CA2078212C - Programmable valve pump - Google Patents
Programmable valve pumpInfo
- Publication number
- CA2078212C CA2078212C CA002078212A CA2078212A CA2078212C CA 2078212 C CA2078212 C CA 2078212C CA 002078212 A CA002078212 A CA 002078212A CA 2078212 A CA2078212 A CA 2078212A CA 2078212 C CA2078212 C CA 2078212C
- Authority
- CA
- Canada
- Prior art keywords
- accumulator
- valves
- outlet
- diaphragm
- spacer plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/14244—Pressure infusion, e.g. using pumps adapted to be carried by the patient, e.g. portable on the body
- A61M5/14276—Pressure infusion, e.g. using pumps adapted to be carried by the patient, e.g. portable on the body specially adapted for implantation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16804—Flow controllers
- A61M5/16809—Flow controllers by repeated filling and emptying of an intermediate volume
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B43/00—Machines, pumps, or pumping installations having flexible working members
- F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
- F04B43/04—Pumps having electric drive
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F11/00—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it
- G01F11/02—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement
- G01F11/08—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with measuring chambers which expand or contract during measurement of the diaphragm or bellows type
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2206/00—Characteristics of a physical parameter; associated device therefor
- A61M2206/10—Flow characteristics
- A61M2206/22—Flow characteristics eliminating pulsatile flows, e.g. by the provision of a dampening chamber
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S128/00—Surgery
- Y10S128/12—Pressure infusion
Abstract
An implantable valve accumulator pump for the delivery of medication is disclosed. The implantable pump comprises a drug reservoir (18) maintained at constant pressure vapor. The medication metering assembly comprises a fixed volume accumu-lator (30) positioned between a pair of valves (26, 28). The valves (26, 28) alternately open and close to admit medication from the reservoir (18) into the accumulator (30) and to dispense a precise volume spike to an outlet catheter (36). In order to minimize dead volume and insure complete discharge, the accumulator (30) employs a titanium diaphragm (90) seated in one position by a recessed stop (92) and in the discharge position by a spacer plate (98) having a concentric groove pattern (106). The grooves (106) are in fluid communication with the inlet and outlet (58, 59). Also, a wide groove (105) extending between inlet and outlet (58, 59) provides fluid communication between the grooves (106). The unit is externally programmed.
Description
2 ~ 7 8 2 1 2 PCr/l~S91102088 p~nt;~MM~r P~ VALVE PrlNP
sAcl~i~uuNL) OF T~E INVENTION
This invention relates to an implantable infusion pump for the dispensing of infusate. In particular, it relates to a pump operating at positive pressure which is ~IO~L hl~ to dispense medication in accordance with different specified flow rates.
Implantable infusion pumps are currently used for a variety of medical E~UL~uoses. Such devices are implantable in the human body and rely on a liquid/vapor equilibrium to maintain constant ~LC s~uLe on the drug which is housed therein so that the drug flows through a capillary in order to maintain a constant f low rate . Such devices are characterized by "constant flow" and are used in a variety of medical applications, for example, to dispense 2 0 chemotherapy at a relatively constant f low rate .
U.S. Patent 4,714,462, commonly assigned, deals specifically with a ~LuyL~ ulldble positive displacement system having a pumping chamber which is placed in the path of fluid communication between the pressurized drug reservoir and a flow restrictor. By use of external PLUYL ;n~, the device can be used to expel infusate from the pumping chamber at varying rates.
Reference is made to commonly assigned U.S. Patent 4,838,887 which describes a ~lUyL hle valve pump that 3 o employs a unique A ~ l Ator having a spacer plate with a series of orthngnnA 1 checkerboard grooves . This is illustrated in Figure 5B of the ' 887 patent. While suitable for a number of applications, it has been found that this spacer plate conf iguration allows the build-up of insulin 3s precipitation. The build-up of precipitation in turn reduces the pulse volume of the system thus reducing efficiency and accuracy of output dosage.
It has also been discovered that air bubbles can become trapped in the cross grooves of a gridded A~c~m~l Ator which,as illustrated in the '887 patent,are at right angles to the direction of the f luid f low . This occurs because _ _ _ _ _ _ _ _ _ _ _ -whlch, as lllustrated ln the ' 887 patent, are at rlght angles to the dlrectlon of the fluld flow. Thls occurs because there 18 no wash-out of the spacer. For the same reason, small partlcles can be trapped between the grldded spacer plate and the dlaphragm. Th~s causes a shlft ln pulse volume.
The grldded spacer plate 18 expenslve to manufacture. It requlres macninlng steps of turnlng and mllllng. The grld pattern 18 then chemlcally etched ln the spacer plate.
Glven these recognlzed shortcomlngs ln the prlor art, lt 18 an ob~ect of thls lnventlon to provlde a posltlve pressure plOyL `~le valve pump whlch operates uslng a wlde varlety of drugs wlthout problems of ~nternal bulld-up and speclflcally preclpltatlon build-up on the accumulator spacer plat e .
SUMMARY OF THE INVENTION
The present lnventlon provldes an lmplantable lnfuslon apparatus lncludlng~ a houslng contalnlng, an lnlet septum, a rechargeable constant pressure lnfusate reservolr, an electronlcally controlled meterlng assembly recelvlng lnfusate from sald reservolr, sald meterlng assembly comprlslng f lrst and second normally closed valves and an accumulator posltloned ln fluld commun~catlon wlth each of sald valves, sald ~ccumulator comprlslng an lnlet and outlet, a chamber havlng a dlaphragm and a spacer plate; electronlc means for controlllng the operatlon of sald valves, and outlet means ln fluld communlcatlon wlth sald meterlng assembly to dlspense lnfusate to a slte ln a llvlng body; characterlzed by sald spacer plate havlng a serles of concentrlc grooves ln fluld communlcatlon wlth sald lnlet and outlet whereln when the flrst of sald valves 18 open, lnfusate flows from said reservolr lnto sald accumulator chamber and lnto said concent rlc grooves, and when the other valve is open and the flrst valve closes, lnfusate flows from sa~d accumulator lnto sald outlet, sald accumulator storlng and dlscharglng predetermined volume splkes o~ lnfusate at a f rer~uency determlned by the cycllng rate of sald palr of valves.
The constant pressure lnfusate or drug reservolr is preferably located ln serles wlth a bacterla/alr fllter. The improved ac~ ator conflguratlon preferably has a number of sharp rldges created between ad~acent grooves. The rldges support the drug slde of the dlaphragm when the Arc~ tor 18 at tne empty portlon of the dellvery cycle. Thls slgniflcantly reduces the contact area between the dlaphragm and the spacer plate. In turn the surface pressure of the drug at the contact polnts lncreases to prevent accumulatlon of drug resldue. These three components comprlse the lmplantable aspect of the pump. The fourth aspect of thls lnventlon 18 the external programmer.
The lnltlal "pumplng" 18 provlded by the reservolr whlch 18 used to f 111 the accumulator to lts f lxed volume .
The accumulator 18 then "dumped" vla the dlscharge catheter to the deslred lnfuslon slte. A pressure whlch ls lntermedlate between the reservolr and the outlet 18 malntalned behlnd tne accumulator 80 that lt fllls and emptles completely and rapldly. The accumulator ls alternatlvely fllled and emptled by the alternate swltchlng of the valves. The rate of swltchlng therefore governs the rate of pumplng and thus the dellvery rate.
Valve control 18 preferably provlded ln the implantable pump by means of an on-board processlng system and power supply. The processor i8 externally accessed through a telemetry llnk which can be used to both program the pump operatlon and obtain dlagnostic lnformatlon as to the operat lon of the devlce .
The lnventlon wlll be better understood from the followlng detalled descriptlon, glven by way of example only, when taken ln con~unctlon wlth the drawlngs, ln whlch Flg. l 18 a schematlc dlagram showlng the complete system and a schematlc dlagram of the flow;
Flg. 2A 18 a schematlc dlagram lllustratlng the pumplng cycle of the accumulator~
Flg. 213 18 a tlme-flow rate chart of the dellvery schedule of the 3ystem;
Flg. 3 18 a cutaway slde elevatlon of the baslc constructlon of the lmplantable pump portlon of the system;
Flg . 4 18 a cutaway schemat lc vlew of the valve/~rc~ qtor meterlng system ln accordance wlth thls lnvent lon;
Flg. 5A 18 a slde vlew of the accumulator;
Flg. 53 18 a top vlew of the spacer plate component of the accumulator ln accordance wlth thls lnvent lon; and Flg. 6 18 a cutaway slde vlew of an electrlcal swltch accumulator ln accordance wlth thls lnventlon.
Referrlng now to Flg. l, schematlc dlagram of the essentlal aspects of thls lnventlon 18 deplcted. The - 3a -WQ9!/16091 - PCI/US91/0208~
~ ~ 20782 1 2 invention is a positive ~L~ uLt: pLu~LG~l,ble valve pump comprising a constant ~Le~ ULc: drug reservoir 10 which is r~ hl e by means of a septum 12 . The system comprises a sealed housing 14 containing a bellows element 16 having a chamber 18 comprising the drug reservoir. The bellows 16 separates the housing into a second zone 20 normally filled with a two-phase fluid which has a significant vapor pressure at body temperature . Thus, as the f luid vaporizes, it compresses the bellows 16 and urges the contents of the refiervoir 18 through an outlet leading to an infusion site.
During the process of rPfillinq~ the chamber 18 via the septum 12, the two-phase fluid is pressurized condensing a portion of the vapor and returning it to its liquid phase.
Typically, the reservoir 18 has a volume of approximately 25ml and the pressurization maintained in the system is approximately 23.2 psia. A sideport 27 can be used for direct bolus injections.
An outlet 22, from the reservoir 18 delivers infusate from the reservoir via a bacterial filter 24 to the electronically controlled metering assembly.
The metering assembly comprises two normally closed valves 26, 28, which are positioned on the inlet and outlet sides of an accumulator 30. The ~rc~ 1l ator operates at a ull,LallL volume, very low, in the range of 1 microliter (~1) 2s pressurized typically to 19.2 psia. The valves 26 and 28 are controlled electronically via an electronics module 32 which is pLU~L ' utilizing an ~YtF~rn;ll yLUl~L -r 34. Fig. 1 illustrated in a chain line, the pump envelope which separates the electronics module 32, that is the system which is implanted, from the external p LUyL -r 34.
The pLVyL -r 34 is a hand held unit using a touch screen. It provides a data transfer link to the electronics 32 implanted as a part of the device (see Fig. 3). In a memory storage element, the ~LUyL ~ 34 maintains a patient history based on storage of real time data. Data as to device status, such as battery condition, diagnostics on valve current, prescription in use and the like are retained.
~- t/02088 WO 91/16091 PCI/US9 ~
207~ 2 The ~ytrrllAl ~LUU,' -r also has different interrogation modes such as initial calibration and protected modes for terhn i r. j An use .
The outlet from the a~ l~tor 30 i5 via a catheter 36 5 which delivers the infu5ate to the site in the body to which drug delivery is required. As indicated by the arrow in Fig.
1, the delivery of infusate occurs at the infusion site below the AC 1 Ator ~ a~uLe forcing discharge through the catheter. This pressure may be ai ^ric (typically 14.7 10 psia) or cardiovascular p~ ~sauL~5 slightly above ai ~ r' -riC~
e . g . 17 . 6 psia arterial .
Referring now to Fig. 2A, the pumping cycle is schematically illustrated. The salient aspects of this section of the system comprise the valves 26, 28 and the ~ 1 Ator 30. The first step is one where both valves 26 and 28 are closed and the A(~r~ l ator 30 is empty. The drug is delivered ~rom the reservoir 18 through conduit 22 and filter 24 to fill the A~-~ lator 30. Thu5, as a second step in the operation the valve 26 is opened while valve 28 is 20 closed to fill the A~ l AtOr to its fixed volume. The third step is then to close both valves 2 6 and 2 8 with the A~ l Ator now full. The final step in the A l Ator cycle is the opening of valve 28 while valve 26 remains closed to empty the arc~m~l Ator through the catheter 36.
25 Consequently, the ;~ lAtor is alternately filled and emptied by the switching action of the valves. A ~lesau~_ intr ';Ate between that of the reservoir and the outlet is maintained behind the A~ 1 Ator so that it fills and empties c~ lr-t~ly and rapidly. The rate of switching of the 30 valves therefore governs the rate of pumping and accordingly de~Prm; nQ~ the delivery rate of infusate.
Referring to Fig. 2B an example of the delivery rate of this system is illustrated. Fig. 2B is a chart plotting a flow rate in the y-axis against time in the x-axis. The 35 output of thQ pump is periodic and is a function of the r,~ . y of the valve cycle. Thus, the faster the valve cycle, the greater the number of i~rcll~--l Ator discharges per ~ \~0 91~16091 PCI/US91/0208~
07~2 1 2 unit. Each discharge i5 in the form of a volume spike.
In Fig. 2B a change from a basal rate to a desired bolus rate, that is an increase in flow rate above the basal rate, is illustrated by means of the square wave on the left-hand 5 portion of the time chart. This would be the ~ ~ O~L tl bolus flow into the electronics package 32. The pump, to e6tablish the required bolus flow rate, would increase the frequency of the discharge spikes by varying its pump cycle during the bolus period as illustrated in the center of Fig.
lO 2s. The total number of spikes are integrated over time 50 that the flow rate volume replicates that required by the desired bolus flow rate . The output through the catheter 3 6 to the bloodstream is illustrated in the right-hand portion of Fig. 2B.
By integrating the volume of the pump over time, given the number of pUlOp cycles, and the volume of each discharge, digital basal and bolus rates closely replicating the required values, that is flow rates having the required amplitude over the required time, are delivered. Wlth 20 sufficiently chosen A~ lAtor volume, drug concentration and discharge rate, the delivery site can filter the output to achieve a desired "continuous" and basal dosage.
Referring now to Fig. 3, the implantable portion of the system is illustrated in cross section. The implantable 25 portion of the reservoir system lO comprises a housing 14 having therein all of the essential elements comprising the reservoir 18, the Freon two-phase pressurizing chamber 20, the electronics module in location 32, and the ~cc1~r-~1Ator valve aspects of the system housed in location 33. The pump 30 reservoir 18 is periodically ~c~~D~cD~ transcutaneously via the reservoir septum 12. The septum i5 a stressed elastomer seal which may be ~ul~LuL~d with a RrDrifi~Al1y shaped needle. It is self-sealing for a finite number of ~U~ LULtS.
As in the case of known systems, reservoir pressure is 35 provided by a moderately high vapor p~ .u~ e: fluid, such as Freon, maintained in a two-phase equilibrium. Pressure in the system is recharged with each refill since the Freon vapor is rel-~n~ nc~
As illustrated in Fig. 3, the mechanical construction of the device comprises a hollow disk-shaped housing generally made of two I-nts. That is, the housing 14 comprises a 5 lower section 40 and an upper or cover section 42. The two main cavities of the system are separated by a solid base plate 44 which defines the central core of the unit. The lower cavity is subdivided into two ~ h: ' `a 18 and 2 0 by means of the bellows 16. Chamber 18 contains the drug while 10 Chamber 20 contains the Freon ples,,uLization system. During manufacture, a relatively small amount of the volatile fluid, typically Freon, is injected into the region 20 via a small fill tube not illustrated. The Freon then comes to a two-phase equilibrium within this chamber. The vapor ~1~5aUL.~ is 15 de~rm;nPd by the ~ ;1;hrium pL~s~uLe and remains constant for constant pump temperature and quasi-static volume changes of the bellows 16. The magnitude of the storage reservoir yLeS:.UL~ is then the sum of this vapor pressure and the mechanical yL~SaUL~I which is associated with the spring rate 20 of the bellows 16.
The central core region contains the needle piercing septum through which drug is injected into the chamber 18.
The septum includes a needle-stop 46. The needle-stop is a non-metallic cup which is used to support the needle and 2~ limit its travel yet at the same time prevent damage to the needle tip. When the needle is removed, drug is sealed in the reservoir 18.
Thus, the needle, not illustrated, yu~l~ LuLe::, the septum 12 and comes to rest on the stop 46. Drug is then ~icrl~nc~
30 into chamber 48 and via flow pACSAg~c 50, is delivered into the reservoir 18. A check valve 52 may optionally be used in the inlet. Thus, as illustrated by the flow arrows in Fig.
3, drug delivered into the chamber 48 passes through the t~L~.uuI. holes 50 and, if in place, the increased pLe:a:~uLI: of 35 the fluid or the force of the needle pushing down on the needle stop 46 opens the check valve 52 to deliver drug into the chamber 18.
WO 91/16091 ~ PCI/US91/0208~
The system includes within the housiny 14, the electronics cavity 32 containing the nef-PcC~ry miuLu~Luceasur electronics and battery. Battery life is sufficient to power the device during its normal intended implantable life. The 5 housing 14 includes within the central core region the twû
valves 26 and 28 and the a: lator 30. The valves 26 and 28 comprise two miniature solenoid valves which are intimately connected to the ~ tor 30. The valves 26 and 28, to be ~l;ccl~csQr7~ herein are r-nllfActl7red by h'ilson lO Greatbatch Company and illustrated in detail in Fig. 4. It is to be understood that such valves are commercially available. The valves h~ ' ical ly isolate the fluid sides of the valve from the electrical side of the valve.
Fig. 3 also illustrates by arrows the flow configuration 15 from the chamber 18 to the outlet catheter 36. The drug, from chamber 18, passes through circular or~"in~,~C 54 through the annular filter assembly 56. The filter 56 is interposed between the base plate 44 and a backing plate 58 and is sealed at its radially inward and outward points by means of 20 annular seals 60 and 62. The drug then passing through the filter 56 is subject to valve action by valve 26 filling the a~ lator 30 and then dumped via valve 28 into the outlet port 64. A right angle ~ nn~ct~r 66, locked into the outlet port and sealed via û-rings 68 and 70, couples the housing 14 25 to the catheter 36.
Referring now to Fig. 4, the details of the valve/
~ lator metering assembly are depicted. Valves 26 and 28 are miniature solenoid valves attached to the ~c. 1ator 30 by means of a weld point 72. Valves are ~l;cp--c-,~ in a side-30 by-side arrangement haYing solenoid assemblies 74 and applicable input power via leads 76. The valves are operably powered to drive a working plunger 78 biased by means of spring 80. The working plunger and return spring assembly are isolated from the solenoids by means of an isolation 35 diaphragm 82. This isolation diaphragm is a welded metal diaphragm sandwiched between both sides, that is the electrical side and the fluid side of the system. The . . _ . . _, . _ _ _ _ . .
WO 91/16091 ~ ~PC11~J~91~02088 g diaphragm 82 does not transmit ~ au~ e: to the working plunger 78 therefore the only ~L.3sau~e: differential which opposes valve motion is that which is across the valYe seat area .
The flow path is illustrated by the arrows in Fig. 4.
At the input conduit 54, the nominal pressure of the infusate is 23.2 psia. With valve 26 in the open position, drug is delivered upward through the valve seat 84 (shown closed in Fig. 4), into the A _ 1Ator flow passage 86. As can be seen from Fig. 4, the configuration m;n;m;zc~c the total volume and any possible stagnant flow pAcRA~c which exist between the valve seats. The area between the valve seats comprises the A~-~llrllAtOr storage space. Conse~uently, to minimize t: ~LLcu~ued air, a low "dead volume" is designed into the system. Dead volume is the nul. l; Ant volume between the valve seats, that is the area between seats which defines the A: lAtor flow passage 86 and the nu-. ~ liant portion of the A( 1 ~tor chamber 102. The valve seats are illustrated at the points 84. The dead volume between the valve seats 84 (not including the compliant acc~lr~ll Ator volume which is - ;n~lly 1~L1) is in the range of 4.9 -8.4,u1. When closed, the Al lAtor 30 is isolated. When opened, the valves allow fluid communication to be established between the Al 1 ator and the inlet conduit 54 25or the outlet conduit 55.
Referring now to Figs. 5A and 5B, details of the A~ 1 ~Ator are depicted. The A 1 Ator comprises a diaphragm go, a backing plate 92, an end cap 94, a fill tube 96, and a spacer plate 98.
The Accllr~llAtor and its diaphragm are a key ---nt in this system. The diaphragm 90, as illustrated in Fig. 5A, is a circular disk of a thin metal sheet. Preferably titanium may be used. The disk is selected to have a ti i ~r and th;rkn~cc of virtually negligible spring rate over the desired range of deflection. Thus, the diaphragm acts as a liAnt, flexible wall which separates fluid from the environment behind it.
20~ PCI/US9l/020~
, The upward motion of the diaphr~gm 90 is limited by the backing plate 92. Backing plate 92 i5 a metal plug of the same material and diameter as that of the diaphragm 90. It is provided with a shallow concave profile l~~n~lf~ct~red lnto its lower surface. This surface 100 acts as a contour stop for the diaphragm 90 . ni- i nnC of the contour are chosen to match the general profile of the diaphragm 90, when it is deflected by a prP~letPrm;n~d fixed volume (e.g. lul). This predetPrminPd fixed volume is the volume desired to be metered, that i5 the volume of one discharge spike as illustrated in Fig. 2.
The backing plate 92 acts as a r~ ni-~Al stop which limits the motion of the diaphragm after the ~ r ll ~tor cavity 102 has been filled to a specified volume. The contour of the plate is lPclf;fnpfi so that it contacts as much of the surface of the diaphragm when the volume in chamber 102 has been reached. This surface on the backing plate 92 then rigidly stops all portions of the diaphragm from moving and for any further increase in yL~:S~uL~, the volume of the a~ 1 ~tor in zone 102 will not change. As long as the operating yL~ UL~ of the pump is higher than the pressure required to fill the Af'f lr~ tor (to be fiiC~ ~C~-cef~ herein) the accumulator will then always store, in zone 102, the same volume iLL~a~e~ Live of operating E~L~ UL~: variations. The ability to store and discharge the same volume repeatedly over a very large number of cycles irrespective of pump pressure, L ~:~IL e~ll Ls an important advantage over other implantable pumps in which the discharge rate is a function of the pLe ~ULi' generated by the two-phase fluid. This is because yrê-~ uL~ changes associated with two-phase fluid pumps are a function of pump temperature. If the user is in an environment where there is a significantly temperature change at skin surface, for example during swimming, the pressure of the device will change.
The yLeS2-uL~ differential across the diaphragm 90 determines whether it fills or empties. On the non-fluid side, the yL~ ~f~UL~: effects both the fill and empty , . _ _ . ... , . .. _ _ _ _ _ _ .
~ WO 91/16091 2 0 ~ 8 2 1 2 ~ p~rl~ls9t/02088 differentials. This y~-:S~u~: must be lower than the main reservoir ~les~,u~ yet higher than the catheter outlet pressure. Consequently, the backfill ~;es~uLe which exists - on the side of the diaphragm 90 opposite that of the 5 ~cc~ l ator zone 102 must be controlled at a value which allows for complete filling yet guarantees complete emptying of the accumulator for any normal variations in reservoir or outlet ~Le:SaULe:. Such a ~Les,.uL~ can be chosen and maintained by controlling the ~t aULa in chamber 104 and 10 having it maintained in fluid communication with the hA~ Ci~P
of the diaphragm 90. The endcap 94 is used to cover this chamber. A fill tube 96 is used to charge the chamber 104 with an inert gas such as Argon maintained at 19.2 psia. The volume defined in the chamber 104 is chosen to be large 15 enough so that any variations in the total volume due to diaphragm ~liqrlA~ L will have negligible effect on the backfill pressure. Once chamber 104 has been filled with a pressurized gas, the fill tube 96 is sealed by welding. The tube 96 is chosen to have a small inside 1;A- t~L 50 that 20 changes in its length during welding or rework will not significantIy effect the chamber volume and conse~uently, the backf i 11 pressure .
Fig. 5B illustrates the details of the spacer plate 98.
The spacer plate performs three major functions. First, it 25 supports the diaphragm 90 during discharge. Secondly, it provides the annular passages as illustrated in Fig. 5s to enhance fluid flow. Thirdly it provides a te~ hnlrl~P for mounting the ~ ~ letPd and tested units to the valve s-~h~c6P~-~ly. In the same manner that the backing plate 92 30 supports the diaphragm during filling of the a~ 1 Ator chamber 102, the spacer plate 98 is used to limit diaphragm motion during discharge. The spacer plate, however, need not be contoured because it Su~-JL Ls the ulla~L~:ssed, that is the flat position of the diaphragm which is established during 35 welding. The continuous contoured surface desirable to use as a mechanical stop on the gas-filled side of the diaphragm, that is in chamber 104, is undesirable on the fluid side.
WO 91/16091 PCIIU591/0208~
~078212 Intimate contact of two relatively flat surfaces with a liquid interface will create a suction effect which makes the separation of those surfaces difficult. This suction effect is U~L- - by the addition of a pattern having a series of 5 ~UIlC~--LLic grûoves as illustrated in Fig. 5B. The prior art employed a series of orthogonal ~h~ k~ u~rd grooves on the surface of the cpacer plate. ~Iowever, it was found that such a grid traps air bubbles in the cross grooves and small particles in the space between the gridded spacer plate and 10 the diaphragm. This causes a shift in the pulse volume of the system. Importantly, it was found that the grid configuration had too much contact area with the diaphragm thus reducing the surface pressure. This resulted in the acc~ tion of precipitates such as insulin. The result was a reduction in 15 the pulse volume. The spacer plate having a grid required a number of machine steps, such as turning and milling. It required t-h~micll etching and therefore the overall cost of manuf acture was high.
It was f ound however that hy the use of a series of 20 annular grooves, the problems of the prior art could be overcome. Figure 5B illustrates the configuration of this invention .
The inlet 58 and outlet 59 are connected by means of a wide trough 105. A series of _u..cc:llLLic circumferential grooves 106 are provided to establish fluid communication between the inlet 58 and the outlet 59. Also, the grooves are in fluid ~ ;ration with the trough 105. Consequently, the spacer plate 98 defines flow paths comprising annular path5 along grooves 106 and a direct lateral flow path along trough 105. The grooving is rl~ciqn-~d to permit complete free flow of fluid lln~lorn~th the flattened diaphragm. Additionally, the grooves facilitate washing of areas because none of the grooves are at right angles to the flow path. Thus every groove experiences some degree of washing.
Di- sionC of the grooves may be chosen to provide a minimum surface to support the diaphragm thereby increasing the contact ~le~L~uL~:, that is the sharp ridges created ' between the adjacent grooves 106. This reduction in contact area prevents build up of drug residue and the potential entrapment of particles between the spacer plate and the diaphragm. At the same tlme thls conflguratlon malntains the accumulator dead volume at a 5 mlnlmum level. The annular grooved spacer plate also promotes the rapld filling and emptylng of the accumulator zone 102 whlch ln turn minlmlzes the time and therefore the energy necessary to hold either valve open. It can be appreclated that decreased valve energy reguirements ln such a system materially increase the llfe 10 of the pump since the overall energy requirements of the system are decreased. Such a configuration can be made without chemical milllng thus reduclng manufacturlng cost.
The top perlpheral surface of the spacer plate 98 has a flat flange portion 107 devoid of any grooving to provide a 15 clamplng and sealing surface to the accumulator. The bottom of the spacer plate 98 as illustrated in Fig. 5A contains two counter bores 58 ' and 59 ' to mate with the valves which are lllustrated ln Flg. 4. The bottom surface 108 of the spacer plate 98 ls controlled to be flat and have a smooth surface flnish which will 20 mate with the surface of the same quality on the valve subassembly. It ls at this point that the weld 72 is made. Such a~ain guarantees a minimum dead volume between parts and the minimum space for air entrapment.
The geometry of the outer flange 110 of the 6pacer plate 25 matches the mating plate from the valves and permits a hermetlc weld 72 around the rlm. The spacer plate 98 outer flat annular portlon 107 matches the shape of the backing plate 92 and provldes a compression zone for sealing the unlt.
Referring now to Eig. 6, a modifled accumulator ls 30 illustrated. This figure depicts a modificatlon which employs the same baslc elements of the accumulator as shown in Figs. 5A and 5B. HoweYer, it employs an electrical switch to signal the level of volume withln the accumulator. In accordance with this lnvention, by the use of the concentric groove spacer plate 98 35 electrlcal swltching is facilitated. The switch plate surface is f lat and the contour is thus cut lnto the groove spacer plate .
The contour ls easlly formed by ad~ustlng the depth or spaclng of _ L the grooves 106.
~ ~078212 W0~91/16091 14 PCT/US91/02088 The dual functionality provided by the configuration of Fig. 6 i8 an important safety feature to indicate the presence of leaks in the valve seats and accumulator welds or, alternatively, stlcking of the valves. Since this invention operates at positive 5 pressure, failure of one or both valve seats may lead to improper dosing of the reservoir contents. A switch accumulator is thus important to sense condition6 which are suggestive of valve misfunction and provide a warning signal to the operator to discontinue dosing.
The operating principles of the switch accumulator of Fig. 6 are identical to those of the accumulator illustrated in Figs. 5A and 5B. However, as mentioned the contour is preferably moved to the spacer plate 98. The backing plate 98 can be manufactured flat. In Fig. 6, those elements which are common to the Fig. 5 configuration have like identification numbers. The backing plate 92 comprises three distinct elements which are used to electrically i~olate the center of the plate from the diaphragm 90 and yet maintain the ability to store a sealed volume of inert gas. The end cap 94 and fill tube 96 have a dual function, that of chamber cover and electrical lead. The lead 110 is shown schematically attached to a flange 112 forming a portion of the end cap assembly. A ceramic assembly 113 is lined by a metallic portion 110 to provide a conductive path between the diaphragm and lead 110. The diaphragm i8 thus used as a moving switch contact.
That is, a full diaphragm will short the lead to the ground via the metalized ceramic 110 on the inside of the ceramlc cup 113. Consequently, a signal is issued indicating that the accumulator is full, that is, the diaphragm in its upward position. This signal can be sensed by the system electronics just prior to opening or ~ust following release of either valve.
Con~equently, by determining conditions during the sense period and by the switch state, a variety of diagnostic determinations can be made.
For example, during a sense period and iust prior to the inlet opening, if an open switch condition exi~ts, then the system is functioning properly. If, however, the switch state is closed then, it can be determined that there is a leak in the inlet valve 26. During the ~ame period but just prior to pulsing the outlet, .
W0/91~16091 14a PCT~U591~02088 to release infusate ~rom the accumulator, if an open switch exists, then a leak exists in the outlet valve seat or one of the valve or accumulator welds.
If, however, the switch of Fig. 6 i8 closed during the 5 ou~let sense period, the system is deemed to be functioning properly. Similarly, by sensing during the inlet portion of the cycle, but immediately following relea~e, an open condition in the switch indicates that the inlet did not open or that there is a leak in the accumulator or valve weld. However, senæing the 10 switch state as closed during the same period will indicate that the system is working acceptably. ~onsequently, by utilizing a switch accumulator of Fig . 6, a signif icant amount of information can be obtained concerning the status of the valve seats or the hermeticity of the metering system. 8y repeatedly pulsing the 15 valve, failure mode can be determined to be repeatable or simply an artifact.
As can be seen by this invention then, a programmable pump exists which operates at positive pre~sures and accurately controls the flow rate by metering discrete and repeatable volumes 20 through a microaccumulator. The accumulator is ~illed and emptied by alternately cycling two control valves which are in series with the accumulator. Thus, by setting the cycling rate of the valves, the pump dispensing rate may be controlled.
The accumulator itsel~ operates at a pressure which is 25 intermediate between the pump reservoir pressure and the outlet pressure. This desiyn pressure, when taken in con~unction with the negligible internal spring rate, guarantees a complete filling and emptying of the system. The volume, however, is repeatedly demonstrated, that is repeatedly dispensed and the valve energy 30 requirements may be minimized. Given the design o~ the valves themselves, minimum dead volume and flow through occur. This minimizes the danger of entrapped air or stagnant flow in the system .
It is apparent that modificationæ of this design and of 35 preferred embodiments therein may be made without departing from the essential scope of this invention.
.
sAcl~i~uuNL) OF T~E INVENTION
This invention relates to an implantable infusion pump for the dispensing of infusate. In particular, it relates to a pump operating at positive pressure which is ~IO~L hl~ to dispense medication in accordance with different specified flow rates.
Implantable infusion pumps are currently used for a variety of medical E~UL~uoses. Such devices are implantable in the human body and rely on a liquid/vapor equilibrium to maintain constant ~LC s~uLe on the drug which is housed therein so that the drug flows through a capillary in order to maintain a constant f low rate . Such devices are characterized by "constant flow" and are used in a variety of medical applications, for example, to dispense 2 0 chemotherapy at a relatively constant f low rate .
U.S. Patent 4,714,462, commonly assigned, deals specifically with a ~LuyL~ ulldble positive displacement system having a pumping chamber which is placed in the path of fluid communication between the pressurized drug reservoir and a flow restrictor. By use of external PLUYL ;n~, the device can be used to expel infusate from the pumping chamber at varying rates.
Reference is made to commonly assigned U.S. Patent 4,838,887 which describes a ~lUyL hle valve pump that 3 o employs a unique A ~ l Ator having a spacer plate with a series of orthngnnA 1 checkerboard grooves . This is illustrated in Figure 5B of the ' 887 patent. While suitable for a number of applications, it has been found that this spacer plate conf iguration allows the build-up of insulin 3s precipitation. The build-up of precipitation in turn reduces the pulse volume of the system thus reducing efficiency and accuracy of output dosage.
It has also been discovered that air bubbles can become trapped in the cross grooves of a gridded A~c~m~l Ator which,as illustrated in the '887 patent,are at right angles to the direction of the f luid f low . This occurs because _ _ _ _ _ _ _ _ _ _ _ -whlch, as lllustrated ln the ' 887 patent, are at rlght angles to the dlrectlon of the fluld flow. Thls occurs because there 18 no wash-out of the spacer. For the same reason, small partlcles can be trapped between the grldded spacer plate and the dlaphragm. Th~s causes a shlft ln pulse volume.
The grldded spacer plate 18 expenslve to manufacture. It requlres macninlng steps of turnlng and mllllng. The grld pattern 18 then chemlcally etched ln the spacer plate.
Glven these recognlzed shortcomlngs ln the prlor art, lt 18 an ob~ect of thls lnventlon to provlde a posltlve pressure plOyL `~le valve pump whlch operates uslng a wlde varlety of drugs wlthout problems of ~nternal bulld-up and speclflcally preclpltatlon build-up on the accumulator spacer plat e .
SUMMARY OF THE INVENTION
The present lnventlon provldes an lmplantable lnfuslon apparatus lncludlng~ a houslng contalnlng, an lnlet septum, a rechargeable constant pressure lnfusate reservolr, an electronlcally controlled meterlng assembly recelvlng lnfusate from sald reservolr, sald meterlng assembly comprlslng f lrst and second normally closed valves and an accumulator posltloned ln fluld commun~catlon wlth each of sald valves, sald ~ccumulator comprlslng an lnlet and outlet, a chamber havlng a dlaphragm and a spacer plate; electronlc means for controlllng the operatlon of sald valves, and outlet means ln fluld communlcatlon wlth sald meterlng assembly to dlspense lnfusate to a slte ln a llvlng body; characterlzed by sald spacer plate havlng a serles of concentrlc grooves ln fluld communlcatlon wlth sald lnlet and outlet whereln when the flrst of sald valves 18 open, lnfusate flows from said reservolr lnto sald accumulator chamber and lnto said concent rlc grooves, and when the other valve is open and the flrst valve closes, lnfusate flows from sa~d accumulator lnto sald outlet, sald accumulator storlng and dlscharglng predetermined volume splkes o~ lnfusate at a f rer~uency determlned by the cycllng rate of sald palr of valves.
The constant pressure lnfusate or drug reservolr is preferably located ln serles wlth a bacterla/alr fllter. The improved ac~ ator conflguratlon preferably has a number of sharp rldges created between ad~acent grooves. The rldges support the drug slde of the dlaphragm when the Arc~ tor 18 at tne empty portlon of the dellvery cycle. Thls slgniflcantly reduces the contact area between the dlaphragm and the spacer plate. In turn the surface pressure of the drug at the contact polnts lncreases to prevent accumulatlon of drug resldue. These three components comprlse the lmplantable aspect of the pump. The fourth aspect of thls lnventlon 18 the external programmer.
The lnltlal "pumplng" 18 provlded by the reservolr whlch 18 used to f 111 the accumulator to lts f lxed volume .
The accumulator 18 then "dumped" vla the dlscharge catheter to the deslred lnfuslon slte. A pressure whlch ls lntermedlate between the reservolr and the outlet 18 malntalned behlnd tne accumulator 80 that lt fllls and emptles completely and rapldly. The accumulator ls alternatlvely fllled and emptled by the alternate swltchlng of the valves. The rate of swltchlng therefore governs the rate of pumplng and thus the dellvery rate.
Valve control 18 preferably provlded ln the implantable pump by means of an on-board processlng system and power supply. The processor i8 externally accessed through a telemetry llnk which can be used to both program the pump operatlon and obtain dlagnostic lnformatlon as to the operat lon of the devlce .
The lnventlon wlll be better understood from the followlng detalled descriptlon, glven by way of example only, when taken ln con~unctlon wlth the drawlngs, ln whlch Flg. l 18 a schematlc dlagram showlng the complete system and a schematlc dlagram of the flow;
Flg. 2A 18 a schematlc dlagram lllustratlng the pumplng cycle of the accumulator~
Flg. 213 18 a tlme-flow rate chart of the dellvery schedule of the 3ystem;
Flg. 3 18 a cutaway slde elevatlon of the baslc constructlon of the lmplantable pump portlon of the system;
Flg . 4 18 a cutaway schemat lc vlew of the valve/~rc~ qtor meterlng system ln accordance wlth thls lnvent lon;
Flg. 5A 18 a slde vlew of the accumulator;
Flg. 53 18 a top vlew of the spacer plate component of the accumulator ln accordance wlth thls lnvent lon; and Flg. 6 18 a cutaway slde vlew of an electrlcal swltch accumulator ln accordance wlth thls lnventlon.
Referrlng now to Flg. l, schematlc dlagram of the essentlal aspects of thls lnventlon 18 deplcted. The - 3a -WQ9!/16091 - PCI/US91/0208~
~ ~ 20782 1 2 invention is a positive ~L~ uLt: pLu~LG~l,ble valve pump comprising a constant ~Le~ ULc: drug reservoir 10 which is r~ hl e by means of a septum 12 . The system comprises a sealed housing 14 containing a bellows element 16 having a chamber 18 comprising the drug reservoir. The bellows 16 separates the housing into a second zone 20 normally filled with a two-phase fluid which has a significant vapor pressure at body temperature . Thus, as the f luid vaporizes, it compresses the bellows 16 and urges the contents of the refiervoir 18 through an outlet leading to an infusion site.
During the process of rPfillinq~ the chamber 18 via the septum 12, the two-phase fluid is pressurized condensing a portion of the vapor and returning it to its liquid phase.
Typically, the reservoir 18 has a volume of approximately 25ml and the pressurization maintained in the system is approximately 23.2 psia. A sideport 27 can be used for direct bolus injections.
An outlet 22, from the reservoir 18 delivers infusate from the reservoir via a bacterial filter 24 to the electronically controlled metering assembly.
The metering assembly comprises two normally closed valves 26, 28, which are positioned on the inlet and outlet sides of an accumulator 30. The ~rc~ 1l ator operates at a ull,LallL volume, very low, in the range of 1 microliter (~1) 2s pressurized typically to 19.2 psia. The valves 26 and 28 are controlled electronically via an electronics module 32 which is pLU~L ' utilizing an ~YtF~rn;ll yLUl~L -r 34. Fig. 1 illustrated in a chain line, the pump envelope which separates the electronics module 32, that is the system which is implanted, from the external p LUyL -r 34.
The pLVyL -r 34 is a hand held unit using a touch screen. It provides a data transfer link to the electronics 32 implanted as a part of the device (see Fig. 3). In a memory storage element, the ~LUyL ~ 34 maintains a patient history based on storage of real time data. Data as to device status, such as battery condition, diagnostics on valve current, prescription in use and the like are retained.
~- t/02088 WO 91/16091 PCI/US9 ~
207~ 2 The ~ytrrllAl ~LUU,' -r also has different interrogation modes such as initial calibration and protected modes for terhn i r. j An use .
The outlet from the a~ l~tor 30 i5 via a catheter 36 5 which delivers the infu5ate to the site in the body to which drug delivery is required. As indicated by the arrow in Fig.
1, the delivery of infusate occurs at the infusion site below the AC 1 Ator ~ a~uLe forcing discharge through the catheter. This pressure may be ai ^ric (typically 14.7 10 psia) or cardiovascular p~ ~sauL~5 slightly above ai ~ r' -riC~
e . g . 17 . 6 psia arterial .
Referring now to Fig. 2A, the pumping cycle is schematically illustrated. The salient aspects of this section of the system comprise the valves 26, 28 and the ~ 1 Ator 30. The first step is one where both valves 26 and 28 are closed and the A(~r~ l ator 30 is empty. The drug is delivered ~rom the reservoir 18 through conduit 22 and filter 24 to fill the A~-~ lator 30. Thu5, as a second step in the operation the valve 26 is opened while valve 28 is 20 closed to fill the A~ l AtOr to its fixed volume. The third step is then to close both valves 2 6 and 2 8 with the A~ l Ator now full. The final step in the A l Ator cycle is the opening of valve 28 while valve 26 remains closed to empty the arc~m~l Ator through the catheter 36.
25 Consequently, the ;~ lAtor is alternately filled and emptied by the switching action of the valves. A ~lesau~_ intr ';Ate between that of the reservoir and the outlet is maintained behind the A~ 1 Ator so that it fills and empties c~ lr-t~ly and rapidly. The rate of switching of the 30 valves therefore governs the rate of pumping and accordingly de~Prm; nQ~ the delivery rate of infusate.
Referring to Fig. 2B an example of the delivery rate of this system is illustrated. Fig. 2B is a chart plotting a flow rate in the y-axis against time in the x-axis. The 35 output of thQ pump is periodic and is a function of the r,~ . y of the valve cycle. Thus, the faster the valve cycle, the greater the number of i~rcll~--l Ator discharges per ~ \~0 91~16091 PCI/US91/0208~
07~2 1 2 unit. Each discharge i5 in the form of a volume spike.
In Fig. 2B a change from a basal rate to a desired bolus rate, that is an increase in flow rate above the basal rate, is illustrated by means of the square wave on the left-hand 5 portion of the time chart. This would be the ~ ~ O~L tl bolus flow into the electronics package 32. The pump, to e6tablish the required bolus flow rate, would increase the frequency of the discharge spikes by varying its pump cycle during the bolus period as illustrated in the center of Fig.
lO 2s. The total number of spikes are integrated over time 50 that the flow rate volume replicates that required by the desired bolus flow rate . The output through the catheter 3 6 to the bloodstream is illustrated in the right-hand portion of Fig. 2B.
By integrating the volume of the pump over time, given the number of pUlOp cycles, and the volume of each discharge, digital basal and bolus rates closely replicating the required values, that is flow rates having the required amplitude over the required time, are delivered. Wlth 20 sufficiently chosen A~ lAtor volume, drug concentration and discharge rate, the delivery site can filter the output to achieve a desired "continuous" and basal dosage.
Referring now to Fig. 3, the implantable portion of the system is illustrated in cross section. The implantable 25 portion of the reservoir system lO comprises a housing 14 having therein all of the essential elements comprising the reservoir 18, the Freon two-phase pressurizing chamber 20, the electronics module in location 32, and the ~cc1~r-~1Ator valve aspects of the system housed in location 33. The pump 30 reservoir 18 is periodically ~c~~D~cD~ transcutaneously via the reservoir septum 12. The septum i5 a stressed elastomer seal which may be ~ul~LuL~d with a RrDrifi~Al1y shaped needle. It is self-sealing for a finite number of ~U~ LULtS.
As in the case of known systems, reservoir pressure is 35 provided by a moderately high vapor p~ .u~ e: fluid, such as Freon, maintained in a two-phase equilibrium. Pressure in the system is recharged with each refill since the Freon vapor is rel-~n~ nc~
As illustrated in Fig. 3, the mechanical construction of the device comprises a hollow disk-shaped housing generally made of two I-nts. That is, the housing 14 comprises a 5 lower section 40 and an upper or cover section 42. The two main cavities of the system are separated by a solid base plate 44 which defines the central core of the unit. The lower cavity is subdivided into two ~ h: ' `a 18 and 2 0 by means of the bellows 16. Chamber 18 contains the drug while 10 Chamber 20 contains the Freon ples,,uLization system. During manufacture, a relatively small amount of the volatile fluid, typically Freon, is injected into the region 20 via a small fill tube not illustrated. The Freon then comes to a two-phase equilibrium within this chamber. The vapor ~1~5aUL.~ is 15 de~rm;nPd by the ~ ;1;hrium pL~s~uLe and remains constant for constant pump temperature and quasi-static volume changes of the bellows 16. The magnitude of the storage reservoir yLeS:.UL~ is then the sum of this vapor pressure and the mechanical yL~SaUL~I which is associated with the spring rate 20 of the bellows 16.
The central core region contains the needle piercing septum through which drug is injected into the chamber 18.
The septum includes a needle-stop 46. The needle-stop is a non-metallic cup which is used to support the needle and 2~ limit its travel yet at the same time prevent damage to the needle tip. When the needle is removed, drug is sealed in the reservoir 18.
Thus, the needle, not illustrated, yu~l~ LuLe::, the septum 12 and comes to rest on the stop 46. Drug is then ~icrl~nc~
30 into chamber 48 and via flow pACSAg~c 50, is delivered into the reservoir 18. A check valve 52 may optionally be used in the inlet. Thus, as illustrated by the flow arrows in Fig.
3, drug delivered into the chamber 48 passes through the t~L~.uuI. holes 50 and, if in place, the increased pLe:a:~uLI: of 35 the fluid or the force of the needle pushing down on the needle stop 46 opens the check valve 52 to deliver drug into the chamber 18.
WO 91/16091 ~ PCI/US91/0208~
The system includes within the housiny 14, the electronics cavity 32 containing the nef-PcC~ry miuLu~Luceasur electronics and battery. Battery life is sufficient to power the device during its normal intended implantable life. The 5 housing 14 includes within the central core region the twû
valves 26 and 28 and the a: lator 30. The valves 26 and 28 comprise two miniature solenoid valves which are intimately connected to the ~ tor 30. The valves 26 and 28, to be ~l;ccl~csQr7~ herein are r-nllfActl7red by h'ilson lO Greatbatch Company and illustrated in detail in Fig. 4. It is to be understood that such valves are commercially available. The valves h~ ' ical ly isolate the fluid sides of the valve from the electrical side of the valve.
Fig. 3 also illustrates by arrows the flow configuration 15 from the chamber 18 to the outlet catheter 36. The drug, from chamber 18, passes through circular or~"in~,~C 54 through the annular filter assembly 56. The filter 56 is interposed between the base plate 44 and a backing plate 58 and is sealed at its radially inward and outward points by means of 20 annular seals 60 and 62. The drug then passing through the filter 56 is subject to valve action by valve 26 filling the a~ lator 30 and then dumped via valve 28 into the outlet port 64. A right angle ~ nn~ct~r 66, locked into the outlet port and sealed via û-rings 68 and 70, couples the housing 14 25 to the catheter 36.
Referring now to Fig. 4, the details of the valve/
~ lator metering assembly are depicted. Valves 26 and 28 are miniature solenoid valves attached to the ~c. 1ator 30 by means of a weld point 72. Valves are ~l;cp--c-,~ in a side-30 by-side arrangement haYing solenoid assemblies 74 and applicable input power via leads 76. The valves are operably powered to drive a working plunger 78 biased by means of spring 80. The working plunger and return spring assembly are isolated from the solenoids by means of an isolation 35 diaphragm 82. This isolation diaphragm is a welded metal diaphragm sandwiched between both sides, that is the electrical side and the fluid side of the system. The . . _ . . _, . _ _ _ _ . .
WO 91/16091 ~ ~PC11~J~91~02088 g diaphragm 82 does not transmit ~ au~ e: to the working plunger 78 therefore the only ~L.3sau~e: differential which opposes valve motion is that which is across the valYe seat area .
The flow path is illustrated by the arrows in Fig. 4.
At the input conduit 54, the nominal pressure of the infusate is 23.2 psia. With valve 26 in the open position, drug is delivered upward through the valve seat 84 (shown closed in Fig. 4), into the A _ 1Ator flow passage 86. As can be seen from Fig. 4, the configuration m;n;m;zc~c the total volume and any possible stagnant flow pAcRA~c which exist between the valve seats. The area between the valve seats comprises the A~-~llrllAtOr storage space. Conse~uently, to minimize t: ~LLcu~ued air, a low "dead volume" is designed into the system. Dead volume is the nul. l; Ant volume between the valve seats, that is the area between seats which defines the A: lAtor flow passage 86 and the nu-. ~ liant portion of the A( 1 ~tor chamber 102. The valve seats are illustrated at the points 84. The dead volume between the valve seats 84 (not including the compliant acc~lr~ll Ator volume which is - ;n~lly 1~L1) is in the range of 4.9 -8.4,u1. When closed, the Al lAtor 30 is isolated. When opened, the valves allow fluid communication to be established between the Al 1 ator and the inlet conduit 54 25or the outlet conduit 55.
Referring now to Figs. 5A and 5B, details of the A~ 1 ~Ator are depicted. The A 1 Ator comprises a diaphragm go, a backing plate 92, an end cap 94, a fill tube 96, and a spacer plate 98.
The Accllr~llAtor and its diaphragm are a key ---nt in this system. The diaphragm 90, as illustrated in Fig. 5A, is a circular disk of a thin metal sheet. Preferably titanium may be used. The disk is selected to have a ti i ~r and th;rkn~cc of virtually negligible spring rate over the desired range of deflection. Thus, the diaphragm acts as a liAnt, flexible wall which separates fluid from the environment behind it.
20~ PCI/US9l/020~
, The upward motion of the diaphr~gm 90 is limited by the backing plate 92. Backing plate 92 i5 a metal plug of the same material and diameter as that of the diaphragm 90. It is provided with a shallow concave profile l~~n~lf~ct~red lnto its lower surface. This surface 100 acts as a contour stop for the diaphragm 90 . ni- i nnC of the contour are chosen to match the general profile of the diaphragm 90, when it is deflected by a prP~letPrm;n~d fixed volume (e.g. lul). This predetPrminPd fixed volume is the volume desired to be metered, that i5 the volume of one discharge spike as illustrated in Fig. 2.
The backing plate 92 acts as a r~ ni-~Al stop which limits the motion of the diaphragm after the ~ r ll ~tor cavity 102 has been filled to a specified volume. The contour of the plate is lPclf;fnpfi so that it contacts as much of the surface of the diaphragm when the volume in chamber 102 has been reached. This surface on the backing plate 92 then rigidly stops all portions of the diaphragm from moving and for any further increase in yL~:S~uL~, the volume of the a~ 1 ~tor in zone 102 will not change. As long as the operating yL~ UL~ of the pump is higher than the pressure required to fill the Af'f lr~ tor (to be fiiC~ ~C~-cef~ herein) the accumulator will then always store, in zone 102, the same volume iLL~a~e~ Live of operating E~L~ UL~: variations. The ability to store and discharge the same volume repeatedly over a very large number of cycles irrespective of pump pressure, L ~:~IL e~ll Ls an important advantage over other implantable pumps in which the discharge rate is a function of the pLe ~ULi' generated by the two-phase fluid. This is because yrê-~ uL~ changes associated with two-phase fluid pumps are a function of pump temperature. If the user is in an environment where there is a significantly temperature change at skin surface, for example during swimming, the pressure of the device will change.
The yLeS2-uL~ differential across the diaphragm 90 determines whether it fills or empties. On the non-fluid side, the yL~ ~f~UL~: effects both the fill and empty , . _ _ . ... , . .. _ _ _ _ _ _ .
~ WO 91/16091 2 0 ~ 8 2 1 2 ~ p~rl~ls9t/02088 differentials. This y~-:S~u~: must be lower than the main reservoir ~les~,u~ yet higher than the catheter outlet pressure. Consequently, the backfill ~;es~uLe which exists - on the side of the diaphragm 90 opposite that of the 5 ~cc~ l ator zone 102 must be controlled at a value which allows for complete filling yet guarantees complete emptying of the accumulator for any normal variations in reservoir or outlet ~Le:SaULe:. Such a ~Les,.uL~ can be chosen and maintained by controlling the ~t aULa in chamber 104 and 10 having it maintained in fluid communication with the hA~ Ci~P
of the diaphragm 90. The endcap 94 is used to cover this chamber. A fill tube 96 is used to charge the chamber 104 with an inert gas such as Argon maintained at 19.2 psia. The volume defined in the chamber 104 is chosen to be large 15 enough so that any variations in the total volume due to diaphragm ~liqrlA~ L will have negligible effect on the backfill pressure. Once chamber 104 has been filled with a pressurized gas, the fill tube 96 is sealed by welding. The tube 96 is chosen to have a small inside 1;A- t~L 50 that 20 changes in its length during welding or rework will not significantIy effect the chamber volume and conse~uently, the backf i 11 pressure .
Fig. 5B illustrates the details of the spacer plate 98.
The spacer plate performs three major functions. First, it 25 supports the diaphragm 90 during discharge. Secondly, it provides the annular passages as illustrated in Fig. 5s to enhance fluid flow. Thirdly it provides a te~ hnlrl~P for mounting the ~ ~ letPd and tested units to the valve s-~h~c6P~-~ly. In the same manner that the backing plate 92 30 supports the diaphragm during filling of the a~ 1 Ator chamber 102, the spacer plate 98 is used to limit diaphragm motion during discharge. The spacer plate, however, need not be contoured because it Su~-JL Ls the ulla~L~:ssed, that is the flat position of the diaphragm which is established during 35 welding. The continuous contoured surface desirable to use as a mechanical stop on the gas-filled side of the diaphragm, that is in chamber 104, is undesirable on the fluid side.
WO 91/16091 PCIIU591/0208~
~078212 Intimate contact of two relatively flat surfaces with a liquid interface will create a suction effect which makes the separation of those surfaces difficult. This suction effect is U~L- - by the addition of a pattern having a series of 5 ~UIlC~--LLic grûoves as illustrated in Fig. 5B. The prior art employed a series of orthogonal ~h~ k~ u~rd grooves on the surface of the cpacer plate. ~Iowever, it was found that such a grid traps air bubbles in the cross grooves and small particles in the space between the gridded spacer plate and 10 the diaphragm. This causes a shift in the pulse volume of the system. Importantly, it was found that the grid configuration had too much contact area with the diaphragm thus reducing the surface pressure. This resulted in the acc~ tion of precipitates such as insulin. The result was a reduction in 15 the pulse volume. The spacer plate having a grid required a number of machine steps, such as turning and milling. It required t-h~micll etching and therefore the overall cost of manuf acture was high.
It was f ound however that hy the use of a series of 20 annular grooves, the problems of the prior art could be overcome. Figure 5B illustrates the configuration of this invention .
The inlet 58 and outlet 59 are connected by means of a wide trough 105. A series of _u..cc:llLLic circumferential grooves 106 are provided to establish fluid communication between the inlet 58 and the outlet 59. Also, the grooves are in fluid ~ ;ration with the trough 105. Consequently, the spacer plate 98 defines flow paths comprising annular path5 along grooves 106 and a direct lateral flow path along trough 105. The grooving is rl~ciqn-~d to permit complete free flow of fluid lln~lorn~th the flattened diaphragm. Additionally, the grooves facilitate washing of areas because none of the grooves are at right angles to the flow path. Thus every groove experiences some degree of washing.
Di- sionC of the grooves may be chosen to provide a minimum surface to support the diaphragm thereby increasing the contact ~le~L~uL~:, that is the sharp ridges created ' between the adjacent grooves 106. This reduction in contact area prevents build up of drug residue and the potential entrapment of particles between the spacer plate and the diaphragm. At the same tlme thls conflguratlon malntains the accumulator dead volume at a 5 mlnlmum level. The annular grooved spacer plate also promotes the rapld filling and emptylng of the accumulator zone 102 whlch ln turn minlmlzes the time and therefore the energy necessary to hold either valve open. It can be appreclated that decreased valve energy reguirements ln such a system materially increase the llfe 10 of the pump since the overall energy requirements of the system are decreased. Such a configuration can be made without chemical milllng thus reduclng manufacturlng cost.
The top perlpheral surface of the spacer plate 98 has a flat flange portion 107 devoid of any grooving to provide a 15 clamplng and sealing surface to the accumulator. The bottom of the spacer plate 98 as illustrated in Fig. 5A contains two counter bores 58 ' and 59 ' to mate with the valves which are lllustrated ln Flg. 4. The bottom surface 108 of the spacer plate 98 ls controlled to be flat and have a smooth surface flnish which will 20 mate with the surface of the same quality on the valve subassembly. It ls at this point that the weld 72 is made. Such a~ain guarantees a minimum dead volume between parts and the minimum space for air entrapment.
The geometry of the outer flange 110 of the 6pacer plate 25 matches the mating plate from the valves and permits a hermetlc weld 72 around the rlm. The spacer plate 98 outer flat annular portlon 107 matches the shape of the backing plate 92 and provldes a compression zone for sealing the unlt.
Referring now to Eig. 6, a modifled accumulator ls 30 illustrated. This figure depicts a modificatlon which employs the same baslc elements of the accumulator as shown in Figs. 5A and 5B. HoweYer, it employs an electrical switch to signal the level of volume withln the accumulator. In accordance with this lnvention, by the use of the concentric groove spacer plate 98 35 electrlcal swltching is facilitated. The switch plate surface is f lat and the contour is thus cut lnto the groove spacer plate .
The contour ls easlly formed by ad~ustlng the depth or spaclng of _ L the grooves 106.
~ ~078212 W0~91/16091 14 PCT/US91/02088 The dual functionality provided by the configuration of Fig. 6 i8 an important safety feature to indicate the presence of leaks in the valve seats and accumulator welds or, alternatively, stlcking of the valves. Since this invention operates at positive 5 pressure, failure of one or both valve seats may lead to improper dosing of the reservoir contents. A switch accumulator is thus important to sense condition6 which are suggestive of valve misfunction and provide a warning signal to the operator to discontinue dosing.
The operating principles of the switch accumulator of Fig. 6 are identical to those of the accumulator illustrated in Figs. 5A and 5B. However, as mentioned the contour is preferably moved to the spacer plate 98. The backing plate 98 can be manufactured flat. In Fig. 6, those elements which are common to the Fig. 5 configuration have like identification numbers. The backing plate 92 comprises three distinct elements which are used to electrically i~olate the center of the plate from the diaphragm 90 and yet maintain the ability to store a sealed volume of inert gas. The end cap 94 and fill tube 96 have a dual function, that of chamber cover and electrical lead. The lead 110 is shown schematically attached to a flange 112 forming a portion of the end cap assembly. A ceramic assembly 113 is lined by a metallic portion 110 to provide a conductive path between the diaphragm and lead 110. The diaphragm i8 thus used as a moving switch contact.
That is, a full diaphragm will short the lead to the ground via the metalized ceramic 110 on the inside of the ceramlc cup 113. Consequently, a signal is issued indicating that the accumulator is full, that is, the diaphragm in its upward position. This signal can be sensed by the system electronics just prior to opening or ~ust following release of either valve.
Con~equently, by determining conditions during the sense period and by the switch state, a variety of diagnostic determinations can be made.
For example, during a sense period and iust prior to the inlet opening, if an open switch condition exi~ts, then the system is functioning properly. If, however, the switch state is closed then, it can be determined that there is a leak in the inlet valve 26. During the ~ame period but just prior to pulsing the outlet, .
W0/91~16091 14a PCT~U591~02088 to release infusate ~rom the accumulator, if an open switch exists, then a leak exists in the outlet valve seat or one of the valve or accumulator welds.
If, however, the switch of Fig. 6 i8 closed during the 5 ou~let sense period, the system is deemed to be functioning properly. Similarly, by sensing during the inlet portion of the cycle, but immediately following relea~e, an open condition in the switch indicates that the inlet did not open or that there is a leak in the accumulator or valve weld. However, senæing the 10 switch state as closed during the same period will indicate that the system is working acceptably. ~onsequently, by utilizing a switch accumulator of Fig . 6, a signif icant amount of information can be obtained concerning the status of the valve seats or the hermeticity of the metering system. 8y repeatedly pulsing the 15 valve, failure mode can be determined to be repeatable or simply an artifact.
As can be seen by this invention then, a programmable pump exists which operates at positive pre~sures and accurately controls the flow rate by metering discrete and repeatable volumes 20 through a microaccumulator. The accumulator is ~illed and emptied by alternately cycling two control valves which are in series with the accumulator. Thus, by setting the cycling rate of the valves, the pump dispensing rate may be controlled.
The accumulator itsel~ operates at a pressure which is 25 intermediate between the pump reservoir pressure and the outlet pressure. This desiyn pressure, when taken in con~unction with the negligible internal spring rate, guarantees a complete filling and emptying of the system. The volume, however, is repeatedly demonstrated, that is repeatedly dispensed and the valve energy 30 requirements may be minimized. Given the design o~ the valves themselves, minimum dead volume and flow through occur. This minimizes the danger of entrapped air or stagnant flow in the system .
It is apparent that modificationæ of this design and of 35 preferred embodiments therein may be made without departing from the essential scope of this invention.
.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An implantable infusion apparatus including:
a housing containing, an inlet septum, a rechargeable constant pressure infusate reservoir, an electronically controlled metering assembly receiving infusate from said reservoir, said metering assembly comprising first and second normally closed valves and an accumulator positioned in fluid communication with each of said valves, said accumulator comprising an inlet and outlet, a chamber having a diaphragm and a spacer plate; electronic means for controlling the operation of said valves, and outlet means in fluid communication with said metering assembly to dispense infusate to a site in a living body; characterized by said spacer plate having a series of concentric grooves in fluid communication with said inlet and outlet wherein when the first of said valves is open, infusate flows from said reservoir into said accumulator chamber and into said concentric grooves, and when the other valve is open and the first valve closes, infusate flows from said accumulator into sald outlet, said accumulator storing and discharging predetermined volume spikes of infusate at a frequency determined by the cycling rate of said pair of valves.
a housing containing, an inlet septum, a rechargeable constant pressure infusate reservoir, an electronically controlled metering assembly receiving infusate from said reservoir, said metering assembly comprising first and second normally closed valves and an accumulator positioned in fluid communication with each of said valves, said accumulator comprising an inlet and outlet, a chamber having a diaphragm and a spacer plate; electronic means for controlling the operation of said valves, and outlet means in fluid communication with said metering assembly to dispense infusate to a site in a living body; characterized by said spacer plate having a series of concentric grooves in fluid communication with said inlet and outlet wherein when the first of said valves is open, infusate flows from said reservoir into said accumulator chamber and into said concentric grooves, and when the other valve is open and the first valve closes, infusate flows from said accumulator into sald outlet, said accumulator storing and discharging predetermined volume spikes of infusate at a frequency determined by the cycling rate of said pair of valves.
2 . The device of claim 1, wherein said first and second valves are positioned side-by-side in fluid isolation with each other, each of said valves having a conduit to said accumulator that may be opened or closed by a valve member and, said accumulator having said inlet aligned with one of said conduits and said outlet aligned with the other of said conduits.
3. The device of claim 1, wherein said accumulator further comprises an end cap, a backing plate having a contoured surface, and said spacer plate has a straight groove connecting said inlet and said outlet, said diaphragm positioned between said backing plate and said spacer plate.
4. The device of claim 3, wherein said backing plate.
contains a recess, said recess covered by said end cap, means to fill said recess with a fluid under pressure and means in said backing plate to establish fluid communication between said recess and one side of said diaphragm.
contains a recess, said recess covered by said end cap, means to fill said recess with a fluid under pressure and means in said backing plate to establish fluid communication between said recess and one side of said diaphragm.
5. The device of claim 3, wherein said backing plate defines a stop for said diaphragm when said accumulator has been filled with infusate, said contoured surface contacting substantially the entire surface of said diaphragm to limit any change in the stored volume of the accumulator irrespective of changes in pressure of infusate delivered from the reservoir to said accumulator.
6. The device of claim 3, wherein said spacer plate concentric grooves are separated by sharp projecting edges, said projecting edges contacting and supporting said diaphragm when said accumulator is emptied.
7. The device of claim 6, wherein said spacer plate straight groove is in fluid communication with said concentric grooves.
8. The device of claim 3, said spacer plate further comprising an outer flat annular surface for sealing said spacer plate within said accumulator.
9. The device of claim l, further comprising programmer means external to sald housing for interrogating and programming said electronic means.
10. The device of claim 1, wherein said outlet means comprises a catheter attached to said housing, said catheter including a connector insertable into an out let port.
11. The device of claim 1, further comprising a sideport for the direct injection of a drug into said outlet.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/514,442 US5049141A (en) | 1990-04-25 | 1990-04-25 | Programmable valve pump |
| US514,442 | 1990-04-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2078212A1 CA2078212A1 (en) | 1991-10-26 |
| CA2078212C true CA2078212C (en) | 1997-02-04 |
Family
ID=24047156
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002078212A Expired - Fee Related CA2078212C (en) | 1990-04-25 | 1991-03-27 | Programmable valve pump |
Country Status (15)
| Country | Link |
|---|---|
| US (1) | US5049141A (en) |
| EP (1) | EP0526475B1 (en) |
| JP (1) | JPH0647012B2 (en) |
| KR (1) | KR0139651B1 (en) |
| AT (1) | ATE98881T1 (en) |
| AU (1) | AU653150B2 (en) |
| CA (1) | CA2078212C (en) |
| DE (2) | DE69100844T2 (en) |
| DK (1) | DK0526475T3 (en) |
| ES (1) | ES2048593T3 (en) |
| IE (1) | IE64362B1 (en) |
| IL (1) | IL97868A (en) |
| PT (1) | PT97443B (en) |
| WO (1) | WO1991016091A1 (en) |
| ZA (1) | ZA913070B (en) |
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- 1991-03-27 WO PCT/US1991/002088 patent/WO1991016091A1/en active IP Right Grant
- 1991-03-27 KR KR1019920702625A patent/KR0139651B1/en not_active IP Right Cessation
- 1991-03-27 DE DE91907094T patent/DE69100844T2/en not_active Expired - Fee Related
- 1991-03-27 AU AU75873/91A patent/AU653150B2/en not_active Ceased
- 1991-03-27 JP JP3506672A patent/JPH0647012B2/en not_active Expired - Lifetime
- 1991-03-27 EP EP91907094A patent/EP0526475B1/en not_active Expired - Lifetime
- 1991-03-27 CA CA002078212A patent/CA2078212C/en not_active Expired - Fee Related
- 1991-03-27 DK DK91907094.6T patent/DK0526475T3/en active
- 1991-03-27 DE DE9190053U patent/DE9190053U1/de not_active Expired - Lifetime
- 1991-03-27 AT AT91907094T patent/ATE98881T1/en active
- 1991-03-27 ES ES91907094T patent/ES2048593T3/en not_active Expired - Lifetime
- 1991-04-16 IL IL9786891A patent/IL97868A/en not_active IP Right Cessation
- 1991-04-23 PT PT97443A patent/PT97443B/en not_active IP Right Cessation
- 1991-04-24 IE IE137191A patent/IE64362B1/en not_active IP Right Cessation
- 1991-04-24 ZA ZA913070A patent/ZA913070B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU653150B2 (en) | 1994-09-22 |
| DE69100844D1 (en) | 1994-02-03 |
| JPH05505123A (en) | 1993-08-05 |
| ES2048593T3 (en) | 1994-03-16 |
| IL97868A0 (en) | 1992-06-21 |
| JPH0647012B2 (en) | 1994-06-22 |
| ZA913070B (en) | 1992-11-25 |
| DE69100844T2 (en) | 1994-04-07 |
| WO1991016091A1 (en) | 1991-10-31 |
| US5049141A (en) | 1991-09-17 |
| IE64362B1 (en) | 1995-07-26 |
| ATE98881T1 (en) | 1994-01-15 |
| AU7587391A (en) | 1991-11-11 |
| IE911371A1 (en) | 1991-11-06 |
| DE9190053U1 (en) | 1993-04-01 |
| PT97443A (en) | 1993-07-30 |
| KR0139651B1 (en) | 1998-07-01 |
| EP0526475B1 (en) | 1993-12-22 |
| EP0526475A1 (en) | 1993-02-10 |
| IL97868A (en) | 1994-08-26 |
| PT97443B (en) | 1998-11-30 |
| CA2078212A1 (en) | 1991-10-26 |
| DK0526475T3 (en) | 1994-01-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |