Abstract:
A compression device includes a compression garment positionable on the limb of the wearer and having an inflatable bladder for providing compression treatment to the limb. A pump assembly is supported by the compression garment. The pump assembly is in fluid communication with the bladder for pressurized fluid delivery. The pump assembly includes at least first and second pumps. Passaging connects each of the first and second pumps for fluid communication with the inflatable bladder.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure generally relates to compression devices, and in particular to pumping fluid to and from compression devices. 
       BACKGROUND OF THE INVENTION 
       [0002]    Intermittent pneumatic compression (IPC) devices are used to improve circulation and minimize the formation of thrombi in the limbs of patients by applying compression treatment to the limb through a series of compression cycles. A compression garment that can be worn on a limb of a patient includes one or more inflatable bladders positioned to apply compression to the limb when the garment is being worn and one or more bladders in the garment are inflated. Some compression devices include pumps that use solenoid valves to deliver pressurized fluid to the bladder in the garment. Diaphragm pumps require an electric motor and other associated mechanical mechanisms to convert rotational motion into reciprocating motion of a diaphragm. One reason these types of pumps are used for compression devices is that their relatively high flow rates (between about 3-5 slpm at 1 psi of backpressure) are generally sufficient to meet the fluid flow demands of a conventional compression garment. 
         [0003]    A single pump is most commonly mounted in a controller that is separate from the compression garment. The controller is typically mounted on a bed or other support next to the patient and tubing carries the compressed air from the controller to the garment. The tubing can be at a minimum a nuisance and may also lead to a loss of full function of the compression device if the tubing becomes kinked or is laid upon by the patient. 
       SUMMARY 
       [0004]    In a first aspect, a compression device may generally comprise a compression garment positionable on the limb of the wearer and including an inflatable bladder for providing compression treatment to the limb. A pump assembly may be supported by the compression garment. The pump assembly may be in fluid communication with the bladder for pressurized fluid delivery. The pump assembly may comprises at least first and second pumps. Passaging may connect each of the first and second pumps for fluid communication with the inflatable bladder. 
         [0005]    In said first aspect, the pumps may be plumbed to each other in at least one of a parallel configuration and a series configuration. 
         [0006]    In said first aspect, a valve may be in fluid communication with each of the first and second pumps. The valve may be operable to selectively connect the first and second pumps in fluid communication with one another in parallel and to selectively connect the first and second pumps in fluid communication with one another in series. 
         [0007]    In said first aspect, a controller may be supported by the compression garment, the controller controlling the valve. 
         [0008]    In said first aspect, the controller may be configured to fluidly connect the first and second pumps in parallel when a pressure in the inflatable bladder is equal to or below a predetermined threshold and to fluidly connect the first and second pumps in series when the pressure in the inflatable bladder exceeds the predetermined threshold. 
         [0009]    In said first aspect, the pump assembly may further comprise a third pump in fluid communication in parallel with the first pump. The valve may be adapted to selectively fluidly connect the first and third pumps in fluid communication in series with the second pump and to selectively connect the first and third pumps in fluid communication in parallel with the first pump. 
         [0010]    In said first aspect, a controller may control the valve. 
         [0011]    In said first aspect, the first and second pumps may each comprise a housing defining an inlet manifold and an outlet manifold. A nipple may project from one of the inlet and outlet manifolds. A first port may communicate with the inlet manifold and a second port may communicate with the outlet manifold. The nipple of the first pump may be adapted for selective sealing reception in the first port of the second pump and in the second port of the second pump. 
         [0012]    In said first aspect, the first and second pumps may each be piezoelectric pumps. 
         [0013]    In a second aspect, a method of delivering pressurized fluid to a compression garment may generally comprise operating at least two pumps of a pump assembly during a compression cycle in a first configuration for delivering pressurized fluid to a compression garment during the compression cycle for compressing a part of a wearer&#39;s body. During the compression cycle, the first arrangement may be changed so that the at least two pumps are arranged in a second arrangement, different from the first arrangement, for delivering pressurized fluid to the compression garment. 
         [0014]    In said second aspect, in the first configuration, the at least two pumps may be arranged in one of series and parallel and, in the second configuration, the at least two pumps may be arranged in the other of series and parallel. 
         [0015]    In said second aspect, operating the pumps in parallel when a pressure in the compression garment is equal to or below a predetermined threshold and operating the pumps in series when the pressure exceeds the predetermined threshold. 
         [0016]    In said second aspect, the predetermined threshold may be about 60 mmHg. 
         [0017]    In said second aspect, operating the at least two pumps in the first configuration may comprise moving a valve to one position and operating the at least two pumps in the second configuration may comprise moving the valve to another position different from said one position. 
         [0018]    In said second aspect, in the first configuration, two pumps of the pump assembly may be arranged in parallel, and in the second configuration the two pumps may be placed in fluid communication with a third pump such that the two pumps in parallel are arranged in series with the third pump. 
         [0019]    In said second aspect, operating the pumps in the first configuration when a pressure in the compression garment is below about 50 mmHg, and operating the pumps in the second configuration when the pressure in the inflation garment exceeds about 50 mmHg. 
         [0020]    In a third aspect, a modular pump assembly for use in a compression device may generally comprise a first modular pump including a housing defining an inlet manifold and an outlet manifold. A pumping unit may be disposed for receiving fluid from the inlet manifold and exhausting fluid into the outlet manifold. A nipple may project from one of the inlet and outlet manifolds. A first port may communicate with the inlet manifold and a second port may communicate with the outlet manifold. A second modular pump may include a housing defining an inlet manifold and an outlet manifold. A pumping unit may be disposed for receiving fluid from the inlet manifold and exhausting fluid into the outlet manifold. A nipple may project from one of the inlet and outlet manifolds. A first port may communicate with the inlet manifold and a second port may communicate with the outlet manifold. The nipple of the first pump may be adapted for selective sealing reception in the first port of the second pump or in the second port of the second pump. The nipple of the second pump may be adapted for selective sealing reception in the first port of the first pump or in the second port of the first pump. 
         [0021]    In said third aspect, the first pump may comprise a valve located in one of the first and second ports thereof and the second pump may comprise a valve located in one of the first and second ports of the second pump. 
         [0022]    In said third aspect, the valve of the second pump may be disposed in the second port of the second pump. The nipple of the first pump may be configured to open the valve of the second pump upon insertion of the nipple of the first pump into the second port of the second pump, placing the outlet manifold of the first pump in fluid communication with the outlet manifold of the second pump. 
         [0023]    Other objects and features will be apparent from the drawings and description and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a block diagram of a compression device. 
           [0025]      FIG. 2  is a schematic of a modular pump of the compression device of  FIG. 1 . 
           [0026]      FIG. 3A  is a schematic of a modular pump assembly including two modular pumps in series. 
           [0027]      FIG. 3B  is a schematic of a modular pump assembly including two modular pumps in parallel. 
           [0028]      FIG. 4  is a schematic of an out-of-plane configuration of a modular pump. 
           [0029]      FIG. 5  is a graph illustrating flow rate of various pump assemblies over a pressure range. 
           [0030]      FIGS. 6A-6E  are schematics of different pump arrangements. 
           [0031]      FIG. 7  is a graph illustrating flow rate of various pump assemblies over a pressure range. 
           [0032]      FIG. 8A  is a schematic of a two-pump assembly including a three way valve in communication with the pumps. 
           [0033]      FIG. 8B  is a schematic of a three-pump assembly including a three way valve in communication with the pumps. 
       
    
    
       [0034]    Corresponding reference characters indicate corresponding parts throughout the drawings. 
       DETAILED DESCRIPTION 
       [0035]    Referring to  FIGS. 1-2 , a compression device  11  applies repeated, sequential compression therapy to a limb of a wearer. The compression device  11  includes a garment  13  sized and shaped to be wrapped around a leg or other limb of the wearer. A pump assembly  15  is fluidly connected to the garment  13  through conduit  17  for selectively pressurizing a bladder  19  of the garment by introducing gas (e.g., air) into the bladder. A controller  21  includes a processor  23  operatively connected to the pump assembly  15  for controlling the pressurization of the garment  13 . A pressure sensor  25  is operatively connected to the processor  23  and coupled to the bladder  19  through the conduit  17  for measuring pressure in the bladder. Although a single bladder  19  is illustrated, the garment  13  can have two or more bladders. Moreover, while the conduit  17  and the controller  21  are shown as being incorporated into the garment  13 , a controller and/or tubing may be separate from the garment and bladder. 
         [0036]    The modular pump assembly  15  may include two or more modular pumps  31 , one of which is schematically illustrated in  FIG. 2 . The modular pump includes a first port  33  leading to an inlet manifold  35 , a pumping unit  37  in fluid communication with the inlet manifold, an outlet manifold  39  in fluid communication with the pumping unit, and an outlet including a nipple  41 . A second port  43  is located in the outlet manifold  39  on an end opposite the outlet nipple  41 . A valve  45  can be disposed in the outlet manifold  39  to prevent fluid from escaping (or entering) the outlet manifold through the second port  43 , as will be explained in greater detail below. The modular pump  31  can be micro pump, such as a piezoelectric pump, capable of about 1 slpm of flow under a backpressure of about 1 psi. Additionally or alternatively, the modular pump  31  can be another type of micropump (e.g., diaphragm, gear, piston, peristaltic, electroosmotic, electrohydrodynamics, magnetic, etc.). Moreover, it should be appreciated that that modular pump  31  can be a type of pump that is not a micropump. Still further, the pumps are shown as modular (e.g.,  FIGS. 3A-4 ), non-modular pumps may be used such that the pumps may be plumbed together in a fixed arrangement. 
         [0037]    Conventional compression devices typically use diaphragm pumps capable of between about 3-5 slpm of flow at 1 psi of backpressure. However, a single modular pump, which cannot operate in this range, may not be sufficient to meet the pressure requirements of a conventional compression device. To meet these pressure requirements, multiple modular pumps are combined to dynamically increase the overall flow rate of the pumps in a scalable and/or incremental manner. The modular pumps  31  can be combined in a variety of ways. For example, the pumps  31  can be combined in series such that an outlet nipple  41  of a first pump P 1  is connected to the first port  33  of a second pump P 2  ( FIGS. 3A and 6A ). As another example, the pumps  31  can be combined in parallel such that the outlet nipple  41  of the first pump is connected to the second port  43  of the second pump ( FIGS. 3B and 6B ). The valve  45  of the second pump P 2  prevents fluid from escaping the second port  43  when the pumps are connected in series. The valve can be an elastomeric (e.g., silicone) membrane which has slits such that insertion of nipple  41  opens the valve for pneumatic communication. Any number of pumps can be combined in series and/or parallel subject to the structural and operational limits of the pump design. The pumps are shown such that manifolds are “in-plane” (i.e., inlet and outlet of the pump extend in the same direction). However, the pumps could be configured such that the manifolds of a given pump are out of plane. In the out of plane configuration, the outlet  41  of a pump  31  can be turned to be, for example, orthogonal to the inlet  33  ( FIG. 4 ). In other examples, the outlet  41  can be disposed relative to the inlet  33  at an angle other than 90 degrees. This out of plane configuration can, for example, make combining the pumps easier and provide a more compact pump assembly. 
