CA2087975A1 - Intravenous metering monitoring device - Google Patents
Intravenous metering monitoring deviceInfo
- Publication number
- CA2087975A1 CA2087975A1 CA002087975A CA2087975A CA2087975A1 CA 2087975 A1 CA2087975 A1 CA 2087975A1 CA 002087975 A CA002087975 A CA 002087975A CA 2087975 A CA2087975 A CA 2087975A CA 2087975 A1 CA2087975 A1 CA 2087975A1
- Authority
- CA
- Canada
- Prior art keywords
- circuit means
- strain gauge
- occlusion
- sensing circuit
- electronic signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M5/16854—Monitoring, detecting, signalling or eliminating infusion flow anomalies by monitoring line pressure
Abstract
The present invention provides an improved, low cost method and apparatus for monitoring the intravenous metering of fluids to a patient. The present invention provides a strain gauge (R1, R2) which is preferably a balanced metal beam (120). Conditioning circuitry is provided which has as input the strain gauge output. The output of the conditioning circuit is inputted into occlusion sensing circuit. The output of occlusion sensing circuit is inputted into an air sensing circuit. The output of both the occlusion sensing circuit and the air sensing circuit are inputted into an analog to digital convertor which is monitored by a microprocessor for abnormal signals.
Description
W o 9~2~337 2 0 g 7 9 7 5 PCr/US'J2/()~22 INTRAVENOUS METERING MONITORING DEVICE
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FIELD OF THE INVENTION
The present invention relates in general to intravenous metering devices and in particular to an intravenous metering device having improved monitoriny.
.
1~ BACK~ROUND OF THE INVENTION
C~nsiderable attention in recent years has been directed ~o the intravenous delivery of fluids such as saline solutions and the like to patierts. Ini~ia11y, these fluids were administered to the patient by means o~ gravity flow from a container holding the fluid to be delivered. Gravity-flow devices, however, can be cumbersome ; to use, inasmuch as pressure sufficient to sustain fluid movement in ; a gravity-flow device often required positioning of the device at a considerable elevation above the patient receiving the fluid.
Moreover, attempts to accurately regulale the amount of fluid administered by gravity-flow devices were often unsuccessful because of the fact that the gr~vity-induced pressure responsible for moving fluid through the device generally decreased during the intravenous delivery operation as the fluid level within ~he container holaing the fluid dropped.
In order to provi~e for improved flow of fluias to patients, pumping devices have been utilized such as found in U.S. Patent NOS.
4,336,~UO; 4,453,Y31; 4,453,Y32; 4,457,753; and U.S~ Application Serial No. 07/411,789. Such pumping devices em~loy d metering ~;
device contrc~ unit into which an intravenous metering device is placed. The intravenous metarin~ device includes a pumping chamber which includes a reciprocal ~iaphragm. The metering device inclu~es d pumping piston which reciprocates the diaphraym there~y changing ' .
-' WO 92/22337 r PC~lJS92/04722 20~79~
, the volume of the pumping chamber. Check valves are positioned at the pumping chamber inlet and oul:let to regulate ~he flow of flui~
and a gas retention chamber is provi~ed upstream of the pumping - chamber and ~he pumping chamber inlet. The gas retention chamber is connec~ed via tubing to a fluid source while the pumping chamber outlet is connected to a patient.
SUMMARY OF THE INVENTION
The present invention provides an improved, 10w cost metho~
and apparatus for monitoriny the intravenous me~ering of fluids to a patient. The present invention provides a strain gauge which is -- preferably a balanced metal beam. Conditioning circuitry is provided which has as input the strain gauge output. The outpu~ of the conditioning circuit is inputted into occlusion sensing circuit. ~he output of the occlusion sensing circuit is inputted into an air sensing circuit. The output of both the occlusion sensing circuit and the air sensing circuit are inputted into an ana10g to digital convertor which is monitored by a microprocessor for abnormal signals.
-~ BRIEF DFSCRIPTIUN OF THE URAWIN~S
FI~U~E 1 is a perspective view of a pumping apparatus which uses an intravenous metering device;
-~ FIGURE 2 is a top view of an intravenous metering device;
FIGURE 3 is a cross-sectional view of the device of FIGURE 2 taken along line III-III of FIGU~E 2;
FIGURE 4 is a cross~sectional view of the device of FIGURE 2 ` taken along line IV-IY of FIGURE 2;
FIGURE 5 is a cross-sectional Yiew of the device of FIGURE 2 3~ taken along line V-V of FI~URE 2;
FI~URE 6A is an upper perspective view of the diaphragm of an intravenous metering device;
FIGURE 6B is a lower perspective view of the diaphra~m of an intravenous metering device;
.~:
' ', : ;
.
FIELD OF THE INVENTION
The present invention relates in general to intravenous metering devices and in particular to an intravenous metering device having improved monitoriny.
.
1~ BACK~ROUND OF THE INVENTION
C~nsiderable attention in recent years has been directed ~o the intravenous delivery of fluids such as saline solutions and the like to patierts. Ini~ia11y, these fluids were administered to the patient by means o~ gravity flow from a container holding the fluid to be delivered. Gravity-flow devices, however, can be cumbersome ; to use, inasmuch as pressure sufficient to sustain fluid movement in ; a gravity-flow device often required positioning of the device at a considerable elevation above the patient receiving the fluid.
Moreover, attempts to accurately regulale the amount of fluid administered by gravity-flow devices were often unsuccessful because of the fact that the gr~vity-induced pressure responsible for moving fluid through the device generally decreased during the intravenous delivery operation as the fluid level within ~he container holaing the fluid dropped.
In order to provi~e for improved flow of fluias to patients, pumping devices have been utilized such as found in U.S. Patent NOS.
4,336,~UO; 4,453,Y31; 4,453,Y32; 4,457,753; and U.S~ Application Serial No. 07/411,789. Such pumping devices em~loy d metering ~;
device contrc~ unit into which an intravenous metering device is placed. The intravenous metarin~ device includes a pumping chamber which includes a reciprocal ~iaphragm. The metering device inclu~es d pumping piston which reciprocates the diaphraym there~y changing ' .
-' WO 92/22337 r PC~lJS92/04722 20~79~
, the volume of the pumping chamber. Check valves are positioned at the pumping chamber inlet and oul:let to regulate ~he flow of flui~
and a gas retention chamber is provi~ed upstream of the pumping - chamber and ~he pumping chamber inlet. The gas retention chamber is connec~ed via tubing to a fluid source while the pumping chamber outlet is connected to a patient.
