U.S. patent number RE45,717 [Application Number 14/261,028] was granted by the patent office on 2015-10-06 for system and method for proportional mixing and continuous delivery of fluids.
This patent grant is currently assigned to Bayer Medical Care Inc.. The grantee listed for this patent is John F. Kalafut, David M. Reilly, Ralph H. Schriver. Invention is credited to John F. Kalafut, David M. Reilly, Ralph H. Schriver.
United States Patent |
RE45,717 |
Reilly , et al. |
October 6, 2015 |
System and method for proportional mixing and continuous delivery
of fluids
Abstract
A system and method for mixing and delivering fluids such as
contrast media and saline is disclosed including .[.at least two
fluid sources,.]. a pump, a joining fluid path .Iadd.for
.Iaddend.connecting .[.the.]. at least two fluid sources to an
inlet .[.to.]. .Iadd.of .Iaddend.the pump, and a valve device in
the fluid path upstream of the pump. The valve device includes an
actuator adapted to restrict flow in at least one of .Iadd.the
.Iaddend.respective fluid lines connecting the at least two fluid
sources to the pump inlet. A patient interface device may be
associated with an outlet of the pump. The valve device actuator is
generally adapted to restrict the flow in at least one of the
respective fluid lines such that a positional change in valve
device actuator position provides a change in fluid mixture ratio
of the fluids from the at least two fluid sources to the pump
inlet.
Inventors: |
Reilly; David M. (Pittsburgh,
PA), Kalafut; John F. (Pittsburgh, PA), Schriver; Ralph
H. (Tarentum, PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Reilly; David M.
Kalafut; John F.
Schriver; Ralph H. |
Pittsburgh
Pittsburgh
Tarentum |
PA
PA
PA |
US
US
US |
|
|
Assignee: |
Bayer Medical Care Inc.
(Indianola, PA)
|
Family
ID: |
40583783 |
Appl.
No.: |
14/261,028 |
Filed: |
April 24, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
11928021 |
Oct 30, 2007 |
7766883 |
|
|
Reissue of: |
12848570 |
Aug 2, 2010 |
8162903 |
Apr 24, 2012 |
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M
5/16827 (20130101); A61M 5/1422 (20130101); A61M
5/007 (20130101) |
Current International
Class: |
A61M
5/00 (20060101); A61M 5/168 (20060101); A61M
5/142 (20060101) |
Field of
Search: |
;604/246,248
;137/625.46 |
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|
Primary Examiner: Gellner; Jeffrey L
Attorney, Agent or Firm: Kent; Joseph L. Schramm; David
Stevenson; James R.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a division of application Ser. No. 11/928,021,
filed on Oct. 30, 2007, the contents of which are incorporated
herein by reference.
Claims
The invention claimed is:
1. A system for mixing and delivering fluids, comprising: .[.a
first fluid source configured to supply a first fluid;.]. .[.at
least a second fluid source configured to supply at least a second
fluid;.]. a first fluid line .[.in.]. .Iadd.configured for
.Iaddend.fluid connection with .[.the.]. .Iadd.a .Iaddend.first
fluid source .Iadd.for supplying a first fluid.Iaddend.; at least a
second fluid line .[.in.]. .Iadd.configured for .Iaddend.fluid
connection with .[.the.]. .Iadd.an .Iaddend.at least second fluid
source .Iadd.for supplying at least a second fluid.Iaddend.; a pump
having an inlet and an outlet; and a mixing stopcock valve having a
first input port, at least a second input port, an outlet port, and
a stopcock actuator, wherein the first input port is in fluid
communication with the first fluid line, the at least second input
port is in fluid communication with the at least second fluid line,
and the outlet port is in fluid communication with .[.an.].
.Iadd.the .Iaddend.inlet of the pump, wherein the stopcock actuator
comprises an internal conduit defining a first conduit portion, a
second conduit portion, and a third conduit portion of reduced
diameter relative to the diameter of the first conduit portion, and
wherein a positional change in .[.the.]. .Iadd.a .Iaddend.position
of the stopcock actuator provides a change in .[.the.]. .Iadd.a
.Iaddend.fluid mixture ratio of the first and at least second
fluids delivered to a patient.
2. The system as claimed in claim 1, wherein the first fluid and
the at least second fluid comprise at least contrast media and a
diluent.
3. The system as claimed in claim 1, wherein the stopcock actuator
is adapted to simultaneously at least partially restrict flow in
each of the fluid lines.
4. The system as claimed in claim 1, wherein the pump comprises a
positive displacement pump.
5. The system as claimed in claim 4, wherein the positive
displacement pump comprises a multi-chamber piston pump.
6. The system as claimed in claim 1, wherein the first fluid line
has a first diameter, the at least second fluid line has an at
least second diameter, and the first diameter differs from the at
least second diameter.
7. The system as claimed in claim 1, further comprising a flow
meter associated with at least one of the fluid lines.
8. The system as claimed in claim 1, wherein the pump comprises a
peristaltic pump.
9. .[.A.]. .Iadd.The .Iaddend.system as claimed in claim 1, further
comprising: a controller operatively associated with the mixing
stopcock valve for controlling .Iadd.the .Iaddend.positional
.[.movement.]. .Iadd.change .Iaddend.of the stopcock actuator; and
a flow meter associated with at least one of the fluid lines.
10. The system as claimed in claim 9, wherein the controller
effects .Iadd.the .Iaddend.positional change of the .[.valve.].
.Iadd.stopcock .Iaddend.actuator at least in part based on feedback
from the flow meter.
11. The system as claimed in claim 9, wherein the first fluid and
the at least second fluid comprise at least contrast media and a
diluent.
12. The system as claimed in claim 9, wherein the stopcock actuator
is adapted to simultaneously at least partially restrict flow in
each of the fluid lines.
13. The system as claimed in claim 9, further comprising a patient
interface device associated with the outlet of the pump.
14. The system as claimed in claim 9, wherein the pump comprises a
positive displacement pump.
15. The system as claimed in claim 14, wherein the positive
displacement pump comprises a multi-chamber piston pump.
16. The system as claimed in claim 9, wherein the first fluid line
has a first diameter, the at least second fluid line has an at
least second diameter, and the first diameter differs from the at
least second diameter, or the first input port has a first port
diameter, the at least second input port has an at least second
port diameter, and the first port diameter differs from the at
least second port diameter.
17. The system as claimed in claim 9, wherein the pump comprises a
peristaltic pump.
18. A method of mixing and delivering fluids from a first fluid
source and at least a second fluid source using a fluid delivery
system comprising a pump having an inlet and an outlet, and a
mixing stopcock valve having a first input port, at least a second
input port, an outlet port and a stopcock actuator comprising an
internal conduit defining a first conduit portion, a second conduit
portion, and a third conduit portion of reduced diameter relative
to the diameter of the first conduit portion, the method
comprising: providing .Iadd.the fluid delivery system having
.Iaddend.a first fluid line with a first end and a second end, and
at least a second fluid line with a first end and a second end;
connecting the first end of the first fluid line to the first fluid
source, and the first end of the at least second fluid line to the
at least second fluid source; connecting the second end of the
first fluid line to the first input port of the mixing stopcock
valve, and the second end of the at least second fluid line to the
at least second input port of the mixing stopcock valve; .Iadd.and
.Iaddend. connecting the outlet .Iadd.port .Iaddend.of the mixing
stopcock valve to the inlet of the pump.[.; and.]..Iadd., wherein
.Iaddend.actuating the stopcock actuator .[.such that.]. .Iadd.to
effect .Iaddend.a positional change in .[.the.]. .Iadd.a
.Iaddend.position of the stopcock actuator .[.provides.].
.Iadd.effects .Iaddend.a change in .[.the.]. .Iadd.a .Iaddend.fluid
mixture ratio of a first fluid and at least a second fluid.
19. The method as claimed in claim 18, further comprising
associating a patient interface device with the outlet of the
pump.
20. The method as claimed in claim 18, wherein the first fluid line
has a first diameter, the at least second fluid line has an at
least second diameter, and the first diameter differs from the at
least second diameter.
21. The method as claimed in claim 18, further comprising:
providing a flow meter associated with at least one of the fluid
lines; and providing a controller adapted to effect .Iadd.the
.Iaddend.positional change of the stopcock actuator at least in
part based on feedback from the flow meter.
.Iadd.22. A method of manufacturing a system for mixing and
delivering fluids, the method comprising: providing a first fluid
line having a first end configured for fluid connection with a
first fluid source for supplying a first fluid; providing at least
a second fluid line configured for fluid connection with at least a
second fluid source for supplying at least a second fluid;
providing a pump having an inlet and an outlet; providing a mixing
stopcock valve having a first input port configured for connecting
to a second end of the first fluid line, at least a second input
port configured for connecting to a second end of at least the
second fluid line, and an outlet port configured for connecting to
the inlet of the pump; and providing a stopcock actuator on the
mixing stopcock valve, the stopcock actuator comprising an internal
conduit defining a first conduit portion, a second conduit portion,
and a third conduit portion of reduced diameter relative to the
diameter of the first conduit portion, wherein the stopcock
actuator is configured to provide a change in a fluid mixture ratio
of the first fluid and at least the second fluid based on a
position of the stopcock actuator..Iaddend.
.Iadd.23. The method as claimed in claim 22, further comprising:
providing a flow meter associated with at least one of the fluid
lines; and providing a controller adapted to effect a positional
change of the stopcock actuator at least in part based on feedback
from the flow meter..Iaddend.
.Iadd.24. The method as claimed in claim 22, wherein the first
fluid line has a first diameter, the at least second fluid line has
an at least second diameter, and wherein the first diameter differs
from the at least second diameter..Iaddend.
.Iadd.25. The method as claimed in claim 22, wherein the outlet of
the pump is configured for connection with a patient interface
device..Iaddend.
.Iadd.26. The method as claimed in claim 22, further comprising:
connecting the second end of the first fluid line to the first
input port of the mixing stopcock valve, and the second end of the
at least second fluid line to the at least second input port of the
mixing stopcock valve; and connecting the outlet port of the mixing
stopcock valve to the inlet of the pump..Iaddend.
.Iadd.27. The method as claimed in claim 22, further comprising:
actuating the stopcock actuator to effect a positional change in a
position of the stopcock actuator to provide a change in a fluid
mixture ratio of the first fluid and at least the second
fluid..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The embodiments of the invention disclosed herein relate generally
to the field of diagnostic and therapeutic medical procedures
involving the intravenous infusion of fluids such as
contrast-enhanced radiographic imaging as an example and, more
particularly, to a system capable of controlled proportional mixing
and delivery of fluid mixtures to a patient. In one specific
application, contrast media may be proportionally mixed with
another fluid such as saline for continuous delivery to a patient
undergoing a medical radiographic imaging procedure.
2. Description of Related Art
In many medical diagnostic and therapeutic procedures, a medical
practitioner such as a physician injects a patient with a fluid. In
recent years, a number of injector-actuated syringes and powered
injectors for pressurized injection of fluids, such as contrast
media (often referred to simply as "contrast"), have been developed
for use in procedures such as angiography, computed tomography
("CT"), ultrasound, and NMR/MRI. In general, these powered
injectors are designed to deliver a preset amount of contrast at a
preset flow rate.
Angiography is an example of a radiographic imaging procedure
wherein a powered injector may be used. Angiography is used in the
detection and treatment of abnormalities or restrictions in blood
vessels. In an angiographic procedure, a radiographic image of a
vascular structure is obtained through the use of a radiographic
contrast medium which is injected through a catheter. The vascular
structures in fluid connection with the vein or artery in which the
contrast is injected are filled with contrast. X-rays passing
through the region of interest are absorbed by the contrast,
causing a radiographic outline or image of blood vessels containing
the contrast. The resulting images can be displayed on, for
example, a video monitor and recorded.
In a typical contrast-enhanced radiographic imaging procedure such
as angiography, the medical practitioner places a cardiac catheter
into a vein or artery. The catheter is connected to either a manual
or to an automatic contrast injection mechanism. A typical manual
contrast injection mechanism includes a syringe in fluid connection
with a catheter connection. The fluid path also includes, for
example, a source of contrast, a source of flushing fluid,
typically saline, and a pressure transducer to measure patient
blood pressure. In a typical system, the source of contrast is
connected to the fluid path via a valve, for example, a three-way
stopcock. The source of saline and the pressure transducer may also
be connected to the fluid path via additional valves, again such as
stopcocks. The operator of the manual system controls the syringe
and each of the valves to draw saline or contrast into the syringe
and to inject the contrast or saline into the patient through the
catheter connection.
Automatic contrast injection mechanisms typically include a syringe
connected to a powered injector having, for example, a powered
linear actuator. Typically, an operator enters settings into an
electronic control system of the powered injector for a fixed
volume of contrast and a fixed rate of injection. In many systems,
there is no interactive control between the operator and the
powered injector except to start or stop the injection. A change in
flow rate in such systems occurs by stopping the machine and
resetting the injection parameters. Automation of contrast-enhanced
imaging procedures using powered injectors is discussed, for
example, in U.S. Pat. Nos. 5,460,609; 5,573,515; and 5,800,397.
It is often desirable to deliver a mixture of contrast and a
diluent such as saline to the patient undergoing the radiographic
imaging procedure. Depending on a patient's particular physical
characteristics, age, and the tissue to be imaged, the desirable
concentration of contrast media varies. Medical practitioners can
purchase pre-mixed solutions of contrast media in various discrete
concentrations and this is a common practice in the medical field.
Presently, contrast media is provided in sterilized glass bottles
ranging in size from 20 ml to 200 ml. Plastic packages are also
available. Presently used contrast media containers are single use
which means that once a container is opened its contents must all
be used for one patient and any residual unused contrast and the
bottle must be discarded. As a result, a medical facility must
purchase and stock many concentrations in multiple container sizes
to provide the right amount of the right contrast concentration for
a specific procedure while minimizing wastage of contrast remaining
in any opened containers. This multitude of sizes and
concentrations increases costs throughout the contrast supply
chain. Contrast manufacturers are required to make many batches
with various concentrations and package each in differently sized
containers. The manufactures must have inventories of each
concentration/container size on hand to quickly meet their
customers' requests. Each concentration level and container size
also entails an added regulatory burden.
In the end-use medical facility environment, there are additional
costs due to the efforts required to purchase and stock various
concentration/container sizes. Bulk storage space is required for
stocking and cabinets are required in each procedure room.
Moreover, labor and time are required to make sure the correct
numbers of each container are kept in each procedure room. Finally,
the present system results in waste and/or less than optimal
studies if this complicated logistics chain fails at any point.
Presently, most medical facilities utilize a standard protocol for
a given set of indications. For instance, for a CT scan of the
liver, the protocol may call for 130 ml of contrast injected at 3
ml/s. This protocol is used for a wide variety of patient weights
and physical conditions. One goal of this standardization is to
minimize errors. Another goal is to decrease the likelihood of
having to repeat the procedure, with the accompanying additional
radiation and contrast dose to the patient. However, there are
costs associated with this method. Many patients may get more
contrast than they need for an image to be diagnostic. Overdosing
wastes contrast but there is no way with the present contrast
supply and delivery system to remedy this without stocking many
more sizes of containers and being more judicious in the filling of
injection syringes. Other patients may have studies that are less
than optimal as they do not receive enough contrast and there is a
much greater chance of having to repeat the procedure.
In angiography, there are no set protocols to the same extent as in
CT because patient size determines vessel size which in turn
determines the volume and flow rate required. This means that a
fixed amount of contrast cannot be prepared ahead of time with any
confidence that more will not be needed during the procedure or
that a significant amount will not remain and be wasted at the end
of the procedure. To avoid delays during an angiography procedure,
the medical practitioner typically loads more contrast than the
average amount to be used with the realization that some contrast
is likely to be wasted.
A further result of the foregoing system is the accumulation of a
significant amount of hazardous medical waste at the conclusion of
the procedure. To save contrast, several small glass bottles may be
opened per patient, one or more plastic syringes may be used, and
various tubing arrangements may be used. Each of these items has an
associated cost to purchase the item and an associated cost to
properly dispose of the item.
Solutions have been proposed to overcome the foregoing problems
associated with the use of a multiplicity of concentrations and
container sizes and, further, to allow for more individualized
contrast mixtures to be produced to meet individual patient
requirements. For example, U.S. Pat. Nos. 5,592,940 and 5,450,847
to Kampfe et al. disclose a mixing system that allows for mixing
contrast medium and saline "on site" at a medical facility. More
particularly, the Kampfe et al. patents disclose an exemplary
mixing system that involves withdrawing or removing predetermined
amounts of contrast medium and a diluent (e.g., saline) from
respective vessels and mixing these fluids in a mixing chamber and
then delivering the mixed fluid to a suitable receiving container,
such as a vial, bag, or syringe which is used to deliver the mixed
fluid to a patient. Other contrast-diluent mixing systems are known
from U.S. Pat. Nos. 6,901,283 to Evans, III et al. and 5,840,026 to
Uber, III. et al., the disclosures of which are incorporated herein
by reference. U.S. Pat. No. 7,060,049 to Trombley, III et al.
discloses a system for injecting a multi-component enhancement
medium into a patient that incorporates an agitating mechanism to
maintain the medium in a mixed state for injection and this patent
is also incorporated herein by reference. Within the representative
"mixing" systems disclosed in the foregoing patents, simple
mechanical mixing devices are used to mix the respective fluids.
For example, in the systems disclosed by Evans, III et al. and
Uber, III et al., the fluids to be mixed are joined together as
they flow through a static mixer that contains helical vanes. In
the Kampfe et al. patents, a bulk mechanical mixer is used to mix
two sequential flows. In each of these cases, fluid mixture
proportions are determined by controlled metering valves or other
devices (e.g., peristaltic pumps) in the flow path.
Other devices are known for use in fluid delivery systems having
medical applications to mix and dispense a mixed fluid, for
example, in preset and "fixed" concentration ratios. For example, a
selector valve such as that disclosed in U.S. Pat. No. 3,957,082 to
Fuson et al. is known to allow an operator to "dial-in" a selected
fluid choice or mixture of fluids in a preset or predefined ratio.
The Fuson et al. patent allows for the choice of a first fluid such
as a drug, a second fluid such as saline, or preset "fixed" mixture
ratio of the two fluids (e.g., a 50%-50% mixture) for delivery to a
patient. U.S. Pat. No. 6,918,893 to Houde et al. discloses a
selector valve having specific application in the delivery of
contrast and saline in contrast-enhanced radiographic imaging
procedures but this selector valve does not have the ability to
dial in a desired mixture ratio of two fluids. The disclosure of
U.S. Pat. No. 3,957,082 is incorporated herein for the selector
valve teaching of this disclosure.
Double or dual pinch valves are also known for use in fluid
handling systems to accomplish one or more of: alternating the flow
of two fluids, blocking flow of the two fluids, or permitting
simultaneous flow of the two fluids in a fluid path as disclosed in
U.S. Pat. Nos. 2,985,192 (Taylor et al.); 3,411,534 (Rose);
3,918,490 (Goda); 4,071,039 (Goof); 4,259,985 (Bergmann); and
4,484,599 (Hanover et al.). U.S. Pat. No. 6,871,660 to Hampsch
discloses a solenoid operated double or dual pinch valve to provide
alternating flow capability in a devices used in medical and
pharmaceutical laboratory research. The various double or dual
pinch valves disclosed in the foregoing patents, as indicated, have
the ability to control the flow of the respective fluids through
two channels by pinching none, one, or both of the channels through
the pinch valve. Accordingly, these pinch valves allow for one
channel to be completely open and the other to be completely closed
so as to allow only one fluid to pass through the pinch valve,
allow for both channels to completely open, or completely block
both channels. As a result, these pinch valves provide no ability
to mix or control the proportional mixing of two or more fluids in
any desired proportion as provided in the embodiments disclosed
herein in this disclosure. Such ability to mix or, more clearly,
control the proportional mixing of two fluids has been attempted by
varying the respective speeds at which two respective pump devices
deliver fluids to a mixing fluid path, such as disclosed in U.S.
Pat. No. 3,935,971 to Papoff et al., but such a system is in
practice difficult to control as it involves regulating precisely
motor speed of the motors driving the respective pump devices. As a
result, such controlled, dual pump systems do not present a very
accurate proportioned mixture to the output or delivery conduit.
The foregoing shortcomings are overcome by the various embodiments
described herein.
SUMMARY OF THE INVENTION
In one embodiment, a system for mixing and delivering fluids such
as contrast media and a diluent such as saline is disclosed
comprising at least two fluid sources, a pump, a joining fluid path
connecting the at least two fluid sources to an inlet to the pump,
and a valve device in the fluid path upstream of the pump. The
valve device comprises an actuator adapted to restrict flow in at
least one of respective fluid lines connecting the at least two
fluid sources to the pump inlet. A controller may be operatively
associated with the valve device for controlling positional
movement of the valve device actuator. A patient interface device,
such as a catheter as an example, may be associated with an outlet
of the pump. The valve device actuator is generally adapted to
restrict the flow in at least one of the respective fluid lines
such that an incremental positional change in valve device actuator
position provides a substantially linear change in fluid mixture
ratio of the fluids from the at least two fluid sources to the pump
inlet.
The fluids may comprise at least contrast media and a diluent such
as saline. The valve device actuator may be adapted to
simultaneously at least partially restrict flow in each of the
respective fluid lines. In one embodiment, the pump comprises a
positive displacement pump, for example, a multi-chamber piston
pump. In another embodiment, the pump comprises a peristaltic pump.
The respective fluid lines may have different diameters. The
respective fluid lines may comprise compressible tubing, and the
valve device may comprise a pinch valve and the valve device
actuator may comprise a pinch block adapted to restrict flow in at
least one of the respective fluid lines via compression of the
compressible tubing. Movement of the pinch block may be effected by
a servomotor. The respective fluid lines may be joined via a branch
connector having an outlet in fluid connection with the pump inlet.
A flow meter may be associated with at least one of the respective
fluid lines. The controller may effect positional change of the
valve device actuator at least in part based on feedback from the
flow meter.
Another aspect disclosed herein relates to a method for mixing and
delivering fluids such as contrast media and a diluent such as
saline to a patient. Such a method generally includes providing a
joining fluid path connecting at least two fluid sources to an
inlet to a pump, providing a valve device including a valve device
actuator in the fluid path upstream of the pump, and restricting
the flow in at least one of the respective fluid lines with the
valve device actuator. The valve device actuator is generally
adapted to restrict flow in at least one of respective fluid lines
connecting the at least two fluid sources to the pump inlet. The
flow is restricted in at least one of the respective fluid lines by
the valve device actuator such that an incremental positional
change in valve device actuator position provides a substantially
linear change in fluid mixture ratio of the fluids from the at
least two fluid sources to the pump inlet.
The fluids may again comprise contrast media and a diluent such as
saline. Another feature of the method relates to associating a
patient interface device, such as a catheter as an example, with an
outlet of the pump. In one alternative, the valve device actuator
simultaneously at least partially restricts flow in each of the
respective fluid lines. A further feature of the method relates to
associating a flow meter with at least one of the respective fluid
lines. In one embodiment, the pump comprises a positive
displacement pump. In another embodiment, the pump comprises a
peristaltic pump. The respective fluid lines may have different
diameters. As noted hereinabove, the respective fluid lines may
comprise compressible tubing, and the method may further comprise
at least partially compressing the compressible tubing of at least
one of the respective fluid lines with the valve device actuator to
restrict flow. In one embodiment, the valve device may comprise a
pinch valve and the valve device actuator may comprise a pinch
block adapted to restrict flow in at least one of the respective
fluid lines via compression of the compressible tubing. A flow
meter may be associated with at least one of the respective fluid
lines and the method may further comprise a controller effecting
positional change of the valve device actuator at least in part
based on feedback from the flow meter.
Further details and advantages will become clear upon reading the
following detailed description in conjunction with the accompanying
drawing figures, wherein like parts are identified with like
reference numerals throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a fluid delivery system wherein two
fluids may be delivered through use of two pumps to a patient.
FIG. 2 is a schematic view of a fluid delivery system wherein
multi-fluids may be delivered to a patient through use of a single
pump.
FIG. 3 is a schematic view of an embodiment of a system capable of
controlled proportional mixing of fluids and continuous or
intermittent delivery thereof to a patient.
FIG. 4 is a perspective view of a portion of the system shown in
FIG. 3 showing a pump and a valve device of the system.
FIG. 5 is a plan view of the valve device provided in the system of
FIGS. 3-4.
FIG. 6 is a front and partial cross-sectional view of the valve
device of FIG. 5.
FIG. 7 is a graphical representation of contrast medium
concentration as a function of position of the valve device of
FIGS. 5-6.
FIG. 8 is a perspective view of an embodiment of a mixing stopcock
valve having applications in mixing two (or more) fluids.
FIG. 9 is a front view of the mixing stopcock of FIG. 8.
FIGS. 10A-10E are respective cross-sectional views of the mixing
stopcock valve of FIGS. 8-9 showing various operational states of
the valve.
FIG. 11 is a schematic view of a variation of the fluid delivery
system of FIG. 2 incorporating a controlled mixing stopcock valve
pursuant to FIGS. 8-10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For purposes of the description hereinafter, spatial orientation
terms, if used, shall relate to the referenced embodiment as it is
oriented in the accompanying drawing figures or otherwise described
in the following detailed description. However, it is to be
understood that the embodiments described hereinafter may assume
many alternative variations and configurations. It is also to be
understood that the specific devices illustrated in the
accompanying drawing figures and described herein are simply
exemplary and should not be considered as limiting.
FIG. 1 illustrates an exemplary system 10 for delivering contrast
media and a diluent, such as saline, to a patient in a sequential
or simultaneous manner via the use of two pump platforms. While
system 10 is described in the context of the delivery of contrast
and saline, for example, to a patient, system 10 may be applicable
for situations where it is desired to supply any two fluids to a
patient intravenously. It will be further appreciated that system
10 may be readily expanded to deliver multi-fluids (e.g., more than
two fluids) to a patient. In the illustrated and non-limiting
example, contrast media of similar or different concentrations is
contained in respective conventional containers 12, 14. Respective
and optional delivery reservoirs 16, 18 are associated with
contrast containers 12, 14. A contrast fluid path 20 joins or
connects the respective contrast reservoirs 16, 18 to a manual or
automatic selector valve 22 provided in contrast fluid path 20.
Contrast fluid path 20 includes a first input line 24 and a second
input line 26 connecting the respective reservoirs 16, 18 to first
and second input ports 28, 30, respectively, to selector valve 22.
An output port 32 of selector valve 22 is associated with or
connected to a first pump 34 and, in particular, an inlet port 36
of first pump 34. First pump 34 may be of conventional design such
as the positive displacement, multi-piston pump disclosed in U.S.
Pat. No. 6,197,000 to Reilly et al. incorporated herein by
reference. Motive forces to operate first pump 34 are provided by a
pump servomotor 38 and pump drive 40. Outlet port 42 of first pump
34 is associated or connected to a patient P via patient fluid path
44 and the output from first pump 34 to patient P is controlled by
interposing a stopcock 46 in patient fluid path 44. Stopcock 46 has
an input port associated with the outlet port 42 of first pump 34
and further includes an outlet port associated with a waste
reservoir 48. Other features of stopcock 46 are described
hereinafter.
Another portion of system 10 is a diluent delivery portion 50
wherein a diluent such as saline is provided in a conventional IV
bag type container 52. A second pump 54, which is typically
identical to first pump 34, has an outlet 55 connected to the
patient fluid path 44 via stopcock 46 to provide saline solution to
patient P and/or saline flush to fluid path 44. Second pump 54 is
provided with its own pump servomotor 56 and pump drive 58. Diluent
container 52 is connected via a diluent fluid path 60 to a second
input port on stopcock 46 so as to provide diluent supply and flush
to patient fluid path 44. As shown in FIG. 1, stopcock 46 has a
first input port A associated outlet port 42 of pump .[.46.].
.Iadd.34.Iaddend., a second input port B associated with associated
outlet port 55 of second pump 54, a first outlet port C associated
with patient fluid path 44, and a second outlet port D associated
with waste reservoir 48. Selector valve 22 may be automatically or
remotely operated via control of a valve servomotor 62 and
associated valve drive 64 and may be, for example, an automated
stopcock. If desired, stopcock 46 may be automated in a similar
manner to selector valve 22. A controller (not shown) may be
provided to automate operation of system 10 via control of pump
servomotors 38, 56 and valve servomotor 62.
In operation, selector valve 22 may be operated to select the
contents of one of the two provided contrast-containers 12, 14
which allows pump 34 to extract the selected contrast medium via
contrast fluid path 20 and selector valve 22 and deliver the
selected contrast medium to patient fluid path 44 via stopcock 46.
Saline may be delivered to patient fluid path 44 via stopcock 46 by
operation of second pump 54 and diluent fluid path 60. Pumps 34, 54
may be alternately operated to sequentially supply selected
contrast medium and saline to patient fluid path 44. Alternatively,
both pumps 34, 54 may be operated simultaneously, with mixing of
the selected contrast medium and saline occurring in the patient
fluid path 44 and/or in stopcock 46. Stopcock 46 is desirably
configured to permit at least partial simultaneous fluid
communication to be present between pump outlet 42 of first pump 34
and pump outlet 55 of second pump 54 with patient fluid path 44 to
permit simultaneous delivery of both contrast medium and saline to
patient fluid path 44.
Typically, mixing of the selected contrast media and saline to
achieve any desired proportional mixture of these fluids is
accomplished by controlling the flow rate delivered by the
respective pumps 34, 54. However, this is also a disadvantage with
system 10 as two separate pumps 34, 54 must be operated and,
further, their operations coordinated to deliver a desired,
proportioned mixture of contrast and saline to patient fluid path
44. This arrangement is similar to that disclosed in U.S. Pat. No.
3,935,971 to Papoff et al. discussed previously, wherein the
operating speeds of two peristaltic pumps must be controlled and
coordinated to obtain a desired proportional mixture of two fluids.
In system 10, similar control of pumps 34, 54 is necessary to
obtain a desired mixture ratio or proportional mixture of contrast
and saline. The pump control aspects of U.S. Pat. No. 3,935,971 to
Papoff et al. applicable to the control of pumps 34, 54 are
incorporated herein by reference.
Mixing of the selected contrast medium and saline may also be
accomplished with use of a "mixing" stopcock valve for stopcock 46,
such as disclosed in U.S. Pat. No. 3,957,082 to Fuson et al.,
incorporated by reference previously (but as a two-fluid version of
this valve), rather than by operational control of pumps 34, 54.
However, a preferred mixing stopcock valve 300 particularly
suitable for this application is discussed herein in connection
with FIGS. 8-10 which accounts for upstream pressure and/or
viscosity differences between contrast medium and saline which is
not a feature or consideration of the Fuson et al. mixing stopcock.
It is noted that selector valve 22 may also be a mixing stopcock
valve as disclosed in the Fuson et al. patent (but as a two-fluid
version of this valve) if it is desired to mix the contents of
contrast containers 12, 14 in a preset or "fixed" proportional
mixture prior to delivering this contrast mixture to first pump 34.
However, again, such a known mixing stopcock valve as disclosed by
Fuson et al. does not account for upstream pressure and/or
viscosity differences which may be present between the contrast
media present in contrast containers 12, 14 as does the mixing
stopcock valve 300 illustrated in FIGS. 8-10 and discussed herein.
Use of mixing stopcock valve 300 in system 10 permits pumps 34, 54
to operate at the same or substantially the same speeds, which
proportional mixing being accomplished by valve 300, as described
herein.
FIG. 2 illustrates a variation of system 10 referred to as system
10a which eliminates second pump 54 by directly connecting diluent
container 52a via diluent fluid path 60a to a third input port 66a
of selector valve 22a. Accordingly, contrast media from contrast
containers 12a, 14a and saline from diluent container 52a are each
connected through single selector valve 22a so that any one of
these three fluids may be provided via pump 34a to patient fluid
path 44a. However, in this specific configuration, typically only
one fluid at a time may be provided to patient P via patient fluid
path 44a providing only the ability to provide sequential flow of
the fluids to patient P. As a result, modified system 10a lacks the
ability to mix contrast media and diluent such as saline,
proportionally or otherwise, and deliver a mixture of contrast and
diluent to patient P without modification to selector valve 22a.
While it may be possible to replace selector valve 22a with the
mixing stopcock valve disclosed in U.S. Pat. No. 3,957,082 to Fuson
et al. which allows an operator to "dial-in" a selected fluid
choice or a preset proportional mixture of fluids (e.g., a 50%-50%
mixture), the Fuson et al. stopcock valve does not account for
upstream pressure and/or viscosity differences, as noted
previously, which may be present between the fluids entering such a
stopcock as does mixing stopcock valve 300 described herein in
connection with FIGS. 8-10. In general, the conventional mixing
stopcock valve disclosed by Fuson et al. is limited in application
to permitting full fluid flow from a first fluid sources, full
fluid flow from a second fluid source, or at most a few preset or
"fixed" proportional mixture settings for the two fluids to be
delivered to a patient and, hence, does not permit a full range of
fluid mixture ratios or proportions to be delivered to a patient as
provided by the system 100 discussed herein in connection with
FIGS. 3-7. The operational control of pumps 34, 54 in system 10
discussed previously may provide a fuller range of fluid mixture
ratios or proportions to be delivered to a patient but respective
operational control of pumps 34, 54 is difficult in practice to
achieve with accuracy particularly when the two fluids have
significantly different viscosities as is the case with contrast
media and saline. It will be clear that, if desired, additional
fluid sources may be provided in system 10a with each having an
additional input line to selector valve 22a.
FIG. 3 is a schematic representation of an embodiment of a system
100 capable of controlled proportional mixing of fluids and further
capable of intermittent or continuous delivery of a proportional
mixed fluid to a patient. In one example, the fluids may be
contrast media and saline which may be proportionally mixed in any
desired mixture ratio and delivered either intermittently or
continuously to a patient undergoing medical radiographic imaging
procedure. System 100 is described for exemplary purposes in the
context of contrast media and saline and the controlled
proportional mixing and delivery thereof to a patient P to explain
the features of the invention. However, this specific application
or explanation should not be considered as precluding the use of
system 100 in other situations. Generally, system 100 is suitable
for use in any situation where it is desired to mix two (or more)
fluids in a controlled proportional manner and deliver such as a
mixed fluid intermittently or continuously to a patient undergoing
a medical procedure involving intravenous fluid infusion, such as
the proportional mixing of a drug with a diluent such as saline as
an example. A full range of proportional mixtures between two (or
more) fluids may be obtained as outputs to the patient P as
described herein. Moreover, it is explicitly noted that the
principle of operation of system 100 may be expanded to
multi-fluids (e.g., three or more) if desired. System 100 has
similar architecture to systems 10, 10a discussed previously with
certain alterations and additions as described herein. Accordingly,
in view of the foregoing, it is expressly noted that system 100 is
not limited to just two fluids and is specifically not limited to
contrast and saline as fluids which may be handled by system
100.
In system 100, contrast media of similar or different
concentrations is contained in respective conventional containers
112, 114. Respective and optional contrast reservoirs 116, 118 are
associated with contrast containers 112, 114. A contrast fluid path
120 joins or connects the respective reservoirs 116, 118 to a
manual or, desirably, automatic selector valve 122 provided in
contrast fluid path 120. Contrast fluid path 120 includes a first
input line 124 and a second input line 126 connecting the
respective contrast reservoirs 116, 118 to first and second input
ports 128, 130 to selector valve 122. An output port 132 of
selector valve 122 is associated with or connected to a pump 134
and, in particular, an inlet port 136 of pump 134 via a joining
fluid path 200 which is associated with an intervening valve device
210. The details of joining fluid path 200 and valve device 210 are
described hereinafter.
Pump 134 may be of conventional design such as the positive
displacement, multi-piston pump disclosed in U.S. Pat. No.
6,197,000 to Reilly et al., previously incorporated herein by
reference. Motive forces to operate pump 134 are provided by a pump
servomotor 138 and pump drive 140. An outlet port 142 of pump 134
is associated or connected to a patient P via patient fluid path
144 and the output from pump 134 to patient P is controlled by
interposing a stopcock 146 in patient fluid path 144. Stopcock 146
has an input port associated with the outlet port 142 of pump 134
and further includes an outlet port associated with a waste
reservoir 148. Peristaltic pumps may also be used as in place of
the positive displacement pump disclosed by Reilly et al.
Peristaltic pumps are well-known in the medical filed for delivery
fluids to patients.
Another portion of system 100 is a diluent delivery portion 150
wherein a diluent such as saline is provided in a conventional IV
bag type container 152. Diluent container 152 is connected via
joining fluid path 200 to inlet port 136 of pump 134. Valve device
210 is operable to control the flow of contrast and saline in
joining fluid path 200 to achieve desired proportional mixing of
contrast and saline entering pump 134 via pump inlet 136. As shown
in FIG. 3, stopcock 146 has a first input port A associated outlet
port 142 of pump 136, and first and second outlet ports C, D
associated with patient fluid path 144 and waste reservoir 148,
respectively. Selector valve 122 may be automatically or remotely
operated via control of a valve servomotor 162 and associated valve
drive 164. If desired, stopcock 146 may be an automated stopcock,
for example, and automated in a similar manner to selector valve
122. Selector valve 122 may also be a "mixing" stopcock valve as
disclosed in the Fuson et al. patent described previously (but a
two-fluid version of this valve), if it is desired to mix the
contents of contrast containers 112, 114 in preset or "fixed"
proportions or ratios prior to delivering this contrast mixture to
joining fluid path 200. As noted previously, the Fuson et al.
"mixing" stopcock valve does not account for upstream pressure
and/or viscosity differences which may be present between the
contrast media present in contrast containers 112, 114 as does
mixing stopcock valve 300 discussed herein in connection with FIGS.
8-10.
Referring further to FIG. 4-7, further details of system 100
including joining fluid path 200 and valve device 210 are shown.
Joining fluid path 200 comprises a first fluid branch or line 202
to conduct selected contrast medium to the pump inlet 136 of pump
134 and a second fluid branch or line 204 to conduct diluent
(typically saline) to the pump inlet 136 of pump 134. The first and
second fluid lines 202, 204 are joined via a joining connector 206,
such as a conventional T-connector or a conventional Y-connector as
shown. Joining connector 206 is in fluid communication with pump
inlet 136 to provide selected contrast medium and saline as a
mixture to pump 134 which delivers this fluid mixture to patient
fluid path 144 via stopcock 146. Desirably, first and second fluid
lines 202, 204 are conventional medical tubing made of a flexible
and resiliently compressible material, such as medical grade
silicone tubing. As shown in FIG. 5, each of the first and second
fluid lines 202, 204 comprises a portion or length L associated
with valve device 210 so that valve device 210 is operable to act
upon this length L of the first and second fluid lines 202, 204 to
restrict fluid flow in one or both of the first and second fluid
lines 202, 204.
As best illustrated in FIG. 6, it will be apparent that first and
second fluid lines 202, 204 may have different diameters with the
second "diluent" fluid line 204 having a smaller diameter than the
first "contrast" fluid line 202. This illustration is relevant for
contrast media and saline as the fluids to be mixed in system 100
and should not be considered as limiting or exhaustive. The
diameters of fluid lines 202, 204 may be set as necessary to
achieve controlled proportional mixing of two fluids to deliver a
desired mixture ratio of these fluids to pump 134, as described
herein. In the case of contrast and saline, which have
significantly different viscosities, diluent fluid line 204 is
typically smaller in diameter than contrast fluid line 202 as
saline has a lower viscosity than typical contrast media. However,
in the case where system 100 is used to mix two fluids of similar
viscosity and upstream head pressure, the diameters of fluid lines
202, 204 may be roughly or exactly equal. Generally, the fluid
associated with fluid line 202 in system 100 has a higher viscosity
than the fluid associated with fluid line 204 in system 100 and
this generally translates into fluid line 202 having a larger
diameter than fluid line 204 to achieve proportional mixing in a
"linear" manner pursuant to the discussion herein.
In one embodiment, valve device 210 may be a dual pinch valve that
includes a valve actuator 212 operably associated with the first
and second fluid lines 202, 204 associated with valve device 220.
In the illustrated configuration, valve device 210 comprises a base
214 having two laterally disposed, spaced apart, and upstanding
sidewalls 216. The base 214 comprises an upstanding dividing
portion 218 in an area 220 defined between sidewalls 216. Sidewalls
216 and dividing portion 218 define a pair of generally parallel
channels 222, 224 which accommodate first and second fluid lines
202, 204, respectively. In particular, channels 222, 224
accommodate the length L of the first and second fluid lines 202,
204 which are to be operably engaged by valve actuator 212 as
described herein. In one embodiment, valve actuator 212 comprises a
pinch block 226 which is movable laterally or horizontally in area
220 to apply compressive forces to one or both of the first and
second fluid lines 202, 204. Pinch block 226 is movable in a
lateral, side-to-side manner in area 220 by a coupled drive
mechanism 228 and servomotor 230. A feature of the configuration of
valve device 210 relates to pinch block 226 being appropriately
sized, configured, and positioned in area 220 such that both the
first and second fluid lines 202, 204 are in a partial state of
compression in channels 222, 224 and, thereby, provide flow
restriction to the respective fluids passing through the first and
second fluid lines 202, 204, namely contrast and saline. Such
mutual compression of fluid lines 202, 204 aid in "linear"
proportional mixing of contrast and saline during operation of
system 100 as described herein. A flow meter 232 is associated with
at least one of the fluid lines 202, 204, typically the second
"saline" fluid line 204 to measure flow rate of saline to pump
inlet 136 of pump 124. Moreover, check valves 234 may be provided
in fluid lines 202, 204 to prevent backflow to contrast media
containers 112, 114 and diluent container 152 during operation of
system 100. A control device or controller 240 is provided in
system 100 to control operation of the system 100. As such,
controller 240 is electronically connected for two-way
communication with at least pump servomotor 138 and pinch block
servomotor 230 used to control movement pinch block 226, and
desirably in two-way communication with flow meter 232 and selector
valve servomotor 162, although flow meter 232 may be adapted just
to provide saline flow rate information to controller 240.
In operation, system 100 in the exemplary embodiment outlined in
the foregoing delivers a mixture of contrast and saline in any
desired proportion or mixture ratio and, with appropriate control
of pump 134, this proportional fluid mixture may be delivered to
patient P continuously or intermittently as desired. Moreover,
system 100 may be controlled such that for incremental or discrete
changes in position of valve actuator 212, substantially linear
fluid mixture ratio changes between contrast and saline are
obtained at the pump inlet 136 which is then delivered by pump 134
via stopcock 146 to patient fluid path 144 and patient P. In system
100, flow rate of saline is determined or known as an input to
controller 240 from flow meter 232 and total output flow from pump
134 is a known quantity as a positive-displacement type pump (e.g.,
operational feedback from pump servomotor 138). From these inputs
to controller 240, the amount of contrast needed for a desired
proportional mixture at pump inlet 136 may be calculated by
controller 240. Controller 240 may then control positioning of
pinch block 226 via pinch block servomotor 230 based on the
feedback from flow meter 232 and pump servomotor 138. Since flow
rate of contrast and saline in fluid lines 202, 204 relates to
pressure drop in each line and this changes with viscosity of the
respective fluids, differential diametrical sizing of fluid lines
fluid lines 202, 204 may be used to provide a generally linear
mixing ratio response with positional change of pinch block 226. In
other words, controller 240 may continuously change lateral
position of pinch block 226 based on inputs (feedback) from flow
meter 232 and pump servomotor 138 to provide more or less
compression to one or the other of contrast and saline fluid lines
202, 204 which are pre-selected in advance such that this changing
compression results in a generally linear mixture ratio response
change at pump inlet 136. Accordingly, this result is achieved by
sizing fluid lines 202, 204 appropriately and feedback control of
pinch block 226 in area 220 such that for each incremental or
discrete change in horizontal, side-to-side position of pinch block
226 in area 220, one and, typically, both of the first and second
fluid lines 202, 204 will undergo different degrees of compression
(more or less) in channels 222, 224 and, therefore, restriction and
as a result the concentration of contrast media entering pump inlet
136 changes by substantially a directly proportional or "linear"
amount. This directly proportional or linear relationship between
pinch block 226 position and contrast medium concentration is
reflected in FIG. 7 illustrating a specific implementation or
example of operation of system 100.
In the specific and non-limiting example resulting in the graphical
model shown in FIG. 7, first or contrast fluid line 202 may have a
diameter of 0.187 in and second or saline fluid line 204 may have a
diameter of 0.062 in. First and second fluid lines 202, 204 are
disposed in respective channels 222, 224. Valve device actuator
212, namely, pinch block 226 is disposed in area 220 such that
pinch block 226 at least partially compresses both fluid lines 202,
204 restricting fluid flow of contrast and saline therein,
respectively. Flow rate of saline is determined or known from flow
meter 232 and total output flow from pump 134 is a known quantity
as described previously. As further described previously, change in
lateral or side-to-side position of pinch block 226 is controlled
by drive mechanism 228 and accompanying servomotor 230. A software
algorithm is desirably provided in a control device or controller
240 to control with precision the movement of pinch block 226 in
area 220. Such controlled movement of pinch block 226 controls with
generally equal precision the amount of compression or restriction
in one or both of fluid lines 202, 204. FIG. 7 illustrates that
with appropriate relative sizing between fluid lines 202, 204 and
feedback control of pinch block 226, incremental positional changes
of pinch block 226 result in substantially directly proportional or
linear changes in contrast concentration to pump inlet 136 of pump
134 over a range of fluid flows. Accordingly, if it is desired to
adjust contrast concentration down or up, movement of pinch block
226 permits additional or less saline pass through valve device
210. For example, if additional saline is required to adjust the
desired ratio, pinch block 226 is controlled in response to provide
less restriction or compression of saline fluid line 204 while
further restricting or compressing contrast fluid line 202. While
the foregoing operation of system 100 was described in a manner
indicating that both fluid lines 202, 204 are each in partial
compression during operation of system 100, it will be clear to
those skilled in the art that this need not always be the case and
that the system 100 may be configured such that only one fluid line
is compressed at a time during operation of system 100.
In the foregoing non-limiting example, the relationship between the
change in position of pinch block 226 and the contrast medium
concentration has been described as substantially linear. However,
it should be noted that nonlinear relationships can be obtained by
variations of system 100. For example, for some incremental changes
in position of pinch block 226, the concentration of contrast
medium may change exponentially or by some other nonlinear factor.
For example, if the position changes by an amount x, the
concentration may increase by an amount proportional to x.sup.n.
Such nonlinear relationships may be achieved depending upon several
factors including the particular sizes and configurations of the
components of system 100, fluid viscosities of the fluids involved,
upstream pressure differential, and flow rates utilized.
While the foregoing system 100 and its operation was described with
reference to two specific fluids, namely, contrast and saline, this
should not be considered as limiting as noted previously.
Additionally, system 100 may be expanded to accommodate additional
fluids beyond just the two-fluid application discussed hereinabove.
This may be accomplished, for example, by adding a third fluid
source and an accompanying third flow path in joining flow path 200
passing through valve device 210 and configuring valve device 210
and, namely, valve actuator 212 to act upon this third or
additional flow path. In such a situation, pinch block 226 may be
sized and configured to include depending portions that can
simultaneously compress or pinch two or more of the multi-flow flow
paths. For example, in a three-fluid modification, an additional
"middle" side wall 216 could be provided to operate on a "middle"
flow path so that the modified pinch block 226 can compress it in
addition to one of the other two paths. In this manner, two of the
three flow paths may be restricted while the other is unrestricted.
Alternatively, two separately controlled pinch blocks 226 may be
used on respective sides of the "middle" flow path so that the
pinching is independently performed by each pinch block 226,
allowing the two pinch blocks to move in opposite directions.
Moreover, while it was indicated in the foregoing that both fluid
lines 202, 204 of joining flow path 200 are each typically at least
partially compressed or restricted during operation of valve device
210 and valve actuator 212, fluid lines 202, 204 and valve device
210 and, namely, valve actuator 212 may be designed such that only
one of these fluid lines 202, 204 needs to compressed at any given
time to achieve proportional fluid mixing and desirably linear
proportional fluid mixing while the other fluid line remains in an
uncompressed or normal state.
Referring to FIGS. 8-10, a "mixing" stopcock valve 300 is
illustrated which may be used in the foregoing systems 10, 10a, 100
in the specific locations/applications identified hereinabove.
Mixing stopcock valve 300 is adapted to provide proportional mixing
of two (and potentially multiple fluids) which have differing
upstream pressures and/or viscosities to realize, according to one
feature, accurate proportional mixtures of the two fluids. As
described previously, mixing-type stopcock valves are generally
known, for example, from Fuson et al. However, the mixing-type
stopcock valve described in Fuson et al. assumes that upstream
pressure and/or viscosity differences are non-existent or minimal
between the two or more fluids being mixed in this valve. In the
case of contrast media and saline as examples, viscosity of the two
fluids differs substantially such that if the Fuson et al. valve
were used with contrast and saline, the preset or fixed
proportional mixtures, for example, a 50%-50% mixture in one
selection position, designed to result from this valve will not
occur with any accuracy. The mixing stopcock 300 of FIGS. 8-10
overcomes this limitation with the prior art as differences in
upstream pressure and/or viscosity are accounted for in the
structure of the valve.
Mixing stopcock valve 300 comprises a stopcock body 302 formed of
plastic material, desirably a medical grade plastic material. A
stopcock actuator 304 is disposed in a valve chamber 306 defined by
stopcock body 302. Additionally, stopcock body 302 defines a
plurality of input ports, namely, a contrast input port 308 and a
saline input port 310 in the illustrated embodiment. While mixing
stopcock valve 300 is described with reference to contrast and
saline for illustrative purposes only, it will be clear that mixing
stopcock 300 valve is suitable for applications where it is desired
to mix any two (or possibly more) fluids of differing upstream
pressure and/or viscosity. Stopcock body 302 further defines an
outlet port 312. Inlet ports 308, 310 and outlet port 312 may be
configured as luer-type connectors as illustrated. Inlet ports 308,
310 comprise contrast and saline inlet ports 308, 310 in the
present example.
Stopcock actuator 304 defines a generally T-shaped internal conduit
314. Internal conduit 314 includes a first conduit portion 316 and
a second conduit portion 318 of generally similar or equal
diameter, and further defines a third conduit portion 320 of
reduced diameter relative to the diameters of first and second
conduit portions 316, 318. The relative difference in diameters
between third conduit portion 320 and first and second portions
316, 318 accounts for upstream pressure and/or viscosity
differences between the fluids to be conducted through stopcock
valve 300 as in the present case involving contrast and saline.
Relative diameter sizing between third conduit portion 320 and
first and second portions 316, 318 to account for upstream pressure
and/or fluid viscosity differences is readily within the skill of
those skilled in the art.
FIG. 10A-10E illustrate operation of mixing stopcock 300 wherein
the various positions of stopcock actuator 304 permit full
contrast, full saline, or a mixture of contrast and saline to be
delivered to outlet port 312. In FIG. 10A, an "off" or no-flow
position of stopcock valve 300 is illustrated, wherein stopcock
actuator 304 is positioned such that internal conduit 314 is
unaligned with inlet ports 308, 310 and outlet port 312 thereby
blocking flow into or from internal conduit 314. In FIG. 10B,
stopcock actuator 304 is positioned such that first and second
conduit portions 316, 318 of internal conduit 314 are aligned with
contrast port 308 and outlet port 312, respectively, to permit
delivery of contrast only to outlet port 312. In FIG. 10C, stopcock
actuator 304 is positioned such that second conduit portion 318 and
reduced diameter third conduit portion 320 are aligned are aligned
with saline port 310 and outlet port 312, respectively, to permit
delivery of saline only to outlet port 312. It is noted that due to
the lower viscosity of saline, the reduced diameter third conduit
portion 320 permits a similar flow rate of saline to result in
outlet port 312 as obtained in the contrast-only setting shown in
FIG. 10A. In FIG. 10D, stopcock actuator 304 is positioned such
that first conduit portion 316 and reduced diameter third conduit
portion 320 are aligned are aligned with saline port 310 and
contrast port 308, respectively, to permit delivery of an accurate
50%-50% mixture of saline and contrast to outlet port 312 via
second conduit portion 318 of internal conduit 314. In FIG. 10D, by
aligning the reduced diameter third conduit portion 320 with
contrast port 308 more restriction is present to the high viscosity
contrast medium while less restriction is present to the lower
viscosity saline passing through saline port 310 and first conduit
portion 316. These relative differences in restriction of flow due
to diameter differences results in the combining of contrast and
saline in an accurate 50%-50% mixture. As shown in FIGS. 8-9, the
contrast only setting of FIG. 10B is represented by a "C" tab mark
on stopcock body 302, the saline only setting of FIG. 10C is
represented by a "S" tab mark on stopcock body 302, and other
proportional mixtures between full contrast and full saline are
denoted by tab marks 322 on stopcock body 302. For example, tab
mark 322(2) corresponds to a 50%-50% mixture of contrast and saline
(FIG. 10D), while tab mark 322(1) corresponds to a 75% saline-25%
contrast mixture and tab mark 322(3) corresponds to a 75%
contrast-25% saline mixture.
FIG. 10E illustrates a further aspect of mixing stopcock 300
wherein a "custom mix" of contrast and saline may be obtained.
Gradations representing these custom proportional mixtures may be
visually and tactilely provided on the stopcock body 302 by
providing a plurality of tab marks similar to tab marks 322
discussed previously between tab mark "S" and tab mark "C" as an
example. In FIG. 10E, stopcock actuator 304 is positioned such that
first conduit portion 316 is in fluid communication but not aligned
directly with saline port 310 resulting in restricted flow of
saline, and reduced diameter third conduit portion 320 is in fluid
communication but not aligned directly with contrast port 308
resulting in restricted flow of contrast. As such, a specific
proportional mixture of contrast and saline is delivered to outlet
port 312 when the stopcock actuator 304 is in the orientation shown
in FIG. 10E.
As stopcock actuator 304 is rotated clockwise, the flow restriction
between third conduit portion 320 and contrast port 308 decreases
and, concurrently, the flow restriction between first conduit
portion 316 and saline port 310 also decreases. Since the diameter
of third conduit portion 320 is less than that of first conduit
portion 316, the rate of flow increases faster through third
conduit portion 320 than through first conduit portion 316. This
result occurs because a larger percentage of third conduit portion
320 comes into increased fluid communication with contrast port 308
more quickly than occurs between first conduit portion 316 and
saline port 310 through the same angle of rotation of stopcock
actuator 304. Because the flow rate of contrast increases faster
and more fluid area is opened to flow more quickly than on the
saline "side" as stopcock actuator 304 is rotated clockwise, the
concentration of contrast medium flowing through second conduit
portion 318 increases with clockwise rotation of the stopcock
actuator 304. Once third conduit portion 320 first comes into
substantially unrestricted fluid communication with the contrast
port 308 (but still less than a direct alignment between third
conduit port 320 and contrast port 308 as in FIG. 10D), some flow
restriction between first conduit portion 316 and saline port 310
is still present. Thus, maximum concentration of contrast will
occur when the third conduit portion 320 first comes into
substantially unrestricted fluid communication with contrast port
308. This maximum concentration is greater than 50% because the
maximum amount of contrast is able to flow though third conduit
portion 320, but first conduit portion 316 is not fully aligned
with saline port 310, as in the orientation shown in FIG. 10D, and
some flow restriction is still present. As stopcock actuator 304 is
rotated further clockwise, the concentration of contrast decreases
as the saline flow restriction is removed and more saline is able
to flow through first conduit portion 316. Eventually, first
conduit portion 316 is fully aligned with saline port 310 as in the
orientation shown in FIG. 10D, making the making the mixture flow
present in outlet port 312 a 50% contrast/50% saline mixture.
As the stopcock actuator 304 is rotated either clockwise or
counterclockwise from the orientation shown in FIG. 10D, the flow
of saline will initially decrease as the flow of contrast remains
the same. This is again due to the diameter differences between
third conduit portion 320 and first conduit portion 316, whereby
first conduit portion 316 is almost immediately subject to flow
restriction while third conduit portion 320 remains substantially
unrestricted. Thus, concentration of contrast will again increase
to greater than 50%. Once third conduit portion 320 begins to close
as stopcock actuator 304 is continued to be rotated either
clockwise or counterclockwise, the rate of flow decreases faster
through third conduit portion 320 than through first conduit
portion 316 and the concentration of contrast in the mixture again
falls. This result is again due to the diameter differences between
the third conduit portion 320 and first conduit portion 316. At
some point in the rotation of stopcock actuator 304, flow of saline
also ceases as the stopcock actuator 304 is placed in the "OFF"
position illustrated in FIG. 10A.
The rate at which contrast medium concentration increases with
rotation of stopcock actuator 304 depends upon the relative shapes
(e.g., diameters) and relative cross-sectional areas of first
conduit portion 316 and third conduit portion 320 open to fluid
flow. These relative shapes and cross-sections may be sized and
configured such that the percentage of contrast medium will vary in
a substantially linear proportion to rotation of stopcock actuator
304. In other words, mixing stopcock 300 may be configured such
that for a known angle of rotation of stopcock actuator 304, a
substantially directly proportional increase or decrease in
concentration of contrast medium is obtained in outlet port 312.
For example, rotating stopcock actuator 304 of mixing stopcock 300
can cause the concentration of contrast in the fluid mixture in
outlet port 312 to range from substantially 0% in the fluid mixture
to a percentage greater than 50%, which can be as much as about
80-90% in the fluid mixture. The rate of change in fluid mixture
ratio or proportion may be substantially linear or directly
proportion between the foregoing minimum and maximum contrast
concentrations.
FIG. 11 illustrates a system 10b which is a variation of system 10a
of FIG. 2 and applies the advantages of the "custom mix"
application of FIG. 10E to a fluid delivery system comprising two
fluids of differing viscosity, such as contrast and saline as an
example. The details of system 10b are generally similar to system
10a except that diluent delivery portion 50a is deleted from system
10b and one of contrast containers 12a, 14a, container 14a as an
example, is now filled with diluent such as saline and identified
in FIG. 11 with reference character 52b for consistency with the
foregoing disclosure. Accordingly, fluid path 20b carries both
contrast and saline in this embodiment. Additionally, selector
valve 22a is replaced with mixing stopcock valve 300, as
illustrated, having the features described hereinabove and
particularly has the features described in connection with FIG.
10E, namely a "custom mix" capability. Moreover, stopcock valve 300
may be automated in a similar manner to valve 22a. With the
positioning of stopcock valve 300 in system 10b, custom
proportional mixing, which changes in a substantially linear or
directly proportional manner, may be accomplished between contrast
medium from container 12b and diluent (e.g., saline) from container
52b which are intended to be exemplary and non-limiting examples of
two fluids that may be mixed and delivered by system 10b. Pump 34b
may thereby deliver a custom proportional mixture of fluids to
patient fluid path 44b via stopcock 46b. A controller 240b similar
to controller 240 described previously may be used to control
operation of pump 34b via pump servomotor 38b and operation of
automatic stopcock valve 300 via valve servomotor 62b.
Additionally, controller 240b receives saline flow rate data from
flow meter 232b associated with saline fluid path 50b and total
flow data via electronic communication with pump servomotor 38b in
a similar manner to that described with respect to system 100
discussed hereinabove. As will be clear from the foregoing
discussion of controller 240 in system 100, controller 240b
provides continuous input to valve servomotor 62b which controls
rotational positioning of stopcock actuator 304 to maintain or
achieve a desired proportional "custom mix" of contrast and saline
to pump inlet 36b. As described previously, flow meter 32b and pump
servomotor 38b provide the feedback information or data to
controller 240b to allow controller 240b to make continuous
rotational updates of stopcock actuator 304 to maintain or achieve
the desired proportional "custom mix" of contrast and saline to
pump inlet 36b. In other words, controller 240b operates in an
analogous manner to controller 240 described previously but in
system 10b rotational positional movement of stopcock actuator 304
is used to achieve the desired result of directly proportional or
linear changes in contrast concentration to pump inlet 36b of pump
34b over a range of fluid flows.
While embodiments of a system capable of capable of controlled
proportional mixing and delivery of fluid mixtures to a patient
and, in one particular application, the controlled proportional
mixing of contrast medium with saline for delivery to a patient
undergoing a medical imaging procedure was provided in the
foregoing description, those skilled in the art may make
modifications and alterations to these embodiments without
departing from the scope and spirit of the invention. Accordingly,
the foregoing description is intended to be illustrative rather
than restrictive. The invention described hereinabove is defined by
the appended claims and all changes to the invention that fall
within the meaning and the range of equivalency of the claims are
to be embraced within their scope.
* * * * *