Patent Application
20150202382
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 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 loaded in the pump. In an embodiment of the present invention, operation of the pump is disabled if a cassette is not loaded in the pump.
The optical cassette detection system includes a light emitter and a corresponding light detector aligned along an optical axis which may extend across a slot in the pump housing. The emitter emits a light beam directed along the optical axis to the detector. The cassette is configured for loading in the pump and includes a tab arranged to block at least a portion of the light beam from reaching the detector when the cassette is properly loaded in the pump. The pump may include a slot between the emitter and the detector configured to receive the tab, such that the tab intersects the optical axis when the cassette is properly loaded in the pump.
The detector signal is evaluated by signal evaluation electronics to determine if the detector signal level is below 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.
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.
Additional reference is now made to
As seen in
Cassette detection system 50 includes an optical emitter 52, which may be arranged on one side of slot 42, and a photosensitive detector 54, which may be arranged on an opposite side of slot 42. In the illustrated embodiment, detector 54 is aligned with emitter 52 along an optical axis 58 passing through slot 42. Cassette detection system 50 further includes 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 an example embodiment, emitter 52 may be a light-emitting diode (LED) and photosensitive detector 54 may be a photodiode. Emitter 52 and detector 54 may be chosen to operate within a predetermined frequency band, including without limitation a non-visible light frequency band such as an infrared or ultraviolet band. When cassette 14 is not loaded in pump 10, light from emitter 52 travels unimpeded across slot 42 and is received by detector 54. 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 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
Thus, tab 38 on cassette 14 provides a physical feature that alters optical communication between emitter 52 and detector 54 when cassette 14 is properly loaded in pump 10. 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 emitter 52 and detector 54 of cassette detection system 50 are hidden within the pump and are inconspicuous to users. Emitter 52 and detector 54 may be recessed slightly from the surface of slot 42 behind respective transparent barriers 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.
