FIELD OF INVENTION 
       [0001]    This invention relates generally to peristaltic pumps used to deliver fluids to patients by way of a pump set, and more particularly to a peristaltic pump that compensates for conditions of the pump set. 
       BACKGROUND 
       [0002]    Administering fluids containing medicine or nutrients to a patient is well known in the art. Typically, fluid is delivered to the patient by a pump set loaded on a flow control apparatus, such as a peristaltic pump, which delivers fluid to the patient at a controlled delivery rate. A peristaltic pump usually comprises a housing enclosing a rotor or the like operatively connected to at least one motor by a gearbox. The rotor drives fluid through tubing of the pump set by peristaltic action caused by rotation of the rotor driven by the motor. The motor is operatively connected to a rotatable shaft connected to the rotor, which progressively compresses the tubing and drives the fluid at a controlled rate through the pump set. The pump set may have a type of valve mechanism for permitting or preventing fluid flow through the pump set. A controller operates the motor or motors used to drive the rotor and, in some cases, controls fluid flow as by operation of the valve mechanism. 
         [0003]    Peristaltic pumps operate by delivering fluid in small charges called “aliquots”. The rotor engages the tubing of the pump set, pinching off a portion of the tubing and pushing fluid ahead of the pinch point (i.e., closer to the patient than to the source of fluid) toward the patient. Typically, the volume of fluid to be administered to the patient is controlled in the pump by counting the number of aliquots, each being of substantially the same volume, and stopping when the number corresponds to a cumulative volume of fluid desired to be delivered. Peristaltic pumps are sanitary and generally highly accurate and therefore very useful in the administration of medication and therapeutic fluids to the patient. However, the accuracy of the pump is dependent upon the dimensional stability of the tubing of the pump set. Over time the pump set tubing can be plastically (i.e., permanently) deformed so that the volume of each aliquot changes. Also, new pump sets can come in various diameters and lengths which can also affect the volume of each aliquot. Therefore, there exists a need for a compensating mechanism to account for the changes in the pump set over time as well as for dimensional variances between pump sets. 
       SUMMARY OF INVENTION 
       [0004]    In one aspect of the present invention, a pumping apparatus for use with a pump set to deliver fluid through the pump set generally comprises a housing capable of receiving at least a portion of the pump set. A pumping device is moveably mounted in the housing and includes a motor that turns independently from movement of the pumping device when activated. The pumping device contacts the pump set when the pump set is received by the housing so the pumping device acts on the pump set to produce fluid flow in the pump set upon activation of the motor. 
         [0005]    In another aspect of the present invention, a pumping apparatus for use with a pump set to deliver fluid through the pump set generally comprises a housing capable of receiving at least a portion of the pump set. A pumping device is capable of acting on the pump set to produce fluid flow within the pump set. The pumping device contacts the pump set when the pump set is received by the housing. The pumping apparatus detects a force applied to the pumping device by the pump set. 
         [0006]    Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective of an enteral feeding pump; 
           [0008]      FIG. 2  is a side elevation thereof showing a fragmentary portion of a feeding set received in the pump; 
           [0009]      FIG. 3  is the side elevation of  FIG. 2  with the feeding set removed; 
           [0010]      FIG. 4  is an exploded perspective of the pump; 
           [0011]      FIG. 5  is a schematic of a pumping unit and positioning sensor mounted in the pump; 
           [0012]      FIG. 6  is a perspective of the feeding set; 
           [0013]      FIG. 7  is a schematic of the pumping unit and positioning sensor having the feeding set loaded on the pumping unit in a zero displacement operational condition; 
           [0014]      FIG. 8  is a block diagram of the components of the enteral feeding pump; 
           [0015]      FIG. 9  is a schematic of the pumping unit and positioning sensor having the feeding set loaded on the pumping unit in a positive displacement operational condition; and 
           [0016]      FIG. 10  is a schematic of the pumping unit and positioning sensor having the feeding set loaded on the pumping unit in a negative displacement operational condition. 