SUMMARY OF THE INVENTION
The present invention provides an improved, 10w cost metho~
and apparatus for monitoriny the intravenous me~ering of fluids to a patient. The present invention provides a strain gauge which is -- preferably a balanced metal beam. Conditioning circuitry is provided which has as input the strain gauge output. The outpu~ of the conditioning circuit is inputted into occlusion sensing circuit. ~he output of the occlusion sensing circuit is inputted into an air sensing circuit. The output of both the occlusion sensing circuit and the air sensing circuit are inputted into an ana10g to digital convertor which is monitored by a microprocessor for abnormal signals.
-~ BRIEF DFSCRIPTIUN OF THE URAWIN~S
FI~U~E 1 is a perspective view of a pumping apparatus which uses an intravenous metering device;
-~ FIGURE 2 is a top view of an intravenous metering device;
FIGURE 3 is a cross-sectional view of the device of FIGURE 2 taken along line III-III of FIGU~E 2;
FIGURE 4 is a cross~sectional view of the device of FIGURE 2 ` taken along line IV-IY of FIGURE 2;
FIGURE 5 is a cross-sectional Yiew of the device of FIGURE 2 3~ taken along line V-V of FI~URE 2;
FI~URE 6A is an upper perspective view of the diaphragm of an intravenous metering device;
FIGURE 6B is a lower perspective view of the diaphra~m of an intravenous metering device;
.~:
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2~ () 3 7 9 7 ~ PCr/lJSg2/0~l7~2 FIGURE 7 is a perspective cutaway view of hardware used in accordance with the principles of the present invention;
FIGURE ~ is a b10ck dtagram showing the logical circuit of the present invention;
FIGURE 9 is a detailed schematic of the electric circuit of the present invention; and FI~URE 1~ is a detailed schematic of an alternative preferred electric circuit in accordance with the principles of the ~:
present invention.
~, 10 DETAILEU DESCRIPTION UF A PREFERRED EMBODIMENT
Referring first to FIGURE 1, an intravenous metering device 10 is shown positioned within a metering device control unit 12.
The intravenous metering device 10 in conjunction with the metering device control unit 12 acts as a pump means to transfer fluid from a - source of fluid 14 to a patient. The intravenous metering device 10 is connected to the source of fluid 14 by means of conventional tubin~ 16. Additional tubing 1~, extending from the outlet of intravenous metering device 10, transfers precise amounts of fluid 2~ to the patient. ~:
Provi~ed between the container of flui~ 14 and the tubing 16 is a conventional drip chamber 15. The drip chamber 15 is partially ! surrounaed by a drop sensing means 17 which senses the drops passing in the drip chamber 15. The drop sensing means 17 can be connected . 25 to the metering device control unit 12 by wiring 13 so that, if theabsence of drops is sensed, an alarm in the metering device control unit 12 can be sounded.
Referring now to FI~URES 2 t~ru 6, construction of an intravenous metering device 1~ is shown in aetail. The intravenous , .
3~ meterin~ device 10 includes a pumping chamber 20 formed in hou~ing ..
3U and a flexible diaphragm 22 which forms an upper portion 21 of pumping chamber 20. The housing 30 includes a housing lid 31 as well as a~housing bottom 32. A pumping chamber inlet 24 and a . : : pumping chamber outlet 26 are formed in pumping chamber 2U. ~umping ; ~ -:.
WO ~)2/22337 pCr/l.J~()2/04722 . . r 2~797~ - 4 -chamber 24 includes a valve seat means 280 Valve actuator 34 controls the admission of fluid into pumping chamber 2U by reciprocating the diaphragm 22 between an open position, shown in solid lines in FI~U~E 3, and a closed position as shown by dot~ea lines in FIGURE 3. As best seen in FI~URE 4, the pumping chamber out1et 26 includes a valve 38 which is normally held in a closed position.
Intravenous metering device lU fur~her includes a meterin~
device inlet 49 which is disposed above an air retention chamber 40 bounded by housing sidewalls 42. The air retention chamber 40 is of sufficient size to include an air retention chamber upper portion 50 providiny for an air-fluid interface. Air retention chamber 4U also includes an air retention chamber lower portion 54 which collects fluid free of air bubbles. The fluid free of air bubbles can then pass throuyh an air retention chamber passageway 56 in tubular conduit 5~ past the open valve seat means 2~ and on into the pumpin~
chamber 20.
The metering device control unit 12 provides means for varying the volume of the pumping chamber 20 in order to pressurize ,~
the pumping cnamber 20 to provide fluid propulsion. These means can - include means for flexin~ diaphragm 22 into pumping chamber 20 which in the present invention is a reciprocating pumping piston 6u whicn presses against f1exible diaphragm 22, whereupon fluid free of air bubbles is pumped through the intravenous metering device 10 as described below. The position of diaphragm 22 shown by solid lines in FIGURE 3 illustrates the condition of the diaphragm 22 when pumping piston 60 is in the upstroke position while the dotted line position of diaphragm 2~ illustrates the position of the diaphragm -- 22 in the associa~a down-stroke position of pumpiny piston 60.
3U Tne i m ravenous metering device 10 includes a pressure measuring chamber 70 seen in FIGURE 5. The pressure measuring chamber 70 is incorporated into the fluid flow path leaving the pumping chamber 20 so that priming will be accomplished in generally the same manner as with the pumping chamber 20. Intravenous 1: .
, WO92/ 2337 ~ 8~ ~r~ ~à PCI`/US92/04722 . , .
- _ 5 _ metering device 10 is constructed with the pressure measuring : chamber 7U and an intravenous metering device outlet 72 positioned at the base of pressure measuring chamber 70, An intermediate passageway 74 is formed to carry fluid from the pumping chamber outlet 26 past valve 38 into the pressure measuring chamber 70 -~ entering at a pressure inlet 78. The intravenous device outlet 7~ `
is located at the ~ottom of presswre measuring chamber 70 so that the pressure measuring chamber 7U is made a part of the fluid flow path through intravenous meteriny device 10. The flow of the fluid . 10 during the intravenous metering device 10 priming operation described below will continue on into the pressure measuring chamber ; 70, removiny air otnerwise present in the intravenous me~ering device 10 from the pressure measuring chamber 7~ as well as the pumpin~ chamber 20.
