compression device. Such methods may also be modified to alert the patient or caregiver to the potential presence of deep vein thrombosis when measured characteristics, such as time periods for reaching certain pressure levels or flow rates during pressure reduction phases, differ from baseline measured characteristics. Increases in the time required to reach a second lower pressure or a reduction in the backfeed flow rate for example, may be characteristic of a reduction in the resistance of the targeted extremity against a known pressure or a reduction of the “spring constant” of an extremity. Such reductions may indicate the existence of blood clot. These methods may be repeatedly performed to assess the patient's baseline physiological characteristics as well as repeatedly performed to diagnose the existence of deep vein thrombosis. The methods may be further modified to alert the patient or caregiver when programmed thresholds are exceeded when faults have occurred when battery life is low, or when the actuators on different cuffs are cycling outside of programmed parameters. The operation of the compression devices may be suspended if failsafe conditions are exceeded.
In another embodiment software algorithms for device usage are modified according to an individual's body geometry such as leg or calf diameters, vital signs, baseline characteristics, range of motion, percentage muscle or fat on the patient's body, and other patient parameters that influence the device's ability to generate a predictable increase in venous flow. In addition, software algorithms may be modified based on statistical sampling or real-time sensor feedback.
Embodiments of the present invention utilize improved sensitivity in measurements via the described bladder systems that have highly sensitive pressure or flow rate sensors that measure minute changes in bladder volume and pressure which in turn reflect changes in limb or extremity volume displacement. Additionally, the compression devices can measure changes in resistive pressure in the extremity, with an increase in resistance indicating an increase in stiffness or pressure in the extremity and a potential diagnosis of thrombosis. Also, an increase in temperature of the extremity in the venous refill phase can also indicate the presence of thrombosis, as venous blood is trapped or obstructed. It will be clear to those in the art that the means for diagnosing deep vein thrombosis using the compression devices are not limited to the provided embodiments. It will also be clear that these embodiments may be combined to provide a highly sensitive measurement system with a compression device that can be used for the treatment of deep vein thrombosis or other circulatory condition or disorder.
In one embodiment the compression device applies intermittent or scheduled compressive pressure to an extremity. The device can be worn over any part of the body, including without limitation extremities such as the foot, ankle, calf, and thigh. A cuff substantially surrounds or envelopes the portion of the body to be treated. The cuff is then snugly secured in place around the patient's extremity. The compression device may include a bladder system that includes one or more elements that can be inflated, expanded and/or contracted. The compression device may be secured around the patient's extremity when the bladder system is unexpanded or minimally inflated. The inflatable or expandable elements, which are commonly placed adjacent to the body, expand under the influx of a compressible or an incompressible fluid and squeeze the extremity. The compression device also may be secured around the patient's extremity when the bladder system is not subject to vacuum pressure. The bladder system elements in these cases will contract under vacuum pressure to provide compressive pressure on the extremity.
The bladder system can include one or more membranes that are adjacent or near the patient's skin. The membranes may be attached or connected to a band that is secured around the patient's extremity. In other embodiments, the bladder system will include one or more cell-like chambers. The chambers may be separated by flexible dividers that allow the assembly of chambers to flex and form around the patient's extremity. When included in the device, the chambers may be expanded to provide compressive pressure on the extremity. In yet other embodiments, the bladder system may include one or more bellows that contract or expand in response to changing vacuum pressure levels. In these instances, contraction of the bellows increases the pressure of the device on the extremity. Of course, any combination of the above elements may be used in other embodiments.
The bladder systems of work in connection with a pump that may be pneumatic or hydraulic. Compressible or incompressible fluid may originate in a separate reservoir or container that is part of the device or separated from the device by appropriate tubing, channels or other delivery means. The fluid or gas reservoir, when connected to a closed bladder system, results in substantially silent operation without the noise associated with the exhaust of gas or fluid to the ambient environment. The pump may deliver gas or fluid to expandable elements or it may subject contractible elements to vacuum pressure. In some embodiments the pump is actuated by an electroactive polymer.
The pump may be designed to operate silently or substantially without noise. The pump works in connection with valves and/or sensors. Valves may be disposed between the bladder system elements and the sources of gas or incompressible fluid. Examples of valves include without limitation solenoid valves, proportioning valves, pinch valves, one-way valves, and valves comprising shape memory alloys such as nitinol. Examples of sensors include pressure sensors, flow rate sensors, temperature sensors, inertial (angular rate and acceleration) sensors, infrared sensors, current sensors, voltage sensors, proximity sensors, Hall effect sensors, touch sensors, quantum tunneling composite sensors, time-domain sensors, and frequency-domain reflectometry sensors.
In some embodiments, the functions of an integral valve, and sensors, are integrated into the pump. The pump, sensors and valves can be monitored and controlled by a control unit that is a permanently or removably attached component. The control unit may include batteries. power converters, high voltage power sources, microprocessors, digital processors, data storage devices, sensors, sensor interfaces, wireless communication circuitry, wireless data transmitters and receivers, visual displays, wireless interfaces, user interfaces, pumps, valves, manifolds and mechanical or electrical connectors.
In one embodiment, a compression device includes more than one bladder system or more than one pump but only a single control unit that coordinates operation of the bladder systems and pumps, as well as all of the valves and sensors in the device. The control unit may coordinate the pump and bladder operation to suit therapeutic need or patient comfort, including controlling the ramp-up of applied pressure or temperature. To improve patient comfort and ease of use, the control unit may be battery operated to improve portability.
In another embodiment includes one compression device on the patient's extremity. The operation of the bladder systems and pumps can be coordinated with respect to cyclic compression to meet therapeutic or patient needs. Coordination can be facilitated by wireless data transmitters and receivers located in the control units of the devices. Examples of suitable wireless communications include BLUETOOTH® wireless transmitters and receivers and radio frequency identification tags (RFID) and associated readers. In some embodiments the coordination between devices is alterable in response to input provided by the patient or the physician from a remote user interface.
Other embodiments are directed to treating patients with venous thrombosis by attaching a compression device to an extremity of the patient. The cuff of a compression device is placed around the extremity and is used to compress targeted portions of the patient's extremity, such as the calf muscle. The compressive pressure is generated by the circumferential contraction of the compression device around the extremity or by the inflation of a bladder adjacent to the extremity that is restricted by a substantially inelastic band or strap.
Still further embodiments are directed to methods of characterizing stiffness characteristics of a portion of an extremity around which the compression device is secured. The methods may be conducted with a compression device having a single bladder system that may provide compressive pressure actuation and sensory feedback simultaneously, thereby eliminating the need for a separate bladder system reference to provide additional sensory input. The pump of a device placed around the extremity is actuated to apply the necessary pressure or vacuum to cause the expansion of membranes or chambers or to cause the contraction of bellows elements, as applicable, while sensor elements record data such as pressure and volumetric displacement. Such measurements are recorded over multiple time intervals within each of one or more contraction cycles to quantify a stiffness characteristic as the relationship between applied pressure or force as a function of volumetric displacement or radial displacement as baseline physiological characteristics. The methods disclosed herein that utilize incompressible fluids enable the accurate estimation of volumetric displacement as a function of other easily measured values including but not limited to applied voltage, output pressure, fluid temperature, and time. Extremity stiffness characteristics may also include such measurements and comparisons.
Other methods are directed to collecting stiffness characteristics from different extremities such as both calves of a patient. Changes in these characteristics between the extremities may indicate the development of deep vein thrombosis in one of the lower legs and indicate a need for further investigation diagnoses or treatment. Still other methods include methods of detecting fluid flow changes in the body that may indicate the presence of deep vein thrombosis. These methods include determining baseline stiffness characteristics as described herein, and repeating the compression cycling and measurement of stiffness characteristics to compare the subsequently measured characteristics against the baseline data. Changes in the stiffness characteristics signal the potential development of deep vein thrombosis and indicate a need for further investigation, diagnoses or treatment.
Other methods include detecting fluid flow changes in the body that may indicate the presence of deep vein thrombosis through the use of two or more bladder systems and pumps to assess the venous fill characteristics of the targeted extremity. Other methods detect temperature changes in the body or detecting heat exchange between the body and the bladder system that may indicate the presence of deep vein thrombosis through the use of temperature sensors disposed on compression devices. Further methods provide massage to users through repeated compression on the targeted extremity.
One skilled in the art will understand that even though various embodiments and advantages of the present invention have been set forth in the foregoing description, the above disclosure is illustrative only, and changes may be made in detail, and yet remain within the broad principles of the invention. Moreover, the functions performed by various components described above may be implemented through circuitry or components other than those disclosed for the various embodiments described above. Moreover, the described functions of the various components may be combined to be performed by fewer elements or performed by more elements, depending upon design considerations for the device or system being implemented, as will appreciated by those skilled in the art. Therefore, the present invention is to be limited only by the appended claims.
The present application claims the benefit of copending U.S. Provisional Patent Application No. 61/380,198, filed Sep. 3, 2010, which application is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61380198 | Sep 2010 | US |
