Abstract:
A pump includes a canister for collecting fluids from a negative pressure wound therapy bandage in which the canister incorporates both tilt and fill sensors operatively connected to a microprocessor to control the operation of the pump in drawing fluids from the negative pressure bandage. The fill sensors include a pair of spaced sensor pins that convey a filled signal when fluid within the canister interconnects the two sensor pins. The tilt sensor is housed within the pump housing. The canister is also formed with an optical sensor that provides an indication of proper alignment of the canister on the pump housing. The optical sensor includes a reflector in the canister that reflects an infrared light emanating from the pump housing. When the light reflection is received properly within the pump housing, the canister is properly aligned and mounted on the pump housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 61/620,616, 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 an exudates canister co-operable with a pump providing a source of negative pressure for the bandage system to collect the exudates and fluid extracted from the negative pressure bandage. 
       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]    In each of the above-described prior art canisters, 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. 
         [0008]    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. To ensure that the fluid and exudates that have been removed from the wound site are not able to flow back into the wound site, or back to the bandage over the wound site, canisters are often provided with tilt sensors that are operably connected to the pump and determine the orientation of the canister. When the angle of tilt exceeds a certain allowed maximum, the operation of the vacuum pump is terminated. 
         [0009]    It would be desirable to provide a fluid and exudates collection system that is less dependent on orientation of the canister to operate properly. It would also be desirable to provide sensors that would accurately reflect the filling of the canister no matter how the canister is oriented with respect to vertical. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an object of this invention to overcome the disadvantages of the prior art by providing a pump for use with negative pressure wound therapy systems and having tilt and fill sensors that indicate when the pump canister is filled with fluid from the wound. 
         [0011]    It is another object of this invention to provide tilt and fill sensors for use on a pump having a canister for collecting fluids from a wound being treated with a negative pressure bandage. 
         [0012]    It is a feature of this invention that a microprocessor operatively coupled with the tilt and fill sensors to avoid a false indication of a full canister. 
         [0013]    It is an advantage of this invention that the negative pressure wound therapy apparatus is less dependent on orientation of the pump for operation. 
         [0014]    It is another advantage of this invention that the person being treated with negative pressure wound therapy is more capable of being mobile while being treated. 
         [0015]    It is still another advantage of this invention that the tilt sensor can be utilized to provide an indication that a triggering of the fill sensor is not indicative of a filled canister. 
         [0016]    It is another feature of this invention that the fill sensor is formed with a pair of spaced sensor pins that provide an indication of a filled canister when liquid in the canister contacts both sensor pins. 
         [0017]    It is a still another feature of this invention that the microprocessor ceases operation of the pump when the microprocessor receives a signal from the fill sensor without a signal from the tilt sensor. 
         [0018]    It is yet another feature of this invention that the microprocessor pauses the operation of the pump when a signal from the tilt sensor is received. 
         [0019]    It is yet another advantage of this invention that the pausing of the operation of the pump can be delayed for a period of time after the tilt signal is received to determine if the tilt signal remains activated. 
         [0020]    It is still another feature of this invention that the microprocessor can sound an alarm when the tilt sensor is activated. 
         [0021]    It is yet another feature of this invention that the microprocessor can cease operation of the pump when both the tilt and fill sensors are received. 
         [0022]    It is still another object of this invention that a pump providing a vacuum to a negative pressure wound therapy bandage which is durable in construction, carefree of maintenance, and simple and effective in use. 
         [0023]    These and other objects, features and advantages are accomplished according to the instant invention by providing a pump having a canister for collecting fluids from a negative pressure wound therapy bandage in which the canister incorporates both tilt and fill sensors operatively connected to a microprocessor to control the operation of the pump in drawing fluids from the bandage. The fill sensors include a pair of spaced sensor pins that convey a filled signal when fluid within the canister interconnects the two sensor pins. The tilt sensor is housed within the pump housing. The canister is also formed with an optical sensor that provides an indication of proper alignment of the canister on the pump housing. The optical sensor includes a reflector in the canister that reflects an infrared light emanating from the pump housing. When the light reflection is received properly within the pump housing, the canister is properly aligned and mounted on the pump housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    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. 