. IS Pressure pin 82 is orientPd over a portion 8~ of diaphragm 22 which covers the pressure measuring chamber 7U as showng and movement of pressure pin 82 in response to upward mot~on of diaphragm portion ~0 can be translated into a pressure reading as will be described in detail belows An elongated passageway 90 is formed in the intravenous metering device 10 to transport fluid from the pumpiny cnamber ~U to the valve 3~. :
:l ` Referring to FI~URES 6A and 6B, a perspective view of the diaphraym 2~ is seen in detail, both from above and below. The diaphragm 22 includes the upper portion 21 of pumping chamber 20 ':
which is reciprocal by pumping piston 6U to vary the volume of the pumping chamber 20. The diaphragm 22 also inclu~es the upper portion 8U of the pressure measuring chamber 70. This portion 8U of the diaphragm 22 includes a generally funnel shaped aperture ~1 in which pressure pin ~2 is held~
3U Diaphragm 22 further includes valve seat means 2~ which, in : ~ conjunction with housing 3U, forms pumping chamber in1et 24. Valve seat means 28 is reciprocal by valve activator 34 to contnol aamission of fluid into pumpiny chamber 20. ~ ;
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WO 9~/22337 Pcr/uss2/o4722 :X~`p~`.P~97~
: ' Extending upwardly from the diaphragm 22 is the integrally formed priminy s~em ll~. The priming stem IOO inc1udes an increased diameter portion 111 and a stem base 113. The junction of the increased diameter portion 111 and stem base 113 defines a stem fl~nge 115. The priming stem llO further includes a grip portion 117 to aid in user gripping. On the di~phragm opposite the primary stem is standpipe contacting portion 119 which establishes contac~
with standpipe 9~.
Extending downwardly from the diaphragm 22 is an integrally 1~ formed flapper valve 1 W which forms with a molded ramp 102 on housing 3~ a one-way valve. This one~way valve separates the intermediat passageway 74 from the pressure measuring cha~ber 70.
Also extenaing downw~rdly is a biasing ringe 79 which dCts to bias flapper valve 10~ against molded ramp9 as seen in FIGURE 5.
Referring back to FI~URES 2-5, operation of the intravenous metering device will be described. When pressure is applied to the pumping chamber 2~ by the pumping piston 60, the fluid flows from ~he pumping chamber 2U through the pumping chamber out1et to thP
elonyated passageway 9~. An annular outlet pressure chamber 96 is formed at the downstream end of elongated passageway 90 having as its u~per wall the diaphragm 2Z. A standpipe 98 having an aperture ~9 defined along its central axis is centered in outlet pressure chamber g6. At its upper periphery, the standpipe ~ is pre10aded against the diaphragm 22 thus forming a fluid seal to prevent fluid flow.
When sufficient pressure is generated in pumping chamber 2 and outlet pressure chamber 96~ the diaphragm 22 is lifted off the standpipe 9~ thus opening valve 3~. With valve 3~ open, fluid passes into the intermediate passageway 74. Because air is compressed more readily than fluid~ if air is trapped in the pumping chamber ~U, sufficient pressure will not be generated in the pumping chamber 2U and outlet pressure chamber 96 to lift the diaphragm 22 off the standpipe 9~. This disables the intravenous metering device 10 which acts as a safety means to prevent air from bein~ pumped downstream to the patient.
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W ~ 92/22337 PCl/US92/0~2 - 7 7 ~ .
From the intermediate passageway 74, the fluid enters the pressure measuring chamber 70~ ~rovided at the opening to the pressure measuring chamber iO is a one-way flapper valve 100 carried on a molded ramp 102 formed integrally as part of cassette housing 30. The flapper valve lU0 is integrally molded as part of diaphragm 22 to be biased against the mol~led ramp 102. The flapper valve lUU
thus acts as a valve to allow fluid to pass into the pressure measuriny chamber 70 but to prevent fluid from flowing back into tne intermediate passageway 74 and back tù the pumping chamber 20. Also lU extending downwardly is a biasiny ridge 79 which acts to bias flapper valve 100 against molded ramp 102, as seen in FIGURE 5.
The diaphraym 22 further includes an integrally molded priming stem 110 extending from the diaphragm 22 above the outlet valve 3~ portion. The priminy stem 110 includes an upper increased diameter portion 111 integrally formed with a stem base 113 thereby - defining a stem flange 115. The priming stem 110 can be pulled to ~- , manually lift the diaphragm 22 off the standpipe 9~ to open the pumping chamber outlet 26. In addition, formed in the housing lid surrounding the priming stem 110 is stem lock housing 1120 The stem ~U lock housiny 112 includes a stem lockiny groove 114, besl seen in FIGU~E 5, in which the stem flange 115 can rest. Also, as best seen in FI~URE 2, the stem lock housing 112 is generally formed as an arrow to direct the user to the stem locking groove 114.
Prior to use, the intravenous metering device mùst be primed to eliminate air from the device. When intravenous metering device lU is to be primed, the device is inverted, and the priming s~em 11U
~ is pulled such that the diaphragm 22 is lifted off the standpipe 9 9 to open the pumping chamber outlet 26 so as to allow the sequential passage of fluid from metering device inlet 49 through the air 3U retention chamber 4U and the pumping chamber 20 to the distal - pressure measuring chamber 70 to the outlet tubing 18. With the device inverted Pach of the chambers 2U and 4U are primed by directing the fluid into the bot~om and allowiny the fluid to fill the chambers upwardly. Such relatively constant flùi~ flow assures - .
, ~
~ ' WO 92~22337 PCr/US92~0472~!
.-` ~
~797~ - 8 - -the e1imination of air prior to use of the intravenous metering device lU, consequently enabling the intravenous metering device 1 to administer fluid free of air bubbles to a patient.
Following the priming operation, the intravenous metering device 10 is returned to its upright position and inserted into metering device control unit 12. Incoming fluid, transmitted by tubing 16 to the intravenous metering device inlet 49, subsequently passes into the air retention chamber 4~ which, due to the downward extension of tubular conduit 5~, prevents any air from entering the I0 pumping chamber 20 and allows for ~he generation of a air-fluid interface in air retention chamber upper portion S~. Fluid free of air bubbles passes from the air retention chamber 10wer portion 54 through passageway ~6. When valve actuator 34 is reciprocate~
upwardly, fluid free of air bubb1es is allowed to pass into pumping chamber 20. Valve actuator 34 is then closed. As the flexible diaphragm 22 is moved downwardly by means of the pumping piston 6U9 the volume within pumping chamber 20 is decreased and the pressure within pumping chamber 2~ and outlet pressure chamber 96 lifts the diaphragm 22 off the standpipe 9~, thereby allowing a precise amount 2U of metered fluid to be pumped from pumping chamber 2U through the intravenous metering device outlet 72 to a patient.
Referring now to FIGURE 7, ~he housing employing the pressure pin 82 is seen in a detailed view which eliminates the additional pump housing. As previously seen, the pressure pin 82 is inserted and is held by a generally funnel shaped aperture 81 in the diaphragm. In this arrangemen~ changes in pressure in the pressure measuring chamber 70 cause the funnel shaped aperture t~ expand and contract. This results in movement of the pressure pin 8~ in -accordance with changes in pressure in the pressure measuriny 3U cham~er 70.
The pressure pin ~2 is contained in housing 118 and is connected to a strain gauge means. ln the preferred em~odiment, the strain gauge means is a balance~ metal beam 120~ The balanced metal :
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WO 92/22337 ~ 7 P~ /US92/0472.2 ' 3 _ g _ :
beam 120 is f1exed as the pressure pin 82 is moved in response to changes in the pressure in pressure measuring chamber 7U. The balanced metal beam 120 acts as known in the art as a voltage divider to provide voltage signal which varies as the metal beam 12U
is flexed. The pressure pin housing 118 is secured to a strain gauge bracket 122 which secures the housing 118 in the proper orientation in the pump. Additionally, an electrical connection 124 is provided between the metal beam 120 and s~rain gauge circuitry which will be described in detail below.
- 10 ~eferring now to FIGURE 8, the logical circuit of the present invention is seen. The present invention includes strain gauge means which is connected through conditioning ~eans to an occlusion pressure monitoring means. The occlusion pressure output is further connected to air sensing means. The output of both the occlusion pressure monitor and the air sensor are inputted into a analog to digital convertor. The analog to digital convertor is monitore~ by a microprocessor which signals when the digital signal is outside of the normal range.
, Referring to FIGURE 9, a first preferred embodiment of the 2U flow monitoring circuit is seen. Initially, the strain gauye circuitry will be described. A pair of variable resistors Rl,R2 are connected 1n series between the power source V+ and ground. Tnus, resistors R1,R2 act as a voltage divider. The variab1e resistors Rl,R2 comprise a balanced metal beam. As the balanced metal beam is flexe~ the resistance varies proportiona11y. This acts to vary the voltagè being supplied at the junction of resistors Rl,R2~
The junction of resistors Rl,R2 is connected to a variable resistor R3 in series wi~h a resistor R4. The series resistors ~ R3,R4 are connected to a variable resistor R6. Variab1e resistor R6 is set by resistors R5,R7 wherein resistor R5 is connected between resistor R6 and the power source V+ while resistor R7 is connected betwe~n resistor R6 and ground. Resistor R6 acts to nu11 the offset voltage at the junction of resistors Rl,R2~ Resistor R3 is provided to adjust the gain of the system to appropriate values.
: -: ~ '~ .. ' j, .
Y~/O 92~22337 ~ r PC r/ US9~/~)4722 ~O~ l97~ ~
' An operational amplifier ~l is provided. Operational amplifier Ql includes a low pass feedback network which also sets gain and helps to assure stability. The low pass feedback network includes a feedback resistor R~ in parallel wi~h a capacitor'Cl.
The high input of operational amplifier Ql is connected to the junction of resistors R4,R6. The low input of operational amplifier Ql is connected to variable resistor R3. Thus, operational amplifier Ql provides a variable gain set by variable resistor R3 and an offset voltage set by Yariable resistor R6. Operational l~ amplifier ~l together with input circuitry acts as a means for electrically conditioning the reading of the strain gauge circuitry.
A second operational amplifier ~2 is provided. Uperational amplifier Q2 includes a low pass feedback ne~work which includes a feedback resistor Rl~ in parallel with a capacitor C~. The low pass feedback network further acts to assist in setting of operational amplifier ~2 and helps to assure stability.
The high input of operational amplifier ~ is also connected - to the junction of resistors R4~R6. The low input is connected to the output of operational amplifier ~1 throuyh a resistor R9. Thus, 2U operational amplifier Q2 a10ng with its connecting cireuitry acts as occlusion c1rcuit means for monitoring the strain gauge signal. The -~
~l output of operational amplifier ~2 contains the in-line pressure -~ signal and is carefully calibrated such that a direct repeatable -, relation exists between voltage and pressure.
The output of operational amplifier Q2 is connec~ed through series capacitors C3,C4 to the high input of a third operational amplifier ~3 forming a high pass filter. Operational amplifi2r ~3 includes a low pass feedback network which includes a fee~back resistor R14 in parallel with a capacitor C5. The feedback network assists in setting the gain of operational amplifier Q3, helps to assure stability and also forms a band pass function with a preferred gain of two.
,i,:
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WO 92/22337 PCr/lJS~2/0~1722 11 20879~ ;
The output of operational amplifier Q3 is also fed back via a resistor R12 to the junction of capacitors C3,C4. The high input of operational amplifier is further connected to voltage dividing resistors R11,R130 The junction of series resistors Rll,R13'is input into the high input of opera~ional amplifier Q3, wi~h resiskor Rll connected to the power source V+ and resistor R13 connected to groundO The lo~ input of operational ampli~ier ~3 is further connected to ground through a resistor R15.
The output of operational amplifier Q3 is inputted into the lU high input of a fourth operational amplifier Q4, Operational amplifier ~4 includes a low pass feedback network to assist in setting the gain of operational amplifier Q4 and help to assure stability which includes a feedback resistor R18 in parallel with a capacitor C6. The low input of operational amplifier Q4 is further connected to the junction of voltage divider series resistors R16,R17, with resistor R16 connected to the power source V+ and resistor R17 connected to ground. The output of operational amplifier ~4 contains the in-line or in-cassette gas signa1 information.
2~ Referring now to Fl~URE 10, an alternatiYe preferred emboaiment of the flow monitoring circuit is seen. In the circuit, like elements are designated by like designations and for brevity the discussion is limited to only those addi~ional elemen~s not previously discussed in reference to FIGURE 9.
The alternative circuit includes an additional set of series variable resistors R25,R26 which act as a voltage divider connected between the power supply V+ and ground. The junction of resistors R25,R26 is connected to the junction of resistor R7 and variable resistor ~6 of the offset adjus~ circutt. Thus, resistors R25,R26 3U act with resistors Rl,R2 as a full bridge strain gauge which improves the sensitivity of the strain gauge by preferably 2 factor of four.
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WO 92/;~2337 PCr/usg~ 722 7 ~
The al~ernative circuit further includes means for electrically offsetting ~he strain gauge. The electrical offset means is provided to balance a forced mQchanical offset of the balanced ~etal beam to achieve linearity. In particular, a specific connection is provided between ~he junction of resistor R6 and resistor R7 of the offset adjust circuit and the junction of resistor R25 iand resistor R~6 of the full bridge strain gauge to create this condition. The forced mechanical offset is created by ~a~
an adjustment screw (not shown) and is extended by insertion of the ~;
cassette into the pumping mechanism.
