Abstract:
Detection of fluid conditions in a section of tube of an administration set. A light source is positioned adjacent to the tube to transmit an infrared light through the tube and any fluid therein. A light sensor senses the infrared light transmitted through the tube and generates an output signal. A frequency of the output signal is a function of an intensity of the light transmitted through the tube. A processor receives and determines the frequency of the output signal, and compares the determined frequency to threshold frequency values to determine whether fluid is in the tube. The processor also monitors the generated output signal to determine if the frequency of the output signal changes over a predetermined period of time, and determines whether fluid is flowing in the tube as a function of the determined change in frequency.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/154,362, filed Apr. 29, 2015. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates generally to the field of fluid administration to patients via a flow control apparatus, and more particularly, to detection of a malfunction of a flow monitoring system of the flow control apparatus. 
       BACKGROUND 
       [0003]    Administering fluids containing medicine or nutrition to a patient is generally well known in the art. Typically, fluid is delivered to the patient by an administration feeding set loaded to a flow control apparatus, such as a pump, which delivers fluid to a patient. 
         [0004]    A flow control apparatus of the prior art may also be capable of monitoring and detecting fluid flow conditions that can occur within the loaded feeding set during operation of the flow control apparatus. For example, prior art flow monitoring systems may include an ultrasonic sensor capable of detecting when fluid is not present in tube of the feeding set. In this example, the ultrasonic sensor transmits an ultrasonic signal through the tube and detects the ultrasonic signal after passing through the tube. The transmitted signal is analyzed, such as by a processor of the flow monitoring system, to determine the presence or absence of fluid within the tube and/or the flow condition of the fluid within the tube. If, for example, the flow monitoring system determines that there is no fluid present in the tube, the flow monitoring system may activate an alarm and/or stop operation of the flow control apparatus to ensure that air is not delivered to the patient. 
         [0005]    It is possible that the flow monitoring system may malfunction, whereby the flow monitoring system fails to detect when there is no fluid in the feeding set. For example, the sensor (e.g., the ultrasonic sensor) may malfunction, whereby the sensor detects an ultrasonic signal that is indicative of the presence of fluid within the tube, for example, when in fact no fluid is present in the tube. In such a case, the flow monitoring system would make an incorrect determination that fluid is present in the tube and the flow control apparatus would continue to deliver air to the patient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective of an enteral feeding pump and a fragmentary portion of a feeding set (illustrated schematically) received on the pump; 
           [0007]      FIG. 2  is a perspective of  FIG. 1  with a cassette housing of the feeding set removed; 
           [0008]      FIG. 3  is an enlarged, fragmentary front elevation of  FIG. 2  with the feeding set removed from the enteral feeding pump; 
           [0009]      FIG. 4  is an exemplary block diagram illustrating a control unit of the enteral feeding pump and components that are in communication with the control unit; 
           [0010]      FIG. 5  is an exemplary flow chart illustrating a method performed in first mode of operation of a fluid monitoring system for monitoring a condition of fluid in the feeding set; 
           [0011]      FIG. 6  is graph depicting the response of a non-malfunctioning fluid monitoring system during a second mode operation; 
           [0012]      FIG. 7  is a graph depicting a low fail response of a malfunctioning fluid monitoring system during the second mode of operation; 
           [0013]      FIG. 8  is a graph depicting a high fail response of a malfunctioning fluid monitoring system during the second mode of operation; and 
           [0014]      FIG. 9  is an exemplary flow chart illustrating a method performed in a second mode of operation of the fluid monitoring system for determining if the fluid monitoring system is malfunctioning. 
       
    
    
       [0015]    Corresponding reference characters indicate corresponding parts throughout the drawings. 
       DETAILED DESCRIPTION 
       [0016]    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  10 . The feeding pump  10  may comprise a housing, generally indicated at  12 , that may be constructed to receive an administration feeding set (broadly, “a fluid delivery set”), generally indicated at  14 . It will be understood that although the illustrated flow control apparatus is an enteral feeding pump  10 , the present disclosure has application to other types of flow control apparatus (not shown), including medical infusion pumps. Moreover, although an administration feeding set  14  is shown, other types of fluid delivery sets (not shown) can be used within the scope of the present invention. 
         [0017]    A user interface, generally indicated at  16 , may be provided on the front of the housing  12 . The user interface  16  may include a display screen  18  that is capable of displaying information about the status and operation of the pump, a plurality of push buttons  20  on one side of the display screen, and a plurality of LEDs  22  on the other side of the display screen. 
         [0018]    Referring now to  FIGS. 1 and 2 , the pump  10  may further comprise a rotor  26  that controls the flow of fluid through the feeding set  14  when a cassette, generally indicated at  30 , of the feeding set is loaded on the pump. The cassette  30  may include a valve mechanism  34  and a mounting collar  36  that are releasably securable to the pump  10 . The feeding set  14  may include tubing  11  having a first section of tube  40  (e.g., feeding inlet tube) upstream of the valve mechanism  34  leading to a feeding fluid source  42 , and a second section of tube  44  (e.g., flushing inlet tube) upstream of the valve mechanism leading to a flushing fluid source (not shown). The feeding set  14 , more specifically the cassette  30 , may include a third section of tube  46  (e.g., cassette tube) extending between and interconnecting the valve mechanism  34  and the mounting collar  36 . A fourth section of tube  50  (e.g., outlet tube) may extend from the mounting collar  36  toward the patient. The valve mechanism  36  may be operable to selectively permit flow of fluid from the feeding fluid source  42  or a flushing fluid source (not shown) into the cassette tube  46 , or prevent any fluid flow communication from the feeding or flushing fluid sources into the cassette tube. When loaded onto the pump  10 , the valve mechanism  34  and the mounting collar  36  may be securely engaged with the pump, and the cassette tube  46  may be placed in a stretched condition around the rotor  26  of the pump. Rotation of the rotor  26 , such as by a motor  52  ( FIG. 4 ), compresses the cassette tube  46  and provides a force for driving fluid in the feeding set  30  from the upstream side of the rotor to the downstream side of the rotor for delivery to the patient. 
         [0019]    Referring to  FIGS. 1 and 2 , at least one fluid sensor associated with the housing  3  may be located in a position to detect a condition of fluid in the feeding set  14 . In the illustrated embodiment, the pump  10  includes two fluid sensors: a first fluid sensor, generally indicated at  56 , is located upstream of the rotor  26 ; and a second fluid detector, generally indicated at  58 , is located downstream of the rotor. It is understood that the pump  10  may include a single fluid sensor or more than two fluid sensors without departing from the scope of the present invention. In one example, the first and second fluid sensors  56  may be ultrasonic sensors for use in detecting a condition of the fluid in the feeding set  14 , although other types of sensors are within the scope of the present invention, including, but not limited to, infrared sensors. The first fluid sensor may be used to detect the presence or absence of fluid in the cassette tube  30 , and the second fluid sensor  58  may be used to detect a downstream occlusion. It is understood that the first and second fluid sensors  56 ,  58  may be configured for use in detecting other conditions of the feeding set  14 , such as fluid flow and opaqueness of the fluid. 
         [0020]    Referring now to  FIG. 4 , an exemplary block diagram illustrates a control unit  60  of the enteral feeding pump  10  and components that are in communication with the control unit. The control unit  60  may include a processor  60   a  (e.g., a microprocessor) and a memory  60   b.  It is understood that the control unit  60  may comprise more than one controller, each of which may have at least one processor and at least one memory. As illustrated, the control unit  60  is in communication with the motor  52  and the user interface  16 . 
         [0021]    Referring still to  FIG. 4 , the pump  10  includes a fluid monitoring system  62 . The fluid monitoring system  62  may include the first and second fluid sensors  56 ,  58 , respectively, the control unit  60  (e.g., a fluid monitoring controller of the control unit), a flow alarm  66 , and a malfunction alarm  70 . The control unit  60  is in communication with the first and second fluid sensors  56 ,  58 , respectively, the flow alarm  66 , and the malfunction alarm  70 . Each of the flow and malfunction alarms  66 ,  70 , respectively, may be audible, visual, vibratory or any combination thereof. In the illustrated embodiment, each of the first and second fluid sensors  56 ,  58 , respectively, may include an ultrasonic generator  56   a,    58   a,  respectively (broadly, a sensor signal generator), and an ultrasonic receiver  56   b,    58   b,  respectively (broadly, a sensor signal receiver). For each sensor  56 ,  58 , the ultrasonic generator  56   a,    58   a  and the ultrasonic receiver  56   b,    58   b  are on opposite sides of the cassette tube  46  such that the cassette tube is received between the generator and receiver (see  FIG. 3 ). Each ultrasonic generator  56   a,    58   a  (e.g., an ultrasonic transducer) is configured to receive a drive signal from the control unit  60  (more specifically, the processor  60   a ), and in response to the drive signal, generate an ultrasonic signal that is transmitted through the cassette tube  46  toward the corresponding ultrasonic receiver  56   b ,  58   b.  Each ultrasonic receiver  56   b,    58   b  (e.g., an ultrasonic transducer) is configured to receive the ultrasonic signal and, in response to the received signal, generate an output signal. The control unit  60  (more specifically, the processor  60   a ) is configured to receive the output signal and determine and analyze a parameter value of the output signal, as described in more detail below. 
         [0022]    The fluid monitoring system  62  may include a first mode of operation (e.g., a fluid monitoring mode) for determining the condition of the fluid in the cassette tube  46 , such as during operation of the pump  10  for delivering fluid to the patient. By determining the condition of the fluid in the cassette tube  46 , the control unit  60  (e.g., the processor  60   a ) may be further configured to determine a condition of the feeding set  14  and the pump  10  in general.  FIG. 5  illustrates instructions (e.g., software) stored in the computer readable storage medium (memory  60   b ) and executed by the processor  60   a  of the control unit  60  during the first mode of operation using the first fluid sensor  56 . Similar, yet different, instructions may be stored for the second fluid sensor  58  or any additional fluid sensors. At  100 , the control unit  60  (e.g., the processor  60   a ) generates a drive signal that is received by the ultrasonic generator  56   a  of the first fluid sensor  56 . The drive signal may have a substantially constant frequency matching a resonant frequency of the ultrasonic generator  56   a  (e.g., between 1 to 3 MHz, and in one example about 2.25 MHz). In response to the drive signal, the ultrasonic generator  56   a  resonates, producing an ultrasonic signal that propagates through the cassette tube  46  and toward the ultrasonic receiver  56   b.  At  102 , the control unit  60  (e.g., the processor  60   a ) receives the output signal from the ultrasonic receiver  56   b  of the first fluid sensor  56 . At  104 , the control unit  60  (e.g., the processor  60   a ) determines the amplitude of the output signal (broadly, a parameter value of the output signal). In other embodiments, other parameter values of the output signal (e.g., frequency, phase shift, etc.) may be determined and analyzed by the control unit  60  (e.g., the processor  60   a ) to determine the condition of the fluid in the cassette tube  46 . At  106 , the control unit  60  (e.g., the processor  60   a ) stores the amplitude of the output signal in the memory  60   b.  At  108 , the control unit  60  (e.g., the processor  60   a ) compares the stored amplitude to a threshold value that is stored in computer readable storage medium. If the stored amplitude is above the threshold value, indicating that there is fluid in the cassette tube  46 , the control unit  60  (e.g., the processor  60   a ) may return to step  100  after a predetermined amount of time and/or communicate to the user, such as by the user interface  16 , that there is fluid in the feeding set  14 . If the determined amplitude is not above (e.g., at or below) the threshold value, indicating that there is air in the cassette tube  46  and/or the tube is empty, then at  110  the control unit  60  (e.g., the processor  60   a ) activates the flow alarm  66  and/or shuts off the motor  52 . It is understood that the fluid monitoring system  62  may include additional instructions and/or different instructions for monitoring a flow condition in the feeding set  14 . 
         [0023]    In another example, turning to the second fluid sensor  58 , the control unit  60  (e.g., the processor  60   a ) may analyze the amplitude of the output signal to determine if the amplitude is above a threshold value stored in computer readable storage medium. This may indicate that the pressure in the cassette tube  46  is indicative of a downstream occlusion. The control unit  60  (e.g., the processor  60   a ) may activate the flow alarm  66  in response to the detection of an occlusion and/or shut off the motor  52 . 
         [0024]    The fluid monitoring system  62  may also include a second mode of operation (e.g., a malfunction detecting mode) for determining if the fluid monitoring system is malfunctioning. In one example, the control unit  60  may be configured (e.g., the processor  60   a  is programmed) to generate a second drive signal that is different from the first drive signal used in the first mode of operation. In response to the second drive signal, the ultrasonic generator  56   a,    58   a  (broadly, the signal generator) generates an ultrasonic signal, different from the first ultrasonic signal, that is transmitted through the cassette tube  46  to the ultrasonic receiver  56   b ,  58   b  (broadly, the signal receiver). The ultrasonic receiver  56   b,    58   b  generates an output signal in response to the transmitted signal. The control unit  60  (e.g., the processor  60   a ) receives the output signal from the ultrasonic receiver  56   b,    58   b,  determines a parameter value(s) of the received output signal, and analyzes the parameter value(s) to determine if it corresponds with an anticipated or expected parameter value(s) associated with the second drive signal(s). In other words, in the second mode of operation, the fluid monitoring system  62  determines whether the ultrasonic receiver  56   a,    58   a  is detecting an anticipated or expected ultrasonic signal in accordance with the second drive signal. If the ultrasonic receiver  56   a,    58   a  is not detecting the anticipated or expected ultrasonic signal, then this indicates that the fluid monitoring system  62  is malfunctioning, and the control unit (e.g., the processor  60   a ) may activate the malfunction alarm  70  and/or shut off the motor  52 . 
         [0025]    In one embodiment of the second mode of operation, the control unit  60  (e.g., the processor) generates a second drive signal having a varying parameter (e.g., a varying frequency, such as when the first drive signal has a constant frequency). For example, where the fluid sensor  56 ,  58  includes an ultrasonic generator  56   a,    58   a,  the control unit  60  (e.g., the processor  60   a ) may generate a sweep drive signal having a frequency (or other parameter) that varies over time. The sweep signal may have an initial frequency that is one of less than and greater than the frequency necessary for the ultrasonic generator  56   a,    58   a  to produce the ultrasonic signal, and an ending frequency that is the other of greater than and less than the frequency necessary for the ultrasonic generator to produce the ultrasonic signal. The control unit  60  (e.g., the processor  60   a ) determines and stores amplitudes of the output signal generated by the ultrasonic receiver  56   b,    58   b.  The stored amplitudes are analyzed by the control unit  60  (e.g., the processor  60   a ) to determine if the output signal had a sufficient change in amplitude that is generally commensurate with the change in frequency of the sweep signal. If the output signal did not have a sufficient change in amplitude that is generally commensurate with the change in frequency of the sweep signal, then this is indicative that the fluid monitoring system  62  is malfunctioning. In response, the control unit (e.g., the processor  60   a ) may activate the malfunction alarm  70  ( FIG. 4 ). 
         [0026]    As non-limiting illustrations,  FIGS. 6-8  are graphs depicting the change in amplitude of the output signal in response to the frequency change of the sweep signal (from 2.2 MHz to 2.8 MHz) delivered to the first fluid sensors  56  of three different fluid monitoring systems  62 . As can be observed from  FIGS. 6-8 , the change in amplitude of the output signal indicative of the sweep signal frequency change in a non-malfunctioning fluid monitoring system  62  (e.g.,  FIG. 6 ) is much greater than the change in amplitude of the output signal indicative of system noise in a malfunctioning fluid monitoring system  62  (e.g.,  FIGS. 7 and 8 ).  FIG. 6  is a graph depicting the response of a non-malfunctioning fluid monitoring system  62  during the second mode operation. As can be observed from  FIG. 6 , there is detectable and constant change in amplitude of the output signal (from about 0 mV to about 1100 mV) as the frequency of the drive signal is swept. As illustrated, the amplitude of the output signal undergoes a corresponding change in response to every change in frequency of the swept drive signal.  FIG. 7  is a graph depicting a low fail response of a malfunctioning fluid monitoring system  62  during the second mode of operation. As can be observed from  FIG. 7 , there is a relatively small change in amplitude of the output signal in a low range (from about 8 mV to about 15 mV) as the frequency of the drive signal is swept. This is an indication that the malfunction is related to the output signal (e.g., the ultrasonic receiver  56   b  is malfunctioning) or the malfunction is related to the input signal (e.g., the ultrasonic generator  56   a  is malfunctioning). Moreover, because the amplitude of the output signal is relatively small, during the first mode of operation the fluid monitoring system  62  may give an indication that there is no fluid in the tube, although this is not necessarily the case.  FIG. 8  is a graph depicting a high fail response of a malfunctioning fluid monitoring system  62  during the second mode of operation. As can be observed from  FIG. 8 , there is a relatively small change in amplitude of the output signal (from about 208 mV to about 215 mV) as the frequency of the drive signal is swept. This is an indication that the malfunction is related to the output signal (e.g., the ultrasonic receiver  56   b  is malfunctioning) or the malfunction is related to the input signal (e.g., the ultrasonic generator  56   a  is malfunctioning). Moreover, because the amplitude of the output signal is relatively large, during the first mode of operation the fluid monitoring system  62  would give an indication that there is fluid in the cassette tube, although this is not necessarily the case. 