           [0025]      FIG. 1  is an exploded front perspective view of a negative pressure wound system pump and canister incorporating the principles of the instant invention; 
           [0026]      FIG. 2  is an exploded rear perspective view of the negative pressure wound system pump and canister shown in  FIG. 1 ; 
           [0027]      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; 
           [0028]      FIG. 4  is a left side perspective view of the pump and canister shown in  FIG. 3 , but having the canister about to patch onto the pump housing; 
           [0029]      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; 
           [0030]      FIG. 6  is a schematic front elevational view of the canister showing a vertical orientation with the canister fill sensors indicating a filled condition; 
           [0031]      FIG. 7  is a schematic side elevational view of the canister shown in  FIG. 6 ; 
           [0032]      FIG. 8  is a schematic front elevational view of the canister tilted to the right side at an angle of 30 degrees with the canister fill sensors indicating a filled condition; 
           [0033]      FIG. 9  is a schematic front elevational view of the canister tilted to the right side at an angle of 75 degrees with the canister fill sensors indicating a filled condition; 
           [0034]      FIG. 10  is a schematic front elevational view of the canister tilted to the left side at an angle of 30 degrees with the canister fill sensors indicating a filled condition; 
           [0035]      FIG. 11  is a schematic front elevational view of the canister tilted to the left side at an angle of 75 degrees with the canister fill sensors indicating a filled condition; 
           [0036]      FIG. 12  is a schematic left side elevational view of the canister tilted backward at an angle of 30 degrees with the canister fill sensors indicating a filled condition; 
           [0037]      FIG. 13  is a schematic left side elevational view of the canister tilted backward at an angle of 75 degrees with the canister fill sensors indicating a filled condition; 
           [0038]      FIG. 14  is a schematic left side elevational view of the canister tilted forward at an angle of 30 degrees with the canister fill sensors indicating a filled condition; 
           [0039]      FIG. 15  is a schematic left side elevational view of the canister tilted forward at an angle of 75 degrees with the canister fill sensors indicating a filled condition; 
           [0040]      FIG. 16  is a logic flow diagram reflecting the operation of the tilt and level sensors in the control of the pump; and 
           [0041]      FIG. 17  is a schematic block diagram representing the control logic functions. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0042]    Referring to  FIGS. 1-5 , a pump for a negative pressure wound therapy system can best be seen. The pump  10  is 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 powering the operation of the pump 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. 
         [0043]    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 . 
         [0044]    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  10  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 . 
         [0045]    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, 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  10  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  10  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  10 . 
         [0046]    Once the canister  20  is properly seated on the pump housing  12 , the pump  10  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  10  via the vacuum port  13 . 
         [0047]    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. 17 . 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  10 . 
         [0048]    As can be seen in  FIG. 16 , the combination of the signals from the fill and tilt sensors  38 ,  39 , will control the operation of the pump  10 . The negative pressure therapy system, specifically the pump  10  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. 
         [0049]    As shown in  FIG. 16 , 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  10  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  10  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 . 
         [0050]    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. 
         [0051]    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  10  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  10  at step  45 . 
         [0052]    The impact of the fluid content within the canister  20  when the canister  20  is tilted in various directions is depicted in  FIGS. 6-15 . The canister  20  is sized to retain approximately 111.5 ml of fluid when the canister  20  is oriented vertically, as is depicted in  FIGS. 6 and 7 . However, when the canister  20  is tilted 30 degrees to the right, as is depicted in  FIG. 8 , the volume of fluid required to activate the fill sensors  38  is 99.2 ml. At a tilt angle to the right of 75 degrees, as shown in  FIG. 9 , the volume of fluid needed to activate the fill sensors  38  is only 55.7 ml. Conversely, a tilting of the canister  20  to the left by 30 degrees, as is depicted in  FIG. 10 , will enable the canister  20  to retain 122.3 ml to activate the fill sensors  38 . At a left tilt angle of 75 degrees, as reflected in  FIG. 11 , the volume of fluid required to activate the fill sensors  38  is 121.6 ml. Accordingly, the microprocessor  51  must monitor both the tilt and fill sensor signals so that the canister  20  does not over fill. 
         [0053]    Forward and rearward tilt angles are shown in  FIGS. 12-15 . In  FIG. 12 , the canister  20  is tilted rearward by 30 degrees, resulting in 116.0 ml of fluid needed to activate the fill sensors  38 . Tilting the canister  20  backwards by 75 degrees, as shown in  FIG. 13 , requires 122.6 ml to activate the fill sensors  38 . Tilting the canister  20  forwardly by 30 degrees, as shown in  FIG. 14 , requires 116.7 ml of fluid to activate the fill sensors  38 , while a forward tilt of 75 degrees, as shown in  FIG. 15 , reduces the fluid volume to 80.8 ml to activate the fill sensors  38 . 
         [0054]    Referring now to the schematic diagram of the control logic in  FIG. 17 , one skilled in the art can see that the microprocessor  51  receives input from the fill and tilt sensors  38 ,  39 , to control the continued operation of the pump  10  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  10 . Without the confirmation signal from the optical sensor  30 , the microprocessor  51  will not allow the pump  10  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  10  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  10 , 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 . 
         [0055]    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.