The alternative preferred embodiment further includes means for compensating temperature chanyes. Particularly, the high input of operatiQnal amplifier Q2 is further connected to a resistor ~24 which is connected in series to a second resistor R23. Resistor R?~
is connected to power source V+ through a diode CR1. The junction of resistor R24 and resistor R23 is connected to ground through a resis~or R22 and a parallel capacitor C9. The voltage change due to temperature changes in the diode characteristic compensates nominal temperature char,ges in the rest of ~he circuitry.
It should be understood that various modifications, changes and variations may be made in the arrangement, operations and details of construction of the el~nents disclosed herein without departing from the spirit and scope of the invention.
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FIGURE ~ is a b10ck dtagram showing the logical circuit of the present invention;
FIGURE 9 is a detailed schematic of the electric circuit of the present invention; and FI~URE 1~ is a detailed schematic of an alternative preferred electric circuit in accordance with the principles of the ~:
present invention.
~, 10 DETAILEU DESCRIPTION UF A PREFERRED EMBODIMENT
Referring first to FIGURE 1, an intravenous metering device 10 is shown positioned within a metering device control unit 12.
The intravenous metering device 10 in conjunction with the metering device control unit 12 acts as a pump means to transfer fluid from a - source of fluid 14 to a patient. The intravenous metering device 10 is connected to the source of fluid 14 by means of conventional tubin~ 16. Additional tubing 1~, extending from the outlet of intravenous metering device 10, transfers precise amounts of fluid 2~ to the patient. ~:
Provi~ed between the container of flui~ 14 and the tubing 16 is a conventional drip chamber 15. The drip chamber 15 is partially ! surrounaed by a drop sensing means 17 which senses the drops passing in the drip chamber 15. The drop sensing means 17 can be connected . 25 to the metering device control unit 12 by wiring 13 so that, if theabsence of drops is sensed, an alarm in the metering device control unit 12 can be sounded.
Referring now to FI~URES 2 t~ru 6, construction of an intravenous metering device 1~ is shown in aetail. The intravenous , .
3~ meterin~ device 10 includes a pumping chamber 20 formed in hou~ing ..
3U and a flexible diaphragm 22 which forms an upper portion 21 of pumping chamber 20. The housing 30 includes a housing lid 31 as well as a~housing bottom 32. A pumping chamber inlet 24 and a . : : pumping chamber outlet 26 are formed in pumping chamber 2U. ~umping ; ~ -:.
WO ~)2/22337 pCr/l.J~()2/04722 . . r 2~797~ - 4 -chamber 24 includes a valve seat means 280 Valve actuator 34 controls the admission of fluid into pumping chamber 2U by reciprocating the diaphragm 22 between an open position, shown in solid lines in FI~U~E 3, and a closed position as shown by dot~ea lines in FIGURE 3. As best seen in FI~URE 4, the pumping chamber out1et 26 includes a valve 38 which is normally held in a closed position.
Intravenous metering device lU fur~her includes a meterin~
device inlet 49 which is disposed above an air retention chamber 40 bounded by housing sidewalls 42. The air retention chamber 40 is of sufficient size to include an air retention chamber upper portion 50 providiny for an air-fluid interface. Air retention chamber 4U also includes an air retention chamber lower portion 54 which collects fluid free of air bubbles. The fluid free of air bubbles can then pass throuyh an air retention chamber passageway 56 in tubular conduit 5~ past the open valve seat means 2~ and on into the pumpin~
chamber 20.
The metering device control unit 12 provides means for varying the volume of the pumping chamber 20 in order to pressurize ,~
the pumping cnamber 20 to provide fluid propulsion. These means can - include means for flexin~ diaphragm 22 into pumping chamber 20 which in the present invention is a reciprocating pumping piston 6u whicn presses against f1exible diaphragm 22, whereupon fluid free of air bubbles is pumped through the intravenous metering device 10 as described below. The position of diaphragm 22 shown by solid lines in FIGURE 3 illustrates the condition of the diaphragm 22 when pumping piston 60 is in the upstroke position while the dotted line position of diaphragm 2~ illustrates the position of the diaphragm -- 22 in the associa~a down-stroke position of pumpiny piston 60.
3U Tne i m ravenous metering device 10 includes a pressure measuring chamber 70 seen in FIGURE 5. The pressure measuring chamber 70 is incorporated into the fluid flow path leaving the pumping chamber 20 so that priming will be accomplished in generally the same manner as with the pumping chamber 20. Intravenous 1: .
, WO92/ 2337 ~ 8~ ~r~ ~à PCI`/US92/04722 . , .
- _ 5 _ metering device 10 is constructed with the pressure measuring : chamber 7U and an intravenous metering device outlet 72 positioned at the base of pressure measuring chamber 70, An intermediate passageway 74 is formed to carry fluid from the pumping chamber outlet 26 past valve 38 into the pressure measuring chamber 70 -~ entering at a pressure inlet 78. The intravenous device outlet 7~ `
is located at the ~ottom of presswre measuring chamber 70 so that the pressure measuring chamber 7U is made a part of the fluid flow path through intravenous meteriny device 10. The flow of the fluid . 10 during the intravenous metering device 10 priming operation described below will continue on into the pressure measuring chamber ; 70, removiny air otnerwise present in the intravenous me~ering device 10 from the pressure measuring chamber 7~ as well as the pumpin~ chamber 20.
. IS Pressure pin 82 is orientPd over a portion 8~ of diaphragm 22 which covers the pressure measuring chamber 7U as showng and movement of pressure pin 82 in response to upward mot~on of diaphragm portion ~0 can be translated into a pressure reading as will be described in detail belows An elongated passageway 90 is formed in the intravenous metering device 10 to transport fluid from the pumpiny cnamber ~U to the valve 3~. :
:l ` Referring to FI~URES 6A and 6B, a perspective view of the diaphraym 2~ is seen in detail, both from above and below. The diaphragm 22 includes the upper portion 21 of pumping chamber 20 ':
which is reciprocal by pumping piston 6U to vary the volume of the pumping chamber 20. The diaphragm 22 also inclu~es the upper portion 8U of the pressure measuring chamber 70. This portion 8U of the diaphragm 22 includes a generally funnel shaped aperture ~1 in which pressure pin ~2 is held~
3U Diaphragm 22 further includes valve seat means 2~ which, in : ~ conjunction with housing 3U, forms pumping chamber in1et 24. Valve seat means 28 is reciprocal by valve activator 34 to contnol aamission of fluid into pumpiny chamber 20. ~ ;
! ~
WO 9~/22337 Pcr/uss2/o4722 :X~`p~`.P~97~
: ' Extending upwardly from the diaphragm 22 is the integrally formed priminy s~em ll~. The priming stem IOO inc1udes an increased diameter portion 111 and a stem base 113. The junction of the increased diameter portion 111 and stem base 113 defines a stem fl~nge 115. The priming stem llO further includes a grip portion 117 to aid in user gripping. On the di~phragm opposite the primary stem is standpipe contacting portion 119 which establishes contac~
with standpipe 9~.