         [0027]    One example of steps that may be performed by the control unit  60  (e.g., the processor  60   a ) in the second mode of operation to test the first fluid sensor  56  is depicted by a flow chart in  FIG. 9 . In particular,  FIG. 9  illustrates instructions stored in the computer readable storage medium (memory  60   b ) of the control unit that are executed or run by the processor  60   a . Similar, yet different, instructions may be stored to test the second fluid sensor  58  or any additional fluid sensors. The control unit  60  may perform the second mode of operation as the pump  10  is operating and on a periodic basis. At  200 , the control unit  60  (e.g., the processor  60   a ) generates a sweep signal that is received by the ultrasonic generator  56   a  of the first sensor  56 . The sweep signal may sweep through a range of drive frequencies. For example, the sweep signal may increase in frequency, at incremental steps, from an initial frequency that is lower than the frequency required to function the ultrasonic generator (e.g., 2.2 MHz) to an ending frequency that is higher than the frequency required to function the ultrasonic generator (e.g., 2.8 MHz). At  202 , the control unit  60  (e.g., the processor  60   a ) receives the output signal from the ultrasonic receiver  56   b  of the first sensor  56 . At  204 , the control unit  60  (e.g., the processor  60   a ) determines the amplitude of the output signal (broadly, a parameter value of the output signal). In other embodiments, other parameter values of the output signal (e.g., frequency, phase shift, etc.) may be determined and analyzed by the control unit  60  (e.g., the processor  60   a ) to determine the condition of the fluid in the cassette tube  46 . At  206 , the control unit  60  (e.g., the processor  60   a ) stores the determined amplitude and the frequency of the sweep signal that produced the determined amplitude in the memory  60   b.  The control unit  60   b  repeats steps  202  to  206  until the sweep signal has ended. At  208 , the control unit  60  (e.g., the processor  60   a ) determines if the amplitude of the output signal changes in accordance with the sweep signal. This step  208  may be accomplished by analyzing the stored amplitudes of the output signal to determine if there was a change in amplitude of the output signal over the frequency sweep. If the amplitude does not change in accordance with the sweep signal, then the control unit  60  (e.g., the processor  60   a ) may activate the malfunction alarm  70  at  210  indicating that the fluid monitoring system  62  is malfunctioning. The control unit  60  (e.g., the processor  60   a ) may also shut off the motor  52 . If the amplitude does change in accordance with the sweep signal, then the control unit  60  (e.g., the processor  60   a ) continues with normal operation (e.g., normal pumping according to protocol) and stops the second mode of operation. 
         [0028]    Embodiments can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations thereof. The controller of the compression system can be implemented in a computer program product tangibly embodied or stored in a machine-readable storage device for execution by a programmable processor; and method actions can be performed by a programmable processor executing a program of instructions to perform functions of the controller of the compression system by operating on input data and generating output. The controller of the compression system can be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program can be implemented in a high-level procedural or object oriented programming language, or in assembly or machine language if desired; and in any case, the language can be a compiled or interpreted language. 
         [0029]    Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Generally, a computer will include one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD ROM disks. Any of the foregoing can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits) or FPGAs (field programmable logic arrays). 
         [0030]    When introducing elements of aspects of the invention or the embodiments 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. 
         [0031]    As various changes could be made in the above constructions, products, and methods without departing from the scope of aspects 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.