       
    
    
       [0017]    Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0018]    Referring now to the drawings, an enteral feeding pump (broadly, “flow control apparatus”) constructed according to the principles of the present invention is generally indicated at  1 . The feeding pump comprises a housing generally indicated at  3  that is constructed so as to mount a feeding set (broadly, a “pump set”) generally indicated at  5  (see  FIG. 6 ). The housing  3  includes a hinged door  7  for swinging between a closed position ( FIG. 1 ) and an open position ( FIG. 2 ), in which a portion of the pump  1  that receives the feeding set  5  is exposed. It will be appreciated that “housing” as used herein may include many forms of supporting structures (not shown), including without limitation multi-part structures and structures that do not enclose or house the working components of the pump  1 . The pump  1  may also have a display screen generally indicated at  9  on the front of the housing  3  that is capable of displaying information about the status and operation of the pump. Buttons  11  on the side of the display screen  9  can be provided for use in controlling and obtaining information from the pump  1  and three light emitting diodes  13  can provide status information for the pump. Legs  15  at the bottom front of the housing  3  support the housing so that the display screen  9  is angled slightly upward for ease of viewing. 
         [0019]    It should be understood that although the illustrated pump  1  is an enteral feeding pump, the present invention has application to other types of peristaltic pumps (not shown), including medical infusion pumps. The general construction and operation of the enteral feeding pump  1 , except as set forth hereinafter, may be generally the same as disclosed in co-assigned U.S. Pat. No. 7,462,170 filed May 24, 2004, entitled ADMINISTRATION FEEDING SET AND VALVE MECHANISM; U.S. Pat. No. 7,608,059 filed May 24, 2004, entitled FLOW CONTROL APPARATUS; U.S. Pat. No. 7,092,797 filed May 25, 2004, entitled FLOW MONITORING SYSTEM FOR A FLOW CONTROL APPARATUS; and U.S. Pat. No. 7,534,009 filed Sep. 30, 2005, entitled ALIQUOT CORRECTION FOR FEEDING SET DEGRADATION the disclosures of which are incorporated by reference. Moreover, although an exemplary feeding set  5  is shown, other types of pump sets (not shown) can be used without departing from the scope of the present invention. 
         [0020]    Referring now also to  FIG. 4 , the display screen  9  is part of a front panel (generally indicated at  19 ) of the housing  3  removably attached to a main compartment (generally indicated at  21 ) of the housing that holds most of the operating components of the pump  1 . The enteral feeding pump further includes a pumping unit (shown separated from the main compartment and indicated generally at  23 ) comprising a pump motor  25  connected to a rotor shaft  27  and also to a valve shaft  29  (see,  FIG. 3 ). It will be understood that the valve shaft  29  could be omitted, and/or that a separate motor (not shown) could be provided to operate the valve shaft without departing from the scope of the present invention. A battery  31  may be received in the main compartment  21  of the housing  3  for powering the pump motor  25 . A battery door  33  hingedly attached to the rear of the main compartment  21  closes the battery  31  within the compartment and provides access as needed. A fastener  35  holds the battery door  33  closed so that access to the battery  31  is normally limited. Of course, a power source other than or in addition to a battery could be used. 
         [0021]    A rotor (generally indicated at  37 ) is mounted on the rotor shaft  27  of the pumping unit  23  by a bolt  42 . The rotor  37  includes an inner disk  39 , an outer disk  41 , and three rollers  43  (only one of which is shown) mounted between the inner and outer disks for rotation relative to the disks about their longitudinal axes. In the illustrated embodiment, the pump motor  25 , rotor shaft  27  and rotor  37  may broadly be considered “a pumping device”. It should be understood that peristaltic pumps that use mechanisms other than rollers may be used without departing from the scope of the present invention. For example, a linear peristaltic pump could be used without departing from the scope of the present invention. The roller  43  engages the feeding set  5 , which is also received in first and second chutes (designated  45  and  47 , respectively) formed on a faceplate  49  of the pumping unit  23 . The pump motor  25  is also mounted on the faceplate  49 . The first and second chutes  45 ,  47  receive portions of the feeding set  5 , as will be described in more detail hereinafter. The door  7  covers the chutes  45 ,  47  and rotor  37  when it is closed as shown in  FIG. 1 . Other fasteners  51  hold various components of the pump  1  together. 