         [0038]    Referring now to  FIG. 5 , an experimentally determined comparison of flow rate versus pressure for a single modular pump and various series and parallel pump combinations is shown. Generally, combining the pumps in series increases the operating range of the pumps (i.e., the pumps will operate at a higher backpressure than a single pump), but does not increase the maximum flow rate. However, the flow rate from the combined pumps in series does not diminish at increasing backpressure at the same rate as for a single pump so that higher flow rates may be attained through the range between the boundaries. Combining the pumps in parallel does not increase the overall pressure range of operation of the pump assembly as compared to a single pump, but increases the maximum flow output at lower backpressures. As shown in  FIG. 5 , the maximum output is nearly doubled for combined pumps in parallel as compared to a single pump, and remains higher at each pressure in the range until the maximum operating backpressure. Thus, in general, running the pump assembly in parallel increases the pneumatic output of the pump assembly at lower pressures, while at higher backpressures it is more beneficial to run the pump assembly in series. 
         [0039]    As mentioned above, the pump assembly  15  can have configurations other than the two-pump series and parallel arrangements described above. For example, the pump assembly  15  may include three or more pumps arranged in various series and parallel configurations.  FIG. 6C  shows a three-pump circuit including a first pump P 1 , a second pump P 2 , and a third pump P 3 . The first pump P 1  is in series with pump P 2 . The series pumps P 1 , P 2  are then together arranged in parallel with pump P 3 .  FIG. 5  shows that this configuration provides increased flow capacity in comparison to the two-pump configurations and the single pump over the entire working range of the pump assembly. 
         [0040]      FIG. 6D  shows a three-pump circuit including two pumps P 1 , P 2  in parallel with each other. An output manifold of the two pumps is in series with a third pump P 3 . 
         [0041]      FIG. 6E  shows a three-pump circuit including a first pump P 1  in series with an inlet manifold of second and third pumps P 2 , P 3  which are in parallel with each other. 
         [0042]      FIG. 7  shows the experimentally determined flow rates of the pump circuits shown in  FIGS. 6A ,  6 B, and  6 D over a pressure range of 0-200 mmHg.  FIG. 7  also shows flow profiles for the pump circuit shown in  FIG. 6D  with the third pump P 3  in various operating configurations (off, 12V, 18V, 25V). The results shown in  FIG. 7  indicate that, depending on the fluid pressure in the device, it may be desirable to use different pump arrangements to maximize flow output. 
         [0043]    To take advantage of the varying fluid flow capabilities of the disclosed configurations, it is possible to construct a pump assembly that can switch between the disclosed configurations. For instance, a valve  51  ( FIG. 8A ) can be disposed in fluid communication between first and second pumps P 1 , P 2  to selectively place pump P 1  in series or in parallel with pump P 2 . The valve  51  can be switched to a first position where the outlet of pump P 1  is fluidly connected to the inlet of pump P 2  (series), or to a second position where the outlet of P 1  is fluidly connected to an outlet of P 2  via the second inlet (parallel). In the illustrated embodiment, the valve  51  is a 3-way/3-position piezo valve. A check valve  52  prevents the pneumatic output of P 1  from being lost to the environment when pump P 1  is in series with pump P 2 . 
         [0044]    Referring to  FIG. 7 , it can be seen that a transition point TP 2  indicates the pressure level where the performance of the two-pump parallel configuration falls below the two-pump series configuration. 
         [0045]    The valve  51  can also be used to switch between the arrangements shown in  FIGS. 6B and 6D  (see  FIG. 8B ). In the pump assembly configuration shown in  FIG. 8B , first and second pumps P 1 , P 2  are arranged in parallel and the valve  51  is disposed between the outlet of P 1  and P 2  and a third pump P 3 . The valve  51  can be switched to a first position where the outlet of P 1  and P 2  is fluidly connected to an outlet passage  53  bypassing P 3  so that that the pump assembly is arranged in the two-pump parallel configuration shown in  FIG. 63 . This configuration presupposes that P 3  is turned to an off position. If P 3  is turned on then the three pumps P 1 , P 2 , P 3  will all be arranged in parallel. The valve  51  can also be switched to a second position where the outlet of P 1  and P 2  is fluidly connected to the inlet of P 3 , placing P 3  in series with P 1  and P 2  and producing the pump assembly shown in  FIG. 6D . 
         [0046]    Referring to  FIG. 7 , it can be seen that a transition point TP 1  indicates the pressure level where the performance of the two-pump parallel configuration in  FIG. 6B  falls below the configuration in  FIG. 6D . Therefore, during operation of the compression device  11 , the processor  23  can operate the pump assembly  15  to switch between the various pump arrangements to optimize flow output over the entire pressure range based on feedback from the pressure transducer. 
         [0000]    Referring again to the arrangement of  FIG. 8B , as compression treatment is initiated (bladder pressure=0) and fluid is pumped into the bladder  19 , the processor  23  can switch the valve  51  to the first position, placing pumps P 1 , P 2  in parallel and bypassing pump P 3  so that the device  11  is operating at an optimal flow capacity as pressure increases from 0 mmHg ( FIG. 7 ). Once the processor  23  determines that the pressure sensor  25  has measured a pressure in the bladder  19  exceeding a predetermined threshold (e.g., about 50 mmHg), the processor  23  can switch the valve  51  to the second position, placing pumps P 1  and P 2  in series with pump P 3  for superior performance in the higher pressure range. In summary, operation of the device  11  where the pressure in the bladder  19  is between about 0 and about 50 mmHg (or initiation of a new cycle) causes the processor  23  to switch the pump assembly  15  to the two-pump parallel arrangement shown in  FIG. 6B , and operation of the device where the pressure in the bladder exceeds about 50 mmHg causes the processor to switch the pump assembly to the three-pump parallel/series configuration shown in  FIG. 6D . It will be understood that this can be achieved by operating the valve  51  shown in  FIG. 8B . As a result, flow output is optimized during the entire compression cycle for this pump assembly. 
         [0047]    By way of another example, if the pump assembly has the configuration shown in  FIG. 8A , where the valve  51  is between pumps P 1  and P 2 , as compression treatment is initiated (pressure=0) and fluid is pumped into the bladder  19 , the processor can switch the valve  51  to the second position placing the pumps P 1 , P 2  in parallel so that the device  11  is operating at an optimal (high) flow capacity as pressure increases from 0 mmHg ( FIG. 7 ). The pressure sensor  25  monitors the pressure in the bladder  19  as compression treatment is continued. Once the processor  23  determines that the pressure sensor  25  has measured a pressure in the bladder  19  that exceeds a predetermined threshold (e.g., 60 mmHg), the processor  23  can switch the valve  51  to the first position placing the pumps P 1 , P 2  in series. The changeover occurs about at the point labeled TP 2  in  FIG. 7 . Thus, operation of the device  11  where the pressure in the bladder  19  is between about 0 and about 60 mmHg (or upon initiation of the new cycle) causes the processor  23  to switch the pump assembly  15  to the parallel arrangement ( FIG. 6B ), and operation of the device where the pressure in the bladder exceeds about 60 mmHg signals to the processor to switch the pump assembly to the series arrangement ( FIG. 6A ). The changeover occurs approximately where transition point  2  (TP 2 ) is identified on  FIG. 7 . It is to be understood that the change in configuration between  FIGS. 6B and 6A  can be achieved by operation of the valve  51  shown in  FIG. 8A . As a result, flow output is optimized during the entire compression cycle. Other possible ways of controlling or setting the configuration of the pumps may additionally or alternatively be used. In  FIG. 7 , four results for using two pumps in parallel with each other in combination with a third pump in series are shown. The difference between these four results is the operating strength of the third pump (i.e., 0V, 12V, 18V or 25V). 
         [0048]    Modifications and variations are possible without departing from the scope of this disclosure. 
         [0049]    When introducing elements in the present disclosure, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
         [0050]    In view of the above, it will be seen that the several objects are achieved and other advantageous results attained. 
         [0051]    As various changes could be made in the above constructions and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.