CA1110733A - Electronic control means for a plurality of intravenous infusion sets - Google Patents

Abstract

Abstract of the Disclosure Electronic control apparatus for controlling the administration of a plurality of separate fluids independently and consecutively, includes electrical circuitry connected with a plurality of valve operators to operate valves in a plurality of sets to control flow therethrough.

Description

Background of_the Invention This invPntion relates generally to apparatus for controlling the flow of fluid~, and in par~icular relates to electronic control apparatu~ for controlling the admini~tration of a plurality of separate fluid~ independently and con- -secutively. The ba~ic IV set itself may be o the type descriked in co-pending application Serial No. 637,208, filed December 3, 1975, or that shown in co-pending application Serial No. 637,206, filed December 3, 1975, both a~igned to the same as~ignee a~ the pre~ent invention.
Still more specifically, the present invention relates to electronically controlled intravenou~ administration sets, wherein electrical circuitry iY connected with a plurality of valve opera~or~ to operate a plurality of valve in a plurality of intravenou3 administration ~et~ to control the flow of intravenous fluid~ from a plurality o$
~eparate sources.
Many di~ferent type~ of elec~ronically controlled a~inistration sets are known in the prior art. However, all ~uch sets known to applicant are aapable of electronically controll.ing only one intravenoua 1uid at a time, and do not . .
have the means or capability of controlling a plurality of fluid~ by mean~ o~ a plurality o val~e~.
Saveral factor~ are important in the intravenou~
administration of fluids, and include, among other~, the nece~sity or desir~bility of pr~venting th~ injection of fluid into the ~ ue ~urround~ng a ~in in the ev~nt the needle i~ improperly in~erted or ~come~ di~placed fro~ a vein into whieh the fluid i~ to bé injected; the d~irability of keeping the injection ~ite open~ or in other worsl3, of '33 preventing clotting at the injection ~i~e in the event the flow through the intravenou~ s~t i~ interrupted or ceas~s for some reason; the de3irabilit~ o alarm means to indicat~ when the unit is not performing properly, as, for example, when the actual flow rate differs from th~ desired or pxe~et rate, the desirabili~y of the unit to operate even in the event of loss of power from the alternating current ~upply;
the desirability of an accurate an~ easily read display of the volume and rat~ of fluid beiny administerecl; the nece~sity of obtaining an accurate and reliable rate of flow through the ~et; and the ability to control the flow of two separate fluids independently and con~ecutively, with circuit mean~
connected with a plurallty of valves to control the two fluids, and including circui~ry ~o effect a~tomatic switching from one set to the other, as, for example, when one side of the circuit goe~ into ~he alarm mode.
~ oreover, a very ~eriou~ problem in hospital~ and the like i~ the occurrence of so-called "runaway" IV ~et~.
Thi~ ~ituation arises, for exa~ple, when an IV set i~ set by a nurse or other attendant ~or the administration of an IV
fluid to a patient ~t a predetenmined rate of flow, and ~ubsequently the rate of flow increa~es for on~ reason or another. ~ furth~r prdbl3m re~ult~ from inaccurately setting conventional clamp~ and the like. The occurrence of flow rate of an intravenou~ fluid in exce~ of that desired or set ~ particul~rly critical in po~t-operative procedure~, ox in any othe~ ~i4uation in which the pati~nt ha~ received ane~the~a. ThiY ia due to the fact that various organ~, such.a~ the kidney3, of ane~thetized per~on~ do not function properly or a brief time after having been anesthetized,~nd the body doe~ not have the ability to `rid itself of fluids at a desired rate. Accordingly, the fluid will build to a point where it can no longer be accommodated by the body's normal functions, and the fluid then begins to build in the person's lungs. This, of course, may result in pneumonia or other serious problems, and in fact, if left unattended, can ~e fatal.
With the present invention, the problems associated with prior art devices are overcome. More particularly, with the present invention injection of the intravenous fluid into the tissue at an injection site i5 avoided by making the intravenous administration set of the gravity ~eed type.
The injection site i~ ~ept open in the pre~ent invention by the provison of the dual control feature, whlch enables the independent and con~ecutive control of a plurality of fluids, whereby in the event the primary fluid is exhausted or terminated for one reason or ano~her, the secondary fluid is automatically caused to flow to keep the injection site open. For example, the primary fluid may be a medication or nutriment required ater a surgical prooedure or the like, and if the ~ource of such fluid is deple~ed or flow thereof otherwi~e interrupted for some reason, the circuit automatically switches to the secondary fluid, which may be a saline solution, for example, which may be ~et at a flow rate consi~rably le~ than that of the primary fluid, as, for example, a rata sufficient only to keep the injection site open and prevent clotting thereat.
Also, the circuitry of the presen~ invention includes sensing means for detec~ing the occurrence of a flow rate other than that set by the attendant and for souncling or giving an appropriate alarm/ and al~o for arresting fl~w through ;

the malfunctionin~ side of the apparatus until the situation is corrected. This, of course, prevents either the failure to inject a desired fluid or the in~ection of an undesired amount of a desired fluid.
Further, the present invention includes both an ac and dc powered capability, whereby the set can continue to operate even in the event of loss of ac power thereto, as, for ~xample, during transport from one location to another or in the event of a power failure or inadverten~ unplugging of the set from an ac outlet and the like.
Additionally, the pre3ent invention includes an easily read LED display for accurately and reliably indicating the amount of fluid to be dispensed in a metered cycle.
Moreover, the electronic control of the present invention includes a memory capability, whereby it remembers the amount of fluid remaining to be dispensed, in the event ; a dispensing cycle i8 interrupted.
Still further, one form of the invention include~
a digitally settable clock, and further include~ circuitry for time sharing of the clock by the ~wo supply circuits for the respective fluids to be controlled.

Object~ of the Invention It is an object of this invention to provide electronic control apparatu~ for con~rolling the ~dministration of a plurality of ~eparate fluids independently and con~
secutively.
Another object of the inven~ion is to pxovide an electronically controlled intravenous admini~tration set, wherein the set inc~udes electrical circuitry for controlling the operation of a plurality of valves in a plurality of 5et8, , whereby the flow of a plurality of separate intravenous fluids may be controlled with the appar~tus.
A still further object ~f the invention is to provide a dual flow electronically controlled intravenous administration set, which includes means for controLling the flow through a plurality of sets and has circuitry associated with the control of each set, with means for automatically switching from one set to the other under predetermined .~
circumstances.
An even further object of the invention is to provide an electronically controlled intravenou~ admini3tration set wherein electrical circuitry i5 provided for controlling the flow of a plurality of separate intravenous fluids~
and includes mean~ for producing an alarm in the event of flow either less than or greater than the desired rate by a predetarmined amount.
Another object of the invention is to provide an electronically controlled in~xa~enous administration se~
which include~ means for automatically keepin~ the injection site open in the event the flow of intravenous fluid from the primary source is interrupted or terminated.
A fur~her object i~ to provide an electronic control for admini~ering intraveno~s fluids, which includes a digitally settable clock, time ~hared by a plurali~y of circuits for controlling flow of a plurality of fluids.
Yet another objec~ i~ to provide an electronically controlled means for independently and consecutively controlling the dispensing of a plurality of fluicls, said means including elec~rical olrcuitry having memory capability for remembering the amount of ~luid remaining to be dispensed, '73~
`- "

in the even-t a dispensing cycle is interrupted.
Thus, in accordance with one aspect of the invention -there is pro-vided a dual intravenous infusion means for -use with two supplies of` in-tra-venous fluid comprising in combination, a firs-t drip chamber adapted to be connected to one of said supplies, a second drip chamber adap-ted to be con-nected -to the other of said supplies, first and second leng-ths of intravenous tubing respectively connected to the first and second drip chambers and form-ing with said drip chambers first and second fluid flow passages, first and second valve means associated with the respective passages, firs-t and second valve operating means associated. with the respective valve means, first and second drop detector means associated with -the respec-tive drip chambers for sensing drops of the intravenous fluid falling -theYe-t:hrough, con-trol circui-t means including f:irst and second supply circuits connected wi.th the valve operating means for controlling -the first and second valve operating means, said control circuit means including clock means for establishing independ-ently selectable drip rates for said first and second supply circuits, means responsive -to said clock means for opening the respective valve m.eans at the associated preselected drip rates, means responsive -to said firs-t and second drop detector means for closing the associated valve means in response to de--tection of a drop, alarm means responsive to variations in the ac-t-ual drop rate f:rom the preselec-ted ra-te for swi-tching the associ.a-ted supp'Ly circui-t in-to an alarm mode, said alarm means including means f'or -terminating flow of fluid from the associated supply in said aLarm mode, and selector means f'or selectively enabling the first or second supply circui-ts for independent op-eration~ said selector means including means for switching from one supply circuit to the other.
In accordance with ano-ther aspect of the in-vention there is pro-vided a dual intravenous infusion means for use with two sources of intra-venous fluid, comprising in cornbina-tion: first and second individual intra-venous inf'usion sets, each set comprising a drip chamber adap-ted to be . ~ 33 :.
connected to one of said fluid supplies, a length of intravenous tubing con-nected to the drip chamber and forming with said drip chamber a fluid flow passage, valve means associa-ted with -the fluid flow passage, valve operating means associated with the valve means, drop detector means associated with the drip chamber for sensing drops of intravenous fluid falling therethrough, and supply circuit means; said supply circuit means including clock means for establishing sn independently selec-table drip rate for said supply circuit, ~I`' .
means responsive to said clock means for opening -the respective valve means ~ at the preselected drip rate, means responsive to said drop deteetor means for -~ 10 closing the valve means in response to detec-tion of a drop, alarm means re-~:- sponsive to variations in the actual drop rate from the preselected drop rate ~ for switching the supply circui-t into an alarm mode, said alarm means inelud- :~

: ing means for terminating ~low of fluid in said alarm modej and selector means ;:~
;
~or seleetively enabling the ~irst or second supply cireuit for independent : ~
operation, said seleetor means ineluding means for switehing from one supply ~1 eireuit to the other.
Aecording to another aspeet of the invention there is provided a ~ .-dual intravenous infusion means for eontrolling the dispensing of intravenous fluid from first and seeond sourees of intravenous fluid eomprising in eom-blnation, first and seeond fluid flow passages conneeted to the respective ;
fluid sourees, first and seeond valve means assoeiated with the respective fluia flow passages for eontrolling flow -therethrough, first and seeond valve eontrol means eonnee-ted with the respeetive valve means for opening and elos-ing the respeetive valve means at individually seleetable rates, and selector means eonneeted with the eontrol means for seleetively enabling eaeh valve means to individually deliver fluid from its assoeiated fluid souree at the rate seleeted therefor, said seleetor means ineluding means ~or switehing control between the first and second valve eontrol means, at least one of said valve eontrol means including alarm means for detecting devia-tions be-tween the actual rate of delivery of said fluid and the selected rate and in a -~` :
~, . .
, ~
response thereto putting the associated valve control means into an alarm condition, said alarm means being coupled to said selector means for switch- ;
- ing control to the alternate control means in response to an alarm condition. `
In accordance wi-th a fur-ther aspect of the invention there is pro-~ vided control means for use with multiple intravenous infusion sets, wherein ; the infusion sets each includes a fluid flow passage means adapted to be con-nected with a source of intravenous fluid, and valve means in the fluid flow passage means operational between an open position and a closed position to control flow therethrough, said control means comprising valve operating means for opening the respective valve means, digitally set-table clock means for ,;, preselecting the rate of operation of the valve operating means and thus for selecting the rate of the valve opening and rate of flow therethrough, counter means for countine the amount of fluid dispensed, selector means for select-ively enabling operation of thereSpectiVÇ valve operating means, said selec-tor means including means for disabling one valve operating means and enabling the other in response-tothe occurrence of a predetermined condition, said selector means further'including means which f~mctions when returning to an ;~ ;
interrupted cycle to prevent the counter means from beginning a new count, whereby the counter means remembers the amount of fluid dispensed and contin-ues the count of the interrupted cycle, supply circuit means connected with each valve opera-ting mean: to control operation thereof, said digitally set-table clock means connected with said supply circuit means -to effect ac-tua-tion thereof to obtain a desired drip rate, said clock means being shared by the supply circuit means~ and alarm means for giving an alarm when the drip rate actually delivered differs by a predetermined amount from that set, and including high rate error accumulating means which counts extra drops over a dispensing cycle and goes into alarm when a predetermined number of excess drop signals are accumulated.
According to another aspect of the invention there is provided a m~tiple intravenous infusion means for independently and consecutively con-- ~b -~3 ~

trolling flow of separate intravenous fluids -through a plurality of in-traven-ous infusion sets, including: a plurality of intravenous in-fusion sets; valve means associated with each set; valve operating means for opening and closing each valve means at a preselected rate; selector means for enabling one valve operating means and disabling -the other; and alarm means associated with at least one of said valve operating means for detecting deviations between -the actual ra-te of delivery of fluid and the selected rate and operative in re-sponse to a deviation to operate said selec-tor means to disable the valve op-erating means associated with the alarm condition and to enable the alternate valve operating means, whereby in the event of an alarm condition occurring in one of the sets, intravenous fluid automatically continues to be supplied through another set.
BrleI` Descri,otion of the Drawings Figure 1 is a ~erspective view of an electronically controlled ap-paratus according to the invention, shown as used to control flow from a pair of independent sources of intravenous fluid.
Figure 2 is a block diagram of the basic elemen-ts of the apparatus according to the invention.
Figure 3 is a schematic view of a pair of electromagne-ts used to control a valve in accordance with the invention.
F'igure 4 is a view similar to Figure 3 of a modified arrangement for controlling -the valve, wherein electromagnets are used to open the valve and permanent ~agnets are used -to hold -the valve closed.
Figure 5 is a fragmentary, p-erspec-tive view, wi-th portions broken away, of the Y-connector used to join the lengths of tubing connected with the two sources of intravenous fluid in Figure 1 with the length of -tubing joined to the cannula and thus to the patient.
Figures 6, 7, 8, 9 and 10 are schematic diagrams of portions of -the electrical circuit in a first form of -the invention, wherein Figure 6 shows the supply and B circuit for controlling flow at one side of the device, and - 7c -. ~ I
~, ~, ., the A-B select circuit; Figure 7 shows the circui-t for controlling the B side of the apparatus and also shows -the divide by 15 counter; Figures 8 and 9 show the volume selector and monitor portions of the circuit for the electronically , :
controlled device; and Figure 10 shows the A-B select circuit and memory.
Figure 11 is a view illustrating the manner in which Figures 6, 7, 8, 9 and 10 are relatively placed to be read.
Figures 12-16 are schematic circui-t diagrams of a second form of control for the invention, wherein:
Figure 12 shows the alarm circuit and a portion of -the volume sel-ector and monitor circuit;
Figure 13 shows a portion of thevolume selector and moni-tor circuit, and a portion of the A-circuit;
Figure 11l shows the B supply circuit and a portion of the A-circuit;
Figure 15 shows the ~gitally settable click, A-B select circuit and memory; and Figure 16 shows a portion of -the A~circui-t and means for clearing the volume counter.

Detailed Description of the Preferred Embodiments In the drawings, wherein like reference numerals indica-te like parts throughout the several views, an electronically controlled apparatus 10 for con-trolling -the flow of a plurality of separate in-travenous fluids Fl and F2 comprises a console or housing 11 suppor-ted on a suitable suppor-t stand or the like S, which may also suppor-t -the fluids Fl and F2.
The console unit 11 has built thereinto a pair of valve control means or assemblies 12 and 13, each comprising an electromagnet 14 positioned -to open a valve associa-ted with a respective in-travenaus set IVa and IVb, and a magnet means 15 to hold the valve closed to prevent backflow through the set, as for example, in the event the outlet therefrom is elevated higher than the valve. As seen in Figure 3, the magnet means 15 may comprise elec-.~

tromagnets, or as seen in Figure 4, -the magnet means 15' may comprise perman-ent magnets to hold the valve closed when the elec-tromagnet 14 is no-t ener-gized.
An on-off switch 16 controls supply of power -to the apparatus~ and the valve control means or assemblies 12 and 13 are connected in electrical circuitry which controls energization of the valve operating means to control the rate of opening and closing of the valve means in -the associated IV set, to thus control the rate of flow of the respective fluids Fl and F2. These rates are accurately established by means of suitable manually operated con-trol knobs or the like 17A and 17B for the primary fluid Fl and the second-ary, or keep-open fluid F2, respectively. Numerals are associa-ted wi-th the con-trol knobs or the like 17A and 17B for visually indicating the selected drop rate. Thumb~heels 1~ are provided for presetting a desired volume to be administered in milliliters, for example, and numerals are associated -there-with for giving a visual indication of the volume selec-ted. A digital display 19 indicates the volume remaining to be administered at any given time.
When the on-off swi-tch 16 is turned -to "On" to supply power to the apparatus, side B of the circuit is automatically energized, and flow starts on side B at the prese-t rate. An A/B select or push-s-tart but-ton 20 is pro-vided for disenabling side B and enabling or energizing side A to obtain a pre-set rate and volume of flow -through the intravenous set IVa. Thereafter, each time the A/B select button is depressed control is switched from the op-erational to the alternate supply. During normal running of side A, there is a continuous readout of volume to be administered. In the event of a dispar-ity, an alarm is given, and the display remains on. If no alarm condition occurs, the unit will continue to run at the preset rate lmtil -the volume -to be adminis-tered reaches zero. The circuit then automatically swi-tches -to side B, and runs at the rate set on that side until the fluid F2 is depleted or some problem causes -the uni~ to go into alarm.
In the even-t that side A is to be run independen-tly, no IV set is .~1 3 ::

`
connected to side B. Side A will thus run at the preset rate until the present volume is administered and will then shu-t down and gi~e the approp-` riate alarm signal.
Flush buttons 21A and 21B are associated with both sides of theapparatus for overriding the control circuit to flush the set, and reset buttons 22A, 22B are provided to reset the circuits. High and low rate indi-cating lights or the like 23A, 24A and 23B, 24B are provided on the respec-tive sides A and B for indicating abnormal conditions, and lights 25A, 25B
are associated with sides A and B, respectively~ for visually indicating when a drop falls. This enables an attendant -to manually check the drop rate, for example. Power indicator lights 26A and 26B are also associated with the respective sides to indicate when that side is energized or running.
The intravenous administration sets IVa and IVb each includes a drip chamber DC o~ conventional design connected with the respective fluids Fl and F2, and constructed in a Xnown manner to obtain a desired drop size, as , - 10 - ' ' .;~''' ~;' .

for example, such that 15 drops equal 1 millili~er. A
clamp C may be provided on the length of tu~ing, if desired, for shu~off of flow through the respective sets. Addition-ally, the lengths of tubing associated with the intravenous administration sets IVa and IVb are each connected with a Y-connector 27, which has ~ further length of tubing 28 connected therewith and extending to a cannula or the like 29, which is inserted into a patient.
As seen in FIG. 5, the Y~connector 26 may ha~e a pair of check valves 30 therein for preventing bacXflow through the branche~ of the Y-connector into the re~pective intravenous administration ~ets.
Rather than use a Y-connector such a3 27, the set may utilize a pair of "piggy back" needles or the like, if desired.
Suitable drop detector as~emblies 31A and 31~ are associated with the respective drip chambers DC for detecting the pre~ence of a drop falling through the drip chambers and producing a signal in response thereto, which is supplied to the unit 11 for e~fecting control of the valve control mean~.
The circuitry includes a divide by N counter, which convPxts drops to milliliter~, which in turn are displa~ed, the drop ~ize being predetermined ~uc~ that a predetermined number of drop~ equals a predeter~ined volume.
As noted previously, duxing nonmal operation, there is a continuous readout of the volume of fluid to be adminis~ered.
When the down counter in as~ociation with the A circuit reaches zero, an A/~ select circuit automatically switche~

control back to ~ide B, which then run3 at a rate equal :`.' to the setting on control knob or the like 17~ until the fluid F2 is exhausted, or until some other problem cau~es the alarm to sound.
The circuitry includes means for automatically energizing electromaqnets 15 when the electromagnets 14 are de-energlzed, and,thus backflow i9 prevented in ~he event one container should be positioned higher th~n the other, or some other condition should occur which would tend to promote backflow.
A bloak diagram illustrating the general structure and function of a dual IV set control con~tructed in accordance with the present invention Ls shown in FI~. a, and for ease of understanding, the following descriptlon will treat the electronic IV set control~ as two separate and dlstinct unit~ con~trained to function a9 determlned by the master control to be described therein. However, it will be apparent to one skilled in the art that certain manufacturing economies may be achieved by providing certain common circuit elements to be ~hared by the two electronic IV
controls, as described herein with referencP to the embodiment in FIGS. 12-lS, for example.
The control circuit includes firs~ and second electronic IV controls 101, 102 and master con~rol 103 for determining which of the I~ controls will control supply of fluid to a patient. The IV control 101 may be considered the B fluid supply de~cribed abo~e, and is adapted to simply supply fluid at a preselected drop r~te. The IV control 102 is coupled to the master control 103 to function as the A
supply described above, o~ allowing an a~tendanl: ~o preselect a volume of fluid to be dispensed, for dispen ing such volume at ~ preselected rate and for t~rmin~ting the supply when the preselect~d volume is dispensed. The master control 103 contxols switching between the circuits 101 and 102 and further functions with the A circuit in metering the volume of fluid delivered.
As more fully described hereinafter, and also as described in the above referenced patent applications, the electronic IV control generally indicated at 101 includes a drop rate selector 104 for opening the IV set valve at a preselected rate to allow drop3 to form and fall at that rate and a drop detector 105 for sensing each drop falling through the drip chamber and closing the valve in response thereto.
More specifically, the rate selector 104 control~ the fre-quency of a variable frequency clock to produce one pulse for each desired drop, the B control circuit 106 responding to each clock pulse by energizing coil driver 107 to energize electromagnet 14 tc open the IV valve. Opening o the valve allows a drop to form and fall in the drip chamber. The falliny drop is sensed by the drop detector 105 which sends a signal to the control circuit 106 to cause the closing of the valve. The IV control 101 includes a no drop detector operative in response to the failure of a drop to form and fall to prevent further energization of the coil drivers 107, thereby to stop the flow of fluid, and ~o energize audible and/or visual alarm~ (not shown) for informing an attendant of a malfunction~
The A circuit 102 contains similar elements including an A rate selectox 108 operating in conjunction with an A control circuit 109 ~or opening the valve in the A circuit via the A coil drivers 110. As with the ~ circuit, 3~ 733 ;

the A circuit includes a drop detector 111 (ldapted to sense each drop falling through the drip chamber and cause the closing of the valve by deenergi~ing the coil drivers 110.
According to one feature of the invention, means are provided, operational in conjunction with the A
circuit, for metering the total volume of fluid Fl to be dispensed in a cycle. To that end, the A circuit 10~ is coupled to the mas~er control circuit 103, which responds to signals indicative of the falling of a drop, and is adapted to count such signal~ to measure the amount of fluid actually dispensed. The ma~ter control circuit 103 include~ meteriny counter 112, presettable via the operator accessible digital ~itches 113 ~18 in FIG. 1). In practice, an attendant pre~ets the volume of desired fluid via the switches 113, thereby setting the modulus for the counter 112. The associated display 114 (19 in FIG. 1) responds to the number within the counter for indicating the amount of fluid yet to be dispensed. It is preferrad that counter 112 be constructed as a down counter 50 that the display 114 indicates the volwme of fluid remaining to be dl~pen~ed.
In an alternative configuration, the counter 112 may be constructed as an up counter, arranged to count from ~ero to the number pre~et on th~ ~witches 113, the display 114 in such configuration indicating the v~lume o~ fluid actually dispensed.
For relating the number of drop~ to ~he volume of fluid di~pensed, a divide by N counte~, shown herein as divide by 15 counter 115 i~ coupled to the A control circuit 109 and responds to signal~ produced by the drop cletector 111.

'733 '~:
The divide by 15 counter 115 is adapted to clock the metering counter 112 onee for each 15 drops dispensed by the A circuit. As noted above, the drip chamber is of conventional construction and is arranged and eonstructed to eontrol the size of drops so that a predetermined nurnber of ;~
drops make up a known volurne of fluid. In the illustrated embodiment, the drip ehamber used is of the type wherein ]5 drops eomprise one milliliter of dispensed fluid. To use the illustrated circuit with drip chambers of other con- ;
structions, such as those dispensing 20 or 60 drops per milliliter, i-t is necessary only to modify the construction of the di~ide by N counter 115 to divide by the proper nurnber of drops.
It will now be apparent that the counter 112 may be preset to dispense any number of milliliters of fluid, the A circuit may be energized to initiate the dispensing, and thecounter 112 and divide circuit 115 monitor -the fluid dispensed to continually indieate via the display 11~ the amount of fluid yet to be dispensed.
In aceordanee with the invention, the master eontrol 103 ineludes means for selee-tively energizing the IV eontrols 101, 102 -to allow dispensing of different fluids at individually preselec-ted rates. To that end, the master control 103 includes an A/B select circuit 116 coupled to the B control eircuit 106 and the A control eireuit 109 and funetioning to energize one or the other of such circuits to allow the dispensing of fluid thereby. The A/B select circuitry 116 incl~ldes means for energizing the B circuit 101 when power is first applied -to the unit. Aceordingly, the B eireuit will eontrol the dispensing of fluid unless, ~C~33 of course, an alarm condition is detected ~ which point the system will enter the alarm mode and fluid dispensing will be terminated. An attendant may initiate the dispensing of a predetermined volume of fluid via the A circuit, by actuating the switch 20 on the control panel which energizes a start A circuit 117 to cause the A/s select circuitry 116 to change states, deenergizing the B circuit 101 and energizing the A circuit 102. In addition to ~witching control to the A circuit, the A/B select circuit 115 acts upon the counter 112 to strobe the number preset on the switches 113 into the counter. The A circuit th~n functions to dispen~e the fluid at the r~te ~elected by rate selector 108, dispensing of each 15 drop~ causing the clocking of the down counter 112. When the counter 112 i5 cycled to zero, indicating the dispensing of the preselected amount of fluid, the counter produce~ a ~ignal which acts upon the A/B
select circuit 11~ to switch control from the A circuit back to the B circuit. An attendant observing the unit functioning on the B supply and indicating zero milliliters remaining to be di~pen3ed on the A supply will realize that the A
circuit has operated successfully through its entire cycle and at the termination thereo switched control back to the B circui~.
As wi~h the B circuit, the A circuit al~o includes an alarm system for indicating malfunction. In the event an alarm condition develop~ whïle the A circuit is functioning to di~pense its predetermined volume, ~he A
circui~ 109 will sense such alarm and in re~pon~e thereto prevent the further energization of coil driver~s 110l ther2by ~erminating the supply of 1uid from the A source, Fl. Upon 3~

this occurrence, the A circuit, being coupled ~o the A/B
select circuit 116, causes the select circuit to change states, automatically activating the s suppl~ 101 for dispensing B fluid F2 at the preselected rate established therefor. The A/B select circuit 116 functions to lock the counter 112 into the state existing at the time of ~he alarm so that the display 114 indicates to an attendant the amount of fluid remaining to be dispensed at the time the ~,ystem went into the alarm mode. The B supply function~ to keep the injection site open until the attendant is appraised of the alarm condition and clears it. When the alarm condi-tion is cleared, the attendant then returns control to the A supply via depression of the appropriate pushbutton switch 20. As opposed to lni~iation of a cycle wherei~ such initiation serves to load the cou~ter 112 to the number preset on the switches 113, the A/B select circuit 116 functions when returning ~o an interrupted cycle to prevent the reloading of the counter 112 so that the counter retains the previous number and begin~ to count down from that number to zero. Thus, the counting circui~ry remembers the amount of fluid still to be dispensed in an interrupted cycle and dispenses only that amount of fluid when control is returned.

3~3~
`:
mbodiment I
Turning now -to Figures 6-11, there is shown -the circuitry of a first embodiment ofthe dual IV control illustrating the present invention. Referring ~irst to Figure 6, there is shown the B circuit control 106, much as described in co-pending application Serial No.
637~206, referenced above. The circuit includes a -transistor switch 179 for controlling -the operation of the IV valve 11~ (see Figure 3) in the B supply circuit via the valve coil 180. The switch 179 is driven from a latch, shown herein as flip-flop 178, the Q ou-tput of which is coupled to the base circuit of switch 179 so that the f]ip-flop in i-ts set condition energizes -the switch to energize the coil to -thus open the valve.
For opening the -valve at an operator preselected ra-te, a variable clock 176 iB provided having an outpu-t coup]ed -to the clock input of -the la-tching flip-flop 178. A po-tentiome-ter 177 in the timing circuit of the clock 176 allows an attendant -to select the clock fre-quency and thereby establish a desired drip ra-te. The latching flip-flop 178 has its K input tied to the positive supply of vol-tage and i-ts J input supplied from a B latching gate 188, -to be described below. In normal operation, the J inpu-t is at a high level at -the time -the vari-able clock 176 produces a valve opening clock pulse. As a resul-t, the latching flip-flop 178 will respond by changing s-tates, driving its Q
output high and energizing the switch 179.
A drop detector 181, operatively associated with the drip chamber, may be configured as described in the above referenced patent application. Briefly, the drop detector includes a light source optically coupled to a photosensor so that any drop of fluid -falling through the drip chamber will interfere with the light falling on the photosensor to produce an output signal. This O~tpllt serves as a clock input for pulse shaper 182, in the form of a conventional mono-stable multivibrator, resulting in the production of a pulse at the output of the pulse shaper 182 for each drop ~ensed ~y the drop detector 181. It is seen that the pulse from the pulse shaper 182 is coupled to th~ reset input of the latching ~lip-flop 17B via inverter 183 and AND gate 184, thereby resett.ing the latching flip-flop 178, driving its Q output low, deenergizing the transistor switch 179 and thus de-energizing the coil 180 and allowing the valve 14 in the supply to close.
A further monostable multivibrator or clrip pul~e extender 185 i9 driven by ~he pulse shaper 182 via .inverter 183 so as to produce a pul~e of sufficient duration in response to each drop falling through the drip chamber to allow the visible flashing o a drop indicator light 2~B. An opexator observing the periodic fla~hing o~ the drop indicator 25~
at the rate selected by the variable clock 176 is apprai3ed that the ~ystem 1~ operating properly.
For sen ing error~ in the flow rate and preventing further energization of the valve in re~ponse thereto, an alarm sys~em is provided, such alarm ~ystem including both low and high rate alarms. The low rate or no drop alarm includes a second flip-flop 18~ having it~ clock input driven fro~ the variable clock 176 and its re~et input driven from ~he drop pulse extender 185. The K input of the flip-flop 186 is coupled to the positive voltage ~uppl~.
In norm~l opera~ion, therefore, the appea:rance of a clock pul~e at the clock in~ut of the flip-flop 1136 will occur with the J input high and K low 50 that th~e flip-fl~p will g~ 3 be clocked to drive its Q OlltpUt low. Upon detection of a drop, the drop pulse extender 185 will couple a sl~nal to the reset input of the fl.ip-flop, resetting it to th~? opposite condition with the Q output hiqh. It will be appreciated that in normal operation th~ latching flip-flop 178 and flip-flop 186 change state generally in synchronism, being dri-~en to a first state in respon~e to a clock pulse and a second state in response to a drop pulse. Hswever, when no drop is detected, neither the latching flip-flop 178 nor the flip-flop 186 i~
reset as de6cribed above. The Q output of the flip-flop 186 i~, therefore, maintained in its low condition, thi~ low ~i~nal being pas~ed through alarm gate 197 and the ~ latching gate 188 in the ma~ter control circuit to appear a~ a low signal on the J input of th~ latching flip-flop l78. As a r~ult, when the next clock pulse i9 generated by the timer 176, tha flip-flop 178 will re~pond thereto by driving i~s Q output low, thereby deenergizing the ~witch 179 and coil 180 and allowing the valve 14 in the B supply to close. Becau3e the J input of the flip-~lop 186 is tied to positiY~ voltag~ and the R
input i~ maintained low by the drop pulse extender 185, the flip-flop 186 will re3pond to ~ucces~ive clock pul~e3 by main~
taining its Q output low, thu~ ~aintaining the J input oP th~
latching flip-flop 178 at a l~w lev~ s a re6ult, the latchin~ flip-flop 178 will b~ ~aintained in condition with it~ Q output low~ preventing further energlzation o~ th~ 8witch 179 and ~urther energiæation of the valv~ coil 14, With the ~re~ult that openirlg of the valve is prevented.
For lndicating a low rat~ alarm cond:it.lon to an attendant, a ~o drop alarm i~ provided, ~hown herein as ~lip-~op 1~9 and low rate ox no drop i~dic~tor light 2~. The f~ lop 189 ha8 a re~et inp~t driven from the Q outpU~ o~ the drop pul~e ~xtender 185. The J and R input8 of the flip-~lop 18 7'33 are tied to the positive ~upply of voltage so tha~ the flip-flop will attempt to toggle for each clock pulse receivedO
It is seen that the clock input of the flip-flop 189 is driven from the Q output of the latching flip-flop 178. As a result, the flip-flop will attempt to toggle each time the Q output of th~ latching flip-flop 178 is driven to a low level to deenergiz2 the switch 179. However, in normal operation, thi~ clocking will occur while the Q output of the drop pulse extsnder is maintaining a low level on the reset input of the flip-10p 189. The reset input will control and accordingly the Q output of the 1ip-flop 189 will be maintained at a low level~ However, in the absence of a detected drop, and when the lat~hing flip-flop 178 is returned to its Q low condition by the second clock pulse wit~out an intervening drop pulse, the clock signal will be coupled to the flip-flop 189 without an overriding re~et signal from the drop pul~e extender 185. As a result, the flip-flop 189 will be caused to change ~tate~, driving lts Q output high and illuminating the no drop indicator 24B. Because the latching flip-Plop 178 iB prevented from changing ~tate during ~hi~ alarm condition, no subsequent clock pulses will be provided to the no drop alarm 189 and it will b0 maintained in it~ alarm condition.
In addition ~o the no drop or low ra~e alarm 189, the B supply circuit illuatrated ln FIG. 6 include~ meana for ~e-tecting high rate alarm conditionst or multlple drop~, and, in response thereto, putting the ~upply circuit into an alarm conditio~.
The multiple drop detç~c~or includes a multiple drop ala~ f lip-flop 192 having the clock input thereof driven by the oU~put of the pulse shaper 182~ It i~ ~een that the K input o~ t~ ~lip~
flop 192 is connected to ground while the reset and J input~
are driven from ~he Q ou~put of latching ~lip-flop 178. A hlgh rate alarm indicator 23B i8 driven ~y the ~ output of multiple drop alarm flip-flop 192 and, a~ will become more appaFent~ i0 illuminated when drops are det~cted out of the norma~l operational cycle.

Remembering -that the Q ou-tput of the latching flip--f]op 178 is driven low when the flip-flop is triggered to open the valve, it is seen that this condition maintains the mul-tiple drop alarm flip-flop 192 in its reset condition. Detection of a drop causes the pulse shaper 182 to produce a pulse which is coupled via inverter 183 and AND gate 18LI to the reset input of latching ~lip-flop 178. The pulse passed by inverter 183 is also coupled to the clock input of flip-flop 192, and attempts to clock that flip-flop to its set condition. However, the latching flip-flop 178 has not yet reverted to its reset condition and, thus, the reset input maintained by the Q output of flip-flop 178 overrides the clock signal on the flip-flop 192 and maintains the multiple drop alarm flip-flop in i-ts reset condi-tion.
However, after -the latching flip-flop 178 switches -to its valve closed position, the reset signal is removed from flip-flop 192 and it is -then adapted to respond to further c].ock pulses. If a drop is then sensed, the pulse shaper 182 will cause the produc-tion of a further clock pulse, such pulse being coupled to the clock input of multiple drop alarm flip-flop 192, causing that flip-flop to change sta-tes to drive its Q output high. As a result thereof, the multiple drop indicator 23B will be illuminated. In addition, the Q output of flip-flop 192 having gone to its low condition, passes that low signal through AND gate 193 and OR gate 194 in -the alarm ga-te 187 and through the B latching gate 188 to impose a low signal on the J input of -the latching flip-flop 178. rrhis~ it is recalled, is the condi-tion which inhibi-ts flip flop 178 from responding to clock pulses to drive the Q output high, thereby maintaining -the associated valve in the closed posi-tion. It is further seen that the Q outputs of the multiple drop alarm flip-flop 192 and no drop alarm flip-flop 189 are coupled to the inputs of an OR
gate 195 so that when either of the alarms is actuated, -the output of the OR
gate will cause the energiza-tion of an audible alarm 196.

.,.,,~

. .
For resetting the visual and audible alarms ancl re-turning the supply circuit to its non-alarm condition, an alarm reset circuit is provided. In the illustrated embodiment the alarm reset circuit includes a monostable multivabrator 197 havin~ a period established by resistor 198 an~ cap~citor 199, such period being longer than the period associated with the slowest clock frequency of interest. The trigger input of the multivibrator 197 is coupled via resistor 200 to the positive ~oltage supply and through a normally open, user accessible reset switch 22B to ground. Depression of the reset switch 22 triggers the mono~table 197 to drive the ou~put thereof high for the time period associated therewith. That output is coupled through OR gate 194 in the alarm gate 187 to the B
latchin~ gate 188. Recalling that the output of OR gate 194 is maintained low in an alarm condition, it i8 seen tha~ the alarm reset multivibrator 197, when triggered, overrides that low signal and causes the output of O~ gate 194 to ~e switched high for the period of the monostable. That high signal i5 passed ~hrough B la~ching gate 188 to the J input of latching flip-flop 178, allowing that flip-flop to responcl to the next clock pulse received to drive the Q output high/ energizing the switch 179, and opening the IV valve. If the alarm conclition ha~ been caused by a high drop rate conditivn, switching of ~he flip-flop 178 to its Q low condition will serve to clear the alarm by imposing a reset signal on ~ultiple drop alarm flip-flop 192.
Contrariwise, if the alarm has been initia~ed by a low drop rate condition, detection of a drop following the chan~e of state of flip-flop 178 will trigger the drop pul~e extender 185, driving its Q output low and imposing a reset ~ignal on ~he no drop alarm flip-flop 189. Thus, depreRsion of reset switch 22B
initiates a period for overriding the low signal on the J input of the latching flip-flop for a time sufficient for that flip-flop to respond to the next clocX pulse. Proper response to the next 3~
,, ~
clock puLse serves to complete the clearing or resetting of the supply circuit.
For preventing the va~Lve in -the IV set from remaining open for an excessive period of time, maximum time limit means are provided, sho~m herein as five second timer 201 and its associated components. The timer 201 is of the retriggerable variety and has a clock input driven from the output of the variable clock 176. Resis-tor 202 and capacitor 203 establish the period for the timer 201 which is selec-ted as the maximwm desired valve open -time, such as five seconds. Each clock pulse produced by the variable clock 176 serves to reinitiate the period of the timer 201. If the maximwm time elapses before a drop is detected, thetimer 201 will time out, driving the output thereof low. That low signal is coup]ed through OR gate 204 and AND
gate 18l~ to the reset input of the flip-E'lop 170, rese-tting that flip-flop.
Thus, even if no drop is detected, the timer 201 wi:Ll serve to positively close the valve after the maximwn desired open period.
As a further feature of the illustrated circuit, means are pro-vided for maintaining the IV valve of -the non-operating supply circuit in the positively closed position, such means being implemented herein by way of pull down magnets indicated generally in Figure 3 as 15. In the circui-t of Figure 6, it is seen tha-t the puLl down magnets 15B are energized by providing 'base drive to switching transistor 205 via inverter 206, tha-t inverter being driven by the Q output oE' the A/B select flip-E'lop 207 in the select circuit 17L~. Thus, when the A supply is operational, the low Q
output of the select flip-flop will cause theoutput of inverter 206 to go high, providing base drive to transistor 205, and continually energizing pull do~m magnets 15B to maintain the valve in -the B supply circuit on its sea-t.

- 2L~ -,~ ,"

~ t~ 3 ~

A Supply Circ it With two exceptions, the A supply circui-t is identical to the B supply circuit, the common elements being ind;cated by primed numbers.
Those elements will not be described further herein. With respec-t to the -two variations, it is seen tha-t the output of the pulse shaper 182', in addition to being connected as described previously, is also connected to the clock input of divide by 15 counter 208. The divide by 15 coun-ter is adapted to rela-te drops of fluid delivered by the A circuit to volume of fluid delivered,the output of the divide by 15 counter being coupled to the volume selector and monitor circuit 175 for monitoring the volume of fluid delivered.
With regard to the second varia-tion, -the output of OR gate 195l, in addi-tion to being coupled to -the audib:Le a:Larm 19S~, is alSo connected via inverter 209 to B reset gate 210. As will be described in more detail below, theB reset gate 210 is adapted to switch control from the A circuit to the B circuit upon the occurrence of prede-termined conditions. It will now be apparent that one of those predetermined conditions is an alarm condition when operating on the A supply circuit, occurrence of the alarm condition serving to switch control to the B circuit for keeping the needle open until the A circuit alarm is cleared.
To allow flushing of the IV sets, -the switching -transis-tors 179, 179~ in -the respective supplies are paralleled by f:Lush swi-tches 21A, 21B. If desired, the switches 2LA, 21B may be ganged with -their associated reset switches 22A, 22B so that flush and reset operations occur simul-taneously.
In practicing the invention, means are provided for selectively energizing the A supply and B supply so that only one of such supplies is active a-t any given time, and for switching control between such supplies.

To allow only one supply -to be energized at any given time, and to -;
selectively energize such supplies in dependence upon control signals, bistable means are provided for energizing the A supply in one stable state and the B supply in the alterna-te stable s-tate. More specifically, A/B
select flip-flop 207 is provided having its Q output coupled to the A latch-ing gate 188 ' and its Q output coupled to the B latching gate 188 ~ As a ; result, when the flip-flop 207 is in its se-t condition, the high Q output thereof applied to the input of A latching gate 188' will allow the signal on the Q output of the no drop detector 186 ' to be passed through such gate to control the J input of the latch 178'~ In normal operation, therefore, .
the latch 178' will be permitted to respond to each clock pulse to open the A supply valve, and in the alarm condition will be constrained to prevent further energization of` the A valve. Further, in the set condition, the low Q output of flip-flop 20rr will maintain the output of B latching gate 188 in a low condition, which, ~ust as in the alarm condition, prevents energization of the switch 179 controlling the B supply valve. Contrariwise, when the flip-flop 207 is in its opposite or reset condition, the low Q
output will act through A latching gate 188' to prevent energization of A
supply switch 179' ~ and the high Q output will allow the passage of signals from the no drop detector 186 through the B latching ga-te 188 to control the B supply latch 178~ In addition, with the Q output of flip-flop 207 low -to maintain the A supply deactuated, -the low Q signal is applied through inverter 206' to provide base drive to transistor 205' thereby energizing the pull down magnets 15A to keep the~ supply valve locked on its seat.
The B latching gate 188 and B supply pull down magnet eircuitry is driven from the Q output of the A/B select flip-flop 207 SO that the condition of the B circuitry is exactly opposite that of the corresponding A circuitry (except, of ~ourse, if both supply circuits are in the alarm condition).

~ 26 ~
"` ~

. . .

. r ~ \ :
The flip-flop 207 is also used to drive the A side ancl B side power indicators, indicator 26A being driven from -the Q output and indicator 26B from the Q output. To assure tha-t -the B circuit is energized when the system is first switched on, means are provided for rese-tting the flip-flop 207 upon -the application of power. To that end, a power on monostable multivibrator 211 has i-ts trigger input connected to a timing circuit comprising resistor 212 connected between the trigger input and the positive supply and capaci~or 213 connected be-tween the trigger input and ground. Application of power to the circuit will cause the capacitor 213 to begin to charge through the resistor 212 at a rate determined by the values of those components. When the signal increases to -the trigger level of the multivibrator, a :Iow going pulse will be produced at the Q
output thereof, the ~idth of the pulse being determined by the values of resistor 21L~ and capacitor 215. That low going pulse is coupled via AND
gate 216 to the reset input of A/B select flip-flop 207. In addi-tion, the low going pulse is coupled through AND gate 217 to the reset input of A
memory flip-flop 218 for bringing that flip-flop back to its reset condition.
For switching from the active to the alternate supply~ means are provided for changing the s-tate of A/B select flip-flop 207, shown herein as A/B select switch 20 coupled between -the positive supply of voltage ~d -the trigger input of an A/B select monostable 219. Momentary depression of the selec-t switch 20 triggers the monostable 219 for a period determined by resis-tor 220 and capacitor 221 -to produce a low going pulse at the Q OlltpUt which is coupled to the clock input of select flip-flop 207. It is seen that both the J and K inputs of the flip-flop 207 are coupled to the positive supply of voltage so that, ~ith the reset circuit inactive, the receipt of a clock pulse will cause the flip-flop to 33;~

toggle from i-ts present to its alternate stable sta-te. Thus, to switch from the A supply to the B supply or vice versa, it is sirnply necessary to momentarily depress the A/B select sw~tch 20.
In accordance wi-th one aspect of the invention, at leas-t one of the supplies is provided with means for metering a predetermined volume of fluid and switching control to the alterna-te supply after such amount is metered. To that end, a volume selector and monitor circuit, generally indicated at 175, is provided for opera-tion in conjunction with the A supply. As shown in Figures 8 and 9, such circuit includes a multi-digit counter 142, presettable to demand a given amo~nt of fluid and preferably graduated in terms of vo:Lume, such as milliliters. The illustrated coun-ter is constructed of t'hree decade counter cllips including uni.ts counter 1ll3, tens colmter 11l4 and 'hundreds counter 145. The counter may be preset via digital swi-tches preferably of -the t'humbwheel type, including units switch 146, tens switch 147 and hundreds switch 148.
It is seen that the binary outputs of the digital swi-tches are coupled to the binary inputs of the associated coun-ters so that provision of a s-trobe signal to the counter will serve -to load the numbers set on the switches in-to the associa-ted counter digits.
The counter is preferably arranged as a down counter, -the borrow outpu-t of each digit being coupled to the down clock inpu-t of the next higher digit so that cycling of any digi-t downward from zero to nine will cause the next higher digit -to be decremented -by one. Alternatively, the counter may be arranged as an up coun-ter appropriately gated with the volume selecting switches 146-148 so tha-t a signal will be produced when the coun-ter reaches the preselec-ted amount.

. !

For relating the.number wi-thin -the counter to volume of fluid dispensed, a divide by 15 counter 208 (usable with a 15 drop per milliliter drip chamber as described above) is interposed between -the pulse shaper 182 ', 183 ' of the A circuit and -the down clock input of the least significant digit counter 143. As a resul-t, the divide by 15 counter 208 wi.ll respond to each drop sensed by the A drop detector 181' and, after the sensing of 15 such drops, will clock the least significan-t digi-t counter 143 to decrement -the number stored within the counter 142 by one.
For displaying to an operator the progress of dispensing the 10 predete~mined volume of fluid, the selec-tor and monitor circui-t 175 includes a display, generally indicated at 150, driven by the counter 142 for showing the number remainine in the counter. In the illus-trated embodiment, seven segment readouts are utilized for the display, including hundreds digit 151, tens digit 152 and units d.-igit 153. For driving the seven segment displays, BCD to seven segmen-t decoders 154, 155, 156 are in-terposed between the associated counter chips and displays.
As is well known, the decoders respond to the binary signals on their input to illuminate the proper LEDs within the seven bar display to show the numbers between zero and nine.
Readabllity of the display may be enhanced b-y including left zero blanking provided by blanking flip-flops 157, 158, 222. The mos-t significant digi-t blanking flip-flop 157 has its J and ~C inprrts tied -to the positive voltage supply, and its clock driven frorn decoding circuitry 159 which monitors the binary outputs of the counter digit 145 to provide a low going signal at the output of NAND gate 160 when the counter 11~5 cycles to its zero state. Upon this occurrence, the flip-flop 157 will be clocked, changing states to drive its Q output high and Q output low. The Q
outpu-t is coupled to the blanking input of decoder 151i serving to inhibit the ;~ ` .

, .....
I ~f..

decoder to prevent the illumination of any of the LEDs driven thereby, The tens and units coun-ters lL~ 3 include decoding circuitry 161, 161l, generally similar to that described above and having NA~D gates 162, 163 for clocking the associa-ted blanking flip-flops 158, 222. However, the J inpu-t of blanking flip-flop 158 is coupled to the Q
output of blanking flip-flop 157 and the K input to ground. As a result, clock pulses will be provided to the blanking flip-flop 158 each time the tens counter 1l~ cycles to its zero condition. As long as a number remains within the most significant digit counter 145, the clock signal provided to flip-flop 158 will serve to maintain the Q output thereof low and the Q
output thereof high, preventing the blanking of the middle digit. However, after the most significant digit counter 145 cycles -to zero, -the J input ; of flip-flop 158 is driven high, allowing the fllp-flop to be clocked to its Q low state in response to the next cycle of counter 1~ to its zero state. At this time, the flip-flop 158 will apply a low signal to the blanking input of decoder 155, causing the blanking of the middle digit.
The units blanking flip-flop 222 has its J input driven from the Q output of tens blankine flip-flop 158 for a similar purpose.
For monitoring the state of the counter 142 and determining 20 when the counter is empty, B reset gate 210 is provided. In the illus-tra-ted embodiment the B reset gate includes a pair of OR ga-tes 166, 167. The OR gate 167 has its inputs coupled to -the Q outputs of the blanking flip-flops 157, 158 respectively. The output of OR gate 167 feeds the OX
gate 166 which has its second input coupled to the Q output of blanking flip-flop 222. As a result, when the counter 1l~2 is completely empty, and only then, the output of OR gate 166 will be driven low. It is seen ; that the output of the OR gate 166 is coupled via A~D gates 223 and 2]6 to the reset input of A/B select flip-flop 207. As a result, when the counter "', i s .
"`. ~ :
~ - 30 -.,': , ~.

7~
;
empty, -the A/B selec-t flip-flop 207 will be locked into its rese-t condition~
automatically switching con-trol from -the A supply to the B supply. Thus, the circuitry functions not only to dispense only the preselected amount of fluid via the A supply bu-t also reactivates -the B supply at the termination of the metered cycle to switch control to the B supply for keeping the . needle open.
In addition to switching control from the A to the B supply at the comple-tion of a metered dispensing cycle, means are also provided for accomplishing such swi-tching in the event an alarm condition is . 10 detected while functioning on the A supply. To that end, the second input of AND gate 223 is driven via inverter 209 from the ou-tpu-t of alarm OR
gate 195'. As a result, whenever the A circuit is in the alarm condition, the high signal produced by OR gate 195' will be inverted by inverter 209, and. cause the output of AND gate 223 to be low, -thus switching the A/B
; select flip-flop 207 -to the rese-t condition, inhibi-ting the A supply and allowing operation of the B supply.
In the event a metered cycle on the A supply is interrupted before the completion thereof such as by sensing an alarm condition, means are provided for remernbering t:he amount of fluid still to be dispensed so tha-t the metered cycle may be reini-tia-ted at the point a-t which it was interrupted. To that end, memory means are interposed between the A/B select monostable 219 and the load inputs of the counter 11~2.
In the illustrated:embodiment, such means include an inhibi-table monostable multivibra-tor 22l~ and an A memory flip-flop 218. As shown in the drawing, the J and reset inpu-ts of the flip-flop 218 are driven via AND gate 217 from the output of OR gate 166 so that the flip-flop is reset upon the occurrence of the counter 1~2 cycling to zero. The Q
output of the flip-flop 218 is coupled to the B inpu-t of the monostable multivibrator 224 so as to preverlt the triggering of such monostable whenever the Q output is low. Fur-ther, -the A input of the monostable multivibrator 224 is coupled to the Q output of the monostable 219 so that the monos-table 224 is triggered by depression of -the pushbutton switch 20 if the B input is at a high level. The Q outpu-t of the monostable mlLLtivibrator 224 is coupled to the load inputs of the coun-ter stages 143, 144, 145 so as to paraLlel load the numbers set on the respective thumbwheel switches 146, 147, 148 when the aforementioned Q output is driven low. In addition, the Q output of monostable 224 drives the reset inputs of blanking flip-flops 157, 158, 222 via AND gate 225, to cause the associated digits to be illumina-ted when -the coun-ter is loaded.
In operation, s-tate of A memory flip-flop ;s controlled in part from the count within the coun-ter :L42, and in part from the A/B
select monostable 219. It is reca:Lled that when the counter :l42 is emp-ty, the output of OR gate 166 will be at a low level. That low level is passed through AND gate 217 to maintain a low signal on the reset input of A
memory flip-flop 218, locking -that flip-flop into its reset condition.
As a resuLt, the Q outpu-t of flip-flop 218 will apply a high signal to the inhibit input of monostable 224, allowing the monostable -to respond to trig-20 ger pulses to produce an ou-tput pulse. Thus, to initiate a cycle on the A
supply, it is mere].y necessary, having set -the desired volume of fluid on -the switches 146-148, to momen-tarily depress the select switch 20.
Because the load monostable is not inhibited, the low pulse produced a-t the Q output of monostable 219 triggerE the load monostable 224 -to produce a low going pulse at the Q output thereof. The low going pulse acts upon the load inputs of counter stages 143-145, causing -the number set on the digital switches to be strobed intc the counter. Addi-tionally, the low pulse produced at the Q output of monostable 224 is coupled through ~4~

t~33 AND gate 225 to apply a low going pulse to the reset inputs of the blanking flip-flops 157, 158 and 222, driving each of those flip-flops-to their reset condition. The Q outputs of each of the flip-flops will, therefore, be driven high, causing the output of OR gate 166 to be driven high. That high signa~L, coupled through AND gate 217, no-t only removes the reset signal from memory flip-flop 218, but additionally brings -the J input -thereof to a high level. At the termination of the pulse produced by select monostable 219, the Q output thereof will fall to a low level, providing a clock signal to the flip-flop 218. Because the J input is being maintained high by AND gate 217 and the K input is coupled to ground, the flip-flop 218 will respond to the clock signal by driving its Q output high and Q
output low. The low Q signal i6 applied to -the inhibit inpu-t of load monostab:Le 224, preventing further triggering of -that monostable until -the coun-ter is aeain emptied and the memory flip-flop 218 reset. I'hus, if for any reason the cycle of the A supply is interrupted (e.g. by an alarm ~; condition, an intended operator action, or any other reason), because both the J and reset inputs of flip-flop 218 are being maintained in the high condi-tion, it will not be possible to change the flip-flop from its Q
low condition and the load monostable 224 will continue to be inhibi-ted.
As the load monostable provides the only means for loading -the counter 142, and as that load monostable is inhibited, it will be impossible to effect -the number in -the counter until -the cycle is complete. The A/B select switch 20 will continue to act through select monos-table 219 to control the A/B
select flip-flop 207 and will allow swi-tching between supplies. ~owever, switching back to -the A supply will serve to continue rather -than reinitiate the cycle because the counter therein is constrained to remember the amoun-t of fluid ye~t to be dispensed. After the monitor circuitry determines tha-t the total desired amount of fluid has been dispensed, this occurrence being indicated by the counter 142 cycling to zero, the output of the B reset gate will be driven low, applying a rese-t signal to A/B select flip-flop 207.
This action will lock the dual IV set into the B supply mode until a subsequent A supply cycle is initiated by reloading the volume selector and monitor counter 142.
In some cases it may be desirable to reset the counter 142 before the completion of a metered cycle. For example, after initiating a cycle an attendant may determine that an improper volume of fluid has been selected. To allow the counter to be reset in unusual circumstances such as these, a switch 212a is provided, and is preferably located in a "" ~
partially inaccessible position, such as behind a hinged access panel or on the rear of the housing. The switch 212a shunts capacitor 213 to ground sueh that when the switch is momentarily depressed it diseharges the eapaeitor. Release of the switeh eauses the monostable 211 to produee a resett-lng pulse ~ust as when power is first applied to -the circuit. It will be apparent after eonsidering the deseription of the memory power supply VDD2, that this eould not be accomplished by momentarily switching the power off. The pulse produced by multivibrator 211 resets the A memory flip-flop 218 even though a count is being maintained in the counter. In addition, the pulse also resets the A/B select flip-flop 207 to return control to the B supply. The attendant may then manipulate the thumbwheel switehes 146-148 to seleet the desired amount of fluid to be dispensed, and upon depression of the A/B select switeh 20 cause the loading of the new number into the counter 142.
According to a further feature of the illustrated embodiment, the circuitry is powered from an a.c./d.c. supply so that circuit operation will continue even though the primary power source is temporaArily interrupted;

- 3~ -, . . , ~

7~33 additionally, the circuitry is arranged so that the monitor counter 1~2 remembers the number stored therein, if interrupted, even though the ; circuitry is completely switched off. Referring to the power supply illus-trated in Figure 6, it is seen that such supply includes a line trans-former 226 supplying a full wave bridge 227 in conventional fashion. A d.c.
power source, such as nickel cadmium battery 228 is coupled across the output of the rectifier 227. With the ganged power switch 229 in the open condi-tion, the battery 228 is charged via resistor 230. With the power switch 229 closed, the battery 228 is coupled directly across the supply to ac-t as a filter when operating from a.c. However, if the source of primary power for the transformer226 is removed, the bat-tery 228 remains connected to the circuitry and operation continues under d.c. supply with no in-terrup-tion. A power on indicator 231 may be coupled across -the power supply if de-sired.
As a -further facet of -the interrupted cycle memory fea-ture, means are provided for maintaining a memory power supply for the monitor counter lL~2 to allow that counter to remember the volume of fluid remaining to be delivered even if the power switch 229 is opened. It is seen that the counter stages ll~3-11~5, the A memory flip-flop 218, and certain associa-ted components are supplied with d.c. power, no-t from the main power source VDDl but from -the memory power supply VDD2. That supply, it is seen, is derived from across the ba-ttery 228 via a se-t of relay contacts 232.
The relay contacts 232 are con-trolled by a coil 233 which, in turn, is driven by a transistor 234. Base drive is provided to the transistor by a displa~ gate 235. It is seen -that one input of OR display gate 235 is connected to the main supply VDDl so that whenever the main supply is active, the output of 0R gate 235 will be high, causing transistor 23~ to conduct, energizing coil 233, closing the contacts 232 and ac-tuating the supply VDD2. The second input of display gate 235 is driven from -the .

. Q output of A memory f`lip-flop 218 which, it is recaLled, is maintained :- at a high level as long as a coun-t is retained within the counter 142. ~ . -As a result, even if the power switch 229 is opened~ if a count is being maintained in the counter 142 indicating an in-terrupted.A cycle, ;~
the output of display ga-te 235 Will be maiNtained high, causing transistor ` 234 to continue to conduct, maintaining the contacts 232 closed and . continuing to energize the supply VDD2 even after the supply V
:; has been switched off. When the attendant operates the power switch ,. .
to resume operation, the circuit will commence operation with the B
supply operational as described above. However, the volume o~ fluid .
remaining to be dispe~sed in the interrupted cycle of the A supply is remembered by the counter :L42, and displayed -to the attendant on the di.splay l9 (151-153). Thus, the at-tendant is appraised to return control -to the A 8upply by operation o:E the A/B select switch 20, so that the amount of fluid remaining will be dispensed to complete the previously initiated cycle. :: -Embodiment II
Turning finally to Figures 12 - 16, there is shown a further embQdiment o~ a dual IV set, illustrating the present invention, and . -incorporating certain refinements over the previously described embodiment.
In common with the embodiment previously described, -the present dual IV set includes a B supply circuit generally indicated at 172, an A supply circuit generally indicated at 173, and A/B select circuit 174 and volume selector and monitor circui-try 175 associa-ted with at least one of the aforementioned supply circuits. Although not illustrated in the drawings, a power supply is provided for the dual IV set including both main and memory power supplies as described in connection with Embodiment I.

~ .

: - 36 -It is seen that certain o~ the elements of Embodiment lI are identical to those de~cribed above, including A/ :E~ select ~;witch 20 drivingA/B select monost~ble 219. TheQ output of monostable 219 clocks the A/B select ~ lop 207, The ~ and Q OUtp-ltS olt' the flip-flop 207 enable one or the other of the ~upply circuitsJ but do so not by controlling the ou~put latch as in the previous e-mboclimen~, but by controlling the delivery of clock pulses to the respective supply circuits. Additional elements identical to the previously described embodiment include the power-on reset monostable 211 for resetting the system on the initial application of power and having switch 212a coupled in its trigger circuit fvr manually clearing the volume co-mter.
AND gate 216 drive~ the reset input of A/ 13 c~elect flip-flop 207 while AND gate 217.drives the J and reset input~ of memos~y flip-flop 218, both as described above, According to one eature of the illustrated embodirnent, a digitably settable clock 300 is provided, time shared between the A
and B supply circuits for independently setting~ the drip rateB of such supply circuits, The clock is c~n~tr~lcted much as described in the above referenced copending application Serial No. 6379 206, ~le specification of which i6 incorporated herein by reference. As described in that application, the clock includes a time base generator in the fvrm of astable multivibrator 301 preadjusted to a set frequency, such as 1 Hz~ The output of the multi~ibrator 301 feed~ a si~nal input terminal 302 of a phase locked loop 303~ 'rhe second input 304 of the phase locked loop i8 prc~vided at the output 305 of a two digit decade counter comprilsing least eigniLficant diigit counter chip 306 and most significant digit co-mter chip 307,. Arl operator selected number i~ strobed inb~ the counter after each cornplete c.ycle ~hereof ~f.~33 and, as described in the aforementioned application, adjusts the output frequency of the phase locked loop 303 (which appears at terminal 320) such that the output frequency i5 equal to the base frequency of the oscillator 301 multiplied by the modulu~
of the feedback counter 306, 307.
In contra~t to the aforementioned application wherein only a single pair of digital thumbwheel switches was provided for establishing the modulus of the counter, the instant applica-tion provides two pairs of thumbwhe~l switche~ and time shares the digital clock between the A and B supp1y circuits at In-dependently selected drip rate~. To that end, a pair of data selectors 310, 311 are provided having outpu~s generally indicated at 312, 313, respectively, couplad to the da~a input~ of the associated counter chip~ 306, 307. A side thumbwhe.el ~witche~
315, 316 ~17A in FIG. 1) are coupled to the A elector input~ o~
the selectore 310, 311 while B ~ide digital thumbwheel ~witche~
317, 318 (179 in FIG.l) are similarly coupled to the ~ ~elector inputs. Control input~ 319, select which ~et of thu~bwheel data will appear at the selector output~ 312-313. When the line 319 i~ at a high logic level, thR numbers selecte~ on th~ B ~ide thumbwheel ~witche~ 317, 31B appear at the outputs o~ the 9electo~
310, 311, ~o that the B side thu~bwheel swi~che~ e3tabli~h the frequency of the clock (which appear~ at terminal 320 of the phase locked loop). By way of contrast, when the ~elector input 319 is lo~, the output~ of A ~ide switche~ 315, 31~ are coupled by the 3electorE 310, 311 to the data input~ of ~ounter~ 306, 307 ~o that the clock frequency of the phase locked 10Q~
determined by the A side thumbwheel ~wi~h~. It i~ ~en tha~
th~ output 320 of th~ pha~e locked loop, which carri~ the baa~
~requency multipliad by th~ modulus of the ~ounter 306 t 3Q7 as determined by the ~electe~ thumbwh~el ~witches for the A or ~ side, i8 coupled to the clock input of time ba~e ~38-.

generator 322. A~ described in the above referenced application, the time ba~e generator 32~ ~erves to divide ~he input signal by 60 and couple that signal a~ an output on te~minal 323 to the remaining circuitry, such ~ignal serving as the pulsed output for establishing th~ des.ired drip rate. In this way, the number~
displayed on the digital swit~hes correspond directly to the drip rate in drops per minute. It is ~een that the selector inputs 319 of selectorR 310, 311 are driven by the Q output o A/B select flip-flop 207 so that the A supply thumbwheel switches will control the clock output when the Q output is high,enabling the B ~upply side.
The drip ratc establlshing clock ~ignal on termînal 323 of the time ba~e generator 322 is coupled via an inter-facing driver 325 to ~ supply AND gate 326 and also to ~ supply AND gate 327. Each of such AND gate~ ha~ a ~econd input driv~n from the A/B ~elect flip-floæ 207, the Q output driving th~
enabling input of B ~upply ~ND ga~e 326, while the Q output driv~s the enabling input of A ~upply AND gate 327. Thu~, when th~
Q output of the flip-flop i8 high, the ~elector~ 310, 311 cau~e the digitally 3ettable clock to re3pond to ~he ~ ~ de thwnbwheel switche~, and the AND gate 326 i~ enabled to pa~ the clock pulse~ from driYer 325 to the ~ aupply cixcuit, th~ AND
gate 327 preventing the pa~age of any ~uch clock pul~e. When th~ flip-flop 207 iEs in its oppo~ite conditic~n, thc ~ ~upE?ly is prev~n~ed fr~m receivi1lg cloak pulse whil~ cloc~ pul~e~ are coupled to the A ~upply clrc:uit Yi~!l AND gat~ 3~7. It will nsaw b~ appreciated that the A an~ upply circuit~ ar~ enabl~d l~y controllin~ the di~tributlon of clock pulses 'cherf~tot while ~he illu~tra~ed c~rcuit u~3e3 i!l, common clock fo~ corltrolling bo h of such ~upply cix~uit~, the conanon clock inclu~in~
separate selector~ for each ~ the 6upply circ:uita~.

'73~
The A and B ~upply circuits in the illustrated embodiment differ somewhat from those described in connection with Embodiment L, and provide certain additional features. T~le B supply ~ircuit 172 will be describ~d in detail, realizing that the A ~upply (~ircuit is constructed in a similar f~lshion, It is s~en that wh~n the AND gate 326 is enabled to pas~ ~lock pulses, such clock pulses are coupled to the clock input of a retrigerable multivibrator 330 and also to the clock input of a J-K flip-flop 331~ Both elements will be triggered on the negative transition of the clock, driving the respective Q output~
high and Q outputs low. It is seen that the Q outputs are coupled to the inputs of AND gate 332 so that when the multivibrator 330 and flip-flop 331 are triggered, the output of AND gate 332 will be driven high. In this condition, base drive will be provided to switching transistor 333 to cause current flow through valve coils 334~ thus openin~ the valve in the B supply circuit, After opening of the valve, a drop will form and fall through the drip chamber, ~uch drop being detected by drop detector 335~ The drop detector 335 is coupled to a pulse shaper 33B which, in re~pon~e to detection of a drop, produces a po~itive pulse at the Q output thereof.
A rnultivibrator 345 has ite clock input driven from the Q output of the pulse shaper 336 and has a Q output driving tran&~i6tor 34B, drop indicator 347 being coupled in the IQad circuit thereof. As deæcribed in connection with ~e previou~ embodiment, the period vf multivibrator 345 is established ~o that the indicator 347 is illurninated for each drop, flashing at the Relected dNp rate to provide an indication of proper operation.
The shaped drop pUl~e9 at the outpul~ of pulse ~haper 336 are inverted by inverter 337 and coupled to the reeet input~ of multivibrator ., : "
330 and flip-flop 331. Thu~, when a drop is detected, both elements are reset to àrive the output of AND gate :~ 3~ low, deenergizing the electro-magnets 334, to close the valve. However, if no drop fall~ after opening of the valve, no signal will be produced l)y l)ulse shaper 336 and no reset pulse will be coupled to the elements ~;~0, 331. At the termination of the tim~ period established by resistor 340 and capacitor 341, the multivibrator 330 will time out, driving the output of AND gate 332 low and deenergizing the electromagnets 3340 The period of multivibrator 330 i8 set at the maximum desired open time of the valve, such as two seconds. Since no reset signal was coupled to flip-flop 331, it will remain set, the ground connection on the K input and the interconnection between the J input and Q output, preventing the flip-flop from responding to clock pulses when in its set condition. Thus the flip-flop 331, in normal operation, is re~ettable only by a signal generated as the result of the detection of a dl~p~
The illustrated supply circuits include not only high rate and low rate alarms, but al30 means for accumulatingerrors before actuating such alarms. As will become more apparent, flip-flop 350 comprises a low rate alarm flip-flop, having a Q output tied to the input of AND gate 351, such that when the flip-flop is in its set condition, the low Q output causes the output of gate 3S1 to switch low. This low signal is coupled to the inhibit input of multivibrator 330, preventing the multivibrator from responding to further clock pulses coupled l~rough AND gate 326, thereby preventing further energization of the ~alve coil 334 or opening of the valve.
To accompli~h error accumulation in the instant embodirnent, the clock input of flip-flop 350 is driven by~the output o~ a four llne to one line data selector 352. In effect the data select~r 352 ma,y ~e considered a dual data ~elector, with the upper half enabled when the lG output is low and the lower half enabled when the 2G input i8 low. It is seen that the lG input is driven from the Q output of A/B select flip flop 207 while the 2G input is driven by the Q outp~t thereof. Thus, t:he upper half of the data selector is enabled when the ~ ou~pu~ of the select flip-~lop is low enabling the ~ ~ide, while the lower half i~ enabled whenever the A side i~ in operation. Assuming that the upper ~i~e of selector 352 is active, the siqnal present on the output line 353 is selected from one of the input signals pre~ent on line~
354 through 356 in dependence on the statu~ of the selectox input~
357, 358. The selector input~, in turn, are driven ~y the mo~t significant digit data selector 311 which, in this condition, will ke passing the data set on the B ~upply thumbwh~el ~witches.
Gatlng circuitry including OR gate 359a, inverter 359b and OR
gate 359c monitors the output of the most ~ignificant digit data 3elector for driving the selector inputc. When the mo3t significant digit set on the thumbwheel ~witch 318 i~ 0, the output of OR gate 359a will be high, cau~ing the vutput vf inverter 359b to be low and the output of OR gate 359c also to be low. Thus, zeros are impo~ed on both input~ oE the data selector 352, coupling the input line 354 to the ou~put line 353. When the most significant digit i8 1, the output of OR
gate 359c will be high, while the output of inverter 359b remaiQ~ low. In thi~ conditio~, with ~elector input 357 low and selector input 358 high, the input line 355 will be coupled to the output line 353. Finally? whenever the most significant digit is 2 or larger, the output3 of both inverter 359b and OR gate 359c will be high, c~using the selector 352 to couple the input line 356 to the output line 353 thereof.
A palr o~ ~lip flops 360, 361 drive the input~

354 through 356 o the selector, ~peci~ically the Q
output of 1ip flop 360 driving the -input 354, the Q output of flip-flop 361 driving the input 355 and the Q output of flip-flop 361 driving the input 356. The flip-flops, in turn, have their clock inputs driven by AND gate 326 which passes clock pulses to the B supply circuit, and are adapted to be clocked by such pulses when the appropriate gates 362, 363 are enabled.
In normal operation, both AND gates 362 and 363 are disabled when a first clock pulse appears, because flip-flop 331 is in its reset condition at that time, maintaining its Q output high and, therefore, the output of inverter 364 low. It is seen that this low signal is coupled via driver 372 to an inpu-t of AND gate 362 to disable that gate, while the low Q outpu-t of flip-flop 360 disables AND ga-te 363. Thus, so long as operation remains normal, with clock pulses and drop pulses alternating, flip-flops 360, 361 remain static in their reset condit:ion. Ilowever, if no drop falls after the valve is opened, fl-lp-flop 331 is not reset, thereby providing a high signal to the associated input of A~D gate 362. Because the Q output of flip-flop 360 is low at this time, AND gate 363 will, however, remain disabled. ;
When the next clock pulse appears with no intervening drop pulse, AND
gate 362 will resond, clocking -the flip-flop 360 to -the set condition.
If the most significant digit of the drop rate is 0, the falling Q signal will pass via input 354 of selec-tor 352 to the outpu-t -thereor, clocking the flip-flop 350 and driving its Q output high. Af-ter the Q ou-tput of multivibrator 330 falls at the termina-tion of its predetermined period, AND gate 362 will be satisfied, producing a high signal at the output thereof and activating the alarm circuitry. It is seen that the output of A~D gate 365 is coupled through OR gate 366 to illuminate the common low alarm indicator 367 and also to activate OR gate 368 to provide base drive to transistor 369, sounding the audible alarm 370.

."r'~,~

3~

If, however9 a drop is detected before the multivibrator 330 tirne~ out, the pending alarrn condition will be cleare~l, the drop pul~e appearing at the output of inverter 337 re~ettirlg the flip-flor) 360 (and also 361 had it been set). Also, while the valve is open the low Q output of multivibrator 330 inv~rted by inYerter 373 enables NANI:) gate 374 so that if a drop falls the NAND gate will be satisfied, coupling a low signal through AND g~te 375 to reset the low rate alarm flip-flop 350.
However, if no drop falls, the flip-flop 350 will remain in its set state, placing the B supply circuit into the alarm mode.
If the most ~ignificant digit of the ~elected drip rate for the B side is gr~ ater than 0, the circuit will not enter the alarm mode in response to the fir~t missed drop, but will avrait the detection of further mis~ed drop~ before dolng ~o. The flip-flop 360 will be clocked as described above in response to the first mis~ed drop, drisrin~ it3 Q
output high, but the selector 352 will not pa~s thi~ transition for clocking the alarm flip-nop 350. When the next clock pulse ~rrive3, corre6ponding to the second mi~sed drop, AND gate 3~3 will be ~ati~f~ed, clocking the flip-flop 361 from it9 re~et to it~ ~et stateO The positi~re tran~ition at the Q output will be coupled through the ~elector to the clock input of flip-flop 350 it the mo~t ~ignific:~nt digit of the E~elected drip rate i~ 1, Operation will be as before to enter the a~arm mode. It i9 noted that the nip-flop 360 does not c}~a~ge ~tate once it i~ 3et because the 3 input i6 tied to the Q output which is low whlle the K input i~ t~ed directly to ground~ If the mo~t sigr~ca2lt digit i~ 2 or more, no cloc?~ ~ignal ~rill be passed to the nip-nc,p 3SQ in re~pon~e to the E3econd m~ ed drop, and operation will continue. Upon receipt ~f the next clock pul~e, cor~e8-ponding to the third mi~3~3ed clrt~p, the flip-~lop 3Sl will algain be cloc}ced, returning to its reE3et state with a re~ulting p~3iti~re trarl~3it;aoll appearlrls -~4-3~33 at the Q output thereof. If the most significant digi-t of -the selected drip rate is 2 or greater, this positive transition will be coupled through the selector 352 to clock flip-flop 350 and cause the circui-t to enter the alarm mode. lhus, at low drip ra-tes~ the circuit is very sensi-tive to missed drops, and will cause the alarm mode to be entered in response to the first such missed drop. However, at higher drip rates, the circuit is more tolerant, requiring two missed drops for drip rates between 10 and 19, and three missed drops for drip rates of 20 or higher.
Detection of high rate alarms is accomplished in a different manner, counting drops out of the normal sequence as they occur, and allowing the circuit to continue to function on a dispensing cycle until sufficient extra drops are counted to indica-te an overall abnormal condition. To that end, a binary couNter 380 is provided, presettable to a predetermined number, selected as the maxi~um tolerable number of extra drops, in the instant embodiment ten. As will become more apparen-t, at the start of a dispensing cycle, when the supply is first enabled, the parallel en-ter input 381 of the counter 380 is driven low, strobing -the preset number 10 into the coun-ter. The counter is arranged in the down counting mode so as to decrement the count contained thereby by one for each drop detected out of -the normal sequence. It is seen -tha-t the clock input 382 is driven via AND gate 383 which has a first input maintained normally high by driver 387 and a second input driven by the positive pulses produced at the output of pulse shaper 336. The counter 380 also has an inhibit input 385 driven by the inverter 364 which responds -to the Q output of the flip-flop 331.
Thus, whenever the valve is open, -the Q output of inverter 331 will be low, coupling a high signal via inverter 364 to the inhibit input of ...... .
I, j counter 380, and preventing such coun~er from responding to clock pulses. Thus, when the ir~t drop falls after opening o the valve, the positive pulse produced at the output of AN~
gate 383 will be incapable of clockingthe counter 380. Howeve~, that first pulse will reset the flip flop 331, returning the Q output high, and coupling a low enabli.ng signal to the input 385. If further drops fall before a sub~equent valve opening clock pulse, positive pulses will be coupled through AND gate 383, clocking the counter 300 to decrement the count ~tored therein by one for each drop sensed. If ten extra clrop~ are ~ensed over the course of a dispensing cycle, the coun~er 380 will be emp~ied, producing a low signal at output 386 th~reof, ~uch low signal being pas3ed by driver 387. ~hat signal iB
applied to one of the input~ of AND gate 3~3, preventing further clock pulses from being coupled to the counter 380. The low signal is al~o coupled to the alarm circuitry, and specifically to NAND gate 388, driving the output thereof high to illuminate the high rate alarm indicator 389. The high at the output of NAND gate 388 al~o causes the output of OR gate 368 to be driven high, providing base drive to tran~istor 369 and ~ounding the audible alarm 370. Finally~ the low signal at the output of driver 387 i8 coupled to an input of ~ND gate 351, driving the output thereof low and presenting an inhibiting signal to multivibrator 330, preventing same from re~ponding to urther clock pul~e~. Thu~, the sy~tem i~ locked into the ala~m mod and further functioning disabled.
. Referring now to the A supply circuit 173, it i~ seen that the clrcuit, with two exceptions, is identical to ~he 8 3u~ply circuit 172. Accordingly, the.corre~ponding part~
have been given primed reference numerals. With re~ard to the differences, the output~ of low alarm gate 36S' and high alar~ driver 387' are monltored by qating -46~

circuitry including inverter 400 and AND gate 401 ~uch that when either alarm is active the output of gate 401 is switched low. This low signal i9 couple~1 to one of the inputs of AND gate 402 whose output drives, via AND gate 216, the reset input of A/B select flilp-flo~ 207, Thus, as in the previous embodim~nt, if an alarm condition is detected when functioning on the .~ supply, control is automatically switched to the B
supply.
With rega~rd to the second difference, it is seen that the drop pulses at the output of inverter 337' are coupled to the clock input of a nip-nop 405 whose Q output drives b~nary counter 40~. The circuit is arranged as a divide by 20 counter, us~ble with a 20 drop per milliliter IV set 50 a~ to produce an output pulse at termlnal 407 for each 20 drops sensed by the drop detector 335'. The output 407 is coupled, as in the previous embodiment, to a three stage counter 410 comprising a units counter 411, tens counter 412 ~d hundreds counter 413. The volume sel~ctor and monitor circuit 175 is basically a~
illustrated in the previous embod~ment, with the exception of the gating circuitry which monitors the outputs o~' the counter ~tages. In the pre~ent instance, NOR gates 420, 421 and 422 monitor the output9 of the as~ociated counter stages to produce a high output slgnal when the a~sociated counter stage is empty. The NO:E~ gate clock~ it~ a~sociated blanking flip-nop 423-425 as described previou~ly. The Q outputs of the nip-nops are monitored in B re~et gate compri~ing OR gates 427, 428 80 that a low ~ignal is produced at the output of OR gate 428 when the c~unter is completely empty. This low ~ignal acts through AND gate 402, jusî
as the A alarm signal, to switch control fi:~orn the A supply to th~ B
supply when the courlter is ernpty., 3~

Means are provided for resetting an alarlll corldition so that an operator, having cleared a fault condition, nlay resume operation on the desired supply circuit. To that end, an A!~'i) gate 430 is pro~ided having an output driving an input of each of AND gat~s 375, 375'.
Accordingly, ~henev~?r the OlltpUt of AND gate 43û switches low, the outputs of the a~sociated AND gates 375, 375' will be switched low, resetting both of the low alarm flip-flops 350, 350'. It is seen that the output of AND gate 430 alsc~ drive~ the parallel enter inputs 381, 381' of the counters 380, 380', thereby ~trobing the predeterminecl maximum number, in the instas~t case ten, into such counter~, and clearing any high rate alarm that might have existed. The alarm reset gate 430 is opelative to drive itH output low in response to several condition~.
Initially, an alarm re6et push button 431 i9 provlded which, when depressed by an operator, switche~ the output of AND gate 430 lo~vs resetting asly alarm condition~ in either of the ~upply circuit~, Secondly the AND gate 430 ha~ an ~nput driven from A/B select multivlbrator 219 so that whenever an operator s~witche~ from one supply circuit to the other by manual depression of the s~vitch 20, the output of AND gate 430 wiLll be brought briefly low, clearlng aFIy alarm conditions that might have existed, FinallyJ gating circuitry including OR gate 432, ir~verter 433 and a timing ci~cuit includin~ resistor 434 and capacitor 435 i~ driven rom the output of AND gate 217. Recalling that the output o~ AND g~te 217 is switched low in two insta~cea, namely when power i~ flr~t applied to the circuit and al~o ~vhen the memory clear ~witch 212A iB
momentarily depres~ed, it i~ ~een that in either of these conditions a brief negative pulse wlll be produced at thë output of OR gate 43~, resetting a~y alarm condit:ion that might have exi~ted.

~48--73~

It will now be apparent that what has been provided is an electronic control for a dual IV set including a select circuit for controlLing administration of fluids at individually r)res~lected rates from separate sources. A control circuit selectively energizes the indiviclual supplies for operatlon, and switches control between.the supplies under pred~termined conditions, A volume selector and monitor circuit is associated with at least one of the sources ~o that a predetermined volume of fluid may be dispensed, the completion of a measured dispen~ing cycle switching control back to the alternate supply. Finally, the monitor circuitry is provided with mernory means to remember the amount of nuid yet to be dispen~ed in an interrupted cycle to prevent an overdose of ~uch fluid.
As thi~ lnvention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the pre~ent embodiment is, therefore, illustra~ive and not restrictive, ~ince the ~cope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are, therefore, intended to be e~mbraced by t.hose claims.

_,~9_

Claims (23)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A dual intravenous infusion means for use with two supplies of intravenous fluid comprising in combination, a first drip chamber adapted to be connected to one of said supplies, a second drip chamber adapted to be connected to the other of said supplies, first and second lengths of intra-venous tubing respectively connected to the first and second drip chambers and forming with said drip chambers first and second fluid flow passages, first and second valve means associated with the respective passages, first and second valve operating means associated with the respective valve means, first and second drop detector means associated with the respective drip chambers for sensing drops of the intravenous fluid falling therethrough, control circuit means including first and second supply circuits connected with the valve operating means for controlling the first and second valve operating means, said control circuit means including clock means for esta-blishing independently selectable drip rates for said first and second supply circuits, means responsive to said clock means for opening the respective valve means at the associated preselected drip rates, means responsive to said first and second drop detector means for closing the associated valve means in response to detection of a drop, alarm means responsive to variations in the actual drop rate from the preselected rate for switching the associat-ed supply circuit into an alarm mode, said alarm means including means for terminating flow of fluid from the associated supply in said alarm mode, and selector means for selectively enabling the first or second supply circuits for independent operation, said selector means including means for switching from one supply circuit to the other.

2. The dual intravenous infusion means as set forth in claim 1, where-in the alarm means associated with at least one of said supply circuits in-cludes means operational upon the selector means and responsive to an alarm mode in said supply circuit for switching control to the alternate supply circuit.

3. The dual intravenous infusion means as set forth in claim 1, including volume selector and monitor means associated with at least one of said fluid supplies, said volume selector and monitor means including means for preselecting an amount of fluid to be dispensed in a dispensing cycle, means responsive to the associated drop detector for measuring the amount of fluid actually dispensed, and means operational upon said selector means for switching control to the alternate supply after the preselected amount has been dispensed.

4. The dual intravenous infusion means as set forth in claim 3, further including display means for indicating the amount of fluid remaining to be dispensed in said dispensing cycle.

5. The dual intravenous infusion means as set forth in claim 3, including remembering means actuated in the event a dispensing cycle is inter-rupted for remembering the amount of fluid remaining to be dispensed in said cycle.

6. The dual intravenous infusion means as set forth in claim 3, where-in the volume selector and monitor means comprises a counter, switch means operational upon said counter for selecting a volume of fluid to be dispens-ed, means for loading said counter with the volume selected by said switch means to initiate a dispensing cycle, and means for detecting a count remain-ing in said counter and inhibiting said loading means in response thereto, thereby to remember the number within the counter in the event said dispens-ing cycle is interrupted.

7. The dual intravenous infusion means as set forth in claim 6, including primary power supply means for supplying power to said dual intra-venous infusion means, memory power supply means for supplying power to said counter, and means responsive to the presence of a count remaining in said counter for actuating said memory power supply means, whereby the volume remaining to be dispensed is remembered even if the primary power supply means is removed.

8. A dual intravenous infusion means for use with two sources of intravenous fluid, comprising in combination: first and second individual intravenous infusion sets, each set comprising a drip chamber adapted to be connected to one of said fluid supplies, a length of intravenous tubing con-nected to the drip chamber and forming with said drip chamber a fluid flow passage, valve means associated with the fluid flow passage, valve operating means associated with the valve means, drop detector means associated with the drip chamber for sensing drops of intravenous fluid falling therethrough, and supply circuit means; said supply circuit means including clock means for establishing an independently selectable drip rate for said supply cir-cuit, means responsive to said clock means for opening the respective valve means at the preselected drip rate, means responsive to said drop detector means for closing the valve means in response to detection of a drop, alarm means responsive to variations in the actual drop rate from the preselected drop rate for switching the supply circuit into an alarm mode, said alarm means including means for terminating flow of fluid in said alarm mode; and selector means for selectively enabling the first or second supply circuit for independent operation, said selector means including means for switching from one supply circuit to the other.

9. The dual intravenous infusion means as set forth in claim 8, where-in the selector means includes bistable means having first and second stable states, said bistable means being coupled to said first and second supply circuits for allowing operation of said first supply circuit in said first stable state and said second supply circuit in said second stable state.

10. The dual intravenous infusion means as set forth in claim 9, where-in each valve means has an open position and a closed position, and includes a lifting magnet for opening said valve under the control of said supply circuit, and a hold down magnet for holding said valve in the closed position, said bistable means being coupled to said hold down magnets for energizing the hold down magnet associated with the valve means in the second supply circuit when the bistable means is in said first stable state, and for energizing the hold down magnet associated with the valve means in the first supply circuit when the bistable means is in said second stable state, where-by backflow through the non-operating set is prevented.

11. The dual intravenous infusion means as set forth in claim 8, where-in the alarm means of at least one of said supply circuits includes means operational upon the selector means and responsive to an alarm mode in said supply circuit for switching control to the alternate supply circuit.

12. The dual intravenous infusion means as set forth in claim 8, including volume selector and monitor means associated with at least one of said supply circuits, said volume selector and monitor means including means for preselecting an amount of fluid to be dispensed in a dispensing cycle, means responsive to the associated drop detector for measuring the amount of fluid actually dispensed, and means operational upon said selector means for switching control to the alternate supply circuit after the preselected amount has been dispensed.

13. The dual intravenous infusion means as set forth in claim 12, further including display means for indicating the amount of fluid remaining to be dispensed in said dispensing cycle.

14. The dual intravenous infusion means as set forth in claim 12, including remembering means actuated in the event a dispensing cycle is interrupted for remembering the amount of fluid remaining to be dispensed in said cycle.

15. The dual intravenous infusion means as set forth in claim 12, where-in the volume selector and monitor means comprises a counter, manually oper-able switch means operational upon said counter for selecting a volume of fluid to be dispensed, means for loading said counter with the volume select-ed by said switch means to initiate a dispensing cycle, and means for detect-ing a count remaining in said counter and inhibiting said loading means in response thereto, thereby to remember the number within the counter in the event said dispensing cycle is interrupted.

16. The dual intravenous infusion means as set forth in claim 15, including primary power supply means for supplying power to said intravenous infusion sets, memory power supply means for supplying power to said counter, and means responsive to the presence of a count remaining in said counter for retaining said memory power supply, whereby the volume remaining to be dis-pensed is remembered even if the primary power supply is removed.

17. A dual intravenous infusion means for controlling the dispensing of intravenous fluid from first and second sources of intravenous fluid com-prising in combination, first and second fluid flow passages connected to the respective fluid sources, first and second valve means associated with the respective fluid flow passages for controlling flow therethrough, first and second valve control means connected with the respective valve means for opening and closing the respective valve means at individually selectable rates, and selector means connected with the control means for selectively enabling each valve means to individually deliver fluid from its associated fluid source at the rate selected therefor, said selector means including means for switching control between the first and second valve control means, at least one of said valve control means including alarm means for detecting deviations between the actual rate of delivery of said fluid and the selected rate and in response thereto putting the associated valve con-trol means into an alarm condition, said alarm means being coupled to said selector means for switching control to the alternate control means in response to an alarm condition.

18. The dual intravenous infusion means as set forth in claim 17, further including volume selector and monitor means associated with at least one of said valve control means, said volume selector and monitor means in-cluding means for preselecting an amount of fluid to be dispensed in a dis-pensing cycle of the associated fluid passage, means for monitoring the amount of fluid actually dispensed during said cycle, and means for switch-ing control to the alternate valve control means after the preselected amount of fluid has been dispensed through one of said valve means.

19. The intravenous infusion means as set forth in claim 18, including means operational in conjunction with said monitoring means for remembering the amount of said preselected volume still to be dispensed in the event a dispensing cycle is interrupted.

20. The dual intravenous infusion means as set forth in claim 18, further including display means operative in response to the amount of fluid dispensed for indicating the amount of fluid remaining to be dispensed in said cycle.

21. The dual intravenous infusion means as set forth in claim 18, including means for interrupting a dispensing cycle, means for remembering the amount of fluid not yet dispensed upon the interruption of said cycle, and means for resuming the interrupted dispensing cycle to dispense only the portion of the preselected amount not dispensed prior to the interruption.

22. Control means for use with multiple intravenous infusion sets, wherein the infusion sets each includes a fluid flow passage means adapted to be connected with a source of intravenous fluid, and valve means in the fluid flow passage means operational between an open position and a closed position to control flow therethrough, said control means comprising valve operating means for opening the respective valve means, digitally settable clock means for preselecting the rate of operation of the valve operating means and thus for selecting the rate of the valve opening and rate of flow therethrough, counter means for counting the amount of fluid dispensed, selector means for selectively enabling operation of the respective valve operating means, said selector means including means for disabling one valve operating means and enabling the other in response to the occurrence of a predetermined condition, said selector means further including means which functions when returning to an interrupted cycle to prevent the counter means from beginning a new count, whereby the counter means remembers the amount of fluid dispensed and continues the count of the interrupted cycle, supply circuit means connected with each valve operating means to control operation thereof, said digitally settable clock means connected with said supply circuit means to effect actuation thereof to obtain a desired drip rate, said clock means being shared by the supply circuit means, and alarm means for giving an alarm when the drip rate actually delivered differs by a predetermined amount from that set, and including high rate error accumulating means which counts extra drops over a dispensing cycle and goes into alarm when a predetermined number of excess drop signals are accumulated.

23. A multiple intravenous infusion means for independently and con-secutively controlling flow of separate intravenous fluids through a plurality of intravenous infusion sets, including: a plurality of intravenous infusion sets; valve means associated with each set; valve operating means for opening and closing each valve means at a preselected rate; selector means for en-abling one valve operating means and disabling the other; and alarm means associated with at least one of said valve operating means for detecting deviations between the actual rate of delivery of fluid and the selected rate and operative in response to a deviation to operate said selector means to disable the valve operating means associated with the alarm condition and to enable the alternate valve operating means, whereby in the event of an alarm condition occurring in one of the sets, intravenous fluid automatically continues to be supplied through another set.