         [0022]    Referring to  FIG. 5 , a mount  53  fixed to a back end of the motor  25  pivotably attaches the motor inside the main compartment  21  of the housing  3 . A pivot pin  54  extends between opposite side walls  56  (only one of which is shown in  FIG. 5 ) in the compartment  21  and through an opening  58  in the mount  53  to pivotably mount the motor  25  in the housing  3 . A spring  60  attached to a top wall  62  of the compartment  21  connects to a top of the motor  25  at a front end of the motor. The spring  60  partially supports the weight of the motor  25  such that in a resting position (without the feeding set  5  mounted on the rotor  37 ) the motor  25  is deflected downward so a central axis CA of the motor extends about 15 degrees below horizontal. A linear potentiometer  81  (broadly, “a sensor”) is mounted to a bottom wall  64  of the compartment  21  below the motor  25  and is attached to a bottom of the motor. The sensor  81  detects the displacement of the motor  25 . Although other potentiometers may be used without departing from the current invention, in one embodiment the potentiometer is a linear potentiometer. It should be understood that other sensors such as pressure sensors for measuring the force applied to the pumping unit  23  can be used with or in place of the potentiometer  81 . 
         [0023]    Referring now to  FIG. 6 , the feeding set  5  comprises tubing, indicated generally by  55 , that provides a fluid pathway between at least one fluid source and a patient. In one embodiment, tubing  55  is made of a medical grade, deformable silicone and comprises a first tube section  57  connected between a valve mechanism  59  and a mounting member  61 . A second tube section  63  is connected to the mounting member  61  and at an outlet of the tubing  55  to a connector, such as a barbed connector  65 , suitable for connecting to a gastrostomy device (not shown) attached to a patient. A third tube section  67  is connected to an inlet of the tubing  55  to a bag  69  of feeding fluid and to valve mechanism  59 , and a fourth tube section  71  is connected to an inlet of the tubing  55  of a bag  73  of flushing fluid and to the valve mechanism. The valve mechanism  59  is operable to selectively permit flow of feeding fluid from the bag  69  or flushing fluid from the bag  73 , or prevent any fluid flow from the feeding or flushing fluid bags  69 ,  73  to the first tube section  57 . The valve mechanism  59  can be turned to three positions. The first closes off all fluid flow from the third and fourth tube sections  67 ,  71  to the first and second tube sections  57 ,  63 , the second allows feeding fluid to flow from the bag  69  to the first and second tube sections, and the third allows flushing fluid to flow from the bag  73  to the first and second tube sections. As previously stated, pump sets of different constructions may be used without departing from the scope of the present invention. As will be explained in greater detail below, the pump  1  is configured to adjust to the particular feeding set installed so the appropriate volume of aliquot is delivered. Examples of suitable pump sets (including valve mechanisms) are shown in co-assigned U.S. Pat. No. 7,462,170, previously incorporated by reference. 