Extending downwardly from the diaphragm 22 is an integrally 1~ formed flapper valve 1 W which forms with a molded ramp 102 on housing 3~ a one-way valve. This one~way valve separates the intermediat passageway 74 from the pressure measuring cha~ber 70.
Also extenaing downw~rdly is a biasing ringe 79 which dCts to bias flapper valve 10~ against molded ramp9 as seen in FIGURE 5.
Referring back to FI~URES 2-5, operation of the intravenous metering device will be described. When pressure is applied to the pumping chamber 2~ by the pumping piston 60, the fluid flows from ~he pumping chamber 2U through the pumping chamber out1et to thP
elonyated passageway 9~. An annular outlet pressure chamber 96 is formed at the downstream end of elongated passageway 90 having as its u~per wall the diaphragm 2Z. A standpipe 98 having an aperture ~9 defined along its central axis is centered in outlet pressure chamber g6. At its upper periphery, the standpipe ~ is pre10aded against the diaphragm 22 thus forming a fluid seal to prevent fluid flow.
When sufficient pressure is generated in pumping chamber 2 and outlet pressure chamber 96~ the diaphragm 22 is lifted off the standpipe 9~ thus opening valve 3~. With valve 3~ open, fluid passes into the intermediate passageway 74. Because air is compressed more readily than fluid~ if air is trapped in the pumping chamber ~U, sufficient pressure will not be generated in the pumping chamber 2U and outlet pressure chamber 96 to lift the diaphragm 22 off the standpipe 9~. This disables the intravenous metering device 10 which acts as a safety means to prevent air from bein~ pumped downstream to the patient.
,, "`, ' :,:
W ~ 92/22337 PCl/US92/0~2 - 7 7 ~ .
From the intermediate passageway 74, the fluid enters the pressure measuring chamber 70~ ~rovided at the opening to the pressure measuring chamber iO is a one-way flapper valve 100 carried on a molded ramp 102 formed integrally as part of cassette housing 30. The flapper valve lU0 is integrally molded as part of diaphragm 22 to be biased against the mol~led ramp 102. The flapper valve lUU
thus acts as a valve to allow fluid to pass into the pressure measuriny chamber 70 but to prevent fluid from flowing back into tne intermediate passageway 74 and back tù the pumping chamber 20. Also lU extending downwardly is a biasiny ridge 79 which acts to bias flapper valve 100 against molded ramp 102, as seen in FIGURE 5.
The diaphraym 22 further includes an integrally molded priming stem 110 extending from the diaphragm 22 above the outlet valve 3~ portion. The priminy stem 110 includes an upper increased diameter portion 111 integrally formed with a stem base 113 thereby - defining a stem flange 115. The priming stem 110 can be pulled to ~- , manually lift the diaphragm 22 off the standpipe 9~ to open the pumping chamber outlet 26. In addition, formed in the housing lid surrounding the priming stem 110 is stem lock housing 1120 The stem ~U lock housiny 112 includes a stem lockiny groove 114, besl seen in FIGU~E 5, in which the stem flange 115 can rest. Also, as best seen in FI~URE 2, the stem lock housing 112 is generally formed as an arrow to direct the user to the stem locking groove 114.
Prior to use, the intravenous metering device mùst be primed to eliminate air from the device. When intravenous metering device lU is to be primed, the device is inverted, and the priming s~em 11U
~ is pulled such that the diaphragm 22 is lifted off the standpipe 9 9 to open the pumping chamber outlet 26 so as to allow the sequential passage of fluid from metering device inlet 49 through the air 3U retention chamber 4U and the pumping chamber 20 to the distal - pressure measuring chamber 70 to the outlet tubing 18. With the device inverted Pach of the chambers 2U and 4U are primed by directing the fluid into the bot~om and allowiny the fluid to fill the chambers upwardly. Such relatively constant flùi~ flow assures - .
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~797~ - 8 - -the e1imination of air prior to use of the intravenous metering device lU, consequently enabling the intravenous metering device 1 to administer fluid free of air bubbles to a patient.
Following the priming operation, the intravenous metering device 10 is returned to its upright position and inserted into metering device control unit 12. Incoming fluid, transmitted by tubing 16 to the intravenous metering device inlet 49, subsequently passes into the air retention chamber 4~ which, due to the downward extension of tubular conduit 5~, prevents any air from entering the I0 pumping chamber 20 and allows for ~he generation of a air-fluid interface in air retention chamber upper portion S~. Fluid free of air bubbles passes from the air retention chamber 10wer portion 54 through passageway ~6. When valve actuator 34 is reciprocate~
upwardly, fluid free of air bubb1es is allowed to pass into pumping chamber 20. Valve actuator 34 is then closed. As the flexible diaphragm 22 is moved downwardly by means of the pumping piston 6U9 the volume within pumping chamber 20 is decreased and the pressure within pumping chamber 2~ and outlet pressure chamber 96 lifts the diaphragm 22 off the standpipe 9~, thereby allowing a precise amount 2U of metered fluid to be pumped from pumping chamber 2U through the intravenous metering device outlet 72 to a patient.
Referring now to FIGURE 7, ~he housing employing the pressure pin 82 is seen in a detailed view which eliminates the additional pump housing. As previously seen, the pressure pin 82 is inserted and is held by a generally funnel shaped aperture 81 in the diaphragm. In this arrangemen~ changes in pressure in the pressure measuring chamber 70 cause the funnel shaped aperture t~ expand and contract. This results in movement of the pressure pin 8~ in -accordance with changes in pressure in the pressure measuriny 3U cham~er 70.
The pressure pin ~2 is contained in housing 118 and is connected to a strain gauge means. ln the preferred em~odiment, the strain gauge means is a balance~ metal beam 120~ The balanced metal :
.
' : :
.;
WO 92/22337 ~ 7 P~ /US92/0472.2 ' 3 _ g _ :
beam 120 is f1exed as the pressure pin 82 is moved in response to changes in the pressure in pressure measuring chamber 7U. The balanced metal beam 120 acts as known in the art as a voltage divider to provide voltage signal which varies as the metal beam 12U
is flexed. The pressure pin housing 118 is secured to a strain gauge bracket 122 which secures the housing 118 in the proper orientation in the pump. Additionally, an electrical connection 124 is provided between the metal beam 120 and s~rain gauge circuitry which will be described in detail below.
- 10 ~eferring now to FIGURE 8, the logical circuit of the present invention is seen. The present invention includes strain gauge means which is connected through conditioning ~eans to an occlusion pressure monitoring means. The occlusion pressure output is further connected to air sensing means. The output of both the occlusion pressure monitor and the air sensor are inputted into a analog to digital convertor. The analog to digital convertor is monitore~ by a microprocessor which signals when the digital signal is outside of the normal range.
, Referring to FIGURE 9, a first preferred embodiment of the 2U flow monitoring circuit is seen. Initially, the strain gauye circuitry will be described. A pair of variable resistors Rl,R2 are connected 1n series between the power source V+ and ground. Tnus, resistors R1,R2 act as a voltage divider. The variab1e resistors Rl,R2 comprise a balanced metal beam. As the balanced metal beam is flexe~ the resistance varies proportiona11y. This acts to vary the voltagè being supplied at the junction of resistors Rl,R2~
The junction of resistors Rl,R2 is connected to a variable resistor R3 in series wi~h a resistor R4. The series resistors ~ R3,R4 are connected to a variable resistor R6. Variab1e resistor R6 is set by resistors R5,R7 wherein resistor R5 is connected between resistor R6 and the power source V+ while resistor R7 is connected betwe~n resistor R6 and ground. Resistor R6 acts to nu11 the offset voltage at the junction of resistors Rl,R2~ Resistor R3 is provided to adjust the gain of the system to appropriate values.
: -: ~ '~ .. ' j, .
Y~/O 92~22337 ~ r PC r/ US9~/~)4722 ~O~ l97~ ~
' An operational amplifier ~l is provided. Operational amplifier Ql includes a low pass feedback network which also sets gain and helps to assure stability. The low pass feedback network includes a feedback resistor R~ in parallel wi~h a capacitor'Cl.
The high input of operational amplifier Ql is connected to the junction of resistors R4,R6. The low input of operational amplifier Ql is connected to variable resistor R3. Thus, operational amplifier Ql provides a variable gain set by variable resistor R3 and an offset voltage set by Yariable resistor R6. Operational l~ amplifier ~l together with input circuitry acts as a means for electrically conditioning the reading of the strain gauge circuitry.
A second operational amplifier ~2 is provided. Uperational amplifier Q2 includes a low pass feedback ne~work which includes a feedback resistor Rl~ in parallel with a capacitor C~. The low pass feedback network further acts to assist in setting of operational amplifier ~2 and helps to assure stability.
The high input of operational amplifier ~ is also connected - to the junction of resistors R4~R6. The low input is connected to the output of operational amplifier ~1 throuyh a resistor R9. Thus, 2U operational amplifier Q2 a10ng with its connecting cireuitry acts as occlusion c1rcuit means for monitoring the strain gauge signal. The -~
~l output of operational amplifier ~2 contains the in-line pressure -~ signal and is carefully calibrated such that a direct repeatable -, relation exists between voltage and pressure.
The output of operational amplifier Q2 is connec~ed through series capacitors C3,C4 to the high input of a third operational amplifier ~3 forming a high pass filter. Operational amplifi2r ~3 includes a low pass feedback network which includes a fee~back resistor R14 in parallel with a capacitor C5. The feedback network assists in setting the gain of operational amplifier Q3, helps to assure stability and also forms a band pass function with a preferred gain of two.
,i,:
. . .
WO 92/22337 PCr/lJS~2/0~1722 11 20879~ ;
The output of operational amplifier Q3 is also fed back via a resistor R12 to the junction of capacitors C3,C4. The high input of operational amplifier is further connected to voltage dividing resistors R11,R130 The junction of series resistors Rll,R13'is input into the high input of opera~ional amplifier Q3, wi~h resiskor Rll connected to the power source V+ and resistor R13 connected to groundO The lo~ input of operational ampli~ier ~3 is further connected to ground through a resistor R15.
The output of operational amplifier Q3 is inputted into the lU high input of a fourth operational amplifier Q4, Operational amplifier ~4 includes a low pass feedback network to assist in setting the gain of operational amplifier Q4 and help to assure stability which includes a feedback resistor R18 in parallel with a capacitor C6. The low input of operational amplifier Q4 is further connected to the junction of voltage divider series resistors R16,R17, with resistor R16 connected to the power source V+ and resistor R17 connected to ground. The output of operational amplifier ~4 contains the in-line or in-cassette gas signa1 information.
2~ Referring now to Fl~URE 10, an alternatiYe preferred emboaiment of the flow monitoring circuit is seen. In the circuit, like elements are designated by like designations and for brevity the discussion is limited to only those addi~ional elemen~s not previously discussed in reference to FIGURE 9.
The alternative circuit includes an additional set of series variable resistors R25,R26 which act as a voltage divider connected between the power supply V+ and ground. The junction of resistors R25,R26 is connected to the junction of resistor R7 and variable resistor ~6 of the offset adjus~ circutt. Thus, resistors R25,R26 3U act with resistors Rl,R2 as a full bridge strain gauge which improves the sensitivity of the strain gauge by preferably 2 factor of four.
:
' . .
WO 92/;~2337 PCr/usg~ 722 7 ~
The al~ernative circuit further includes means for electrically offsetting ~he strain gauge. The electrical offset means is provided to balance a forced mQchanical offset of the balanced ~etal beam to achieve linearity. In particular, a specific connection is provided between ~he junction of resistor R6 and resistor R7 of the offset adjust circuit and the junction of resistor R25 iand resistor R~6 of the full bridge strain gauge to create this condition. The forced mechanical offset is created by ~a~
an adjustment screw (not shown) and is extended by insertion of the ~;
cassette into the pumping mechanism.
The alternative preferred embodiment further includes means for compensating temperature chanyes. Particularly, the high input of operatiQnal amplifier Q2 is further connected to a resistor ~24 which is connected in series to a second resistor R23. Resistor R?~
is connected to power source V+ through a diode CR1. The junction of resistor R24 and resistor R23 is connected to ground through a resis~or R22 and a parallel capacitor C9. The voltage change due to temperature changes in the diode characteristic compensates nominal temperature char,ges in the rest of ~he circuitry.
It should be understood that various modifications, changes and variations may be made in the arrangement, operations and details of construction of the el~nents disclosed herein without departing from the spirit and scope of the invention.
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.::
" ;, ' .
.
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Claims (10)
1. An apparatus for monitoring the intravenous metering of liquid to a patient comprising:
strain gauge means responsive to changing pressure conditions in the metering of liquids for providing an electronic signal which varies as a function of the pressure conditions;
occlusion circuit means having as an input the electronic signal provided by the strain gauge means for monitoring the strain gauge signal to provide notification when the metering of liquids is precluded; and air sensing circuit means having as an input an electronic signal from the occlusion circuit means for monitoring the occlusion circuit signal to provide a notification when the metering of liquids further includes gas.
strain gauge means responsive to changing pressure conditions in the metering of liquids for providing an electronic signal which varies as a function of the pressure conditions;
occlusion circuit means having as an input the electronic signal provided by the strain gauge means for monitoring the strain gauge signal to provide notification when the metering of liquids is precluded; and air sensing circuit means having as an input an electronic signal from the occlusion circuit means for monitoring the occlusion circuit signal to provide a notification when the metering of liquids further includes gas.
2. The apparatus of claim 1 further including conditioning circuit means having as an input the electronic signal from the strain gauge means and outputting a conditioned electronic signal to the occlusion circuit means.
3. The apparatus of claim 1 further wherein the occlusion circuit means provides a refined electronic signal as input to the air sensing circuit means.
4. The apparatus of claim 1 wherein the strain gauge means comprises a voltage divider.
5. The apparatus of claim 1 wherein the occlusion circuit means comprises an operational amplifier.
6. The apparatus of claim 1 wherein the air sensing circuit means comprises a pair of series amplifiers.
7. An apparatus for monitoring the conditions in an intravenous metering device having upstream and downstream tubing comprising:
strain gauge means for providing an electronic signal which varies in accordance with pressure conditions in the intravenous metering device;
occlusion sensing circuit means having as an input the strain gauge signal for sensing and providing a notification when liquid is precluded from flowing into the metering device; and air sensing circuit means having as an input the strain gauge signal for sensing and providing a notification when a gas is present in the metering device.
strain gauge means for providing an electronic signal which varies in accordance with pressure conditions in the intravenous metering device;
occlusion sensing circuit means having as an input the strain gauge signal for sensing and providing a notification when liquid is precluded from flowing into the metering device; and air sensing circuit means having as an input the strain gauge signal for sensing and providing a notification when a gas is present in the metering device.
8. The apparatus of claim 7 further including conditioning circuit means having as an input the electronic signal from the strain gauge means and outputting a conditioned electronic signal to the occlusion sensing circuit means and the air sensing circuit means.
9. The apparatus of claim 7 further wherein prior to inputting into the air sensing circuit means the strain gauge signal has been inputted into the occlusion sensing circuit means which output is inputted into the air sensing circuit means.
10. A system of metering liquids for delivery from a source of liquid to a patient comprising:
an intravenous metering device having a pressure measuring chamber in fluid communication with the liquid;
a pressure pin functionally associated with the pressure measuring chamber such that changes in the pressure measuring chamber result in movement of the pressure pin;
a balanced metal beam in contact with the pressure pin such that the balanced metal beam moves in response to movement of the pressure pin, the balanced metal beam further providing an electronic signal which varies as a function of movement of the balanced metal beam; and electronic circuit means for monitoring the balanced metal beam electronic signal and providing notification when liquid flow through the intravenous metering device is precluded and for monitoring the balanced metal beam electronic signal and providing notification when gas is present in the intravenous metering device.
an intravenous metering device having a pressure measuring chamber in fluid communication with the liquid;
a pressure pin functionally associated with the pressure measuring chamber such that changes in the pressure measuring chamber result in movement of the pressure pin;
a balanced metal beam in contact with the pressure pin such that the balanced metal beam moves in response to movement of the pressure pin, the balanced metal beam further providing an electronic signal which varies as a function of movement of the balanced metal beam; and electronic circuit means for monitoring the balanced metal beam electronic signal and providing notification when liquid flow through the intravenous metering device is precluded and for monitoring the balanced metal beam electronic signal and providing notification when gas is present in the intravenous metering device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US71285091A | 1991-06-10 | 1991-06-10 | |
| US7/712,850 | 1991-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2087975A1 true CA2087975A1 (en) | 1992-12-11 |
Family
ID=24863816
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002087975A Abandoned CA2087975A1 (en) | 1991-06-10 | 1992-06-05 | Intravenous metering monitoring device |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5399171A (en) |
| EP (1) | EP0542982B1 (en) |
| JP (1) | JPH06501870A (en) |
| AU (1) | AU645710B2 (en) |
| CA (1) | CA2087975A1 (en) |
| DE (1) | DE69219726T2 (en) |
| WO (1) | WO1992022337A1 (en) |
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| US4981467A (en) * | 1990-02-27 | 1991-01-01 | Baxter International Inc. | Apparatus and method for the detection of air in fluid delivery systems |
| US5055001A (en) * | 1990-03-15 | 1991-10-08 | Abbott Laboratories | Volumetric pump with spring-biased cracking valves |
| US5039279A (en) * | 1990-03-15 | 1991-08-13 | Abbott Laboratories | Sensor for detecting fluid flow from a positive displacement pump |
-
1992
- 1992-06-05 JP JP5500937A patent/JPH06501870A/en active Pending
- 1992-06-05 AU AU21800/92A patent/AU645710B2/en not_active Ceased
- 1992-06-05 EP EP92912799A patent/EP0542982B1/en not_active Expired - Lifetime
- 1992-06-05 CA CA002087975A patent/CA2087975A1/en not_active Abandoned
- 1992-06-05 WO PCT/US1992/004722 patent/WO1992022337A1/en active IP Right Grant
- 1992-06-05 DE DE69219726T patent/DE69219726T2/en not_active Expired - Fee Related
-
1993
- 1993-04-01 US US08/033,710 patent/US5399171A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0542982A4 (en) | 1994-03-24 |
| US5399171A (en) | 1995-03-21 |
| WO1992022337A1 (en) | 1992-12-23 |
| AU2180092A (en) | 1993-01-12 |
| AU645710B2 (en) | 1994-01-20 |
| EP0542982A1 (en) | 1993-05-26 |
| JPH06501870A (en) | 1994-03-03 |
| DE69219726T2 (en) | 1997-11-27 |
| DE69219726D1 (en) | 1997-06-19 |
| EP0542982B1 (en) | 1997-05-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |