Patent Application
20150202383
The present invention relates generally to infusion pumps for controlled delivery of liquid food and medications to patients. More specifically, the present invention relates to a sensor system in an infusion pump for detecting the presence or absence of a cassette by which an administration tubing set is operatively connected to the pump.
Programmable infusion pumps are used to carry out controlled delivery of liquid food for enteral feeding and medications for various purposes, for example pain management. In a common arrangement, an infusion pump receives a disposable administration set comprising a cassette removably received by the pump and flexible tubing connected to the cassette for providing a fluid delivery path through the pump.
The cassette itself may be intended for use with a particular infusion pump model or models, and/or with tubing having predetermined properties. In this regard, the cassette may include safety features that are designed and manufactured according to specifications determined at least in part by the intended infusion pump model and/or administration set tubing. The safety features of the cassette may cooperate with corresponding features on the matching pump, and may be manufactured according to size tolerances related to tubing diameter and flexibility. For example, the cassette may have an anti-free flow mechanism for protecting the patient from uncontrolled fluid delivery. The anti-free flow mechanism may take the form of an external pinch clip occluder actuated when the cassette is properly loaded in the pump and a door of the pump is closed. Alternatively, the anti-free flow mechanism may take the form of an internal “in-line occluder” that resides within the flow passage of the tubing, wherein a flow passage is only opened when the cassette is properly loaded in the pump and the pump door is closed.
The cassette may provide additional safety features beyond free flow protection. For example, the cassette may be matched to the pump to maintain a desired volumetric accuracy of the pump, and to ensure correct function of occlusion and air-in-line sensors used to trigger safety alarms.
In view of the safety importance of the cassette, it is desirable to provide means to detect whether or not a matching cassette is properly loaded in the pump as a precondition to enabling pump operation.
In accordance with the present invention, an infusion pump in which an administration set is removably received is provided with an optical detection system for determining whether or not a cassette of the administration set is properly loaded in the pump. In an embodiment of the present invention, operation of the pump is disabled if a cassette is not properly loaded in the pump.
The optical cassette detection system comprises an optical emitter mounted to the pump and arranged to emit a light beam directed along an emission optical axis, and a photosensitive detector mounted to the pump so as to define a light detection optical axis different from the emission optical axis. The cassette detection system further comprises at least one optical element carried by the cassette, including an optical element positioned to receive the light beam when the cassette is properly loaded in the pump. The at least one optical element redirects at least a portion of the light beam along the detection optical axis for receipt by the photosensitive detector. The photosensitive detector generates a detector signal representing an intensity of light received thereby.
The detector signal is evaluated by signal evaluation electronics to determine if the detector signal level is above a predetermined threshold, indicating presence of the cassette. The signal evaluation electronics may be in communication with a pump controller, wherein the pump controller is programmed to disable pump operation unless a cassette is present as determined by the optical cassette detection system.
In one embodiment, the emission optical axis is parallel to the detection optical axis, and the at least one optical element includes a parallel surface beam displacer arranged to displace the light beam from the emission optical axis to the detection optical axis when the cassette is properly loaded.
In another embodiment, the at least one optical element includes a prism or a wedge causing spectral dispersion of the light beam. The photosensitive detector may be arranged and configured to detect a portion of the dispersed beam in a predetermined narrower wavelength band.
In a further embodiment, the at least one optical element includes a Porro prism that reverses the direction of the light beam.
The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:
In the illustrated embodiment, pump 10 is a rotary peristaltic pump having a rotor 30, wherein pumping segment 28 is wrapped around rotor 30 and is engaged by angularly spaced rollers on rotor 30 as the rotor rotates to provide peristaltic pumping action forcing liquid through the tubing of administration set 12. As may be understood by reference to
Cassette 14 may include an in-line occluder 32 which may be incorporated into downstream loop connector 20. In-line occluder 32 prevents flow when pump door 34 is open. An actuator 36 on an underside of pump door 34 engages pumping segment 28 in a manner which opens a flow path around occluder 32 when door 34 is closed.
Reference is now made to
Pump 10 includes an optical cassette detection system 50 operable to detect whether or not cassette 14 is properly loaded in pump 10 with cassette tab 38 present in slot 42. Cassette detection system 50 includes an optical emitter 52 and a photosensitive detector 54 each mounted in pump 10. Cassette detection system 50 further includes at least one optical element 55 carried by cassette 14. In accordance with the present invention, the at least one optical element 55 establishes an optical path from emitter 52 to photosensitive detector 54 when cassette 14 is properly loaded in pump 10. Cassette detection system 50 may also include signal processing electronics 56 connected to photosensitive detector 54 for receiving an electronic signal generated by detector 54 and evaluating the signal. Signal processing electronics 56 may be in communication with a pump controller 60, whereby operation of pump 10 may be controlled based on an evaluation of the detector signal.
In the embodiments described herein, emitter 52 and photosensitive detector 54 are each mounted in pump 10 adjacent to slot 42, and the at least one optical element 55 is part of tab 38, however other configurations and arrangements are possible. In the embodiments described herein, the at least one optical element 55 is a single optical element, however more than one optical element may be carried by cassette 14 and configured to selectively establish an optical path from emitter 52 to detector 54.
In the embodiment shown in
As best seen in
An optical cassette detection system according to a further embodiment is illustrated in
In the embodiments described above, a single optical element is used to redirect the light beam. However, a combination of optical elements may be used for redirection of the light beam without straying from the invention.
With respect to each embodiment, detector 54 generates a signal, for example a current or voltage signal, having a level corresponding to the intensity of light received thereby. In the unblocked condition shown in
Signal processing electronics 56 evaluates the signal from detector 54 to determine if cassette 14 is properly loaded in pump 10. The signal processing and evaluation may be completely analog, or the detector signal level may be converted to a digital value and compared to a threshold in a digital comparator circuit. As illustrated in
Emitter 52 may be a light-emitting diode (LED) or other light source, and photosensitive detector 54 may be a photodiode or other photosensitive element capable of generating an electrical signal in response to incident light. Emitter 52 and detector 54 may be chosen to operate within predetermined wavelength bands. For example, where optical element 55 is a dispersing prism, emitter 52 may be chosen to emit light in a relatively wide wavelength band, and detector 54 may have a spectral responsivity confined to a relatively narrow wavelength band or detector 54 may include a wavelength filter for selecting a relatively narrow wavelength band. Alternatively, emitter 52 may be a narrow band emitter, for example a laser diode. Likewise, detector 54 may have a spectral responsivity across a relatively wide wavelength band that includes the emission wavelength band. Emitter and detector may be optically coupled by light outside the visible spectrum, e.g. infrared or ultraviolet light. While not shown, emitter 52 and detector 54 may have lenses, fiber optics, or other optical elements associated therewith for collimating, focusing, and/or directing the beam.
Tab 38 on cassette 14 provides structure that may be used for carrying the at least one optical element 55 and positioning the at least one optical element 55 in optical cassette detection system 50. A wide variety of tab arrangements and optical detection system configurations are of course possible. The centered arrangement of a thin tab 38 on the underside of cassette 14, and the use of a thin slot 42 in pump 10, takes advantage of the tab and slot as a means for guiding and centering the cassette 14 during installation. Moreover, the cassette detection system 50 is hidden within the pump and is inconspicuous to users. Emitter 52 and detector 54 may be recessed slightly from the surface of slot 42 behind respective transparent barriers (not shown) to keep dirt and fluid away from the emitter and detector.
While the invention has been described in connection with exemplary embodiments, the detailed description is not intended to limit the scope of the invention to the particular forms set forth. The invention is intended to cover such alternatives, modifications and equivalents of the described embodiment as may be included within the spirit and scope of the invention.