         [0024]    In use, the feeding set feeding fluid bag  69  and flushing fluid bag  73  can be hung from a suitable support, such as an IV pole (not shown). The door  7  on the side of the pump  1  is opened and the valve mechanism  59  is placed in the first chute  45  so the valve shaft  29  of the pump is engaged with the valve mechanism ( FIG. 2 ). Thus, rotation of the valve shaft  29  controls in which of the three positions the valve mechanism  59  is placed. The first tube section  57  is positioned around the lower part of the rotor  37  and the mounting member  61  is placed in the second chute  47 . The second chute is generally funnel-shaped so the mounting member  61  can be placed in the chute  47  at a location so the first tube section  57  is substantially stretched around the rotor  37 . The first tube section  57  can relax slightly, pulling the mounting member  61  farther down in the second chute  47 . However, the first tube section  57  is maintained in a stretched condition around the rotor  37  when properly installed on the pump  1 . The door  7  can be closed to cover the first and second chutes  45 ,  47  and the rotor  37 . The connector  65  at the end of the second tube section  63  can be connected to a conduit (not shown) attached to the patient in a known manner. It should be understood that any suitable connector for delivering the fluid to the patient may be used without departing from the scope of the present invention. 
         [0025]    In the stretched condition, the first tube section  57  causes the feeding set  5  to apply an upward force on the rotor  37 . This upward force causes the motor  25  to pivot on the pivot pin  54 , displacing the motor upward in proportion to the amount of the force applied by the feeding set  5  ( FIG. 7 ). A feeding set of the customary length (e.g., about 4.75 in), when properly loaded in the pump  1 , will apply about 2 lbs. of force in an upward direction, displacing the motor  25  upward about 15 degrees so that the central axis CA of the motor is substantially horizontal. The sensor  81  records a reading corresponding to the horizontal position of the motor  25 . In the illustrated embodiment, the horizontal orientation represents a zero displacement operating condition. This configuration allows the pump  1  to operate optimally. 
         [0026]    The pump  1  can be programmed or otherwise controlled to operate as desired. For instance, the pump  1  can begin operation to provide feeding fluids from the bag  69  to the patient. The care giver may select (for example) the amount of fluid to be delivered, the rate at which the fluid is to be delivered, and the frequency of fluid delivery. The pump  1  has a controller  77  (see  FIG. 8 ) including a microprocessor  79  that allows it to accept programming and/or to include pre-programmed operational routines that can be initiated by the care giver. The controller  77  is in communication with the positioning sensor  81  detecting the amount of deflection of the feeding set  5 , as previously described. Other sensors (not shown), such as a sensor that determines the type of feeding set placed in the pump  1  and/or a flow monitoring sensor can be in communication with the controller  77  to facilitate accurate pump operation. The controller  77  is also connected to the pump motor  25  for controlling its operation to actuate the valve mechanism  59  and the rotor  37 . The pump motor  25  can operate the valve mechanism  59  and rotor  37  independently from each other. 
         [0027]    If the pump  1  is to deliver feeding fluid from the bag  69  to the patient, the valve shaft  29  is rotated so the valve mechanism  59  is moved to the second position in which fluid flows from the feeding fluid bag  69  to the first tube section  57 . The amount of feeding fluid delivered to the patient is controlled by the number of rotations of the rotor  37  (in a counterclockwise direction as viewed in  FIG. 2 ). In the illustrated embodiment, the rotor  37  includes the three rollers  43  so each third of a rotation delivers one aliquot of fluid to the patient. As each roller  43  first engages the first tube section  57 , it pinches off the first tube section, closing off an amount of fluid (i.e., toward the patient) from the fluid coming from the feeding fluid bag  69 . The roller  43  continues to the right, pushing fluid ahead of the roller toward the patient. Finally, the roller  43  releases engagement with the first tube section  57 . As the roller releases the first tube section  57 , the trailing roller engages the first tube section, pinching it off for delivering the next aliquot of fluid. Thus, when the microprocessor  79  receives a command to deliver a fluid flow rate, it calculates the number of rotations within a given period of time that will deliver a number of aliquots producing the desired flow rate. More specifically in the illustrated embodiment, the controller  77  determines the amount of time between rotations of the rotor  37 . The amount of time between rotations depends upon the volume of the aliquots delivered in a single rotation. When a feeding tube of the customary length is loaded in the pump  1 , the actual amount delivered to the patient is substantially the same as the amount selected by the care giver. Therefore, the controller  77  does not have to alter operation of the pump  1  to compensate for the feeding set. It should be understood that other ways of changing rotor operation could be used to maintain a constant flow rate. It has been determined that if the microprocessor programming assumes the volume of each aliquot is the same or varies only as a function of flow rate, the actual flow rate of fluid delivered. will be in error 
         [0028]    Additionally, the controller  77  of the present invention includes a timer  83  and a memory area  84  having an aliquot volume degradation compensator  85  ( FIG. 8 ). In the illustrated embodiment, the degradation compensator  85  includes degradation compensation instructions  86 . The timer  83  is initiated in a suitable manner when the feeding set  5  is first installed in the pump  1 . The initiation is preferably automatic. For example, the timer  83  may initiate when the mounting member  61  is detected as being in the proper position for a certain period of time. The degradation compensator  85  operates to correct for variation in the volume associated with each aliquot of fluid delivered by the pump  1  to the patient. 
         [0029]    The degradation compensation instructions  86  of the degradation compensator  85  are used to account for variations in aliquot volume as a result of the length and type of feeding set loaded on the pump  1 . The degradation compensation instructions  86  are machine readable instructions stored on any suitable medium, broadly identified as the memory area  84 . These instructions can be carried out by the microprocessor  79 . The degradation compensator  85  is used to counteract the change in aliquot volume produced when feedings sets that are longer or shorter than the customary length are loaded in the pump  1 . Additionally, the compensator  85  compensates for a feedings set that lengthens after a period of use. 
         [0030]    In the instance where a short feeding set  5 ′ is loaded in the pump  1 , the feeding set will generate a force on the rotor  37  that is greater than the about 2 lbs of force generated by the customary length feeding set  5  discussed above. This will cause the motor  25  to pivot upward on the pivot pin  54  such that the central axis CA of the motor extends at an angle above horizontal ( FIG. 9 ). The sensor  81  will record a reading corresponding to the position of the motor  25 . In the illustrated embodiment, the above horizontal orientation represents a positive displacement operational condition. Because the feeding set  5 ′ will be stretched to a greater degree than the “correct” length feeding set  5 , the volume in the first tube section  57 ′ of the feeding set  5 ′ will be decreased. Thus, the aliquot volume will be less, resulting in less fluid being delivered to the patient than actually selected by the care giver. To counteract this reduction in volume, the degradation compensator  85  processes the reading from the sensor  81  and determines that the pump  1  is operating in a positive displacement operational condition. The degradation compensation instructions  86  then signal to the motor  25  to increase the rate of delivery of the fluid to compensate for the smaller volume aliquots (i.e., increase number of rotations of the rotor  37 ). Therefore, in a given amount of time, the pump  1  will deliver the same amount of fluid to the patient as would have been delivered with a feeding set of the customary length. 
         [0031]    Conversely, if a long feeding set  5 ″ is loaded in the pump  1 , the feeding set will generate a force on the rotor  37  that is less than the about 2 lbs. of force generated by the customary length feeding set  5  discussed above. This will cause the motor  25  to pivot downward on the pivot pin  54  such that the central axis CA of the motor extends at an angle below horizontal ( FIG. 10 ). The sensor  81  will record a reading corresponding to the position of the motor  25 . In the illustrated embodiment, the below horizontal orientation represents a negative displacement operational condition. Because the feeding set  5 ″ will be stretched to a lesser degree than the customary length feeding set  5 , the volume in the first tube section  57 ′ of the feeding set  5 ″ will be increased. Thus, the aliquot volume will be greater, resulting in more fluid being delivered to the patient than actually selected by the care giver. To counteract this increase in volume, the degradation compensator  85  processes the reading from the sensor  81  and determines that the pump  1  is operating in a negative displacement operational condition. The degradation compensation instructions  86  then signal to the motor  25  to decrease the rate of delivery of the fluid to compensate for the larger volume aliquots (i.e., decrease number of rotations of the rotor  37 ). Therefore, in a given amount of time, the pump  1  will deliver the same amount of fluid to the patient as would have been delivered with a feeding set of the customary length. It will be understood that the pump  1  can perform the same compensation process for a customary length feeding tube that has been stretched over time. The sensor  81  can record a reading of the motor displacement prior to operation of the motor  25  and during operation to provide a continuous monitoring of the fluid delivery. Also, the pump  1  and motor  25  could be configured to operate in an optimal condition in a position other than substantially horizontal. Although a pivot connection for pivoting movement is shown in the illustrated embodiment, the motor  25  could be configured to move in other ways, such as by substantially linear movement or a combination of rotational and linear movement. 
         [0032]    As a safety measure, the aliquot correction mechanism of the present invention can be used as a limit for feeding sets that exceed minimum and maximum allowable lengths. In this case, deflection by the motor  25  above or below the horizontal beyond a predetermined degree will result in the controller  77  instructing the pump  1  that it is in a “no pump” configuration. If a pressure sensor is used, forces above or below predetermined values will indicate to the controller  77  that the feeding set is not within the allowable length range. Further, the mechanism can function as an indicator for determining whether the feeding set has been installed on the pump. In this instance, movement of the motor  25  from its resting position shown in  FIG. 5  will signal to the controller  77  that a feeding set has been loaded in the pump  1 . A feeding set having a length that is unable to move the motor  25  from its resting position will not be sufficient to signal to the controller that a feeding set has been properly loaded. A feeding set having this length will also signal to the controller that it exceeds the maximum allowable length. Embodiments using a pressure sensor can also be used to indicate whether a feeding set has been loaded in the pump  1 . Here, a pressure change from the state of the pump  1  in  FIG. 5  will signal to the controller  77  that a feeding set has been loaded. If no pressure change occurs, then the pump  1  will indicate that a feeding set has not been loaded or alternatively, that the feeding set exceeds the maximum allowable length. 
         [0033]    Thus it may be seen that the various objects and features of the present invention are achieved by the embodiment of the pump  1  disclosed herein. The pump controller  77  has the degradation compensator  85  allowing the microprocessor  79  to compensate for changes in aliquot volume of the pump  1  based on the displacement of the motor  25  by the feeding set  5 . The pump  1  is able to allow for the degradation (or changes) in the dimensions of the feeding set  5  both over time and by changing the feeding set. Therefore, the patient can receive accurate flow rates of fluid regardless of the feeding set. 
         [0034]    Embodiments of the invention may be described in the general context of computer-executable instructions, such as program modules, executed by one or more computers or other devices. The computer-executable instructions may be organized into one or more computer-executable components or modules including, but not limited to, routines, programs, objects, components, and data structures that perform particular tasks or implement particular abstract data types. Aspects of the invention may be implemented with any number and organization of such components or modules. For example, aspects of the invention are not limited to the specific computer-executable instructions or the specific components or modules illustrated in the figures and described herein. Other embodiments of the invention may include different computer-executable instructions or components having more or less functionality than illustrated and described. 
         [0035]    Further, the order of execution or performance of the operations in embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention. 
         [0036]    In operation, microprocessor  79  of the controller  77  executes computer-executable instructions such as those illustrated in the figures to implement aspects of the invention. Aspects of the invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices. 
         [0037]    When introducing elements of the present invention or the preferred embodiment(s) thereof, 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. Moreover, the use of “up”, “down”, “top”, and “bottom” and variations of these terms is made for convenience, but does not require any particular orientation of the components. 
         [0038]    As various changes could be made in the above without departing from the scope of the invention, 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.
A pumping apparatus for use with a pump set to deliver fluid through the pump set includes a housing capable of receiving at least a portion of the pump set. A pumping device is moveably mounted in the housing and includes a motor that turns independently from movement of the pumping device when activated. The pumping device contacting the pump set when the pump set is received by the housing so the pumping device acts on the pump set to produce fluid flow in the pump set upon activation of the motor.