Abstract:
An operating system for a medical device pump has a microprocessor controlling the operation of the pump features in a manner to minimize power consumption and maximize the life of the batteries powering the pump. The microprocessor associated with the medical device pump includes a modulation circuit that operates the pump on an intermittent basis and only when a pressure sensor indicates that the pressure asserted by the pump is at a threshold level. The operation of other sensors are powered only in situations when information from the sensor is needed, while other more essential sensors are operated on an intermittent basis by the modulation circuit. A fill sensor is operated intermittently, while a tilt sensor is only activated when a signal is received from the fill sensor. An optical sensor is only activated when the canister is removed from the pump housing, during which the pump is de-powered.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 61/620,608, filed on Apr. 5, 2012, the content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to negative pressure wound therapy system and, more particularly, to a control system that will control energy consumption from the battery powering the operation of the negative pressure pump. 
       BACKGROUND OF THE INVENTION 
       [0003]    Negative pressure wound therapy involves a bandage system that is applied to the wound site on the patient to create a seal around the perimeter of the bandage system and around a periphery of the wound to be treated. The negative pressure bandage system is provided with a connector that connects to a pump that draws a vacuum on the bandage system to urge any fluid and exudates within the wound site to move toward the pump through a conduit interconnecting the connector and the pump. A canister is connected to the conduit to intercept the fluids and exudates before reaching the pump to collect the fluids and exudates until the canister is filled to a predetermined level. Preferably, the canister can be removed from the pump housing and replaced when filled. 
         [0004]    In U.S. Pat. No. 6,139,982, granted to Kenneth W. Hunt, et al on Nov. 7, 2000, a negative pressure wound therapy apparatus is disclosed in which a canister is removably mounted in a pump housing and connected by a conduit to the pump to draw a vacuum on the canister. A separate conduit connects the canister to the negative pressure bandage system to draw the fluids and exudates from the wound being treated into the canister. A filter is provided at the outlet end of the canister where the conduit interconnecting the canister and the pump is located to prevent the introduction of the fluids and exudates collected into the canister from the bandage system into the pump. 
         [0005]    U.S. Pat. No. 7,004,915, issued to Thomas A. Boynton, et al on Feb. 28, 2006, discloses a canister that is connected by a first conduit to the negative pressure bandage system and by a second conduit to the pump that asserts a negative pressure on the canister through the second conduit, which vacuum is asserted through the canister to the first conduit and the connected bandage system. The canister incorporates first and second hydrophobic filters at the connection of the second conduit to the canister such that the first hydrophobic is adapted to operate as a fill sensor for the canister and the second hydrophobic filter further inhibits contamination of the pump by the collected fluids and exudates from the wound site. An odor filter is also provided between the first and second hydrophobic filters to counteract the production of malodorous vapors present in the collected wound exudates. 
         [0006]    In U.S. Pat. No. 7,611,500, granted on Nov. 3, 2009, to Cesar Z. Lina, et al, the canister includes an outlet that is plugged onto a port supported on the pump housing to connect the canister with the vacuum source. A switch carried on the pump housing closes when the canister is properly seated on the port. The canister incorporates a filter cap that allows the pump to draw air from the canister through the port and assert a vacuum on the negative pressure bandage system. The canister also incorporates a fill sensor in the form of a capacitive sensor that identifies a change in capacitance within the canister corresponding to the fluid level reaching the fill sensor located on the side of the canister near the outlet. 
         [0007]    U.S. Pat. No. 7,927,319, granted on Apr. 19, 2011, to Thomas Lawhorn, et al, discloses a leak detection system in a negative pressure wound therapy apparatus by monitoring the power consumption of the pump in comparison with a target power level such that a processing unit comparing the actual power level of the pump to a target power level triggers an alarm when the actual power level is greater than the target power level for a predetermined period of time, which identifies the presence of a leak in the exudates collection apparatus. In U.S. Pat. No. 7,876,546, granted to Christopher Locke, et al, on Jan. 25, 2011, discloses a modular component system for a negative pressure wound therapy apparatus that is respectively operated by the software driven control system. 
         [0008]    In each of the above-described negative pressure wound therapy devices, the fluids and exudates are drawn from the negative pressure bandage directly into the canister where the fluids and exudates are collected. Typically, the movement of the fluids and exudates is restricted from contaminating the pump by a hydrophobic filter that prevents the fluids and exudates from entering the vacuum line to the pump. The canister is preferably removable from the pump housing and disposed when filled, to be replaced by a new canister. With fill sensors specifically located on the canister, orientation of the canister is highly critical to prevent the fluids from being sensed by the fill sensor. 
         [0009]    Many known negative pressure wound therapy systems commercially available are portable devices, meaning that the pump and the canister are sufficiently small as to be capable of being attached to the patient and moved from one location to another as the patient moves about. The power to operate the pump is provided by a battery or by a battery pack that enables the negative pressure wound therapy apparatus to be completely portable. Powering a multi-component apparatus from disposable batteries having limited stored energy is difficult to maintain. Replacement of the bandage is typically performed by a medical care professional, at which time the disposable batteries can be easily replaced without interrupting the operation of the negative wound therapy. With a target of bandage replacement every 48-72 hours, battery power should preferably last for at least 72 hours before requiring replacement. 
         [0010]    It would thus be desirable to provide a control system for a multi-component negative pressure wound therapy apparatus that would provide energy saving function to enable the disposable batteries to operate the pump continuously for at least 72 hours. It would also be desirable to provide a software driven control system for a negative pressure wound therapy apparatus that is operable to conserve energy consumption. 
       SUMMARY OF THE INVENTION 
       [0011]    It is an object of this invention to overcome the disadvantages of the prior art by providing an energy saving operating system for a battery operated pump. 
         [0012]    It is another object of this invention to provide an energy saving operating system for the pump utilized in a negative pressure wound therapy system. 
         [0013]    It is an advantage of this invention that the battery powered pump will be operable for a maximum length of time without requiring a change of batteries. 
         [0014]    It is a feature of this invention that all non-essential features of the pump are shut down by the operating system until an operation of the feature is required. 
         [0015]    It is another feature of this invention that the fill sensor for the pump is operated intermittently to check levels within the canister collecting fluids from a negative pressure bandage. 
         [0016]    It is still another feature of this invention that the tilt sensor is actuated only if a signal is received from the fill sensor. 
         [0017]    It is yet another feature of this invention that the display screen is deactivated until a message needs to be sent from the microprocessor to the user of the negative pressure wound treatment apparatus. 
         [0018]    It is another advantage of this invention that the pump is operated intermittently and only when a pressure sensor provides an indication that the negative pressure is at a threshold value. 
         [0019]    It is a further feature of this invention that the optical sensor used to determine if the canister is properly mounted on the pump housing is activated only when the canister is removed from the pump housing until the canister has been properly mounted. 
         [0020]    It is still a further feature of this invention that the pump is not operated when the optical sensor is activated. 
         [0021]    It is yet another advantage of this invention that the power consumption of the pump is minimized while providing an effective operation of the pump. 
         [0022]    It is still another object of this invention that the pump includes a microprocessor to control the operation of the pump with the microprocessor incorporating a modulation circuit. 
         [0023]    It is a further advantage of this invention that the modulation circuit provides an intermittent operation of the pump as required by the microprocessor for the operation of the medical device associated with the pump. 
         [0024]    It is yet another object of this invention to provide a medical device pump with an operating system which is durable in construction, carefree of maintenance, and simple and effective in use. 
         [0025]    These and other objects, features and advantages are accomplished according to the instant invention by providing an operating system for a medical device pump in which the microprocessor controls the operation of the pump features in a manner to minimize power consumption and maximize the life of the batteries powering the operation of the pump. The microprocessor associated with the medical device pump includes a modulation circuit that operates the pump on an intermittent basis and only when a pressure sensor indicates that the pressure asserted by the pump is at a threshold level. The operation of other sensors are powered only in situations when information from the sensor is needed, while other more essential sensors are operated on an intermittent basis by the modulation circuit. A fill sensor is operated intermittently, while a tilt sensor is only activated when a signal is received from the fill sensor. An optical sensor is only activated when the canister is removed from the pump housing, while the pump is de-powered whenever the optical sensor is activated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows, in conjunction with the accompanying sheets of drawings. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention. 
           [0027]      FIG. 1  is an exploded front perspective view of a negative pressure wound system pump and canister incorporating the principles of the instant invention; 
           [0028]      FIG. 2  is an exploded rear perspective view of the negative pressure wound system pump and canister shown in  FIG. 1 ; 
           [0029]      FIG. 3  is a left side perspective view of the pump and canister shown in  FIGS. 1 and 2 , but depicting the initial engagement of the canister onto the pump housing; 
           [0030]      FIG. 4  is a left side perspective view of the pump and canister shown in  FIG. 3 , but having the canister about to latch onto the pump housing; 
           [0031]      FIG. 5  is a front perspective view of a negative pressure wound system with the assembled pump and canister connected to a negative pressure bandage; 
           [0032]      FIG. 6  is a logic flow diagram reflecting the operation of the tilt and level sensors in the control of the pump; and 
           [0033]      FIG. 7  is a schematic block diagram representing the control logic functions. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    Referring to  FIGS. 1-5 , a pump for a negative pressure wound therapy system  10  can best be seen. The system  10  includes a pump  11  mounted in a pump housing  12  that draws a vacuum from the vacuum port  13  for the purposes of extracting fluids and exudates from a negative pressure bandage  34 , as will be discussed in greater detail below. The pump housing  12  is provided with a display screen  15  and control buttons  16 - 19  for operating of the pump  11  and monitoring the function thereof. The top surface of the pump housing  12  is formed with a latch keeper  14  to retain the canister  20  on the pump housing in operative communication therewith, as will also be described in greater detail below. In the way of examples, the control buttons  16 - 19  can provide operations control for the pump  10 . The control button  16  can be used to set the operating pressure for the pump  10 . Control button  17  can be used to turn the pump  10  on and off to start or stop the negative pressure therapy. Control button  18  can define the mode of operation, such as continuous or intermittent operation of the pump  10 . Control switch  19  can be used to turn the electronics on and off, the powering of the electronics being necessary before the other control buttons  16 - 18  can be operated. 
         [0035]    The canister  20  is a hollow structure for collecting and storing the fluids and exudates extracted from the negative wound therapy bandage  34 . The canister  20  is detachably supported on the mounting ledge  25  of the pump housing  12  and operatively cooperable therewith to receive a vacuum therefrom and to apply that vacuum to the negative pressure bandage  34  to extract fluids and exudates therefrom. The canister  20  is formed with a latch member  22  at the upper edge thereof to be positionable for engagement with the latch keeper  14  on the pump housing  12 . Also, the bottom surface of the canister  20  is formed with a mounting tab  23  that is sized to insert into a positioning slot  24  formed in the housing ledge  25  to secure the canister  20  on the pump housing  12  and to assure that the canister  20  is properly mounted on the pump housing  12 . 
         [0036]    The canister  20  is provided with a receiver port  26  that is aligned with the vacuum port  13  when the canister  20  is properly mounted on the pump housing  12  so that the pump  11  can draw a vacuum on the canister  20 . The canister  20  is also provided with retainer holes  27  that receive retainer tabs  28  formed on the pump housing  12  to stabilize the positioning of the canister  20  on the pump housing  12 . The process to mount the canister  20  on the pump housing  12  is shown in  FIGS. 3 and 4 . The canister  20  is first positioned on the ledge  25  of the pump housing  12  so that the mounting tab  23  slides into the corresponding positioning slot  24 . The canister  20  is then rotated about the mounting tab  23  until the latch  22  snaps over the latch keeper  14  to secure the canister  20  onto the pump housing  12 . If the canister  20  is properly aligned, the retainer tabs  28  will fit into the corresponding retainer holes  27  to provide lateral stability for the canister  20  relative to the pump housing  12 . 
         [0037]    Because of the required connection of the vacuum port  13  within the receiver port  26  to enable proper operation of the negative pressure wound therapy system  10 , the pump housing  12  is provided with an optical sensor  30  that directs an infrared light onto a reflector  33  mounted on the canister  20 . If the reflector  33  is not properly aligned, i.e. perpendicular to the optical sensor  30 , the infrared light beam will not be reflected back into the infrared optical sensor  30 . The pump  11  is operably connected to the optical sensor  30  such that the receipt of a return signal from the reflector  33  is required in order for the pump  11  to be activated. Preferably, the optical sensor  30  will initiate a message on the display screen  15  to alert the user that the canister  20  is or is not properly aligned for operation of the pump  11 . 
         [0038]    Once the canister  20  is properly seated on the pump housing  12 , the pump  11  is free to operate and draw a vacuum through the vacuum port  13  engaged with the receiver port  26  into the canister  20 , which is turn is applied to the tubing  35  connected to the inlet port  36  of the canister  20  and extending to the negative pressure bandage  34 , as is shown in  FIG. 5 . Fluids and exudates are drawn into the canister  20  via the tubing  35  and fall to the bottom of the canister  20 . A hydrophobic filter (not shown) is preferably utilized on the interior side of the receiver port  26  to prevent the fluids and exudates from entering into the pump  11  via the vacuum port  13 . 
         [0039]    The canister  20  is provided with a pair of resister-type fill sensors  38  that project into the interior of the canister  20  and are connected to the microprocessor  51  mounted in the pump housing  12  via the contacts  37 , as is depicted in the schematic block diagram of  FIG. 7 . The fill sensors  38  are positioned adjacent the optical sensor  30  and the reflector  33  and provide a signal to the microprocessor  51  that fluid is cross-connecting the two fill sensors  38  which allows electrical current to cross from one fill sensor  38  to the other. The completion of that electrical circuit signals the microprocessor  51  that the fill sensors  38  are being engaged by fluid within the canister  20 . In addition, the pump housing  12  supports a tilt sensor  39  that can determine the direction and the angle at which the pump housing  12 , and therefore the canister  20 , is oriented. The signals from both the tilt sensor  39  and the fill sensors  38  are sent to the microprocessor  51  to control the operative function of the pump  11 . 
         [0040]    As can be seen in  FIG. 6 , the combination of the signals from the fill and tilt sensors  38 ,  39 , will control the operation of the pump  11 . The negative pressure therapy system  10 , specifically the pump  11  and canister  20 , will work most efficiently when the canister is oriented in an upright position. Thus, when the canister  20  is not in the upright position, the user needs to be informed of the inappropriate orientation so that the user can correct the orientation of the canister  20 . Preferably, the tilt sensor  39  will be able to ascertain the number of degrees of the tilt, but will have some latitude with respect to accuracy. For example, identifying the canister  20  at a vertical orientation can encompass a vertical orientation plus or minus a few degrees. 
         [0041]    As shown in  FIG. 6 , the process  40  begins at step  41  with a query as to whether the tilt sensor  39  is activated. If the tilt sensor  39  is not activated, the next query at step  42  defines whether the fill sensor  38  has been activated. If the fill sensor has not been activated, the operation of the pump  11  would continue as intended. If the fill sensor  38  has been activated at step  42 , the process is delayed for about twelve seconds and then at step  43  to provide assurance that the fill sensors  38  are not being activated by a splashing of the fluids within the canister  20 , which would present a false alarm. After the delay circuit is exhausted, the process  40  queries at step  43  whether either the fill sensor  38  or tilt sensor  39  status has changed. If no change in status is ascertained at step  43 , then the pump  11  is turned off automatically at step  45  as the canister  20  is full. If the status at step  43  has changed, the process starts again at step  41 . 
         [0042]    If at step  41 , the tilt sensor  39  has been activated, the process delays activity for eight seconds to provide a safeguard against a false signal due to movement of the canister  20  splashing fluids onto the fill sensors  38 . Then at step  44 , the process queries whether the tilt sensor  38  has undergone a status change. If at step  44  the tilt sensor  39  has a changed status, the process returns to step  41  to query if the tilt sensor  39  has been activated. If the response to the query at step  44  is in the negative, the process  40  queries the fill sensor  38  at step  46  to see if the fill sensor  38  has been activated. If the fill sensor  38  has not been activated, the process triggers an alarm, preferably both audible and visual, at step  47 , to inform the user to reorient the canister  20 , while the operation of the pump is paused until the canister has been returned to a vertical orientation. 
         [0043]    The process  40  then returns to step  44  to see if the status of the tilt sensor  39  has changed. The alarm will not be disengaged nor the pump returned to operation until the status of the tilt sensor  39  has changed at step  44 . If at step  46  the fill sensor  38  has been activated, the alarm is also triggered and the operation of the pump  11  is paused. If after sixty seconds at step  49  the status of the fill sensor has changed, then the process returns to step  41  to determine if the tilt sensor  38  is still activated. If at step  49  both the fill and tilt sensors  38 ,  39  remain activated, then the process will automatically shut down the pump  11  at step  45 . 
         [0044]    Referring now to the schematic diagram of the control system  50  in  FIG. 7 , one skilled in the art can see that the microprocessor  51  receives input from the fill and tilt sensors  38 ,  39 , to control the operation of the pump  11  in the manner described above. Furthermore, the optical sensor  30  is connected to the microprocessor  51  to control the initial start up of the pump  11 . Without the confirmation signal from the optical sensor  30 , the microprocessor  51  will not allow the pump  11  to start operation. The microprocessor  51  also receives confirmation signals from a pressure sensor  55  to monitor the negative pressure asserted through the vacuum port  13 . If the pressure rises or falls significantly, the pump  11  will also cease operating and provide a message to the user by the display screen  15  to inform the user of a pressure problem, which could be caused by a failure of the pump  11 , a plugged tubing  35 , or an overfilled canister  20 , among other things. The visual display of an alarm or of an error message or the like, is provided to the user via the LCD display screen  15  while the auditory alarm or signal is provided via a buzzer  59  operatively coupled to the microprocessor  51 . 
         [0045]    The control system  50  is operated by the software driven microprocessor  51  to control the respective components of the negative pressure wound therapy system  10  in a manner to conserve energy consumption from the disposable batteries  57 . Preferably, the components requiring power to operate, including the pump  11 , the valve  53 , the alarm  59 , and the LCD display screen  15 , including the LED indicator light and the screen back light, are selected to be of a low power consumption type for use in the system  10 . The pump  11  is the component that consumes the most energy to operate in drawing the fluids and exudates from the bandage  34  to the canister  20  for collection and removal from the system  10 . To control the energy consumption of the pump  11 , the microprocessor  51  incorporates a modulation circuit that is operable to drive the pump only when pressure in the canister  20  has dropped below a threshold level as sensed by the pressure sensor  55 . Thus, the pump  11  is not operated continuously, but intermittently, to maintain an effective operating vacuum within the canister  20  and the tubing  35  to the bandage  34 . 
         [0046]    All key components in the system  10  are controlled by the software stored in the microprocessor  51  in a manner that each respective component is only turned on to operate whenever the component is needed for operation of the negative pressure wound therapy system  10 . The valve  53  is operatively associated with the pump  11  to open and close when needed to allow the pump  11  to increase the level of the negative pressure applied to the canister  20 . Thus, the valve  53  is opened only when needed for the pump  11  to operate as defined by the pressure sensor  55 . Furthermore, not all of the sensor circuits will be active during the operation of the system  10 , unless the circuit is needed for operation of the system  10 . For example, the circuit for the optical sensor  30  is only active whenever the canister  20  is disengaged from the pump housing  12 . The circuit for the tilt sensor  39  can be turned off until the level sensor  38  indicates that the canister  20  appears to be filled. Then, the tilt sensor  39  and the level sensor  38  can operate as reflected in  FIG. 6 . The LCD display  15  can be deactivated unless the microprocessor  51  determines that a message needs to be sent to the user, such as an error message, or unless the user is selecting one of the control buttons  16 - 18  to make system adjustments or inquiries. 
         [0047]    A side benefit to the deactivation of components not absolutely needed for the operation of the negative pressure wound therapy system  10  is that the system  10  will have a quieter operation. With the pump  11  operating intermittently, the overall noise production of the pump  11  will be significantly lower than with a continuously operated pump  11 . Furthermore, the deactivation of key components and non-essential circuits also reduces noise production. As a result, the energy saving function of the microprocessor  51  will provide a more quietly operating system  10 . 
         [0048]    The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure.