CA2187769C

CA2187769C - Systems and methods for cassette identification for drug pumps

Info

Publication number: CA2187769C
Application number: CA002187769A
Authority: CA
Inventors: James M. Olson; Jay G. Johnson; Jia Hu
Original assignee: Sims Deltec Inc
Current assignee: Smiths Medical ASD Inc
Priority date: 1994-04-15
Filing date: 1995-04-12
Publication date: 2007-06-19
Anticipated expiration: 2015-04-12
Also published as: CA2187769A1

Abstract

The present invention concerns a pump pro-vided with a control module and an attachable fluid reservoir cassette. The control module includes a pumping mechanism for pumping fluid from the fluid reservoir to the patient. The cassette is pro-vided with appropriate indicia to identify differ-ences between a plurality of cassettes. The control module further includes cassette indicia identifica-tion structure for identifying indicia on the cas-sette. One type of cassette identification system includes a projection extending from the cassette and structure associated with the control module which engages the projection. Another type of cas-sette identification system includes a light reflect-ing system which utilizes light from the control module and reflected off the cassette. Still other types of cassette identification systems utilize other non-contact switches or sensors to sense indicia on the cassette to identify the cassette from a plurality of cassettes.

Description

SYSTEMS AND ML''TfIO S FOR CASSETTE TD NTTFTCLTTtIN
FOR DRUG PUMPS
Field of the Invention The present invention relates generally to drug pumps for pumping fluid to a patient. More particularly, the present invention relates to systems and methods for identifying attachable fluid cassettes which supply fluid to the drug pump for pumping to the patient.

--- Background of the Invention Various drug pumps are known for pumping fluid to a patient in connection with treatment of various medical conditions. Drug pumps are known which include a reusable control module with-a disposable or reusable fluid reservoir cassette wherein the reservoir is either self-contained with the cassette or remote from the cassette. The control module pumps fluid from the cassette to the patient when the cassette is attached or mounted to the control module.

There is a need for using the control module in connection with different fluid reservoir cassettes.
The cassettes may differ in the nature of the drugs or other fluid contained therein. Other differences might relate to the manner in which the fluid reservoir component cooperates with the control module to deliver the fluid to the patient. For example, the control module may include a pumping mechanism which engages a tube extending from the fluid reservoir cassette. The fluid reservoir cassettes may have variations in tubing size. In thatcase, it is important to identify to the R'O 95/28190 21 8 7 7 6 9 PCT1US95l04527 =

control module the size of the tubing attached to the fluid reservoir cassette so-.that the proper amount-of drug is delivered to the patient.
-There-is also a need for identifying a proper cassette from an improper-cassette mounted to the control module. In some cases; the control module inay be programmed or configured:to pump fluidin a certain therapy from a particular cassette. If an improper cassette is mounted to the control module, there is a danger the patient may be given an improper-drug.
There has arisen a need for systems and methods for identifying a fluid reservoir cassette which mounts to a control module of a drug pump.

Summarv of the Invention -- The present invention relates to a pump including a control module having a dbntrol system with a processor and associated memory for controlling operation of--the pump. Thecontrol system also includes a pumping mechanism for pumging_fluid which is controlled by the processor. A fluid reservoir or cassetteis selectively mountable to.the control module.
The fluid reservoir includes indiciafor ideritifying a property ofthe fluid cassette such as tube size, drug type, or other_ The control system includes structure for identifying the indicia=associated with the fluid cassette_ The structure for identifying indicia sp-nds a signal to the processor indicative of the irndicia sensed. An-appropriate signal is generatedfor WO 95/28190 2 3 8 7 7 6 9 pCTfUS95/04527 controlling the pumping mechanism or other pump functioa based upon the indicia identified. If an improper cassett-e,is sensed, then a pump disabling program disables the pump mechanism from pumping even though the operator attempts to initiate_.the pumping operation.
In one preferred embodiment, the reservoir includes a base plate and a tube extending from the fluid reservoir which is interconnectable to the patient. The control module includes a pumping mechanism which engages the tube during pumping to move fluid from the reservoir to the patient.

There are various different indicia which may be provided on the base plate to identify a property of the_reservoir. The base plate may include one or more projections. The structure for identifying indicia may include a force sensitive resistor mounted to the control module for engaging the projection on the base plate. The force sensitive resistor generates a signal for the processor of the control system.

Alternatively, the structure for identifying indicia may include a microswitch mounted to the control module which engages the projection on the base plate and sends a signal to the processor of the control system.

- A further alternative for the structure for identifying indicia may include a slotted optical sensor and a reciprocally mounted plunger. The slotted optical sensor and the plunger are mounted to the control W 95128190 2 i 8 7 7 6 9 PCT1U895/04527 module. The plunger is engaged by the projection to move the projection relative to the optical sensor. The-optical sensor generates a signal for the processor of the control system indicative_of the change in position S of the plunger. In-another alternative embodiment, the --structure for identifying indicia may include a reciprocally mounted plunger which makes or breaks electrical connection between electrical contacts during engagement by the projection of the base plate. This electrical connection or disconnection generates a--signal for the processor.

Instead of a mechanical interaction between indicia on the base plate and the structure for -identifying the indicia associated with the control.

module, optics may be utilized wherein no contact between the control module and the cassette occurs with respect to the indicia'identification structure. In one embodiment, the control module includes a light emitter for directinglight toward thebase plate. The indicia on the base plate includes an appropriately located.
prism arrangement for reflecting the light back toward the control module. The structure for i-dentifying indicia further includes a light receiver for receiving the light reflected from the prism arrangement associated with the base plate and sending a.signal to the processor_ Alternatively, the structure for identifying WO 95128190 _-'2 i87 7 6 9 PCT/US95/04527 indicia-may include a light emitter for directing light toward the base plate and the base plate may include a reflective patch for reflecting the light back toward the control module. The structure for identifying 5 indicia further includes a light receiver for receiving the light reflected from the reflective patch and sending a signal to the processor.

Other cassette identification systems are usable including those relating to capacitive switches, Hall effect switches, reed switches, inductive switches, piezoelectric switches, magneto-resistive switches, and other non-contact switches. Acoustic switches are also usable. Also, optical print sensors may also be utilized for reading bar code information or the like printed on the cassette. Laser positioning sensors may be utilized where the height of a projection extending from the base plate is measured to identify the cassette: -The pump may include a display interconnected to the processor of the control system. Appropriate display programs are associated with the processor for generating an appropriate display depending on the cassette sensed by the control module. The pump apparatusmay include an audible signal device for generating an-appropriate audible signal when the control module has identified either a correct cassette or an incorrect cassette. Visual signals, such as a green and/or red LED, may be provided with the pump to-WO 95/28190 21 g 7' 69 PCT1US95/04527 =

indicate the appropriateness of the cassette sensed.
Drief Describtion of the Drawings Figure i.,.is a schematic diagram of a pump apparatus according to thepresent invention, showing a self-contained fluid cassette separated from the control module.

Figure LA is a schematic diagram of a remote -reservoir adapter and remote fluid reservoir useable with the control module of Figure 1.

Figure 2 is a schematic diagram of the control system of the control module shown in Figure 1.

Figure 3 is a-first cassette identification system including a plurality of force-sensitive -resistors.--Figure 4-is a second alternative cassette_ identification system including a force-sensitive resistor and an elastomer.

Figure 5 is a third alternative cassette identification system including a force-sensitive resistor and a coil spring.

Figure 6 is a fourth alternative cassette identification system including a force-sensitive resistor and a flexible beam.

Figure 7 is a fifth alternative cassette-_ identification system including a prism arrangement:
Figure 8 is a cross-sectional-view of the identification system shown in Figure 7takenalong lines 8-8.

= WO 95128190 2 1 8 7 769 pCT/US95/04527 Figure 9 is a view of the light emitter of the._ cassette identification-system shown in Figures 7 and 8.
Figure 10 is a sixth alternative cassette identification system including an alternative prism arrangement.

Figure 11 is a seventh alternative cassette identification system including a reflective patch.
Figure 12-is ari eighth alternative cassette identification system including a microswitch.

Figure 13 is a ninth alternative cassette identification system including a reciprocally mounted plunger with an electrical contact thereon.

Figure 14 is a tenth alternative cassette identification system including a slotted optical sensor and a reciprocally mounted plunger.

Figure 15 is a side view of the cassette identification system shown in Figure 14, showing three slotted optical sensors and three_.reciprocally mounted plungers..

Figure 16 is a second alternative plunger arrangement to the arrangement shown in Figures 14 and 15. -Figure 17 is a third alternative plunger arrangement to the arrangement shown in Figures 14 and 15.

Figure 18 is a fourth alternative plunger arrangement to the arrangement shown in Figures 14 and 15. --WO 95/28190 218 7 7 6 9 pCT/US95/04527 =

Figure 19 is a fifth alternative plunger arrangement to the arrangement shown in Figures 14 and --15. -Figure 20 is a sixth alternative plunger arrangement to the arrangement shown in Figures 14-and 15.

Figures 21-29 illustrate one preferred -cassette identification system. Figures 21-23, 26, 27 and 29 show a control module and a first cassette.-Figures 24 and 25 show a second cassette. Figure 28 shows a third cassette. --Detailed Descriution of the Preferxed Embodiments Thepresent invention relates to systems and methods for automatically identifying a cassette mounted to a control module of a fluid pumping system, such as a drug infusion system. The identification system can identify indicia on the cassette relating to the type of drug,-the concentration o~.-the drug, the volume ofthe fluid reservoir, or the amount of d.rug pumped per activation of the pump, i.e., tube size. Such information is important to safeand effective drug therapy. When the information is entered automatically to the control module, such-as with-the indicia -identifying system, a saferand-more effective system results. There-is less chance for human error, as would ---be the case if such information were-entered manually.

Also, the indicia-identifying system can be used to prevent operation of the pump if an unauthorized - -WO 95128190 ~ 1 817 6 9 PCT/US95/04527 cassette is attached.

Various cassettes are provided to be identified by the control module. The control module identifies the cassettes in one of a variety of manners, including engagement with a projection on the.cassette or sensing optical signals or the absence of optical signals due to the presence of the cassette. Other structures and methods are provided to identify the cassettes.

Referring now to Figure1, a pump apparatus or pump 20 is shown. Pump 20 includes a control module 24 and a separate self-contained fluid cassette 26 which is mountable to the control module 24. Control module 24 is reusable. Cassette 26 may be disposable, or in some cases reusable after refilling. As will be discussed below in greater detail, cassette 26 can be configured as a remote reservoir adapter linking a remote fluid reservoir to control-module 24. -One lock/latch mechanism for mounting cassette 26 to control 24 includes one or more hooks 45 which each engage a rod 46 mounted to control module 24. Loop 47 is grasped by loop engaging device 48_to releasably hold cassette 26 in place with hook 45 around rod 46.
Other lock/latch mechanisms are anticipated for holding cassette 26 adjacent control module 24 tofacilitate operation.

Control module 24 includes a pumping mechanism 28 which pumps fluid from cassette 26. Cassette 26 WO 95/28190 PCT/US95{04527 includes a fluid reservoir 30 with a compressible tube 32 extending therefrom. Tube 32 is interconnectable to the patient. Cassette 26 includes a base plate or pressure plate 34 having a top surface facing control 5 module 24. Tube 32 is positionable between base plate 34 and pumping mechanism 28. Pumping mechanism 28 includes reciprocally mounted members which engage tube 32 in a particular manner to move fluid through tube 32.
In one preferred embodiment, pumping mechanism 28 10 includes a reciprocally mounted inlet valve, a reciprocally mounted outlet valve, and a reciprocally mounted expulsor. The expulsor pushes fluid through the tube 32. The inlet and outlet valves, on opposite sides of the expulsor, open and close the tube to permit the passage of fluid through the tube 32. Pumping mechanism 28 includes a rotatable cam shaft controlled by a motor which moves the inlet and outlet valves and the expulsor in the appropriate manner. Base plate 34 and outer housing 44 cooperate to enclose reservoir 30 in Figure 1. An example of one pumping mechanism useable in pump 20 is shown in U.S. Patent No. 4,559,038.

Control module 24 further includes a plurality of keys 36 for providing input.structure for the operator to input information into control module 24.
Control module 24 also includes a display 38, such as an LCD (liquid crystal display) for displaying information to the operator. An audible signal device 56 may be provided to send an audible signal to the operator indicative of various conditions of pump 20. For --example, a beeper may be provided for audible signal device 56. A visual signal device 58 may be provided for sending a visual signal to the operator indicative of various conditions of pump 20. For example, red and green LED (light-emitting diodes) may be provided for visual signal device 58.

Control module 24 includes a device 42 for identifying indicia 40 on cassette 26. Various cassette identification systems are anticipated including a variety of different identifying devices 42 and indicia 40. -Referring now to Figure 2, a control system 50 for control module 24 is shown. Control system 50 includes a processor-52 electrically interconnected to keypad 36, display 38, pump mechanism 28, and indicia identifying device 42. Audible signal device 56 and visual signal device 58 are interconnected to processor 52. Control system 50 further includes a memory 54 for storing various programs for operating pump 20. One program to be stored in memory 54 is pump disabling program for disabling pump mechanism 28 if an improper cassette is sensed.

Figure 2 also shows a lock/latch sensor 60 interconnected to processor 52. Lock/latch sensor 60 senses when cassette 26 has been locked/latched to control module 24 through the operator activated latch structure 45, 46, 47, 48 which holds cassette 26 adjacent control module24. Figure_2further shows a pressure sensor 62 interconnected to processor 52.
Pressure sensor 62 is utilized to seiise pressure in-tube 32. Pressure-sensor 62and~lock/latch sensor 60 ate optional with respect to cassette identification.
However, these sensors are tised to advantage 3uring cassette identification. These-sensors can be utilized -by processor50 to identify if therehappens to be.a malfunction of the cassette=identification system.
Processor 52-will know when-cassette-26 has been mountecl to control module 24 by receipt of a lock/latch signal and an appropriate pressure signal (i.e., a pressure sensed within an acceptable operating range). At that point, processor 52 can begin iooking for an appropriate signal from theidentifying_device 42 for identifying the indicia 40. If no identification signal is present, processor 52 does not permit initiation or centinuation of the pumping operation bypump mechanism 28.

Processor 52 may also send an appropriate error signal to display 38, audible signal device 56, and/or visual signal device 58. Processor 52 checks for a cassette identification signal periodically or continuously.
Periodic is preferred as a manner of reducing energy consumption of pump 20.

In Figure 2, the various sensors, switches, and other components of control system 50 are interconnected.to processor=52 through interconnection link 64.

Referring now to Figure lA, a remote reservoir adapter 26a is shown which is mountable to control module 24 in a similar manneras cassette 26. However, instead of including a self-contained fluid reservoir, adapter 26a is separate from remote fluid reservoir 30a.
A tube 31a links remote fluid reservoir 30a to adapter 26a. Adapter 26a includes a base plate 34a with an extending base or housing 44a, hooks 45a, and a loop 47a. Housing 44a is smaller than housing 44 typically since no fluid reservoir is contained therein. Tube 32a extends from adapter 26a to be linked to the patient.

As with respect to cassette 26, adapter 26a includes identifying indicia 40a to permit identification by control module 24.

In the following description of various preferred embodiments, reference to cassette 26 is to be interpreted as either cassette.26 of Figure 1 or adapter 26a of Figure lA.

Referring now to Figure 3, a first cassette identification system 70 is shown including indicia associated with cassette 26 and indicia identifying structure associated with control-module 24. The indicia on--cassette 26 includes a projection 84 projecting upwardly from top surface 86 of base plate 34. The indicia identifying structure on control module 24 includes a plurality of forde-sensitive resistors (FSRs). FSR 72 senses contact by projection 84. FSR 72 sends an appropriate signal through electrical connection 78 to processor 52 of control system 50.

As shown in Figure 3, second FSR 74 and third FSR 76 are not ehgaged by any projections extending from cassette 26. Electrical connection-80 can send an -appropriate signal from a second FSR 74 indicative-of a condition where no-projection is sensed. Similarly, electrical connection 82 can send a signal from third FSR 76 indicative of no projection sensed.

- Cassette identificatiori system 70 is capable of identifying at least three different cassettes 26.
System 70 is shown identifying a first cassette 26. A
second cassette could include a projection-appropriately positioned to engage only second FSR 74. Similarly, a projection could be provided in the appropriate position to engage only third FSR 76. In this manner, a failure of one of the FSRs to sense the presence of-a projection does not give an erroneous signal.to proces5or 52..

If it is a desireable-to identify more than three cassettes 26 utilizing only three FSRs, it is possible to utilize the FSRs in a manner which -identifies up toeight different cassettes_ However, it is not possible to differentiate between cassettes if one-or more of the FSRs would happerito_fail-to idesitify a projection which is an engagement with thexespective FSR, or-if one-of the projections is somehow damaged or malformed such that no engagement occurs. When only three different cassette sensors are provided, and only three cassettes are identified with them, then_only one cassette projection is sensed. If no projection is sensed, or if more than one projection is sensed, then control module 24 recognizes an improper-or damaged 5 cassette has been attached. -Referring now to Figure 4, a second alternative cassette identification system 90 is shown.
Like system 70, system 90 includes FSRs. In Figure 4, FSR 94 is shown for sensing projection 96 extending from 10 cassette 26. Compressible elastomer 92 is positioned between base surface 91 of control module 24 and FSR 94.
Elastomer 92 provides a greater.range of variation with respect to the height of projection 96 extending from cassette 26 relative to control module 24. Without 15 elastomer 92, it may be possible for projection 96 to damage FSR 94 if projection 96 happens to extend too far from cassette 26 or-if projection 96 is pushed too far into FSR 94. Similarly, if projection 96 does not extend far enough, FSR 94 will not sense the presence of projection 96 if there is insufficient contact below the threshold-amount of the FSR or-if there is no contact at all. Elastomer 92 extends the range of operation of FSR
94 such that variations in the height of projection 96 can be accommodated. Such accommodation is useful during manufacturing because the ranges on the possible height of projection 96 do not have to be as narrow as they might if no elastonmer is present. Also, damage to the FSR may be avoided if the projection is pushed into WO 95/28190 218 7 7 6 9 PC'T/US95l04527 the FSR at some point during mountin_g or dismounting of cassette 26.

Referring-now to Figure 5, a third alternative cassette identification system 100 is shown. Instead of an elastomer 92 in pystem 90, system 100 includes a coil_. ..
spring 104 which biases-FSR_102 away from base surface 101 of control module 24. FSR 102 sensee the presence of projection 106 extending from cassette 26.. Spring 104 provides for an-extended range in the height of projection 106 relative to control module 24. it will --be appreciated that other.types of springs,such as wavy, belleville and others-could be used instead of coil spring 104. _ Referring now to Figure 6, a fourth -alternative cassette identification system 110 is shown.
Instead of anelastomer 92 as in system 90,or a spring 104 as in system 100, system 110 includes a flexible beam 114 extending from top surface 111,of control-module 24. Flexible beam 114 positions FSR 112 at_a spaced apart distance from top surface 111.FSR 112 senses the presence of projection 116. Flexible beam 114 accommodates variations in the extension-of projection 116.relative to control fnodule.24.

Referring now to Figures 7-9, a fifth alternative cassette.identification system 130 is shown.
Cassette 26-includes a prism arrangement 140 for reflecting light from control module 24_.in an.. -appropriate manner back toward control module 24 to identify cassette 26. Prism arrangement 140 includes a top surface 142, a first prism surface 144, a second prism surface146, and a top surface 148. Base plate 34 is constructed to include prism arrangement 140 with the top surfaces 146, 148 forming a top surface portion of base plate 34-and surfaces 144, 146 forming a bottom surface portion of base plate 34._ Light emitter 132 emits light represented by arrows 133 which enters prism arrangement 140 and is reflected back toward control module 24. As shown in Figure 7, prism arrangement 140 is reflecting light from emitter-132 to receiver 134. Receiver 134 sends an appropriate signal to processor 52_indicative of the presence of prism arrangement 140 reflecting light to receiver 134. Base plate 34 of cassette 26 is made from a material which permits the passage of light from emitter 132 to be reflected internally at surfaces 144 and 146. In one preferred embodiment, base plate 34 is made from polycarbonate which has an index of refraction of about 1.6 relative to air. Angles of 45 degrees relative to the direction of light passage are utilized for surfaces 144 and 146 in order to obtain sufficient internal reflection to have receiver 134 sense light being emitted from emitter 132. -- To indicate the presence of a second cassette different from cassette 26, prism arrangement 140 is provided with a different_configuration. Receiver 136 is utilized instead of receiver 134. In order to have receiver 136 receive light from emitter 132, surface 146 is moved adjacent (belooi in Figure 7) receiver 136_ Surface.144 would remain in the same location that is depicted in Figure 7. Receiver 136 would send an appropriate signal to processor 52 indicative of the presence of prism arrangement 140 reflecting light to receiver 136.

To indicate the presence of a third cassette, receiver 138 is utilized. In order to have_receiver 138 sense-light from emitter 132, surface 144 is positioned in a reverse-direction to reflect light from emitter 132 toward receiver 138. Surface 146 is appropriately positioned beneath receiver.138. I.in-this manner, three different cassettes can be sensedby control module 24.

As shown in Figure 7, top surface-142 is configured as a lens surface for columnating the light from emitter 132. As shown in Figures 7 and s, top surface 148 is also configured as a lens for focustng the light passing through base plate 34 toward receiver - -134.

Receivers 134,-=I36; 138 ca.n be any of a-variety of light receivers which generate a signal-when light is present. Receivars 134, 136, 138 may be phototransistors, photodiodes, or photodarlingtons.

- - Referring toFigure 9, an example of an ---emitter 132 is-shown in greater detail. Emitter 132 may be an infrared emitting diode. An epoxy coating 154 encloses chip 156 which emits the infrared light.

WO 95/28190 21$ 7 76 9 pCT/US95/04527 Extending from emitter 132 are.two leads 150, 152 to connect to processor 52. - -In cassette identification system 130, a comparitor circuit is useful for comparing the signals from all three receivers 134, 136, 138. It is preferred that the three receivers, 134, 136, 138-each generate a signal, with one signal being strong and two being weak.
The comparitor circuit identifies the receiver with the stronger signal as being the receiver positioned in the appropriate manner relative to the prism arrangement 140 for identification of the cassette. -The two weaker signals indicate that some light is reaching the receivers, but that light is not intended to cause those receivers to indicate the.presence of the prism arrangement 140. The light that is being received by receivers 136, 138 which generates the weaker signals could come from emitter 132. Also, the light could come from external of pump 20.

One preferred cassette identification system 130 may include a modulating signal with respect to emitter 132- The light would preferably flash at a frequency not commonly found in the environments where pump 20 is to be used. This would increase the accuracy of cassette identification system 130. The modulating signal set.at the uncommon frequency would help reduce inaccurate results caused by sunlight, room lighting, or other lighting devices which produce light which could hit pump 20, possibly causing an inaccurate reading of WO 95/28190 2 18 7 7 6 9 pC'1'/US95/04527 =

the cassette identification system.

Referring now to Figure 10, a sixth alternative cassetteidentification system 160 is shown.
Control module 24 in Figure 10 is similarly arranged as 5 control module 24 of Figures 7 and S. An emitter 162 is provided for directing light toward cassette 26.
Cassette 26 includes structure for reflecting the light back toward control module 24. In particular, base plate 34 of cassette 26 includes a prism arrangement 170 10 which has a plurality of indentations. A first indentation 171 includes a first prism surface 174: A
second indentation 175 provides a second prism surface 176. 7is shown in Figure 10, light, represented byarrow 177, is emitted by emitter 162, passes through top 15 surface 172 of=base-plate 34, and is reflected by first prism surface 174 toward second prism surface 176.
Second prism surface 176 reflects the light back toward receiver 164_..___ __ - ~- -As shown in Figure 10, prism arrangement 170 20 is not directing light toward either second receiver 166 or third receiver 168. fihese receivers are'utilized to identify different cassettes from cassette 26. A

different prism arrangement 170 would be provided--to reflect light from emitter 162 to receiver 166. In particular, indentation 175 and second prism surface-176. --would-be positioned beneath second receiver_166.

Similarly, prism arrangement 170 would be modified in order-to direct light from emitter 162 to third rec.eiver, 168 in order to identify a third cassette. In particular, indentation 171 and indentation 175 would be provided in a manner that first prism surface 174 and second prism surface 174 would direct light from emitter 162 toward receiver 168.

In cassette identification system 160, a comparitor circuit is useful for comparing the signals from all of the receivers 164, 166, 168. This identifies the stronger signal which is associated with the prism arrangement 170 directing light toward a particular receiver for-cassette.identification.

In an alternative arrangement (not shown) to the -systems 130 and 160 of Figures 7-10, three emitters and one receiver could be provided. In that case, the emitters are switched on and off at different times and a comparitor circuit compares the signal received at the receiver from each emitter to identify which cassette 26 is being identified. -Referring now to Figure 11, a seventh alternative cassette identification system 180 is shown.
Instead of a separate emitter and receivers, system 180 includes three components 182',- 184, and 186, which each function as an emitter of light and a receiver of light.
Cassette 26 is provided with a reflective patch 188 for 25- reflectirig light back toward control module 24. -Reflective patch 188 is appropriately positioned to reflect light back at one of the emitter/receiver components 182, 184, 186. In this case, patch 188 is below emitter/receiver component 182. The system 180 of Figure ],1 requires that reflective patch 188 be appropriately positioned during manufacturiiig. Base plate 34 reflects light, but in-a different amount from reflector 188. It is not necessary that reflector_188- _ reflect more light than base plate 34.

An advantage of system i30 shown in Figures 7-9, and system 160 shown inFigure 10 is that base plate 34 is molded with the appropriate configuration concerning the prism arrangement. No additional steps of placing a component or part on cassette 26 is needed- --with respect to systems 130, 160.

In cassette identification system 180, a comparitor circuit is useful for comparing the signals from the receivers-of all threecomponents 182, 184, 186. This identifies the stronger_ (or-weaker) signal which is associated with the component positioned adjacent reflective patch 188.

Referring now to Figure 12, an eighth cassette identification system 200 is shown. A microswitch 202 is activated when projection 216 moves plunger 204.

Plunger 204 is positioned in opening205 through chassis -207 of control module 24. A rubber boot 206 closes opening 205 from_contaminants. Spring 208 biases plunger 204 away from microswitch 202. Spring 208 is positioned between spring retainer 210 mounted to.-chassis 207 and flange 212 of plunger 204.. _A seal__214 seals opening 205 fromcontaminants entering an interior of control module 206. Seal 214 and boot 206 serve similar functions in keeping contaminants out of control module 26. As such, it is anticipatedthat only one is needed_- - -Microswitch 202 is preferably adjustably mounted to board 209. Board 209 is mounted to chassis 207. Soard 209 is useful formounting other pump circuit components. An adjustable mounting permits adjustability of switch 202 such that the anticipated range of motion of plunger 202, including the various tolerances of projection 216, can be accommodated for during assembly and use such that consistent operation is achieved.

Referring now to Figure 13, a ninth alternative cassette identification system 260 is shown.
A plunger 262 is reciprocally mounted in aperture 263 in chassis 261 of control module 24. Plunger 262 is spring biased by spring 266 toward the position shown in Figure 13. Seal 265 seals control module 24 from contaminants that come in contact with control module 24. Seal 265 also biases plunger 262.to the position shown in Figure 13. Spring 266 is positioned between flange -end 264 and spring retainer 274. When projection 280 engages flange cap 268 such that plunger 262 is moved upwardly, electrical contact is broken between upper contact 276 and a lower contact 275 located on spring -retainer 274. Alternatively, electrical contact can be made when plunger 262 is moved upwardly toward a contact WO 95/28190 2187-767 n PCT/US95/04527 r 24 positioned above upper contact 276. Cap 268 is pressed into foam seal 270 in this-position. An insulator 278 is press fit on an end of plunger 262.- Insulator 278 is positioned between plunger 262 and upper contact 276 to insulate plunger 262.

Referr.ing now to Figures 14 and 15, a tenth alternative cassette identification system 320 is shown.
The cassette identification system 320 includes a board 322 positioned in an interior of-control module 24_ Mounted to board 322 are three slotted optical sensors 324, 350, 354. The optical sensors 324, 350, 354 may be soldered to board 322 at pins 329. The optical sensors are electrically connected-to the processor-of the control module. Board 322 is used for mounting various other circuit components of pump 20. Board is mounted to chassis 341 of control module 24-with at least one bolt 356 and a spacer-357:-- Pirns (not shown) inserted -into board 322 and chassis 341 may be used to achieve greater accuracy in moun.tirig board 322 to chassis 341 during manufacturing. -In Figures 14 and 15, each optical sensor 324, 350, 354 is identical. -Sensor 324 includes a light emitter-.on one-side of slot 325 and a receiver on the opposite side of slot 325. Sensor 324 sends an --appropriate signal to the processor of the controL
module indicative of whether, or to what degree,- light from the emitter is being received by the receiver_of sensor 324_ -WO 95128190 2 1 8 7 7 6 9 pCT/US95/04527 In system 320, three plungers 326, 352, 358 are reciprocally mounted to chassis 341. Plungers 326, 352, 358 are shown in a first position in Figures 14 and 15. In the.first position, the path between the emitter 5 and the receiver of each optical sensor is unobstructed.
In some cases, the end of the plunger may be partially received by the sensor-in the first position. In that case, the light path between the emitter and the receiver in the first position is less obstructed than 10 in a second position. In one preferred embodiment, a higher voltage signal is sent to the processor of the control module when the plunger is in the fist position than when the plunger is in the second position.

In the system of Figures 14 and 15, slot 325 15 of optical sensor 324 receives an end 327 of plunger 326 when plunger 326 is moved upwardly to a second position.
In the second position, the path between the emitter and the receiver is at least partially obstructed (or more obstructed__than the first position). In one preferred 20 embodiment, a lower voltage signal is sent to the processor of the control module than when the plunger is in the first position. Alternatively, the light path can become less obstructed when plunger 326 is moved by the projection to the second position:

25 Extending from the base plate 348 of cassette 24 is a projection 346 which engages an end 328 of one of the plunger 326 to move that plunger from the first position to the second position when cassette 26 is ~

mounted to control module 24. An appropriately positioned projection 346 can be use3dto .ide,ntify that cassette from one or more other cassettes which are not provided with a projection- -The processor of control module 24 looks for the optical sensor sending the lower voltage signal indicative of the presence of a particular plunger in the second position. Preferably, although not required, control module 24 looks fora single projection. Identification of one, two or three-projections may be used to_identify up to eight cassettes, if desired. - -Plunger 326 is spring biased away from the respective optical sensor 324 by spring 332 and seal 340.- Spring 332 is positioned-between spring retainer 334 mounted-to chassis 341_ A flange 330 is provided on plunger326 to trap spring 332 between spring reta-iner 334 and flange 330. Chassis 341 further includes a recess 342 for receipt of seal 340. Seal 340 may be a foam seal for preventing mo-isture from entering the inside of the-control module 24.

Plunger 326-can be made from round stock: End 327 is flattened to an appropriate width to be received by slot325 of slotted-opt'ical sensor 324. -"A C-clip 359=.
limits each of the plungers 326 from movingtoo faY away from the optical sensors 324. A groove orziotch may be-provided on plunger 326 to_hold C-clip from axial movement along the plunger.= --Referring to FiguYe 16, a sec6nd alternative = WO 95/28190 2 i 8 7 7 6 9 PCT/US95104527 plunger arrangement is shown. Spring retainer 400 is provided with a slot 402 instead of an opening as in spring retainer 334. Plunger 404 is provided with a notch 406. The length of notc.h 406 along the longitudinal axis 408 of plunger 404 defines a range of possible movements of plunger--404.

Referring to Figure 17, a third alternative plunger arrangement is shown. Instead of a C-clip 359, a pin 410 is inserted through plunger 412. Pin 410 engages spring retainer 414 to limit movement of plunger 412.

Referring to Figure 18, a fourth alternative plunger arrangement is shown. A flange 430 is provided on_plunger 426 to trap spring 432 between spring retainer 434 and flange 430. A stop surface 436 on plunger 426 engages stop surface 438 on chassis 424 to limit the distance plunger 426 can be biased away from the-optical sensor. Chassis 424 further includes a recess 442 permitting receipt of seal 440 when plunger 426 is moved toward the optical sensor. A groove 444 is provided on plunger 426 to hold seal 440 in an appropriate position.

Referring now to Figure 19, a fifth alternative plunger arrangement is shown.- Plunger 452 is mounted to chassis 450 wherein a resilient silicon seal 458 seals the opening in chassis 450 for plunger 452. Seal 458 fits in recess 454. A metal ring 466 helps hold first end 462 of seal 458 in the position W 95128190 2 1 8 7 7 6 9 PC'1'/[7S95104527 10 shown. Second end 464 of seal 458 holds plunger 456 in ra-cess 460. As plunger 456 is moved up and down during use, such as in system 220 as shown in Figures 14 and 15, second end 464 moves with plunger, thereby effectively sealing the.opening in the chassis.
Referring now to Figure 20, a sixth alternative plunger arrangement-is shown. Instead of -seal 458 of-Eigure 19, seal 474 is provided for-sealing the opening in the chassisfor plunger 478._-_First- end 475 of seal 474engages the chassis. A second end 476 engages a recess 480 in plunger 478. Second end 476 of-seal 474 moves with plunger 478 as plunger 478 moves up and down during attachment and detachment of cassette 26. - - -Figures 3-20 illustrate various cassette identification systems involving either contact or-non-contact between cassette 26 and control niodule 24. Some alternative non-contact cassette identification systems include-those utilizing a magneto-reEistive switch.as part of the cassette identification device 42, and-a magnet associated with cassette 26.as the indicia 40.
The magneto-resistive switch sends a signal to the processor 52 that the.resistivity induced in a-current carrying conductor_or semiconductor is-changed by the application of the magnetic field-from the magnet an cassette 26. - - -The cassette.-identifying device 42 could--instead include a Hall eff-ect sensor, with indicia 40 = WO 95/28190 2187 7 6 9 PCTIUS95/04527 including a magnet. A Hall effect switch is a magnetically activatedswitch that uses a Hall generator, a trigger circuit, and a transistor amplifier on a silicon chip. A further_alternative may include a cassette identifying device having a reed switch, with indicia 40 including a magnet_ A reed switch typically has contacts mounted on ferromagnetic reads sealed in a glass tube designed for actuation by application of the magnetic field of the magnet.

Another alternative indicia identifying device-42 may include a piezoelectric switch or a capacitive switch. Further alternative embodiments may include an acoustical emitter/detector for indicia identifying device 42-- Additional embodiments of indicia identifying device 42 include bar code readers or other text or printed marking readers which can read printed material on cassette 26. Laset positioning sensors may be utilized where the height of a projection extending from the base plate is measured to identify the cassette.

While the systems shown in Figures 3-20 identify cassettes 26 by identifying a single indicia 40 on each cassette, it is to be understood that the identification system could look for two indicia, such as two projections,-for each cassette. A redundant system could still be provided in that case since the control module would request that two signals be received.- Less than two or more than two would indicate WU 95/28190 2 1 8 , 7 ~ ~ PCT/OS95104527 =

an error condition. Moreover, the invention is-not to be limited to three sensors. More than three, or-less than three, are possible whether the systems sense the ---presence-of-one indicia, the absence of one-indicia, or 5 variations in the number of indicia sensed, such as zero, one, two, three, etc. corresponding to the number of sensors provided and the possible combinations--thereof Referring now to-Figures 21-29, a preferred 10 cassette identification system is shown. Figures 21-23, 26, 27 and 29 show a preferred control module 550, a preferred cassette sensing-mechanism 542, and a first preferred cassette 526. Figure 21 shows first cassette 526 assembled and mounted to controT module550. --' 15 Figures 26, 27 and 29 show-various side and top views of a base plate 530 of cassette 526, and a perspectiue.view of a base 532 of cassette 526. Figure 22 shows only chassis 552 with the various plungers mounted thereto.
Figure'23 is an enlarged view of a portion=of -20 chassis 552 with aslotted-optical sensor 676 shown in --its relative-position to plunger-,666.- Figures 24-and25 show a second cassette626-in side and top views, respectively_ Figure 28-shows a third-cassette portion, base plate 730, useable with base 532 of Figure 29-to 25 form third cassette726 in a similar manner as first cassette 526- The second--and third preferred cassettes-626 and 726_-are also part of the.preferred-cassette identification system. Cassette sensing mechanism 542 -= WO 95128190 2 i 8 7 7 6 9 PCT/US95/04527 can distinguishbetween cassettes 526, 626, 726. For example, first cassette..526 can have a first pumping volume per activation, i.e., 50 l. Second cassette 626 can have a second pumping volume per activation, different from the first pumping volume, i.e., 100 l.
It is critical for control module 550 to know how much fluid is pumped per activation of the pumping mechanism to deliver the desired drug therapy. In an improper drug therapy, either too much or too little drug can be harmful, and in some cases, fatal.

While variations of cassette identification systems have been shown in Figures 1-20, and described above, the cassette identification system of Figures 21-29 is preferred. As shown in Figure 21, first cassette 526 includes base plate 530 and base 532 mounted thereto. Base plate 530 is shown in greater detail in Figures 26 and 27. Base 532 is shown in greater detail in Figure 29. Base plate 530 is adhesively attachable to base 532. Alternatively, a snap arrangement can be provided. In a further alternative, a snap arrangement and adhesive can be utilized. In a further alternative, base plate 530 and base 532 can be integrally formed as a single unit, such as by molding in the case of plastics.

Control module 550 includes a chassis 552 and an outer housing 554. A seal 556 seals between chassis 552 and housing 554. A component board 558 is mounted to chassis 552 via screws 560, spacers 562, and W O 95/28190 218 7 7 6 9 PCT/US95/04527 .' alignment pins_564. A first plunger 566 is reciprocally mounted-to chassis 552. Second plunger 666-and tIiird -plunger 766arealso reciprocally mounted to-chassis 552. Plungers 566, 666, 76-6 are-similarly configured and operated. Figure 23 shows second-plunger 666 in greater detail. A seal 668_ seals ari end of"second plunger 666. A spring-670 biases second plunger 666 to-the position shown in Figures 21-23. -A-bezel 672 traps spring 670 in position as shown. A flange 674 limits second plunger 666 frdm beirig pulled downwardly out of the position shown in Figures 21-23. During operation, a projection-extending from the cassette engages end 667 and causes upward movementof second plunger 666 such -that end 678 of second plunger 666- moves into a new position relative to slotted-optical sensor-676, which causes a signal to be sent to the processor-af control module 550 that a projection has been sensed.

First plunger_566 and third plunger 766 are -provided for sensing additional projections'.- In particular, first plunger 566 engages projection 534 extending from the main surface 536 of base=plate 530 of first cassette 526_ Second plunger-665 engages second-projection 634 extending from main surface 636 of_-base -plate 630 of..seconsi cassette 626. a'hird plunger 7-66 .

engages projection 734 extending from base plate 730 of third cassette 726. In this manner, control module 550 _ can identify at least three different 3fassettes 52-6, 626, 726.

Referring in particularto-Figures 21, 26, 27 and 29, base plate 530, and base 532-are shown.
Extending from main surface 536 are a pair of hooks 538 adjacent to a first transverse end 540. A loop 542 extends from the main surface 536 adjacent to a second transverse end 544. A plurality of tube guide pairs 545, 546, 547, 548 extend from main surface 536 and are spaced apart to receive a flexible tube, in a general direction parallel to first and second longitudinal sides 541, 543 of main surface 536. In Figure 26, background portions have been removed behind the cross-sectional portion for clarity. In Figure 27, a tube-549 is shown in dashed lines.

Referring now to Figures 24 and 25, base plate 630, and base 632 are shown in greater detail.

Extending from main surface 636 are a pair of hooks 638 adjacent to a first transverse end 640. A loop 642 extends from main surface 636 adjacent to a second transverse end 644. A plurality of tube guide pairs 645, 646, 647, 648 extend from main surface 636 and are spaced apart to receive a flexible tube, in a general direction parallel to first and second longitudinal sides 641,- 643 of sedond cassette 666. In Figure 25, a tube 649 is shown in dashed lines.

As shown by a comparison of Figures 24-and 25 with Figures 26 and 27, projection 534 is in a different relative location to projection 634 in a direction parallel to longitudinal sides 641, 643. It should also WO 95/28190 2 18 T 7 6 9 PCT/1JS95/04527 0.

be noted that Figures 24 and 25 illustrate the integral-constxuction between base plate 630 and base 632.
Cassette 626 also includes features for more accurate centering of tube 649 which is larger than tube 549, such-as the V-shaped passages provided in connection with guide pairs 645, 646, 647, 648.

Also, cassette 626 includes clip features for releasably gripping tube 649 to provide-a mechanical hold down during adhesive attachment of tube 649 to cassette 646. In particular, first clip 650 and second .
clip 652 provide hold downof tube 649 to cassette_.626.
First clip 650 and second clip 652 hold the tube in place during assembly, allowing the adhesive-to set up without the need for special clamps or external --fixtures.

Referring now to Figure 28, third cassette 726 is shown. With respect to_Figure 28, a base plate 730 is illustrated. Base 532 shown in Figure 29 is useable with base plate 730 shown in Figure 28. Projection 734 is in a different.relative location on base plate..730 than projection 534 of base plate 530 and projection 634 of base plate 630. Projection 734 can be_indicative of a different cassette ptoperty to differentiate cassette 726 from cassettes 626, 526. For example, cassette 726 may include an indication that an air filter is present to identify to the control module when the cassette is utilized with a reservoir=including an in-line air -filter.

WO 95128190 2187769 PCT/US95l04527 The cassette identification system of Figures 21-29 incorporates features of embodiments described in various of Figures 1, lA, 2, 14, 15, 18, and 20, for example. The system of Figures 21-29 may be 5 advantageous over mechanical switches, such as microswitches, since little or no emphasis need be placed on overtravel, individual adjustment, arcing problems, and mechanical-wearing of the switch.
Inductive, magnetic, or reflective systems may require 10 the placement of an additional element on the cassette during manufacture. A projection as in Figures 21-29 can be integrally formed on-the cassette during manufacture, possibly simplifying manufacture. Force sensitive resistors may be prone-to problems due to 15 typical range of necessary movement and the typical tolerances of the disposable cassettes. Also, the plastics associated with the FSR or its spring may be subject to creep problems over time, possibly further complicating the range of motion and tolerance problem.

20 Make or break switches where the contacts aremounted to a moveable plunger, for example, may be prone to failure due to the failure of the contact points, such as due to pitting or corrosion, or due to the components getting stuck open or closed.

25 Reciprocally mounted plungers and slotted optical sensors are useful to solve some ofthe above-possible problems and other problems with cassette identification systems. However, it is to appreciated WO 95/25190 - - PCT/US95/04527 .

that insome instances the-use of microswitches, FSR's, inductive switches, magnetic switches, reflective .
elements, moving contacts,. or other systems noted above may be desireable.

While the present invention has been described in connection with the preferred embodiments thereof, it will be understood-many modifications will be readily apparent-to_those skilled,_in the art, and this application-is intended to-cover any adaptations or -variations thereof_ It is_intended this invention be limited only by the claims and equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. A base plate for use with a control module having a projection sensing member, comprising:
a body having a main surface facing in a first direction and including first and second longitudinal sides, and first and second transverse ends;
a pair of hooks extending from the main surface adjacent to the first transverse end;
a loop extending from the main surface adjacent to the second transverse end;
a plurality of tube guide pairs extending from the main surface and spaced apart to receive a flexible tube in a direction generally parallel to the first and second longitudinal sides; and a projection extending from the main surface positioned to engage the projection sensing member of the control module.

2. The base plate of claim 1, the flexible tube being mounted to the body.

3. The base plate of claim 2, wherein the body includes a self-contained fluid reservoir.

4. The base plate of claim 2, wherein the body is mountable to a pump and is separate from a remote fluid reservoir.

5. The base plate of claim 2, the control module including a processor and a pumping mechanism for pumping fluid through the tube, the base plate comprising:
two reciprocally mounted plungers mounted to the control module; and two optical sensors mounted to the control module, each of which is capable of sensing a portion of one of the plungers and sending a signal to the processor, the plungers being movable between a first and a second positions, the first position including a portion of the plunger positioned in a first position relative to the optical sensor, and the second position including a portion of the plunger positioned in a second position relative to the optical sensor, different from the first position relative to the optical sensor, at least one of the plungers being moved by the projection.

6. The base plate of claim 5, further comprising a third reciprocally mounted plunger mounted to the control module, and a third optical sensor mounted to the control module which is capable of sensing a portion of the third plunger.

7. The base plate of claim 5, wherein the control module includes a display interconnected to the processor, the processor including means for receiving a signal and for sending a display signal to the display indicative of a presence of the projection.

8. The base plate of claim 5, wherein the processor includes means for disabling the pumping mechanism until the processor receives a signal indicative of a presence of the projection.

9. The base plate of claim 5, wherein the two optical sensors are slotted optical sensors.

10. The base plate of claim 6, wherein all of the optical sensors are slotted optical sensors.