U.S. patent application number 17/686929 was filed with the patent office on 2022-06-16 for method for controlling fluid accuracy and backflow compensation.
The applicant listed for this patent is Bayer Healthcare LLC. Invention is credited to Adam Caruso, James Dedig, Herbert Grubic, Andreas Maihoefer, Ralph Schriver, Michael Spohn, Michael Swantner.
Application Number | 20220184568 17/686929 |
Document ID | / |
Family ID | 1000006178185 |
Filed Date | 2022-06-16 |
United States Patent
Application |
20220184568 |
Kind Code |
A1 |
Schriver; Ralph ; et
al. |
June 16, 2022 |
Method For Controlling Fluid Accuracy And Backflow Compensation
Abstract
A method for controlling fluid ratio accuracy during a dual flow
injection with a powered injection system is described. The method
includes predicting a first capacitance volume of a first syringe
comprising a first medical fluid and a second capacitance volume of
a second syringe comprising a second medical fluid with a first
capacitance correction factor and a second capacitance correction
factor, respectively, selecting a ratio of the first medical fluid
and the second medical fluid to be administered to a patient in the
dual flow injection, determining a relative acceleration ratio of a
first piston of the first syringe and a second piston of a second
syringe based on the predicted first capacitance volume and the
predicted second capacitance volume, wherein the relative
acceleration ratio is selected to maintain the selected ratio of
the first medical fluid and the second medical fluid during the
dual flow injection, and injecting a mixture of a first medical
fluid and a second medical fluid having the selected ratio with the
powered injection system.
Inventors: |
Schriver; Ralph; (Tarentum,
PA) ; Maihoefer; Andreas; (Cheswick, PA) ;
Dedig; James; (Pittsburgh, PA) ; Spohn; Michael;
(Fenelton, PA) ; Grubic; Herbert; (Pittsburgh,
PA) ; Swantner; Michael; (Saxonburg, PA) ;
Caruso; Adam; (Trafford, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bayer Healthcare LLC |
Whippany |
NJ |
US |
|
|
Family ID: |
1000006178185 |
Appl. No.: |
17/686929 |
Filed: |
March 4, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16013050 |
Jun 20, 2018 |
11278853 |
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17686929 |
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15417945 |
Jan 27, 2017 |
10029220 |
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16013050 |
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13799426 |
Mar 13, 2013 |
9555379 |
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15417945 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01F 25/45243 20220101;
A61M 39/105 20130101; B01F 25/23 20220101; A61M 5/16827 20130101;
A61M 2039/0027 20130101; B01F 2215/0468 20130101; B01F 25/45241
20220101; B01F 23/45 20220101; B01F 2025/916 20220101; B01F 25/4334
20220101; B01F 25/105 20220101; Y10T 137/0329 20150401; A61M
2039/1077 20130101; B01F 25/43231 20220101; B01F 27/55 20220101;
B01F 2101/2202 20220101; B01F 25/4336 20220101; A61M 2206/16
20130101; B01F 33/50112 20220101; B01F 35/51 20220101; B01F 27/111
20220101; B01F 25/43171 20220101; A61M 5/007 20130101; B01F
25/431971 20220101; B01F 25/43141 20220101; B01F 25/431974
20220101; A61M 2206/14 20130101; B01F 27/50 20220101; B01F 25/4521
20220101; B01F 25/431 20220101; B01F 2025/931 20220101; B01F
2215/0459 20130101 |
International
Class: |
B01F 25/431 20060101
B01F025/431; A61M 5/00 20060101 A61M005/00; A61M 5/168 20060101
A61M005/168; A61M 39/10 20060101 A61M039/10; B01F 23/45 20060101
B01F023/45; B01F 25/23 20060101 B01F025/23; B01F 25/00 20060101
B01F025/00; B01F 25/433 20060101 B01F025/433; B01F 25/452 20060101
B01F025/452; B01F 25/4314 20060101 B01F025/4314; B01F 25/432
20060101 B01F025/432; B01F 27/50 20060101 B01F027/50; B01F 27/55
20060101 B01F027/55; B01F 27/111 20060101 B01F027/111; B01F 33/501
20060101 B01F033/501; B01F 35/51 20060101 B01F035/51 |
Claims
1-20. (canceled)
21. A method for controlling fluid ratio accuracy during a dual
flow injection with a fluid delivery system including a powered
fluid injector, the method comprising: selecting, using a fluid
control module operatively associated with the powered fluid
injector, a fluid ratio of a first medical fluid and a second
medical fluid to be administered to a patient in the dual flow
injection; determining, using the fluid control module operatively
associated with the powered fluid injector, a relative acceleration
ratio of a first piston for injecting the first medical fluid and a
second piston for injecting the second medical fluid, wherein the
relative acceleration ratio is selected to compensate for
capacitance of the fluid delivery system while maintaining the
selected fluid ratio during the dual flow injection; and injecting
a mixture of the first medical fluid and the second medical fluid
having the selected fluid ratio with the fluid delivery system.
22. The method of claim 21, wherein the acceleration ratio of the
first piston relative to the second piston is less than 1:1.
23. The method of claim 21, further comprising: initially during
injection of the mixture, accelerating the first piston to a first
steady state velocity over a longer time period than a time period
for accelerating the second piston to a second steady state
velocity.
24. The method of claim 23, further comprising: after the first
piston reaches the first steady velocity, maintaining the first
steady state velocity during the injection of the mixture, and
after the second piston reaches the second steady velocity,
maintaining the second steady state velocity during the injection
of the mixture.
25. The method of claim 23, wherein the first steady state velocity
is higher than the second steady state velocity.
26. The method of claim 21, further comprising: initially during
injection of the mixture, accelerating the second piston at a
maximum acceleration that the second piston can achieve.
27. The method of claim 21, further comprising: initially during
injection of the mixture, accelerating the second piston to
minimize the amount of time required for the second piston to reach
a steady state velocity.
28. The method of claim 21, further comprising: initially during
injection of the mixture, accelerating the second piston to reach a
steady state velocity in less than 0.5 seconds.
29. The method of claim 21, wherein the first piston is accelerated
at an acceleration value A.sub.1, where the acceleration value
A.sub.1 is determined by equation (1),
A.sub.1=A.sub.2/(c(V.sub.1/V.sub.2)) (1) wherein A.sub.2 is an
acceleration value for the second piston, c is a scalar correction
factor selected to compensate for the capacitance of the fluid
delivery system, V.sub.1 is a velocity of the first piston, and
V.sub.2 is a velocity of the second piston.
30. The method of claim 29, further comprising: selecting the
scalar correction factor using the fluid control module operatively
associated with the powered fluid injector.
31. The method of claim 21, wherein the capacitance of the fluid
delivery system comprises at least one of: capacitance of a first
syringe containing the first medical fluid; capacitance of a second
syringe containing the second medical fluid; capacitance of a
tubing set connected to the first syringe; and capacitance of a
tubing set connected to the second syringe.
32. The method of claim of claim 31, further comprising:
predicting, using the fluid control module operatively associated
with the powered fluid injector, at least one of: a capacitance
volume of the first syringe and a capacitance volume of the second
syringe.
33. The method of claim 21, wherein the first medical fluid has a
different viscosity than the second medical fluid.
34. The method of claim 21, wherein the first medical fluid has a
higher viscosity than the second medical fluid.
35. The method of claim 21, wherein the first medical fluid is an
imaging contrast agent and the second medical fluid is saline.
35. The method of claim 35, wherein the fluid ratio of the first
medical fluid to the second medical fluid ranges from 10:90 to
90:10 imaging contrast agent to saline.
36. The method of claim 21, wherein the fluid delivery system
further comprises a first tubing set connected to a distal end of a
first syringe containing the first medical fluid and a second
tubing set connected to a distal end of a second syringe containing
the second medical fluid.
37. The method of claim 28, wherein a backflow volume of the first
medical fluid into the second tubing set is less than 0.5 mL.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of U.S. Ser.
No. 16/013,505, filed Jun. 20, 2018, which is a Continuation
Application of U.S. Ser. No. 15/417,945, filed Jan. 27, 2017, which
is a Divisional Application of U.S. Ser. No. 13/799,426, filed Mar.
13, 2013, now U.S. Pat. No. 9,555,379, the disclosures of which are
incorporated herein in their entirety.
BACKGROUND
Field of the Invention
[0002] The invention described herein relates to medical fluid
delivery applications and, particularly, to a system for the
delivery of one or more medical fluids to a patient using a fluid
path set with a turbulent mixing chamber, backflow compensator,
and/or air bubble trap.
Description of Related Art
[0003] 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 solution (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.
[0004] 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 fluid 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 vascular structures containing the contrast. The resulting
images can be displayed on, for example, a monitor and
recorded.
[0005] In a typical angiographic procedure, 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 contrast injection mechanism 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.
[0006] Automatic contrast injection mechanisms typically include a
syringe connected to one or more powered injectors 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 saline, and a fixed rate of
injection for each. Automatic contrast injection mechanisms provide
improved control over manual apparatus where successful use of such
manual devices is dependent on the skill of the medical
practitioner operating the device. As in a manual system, the fluid
path from the automatic contrast injection mechanism to the patient
includes, for example, a source of contrast, a source of flushing
fluid, typically saline, and a pressure transducer to measure
patient blood pressure. 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.
[0007] When the contrast and the flushing fluid are injected, it is
desirable for the two fluids to be mixed well before injection into
the patient. However, because the contrast and the flushing fluid
typically have different specific gravity and viscosity, the two
solutions may not be thoroughly mixed using a known mixing valve,
such as a T- or Y-shaped joint, or a three-way stopcock. As a
result, when the contrast and the flushing fluid are not mixed
properly, the resulting image taken by a fluoroscopic imaging
apparatus may be uneven, thereby making it difficult to image the
blood vessel clearly. Within the prior art, International
Application Publication No. WO 2011/125303 discloses a mixing
device for mixing two kinds of fluids. The mixing device includes a
first inflow opening and a second inflow opening that is tangential
to the first inflow opening to generate a swirling flow as the
first and second fluids come into contact. The mixing chamber has a
conical shape that is continuously narrowed to an outlet opening.
However, existing solutions are often not adequate in promoting
thorough mixing of the fluids when small amounts of contrast and
flushing solution are introduced and/or when the injection duration
is short. Additionally, such existing mixing devices do not
compensate for backflow of the contrast or the flushing fluid.
[0008] An additional problem with the known multi-fluid injectors
is that fluid backflow occurs in injections where a viscous first
fluid is injected at a higher ratio than a less viscous second
fluid. In such a scenario, before a uniform fluid flow is
established, the fluid pressure of the more viscous first fluid
that is injected at a higher ratio acts against the fluid pressure
of the less viscous second fluid that is injected at a lower ratio
to force the second fluid to reverse the desired direction of flow.
After injection, pressures equalize, and the fluid injection system
achieves a steady state operation where first and second injection
fluids are injected at a desired ratio. However, in small volume
injections, steady state operation cannot be achieved prior to the
completion of the injection process and the total volume of first
and second fluids being delivered. Thus, even though a desired
ratio of first and second fluids may be 80% first injection fluid
to 20% second injection fluid, the actual ratio due to backflow of
the first fluid may be higher. This problem is further compounded
with an increase in injection pressure. Utilizing check valves
downstream of the syringes containing the first and second
injection fluids only prevents contamination of the syringes from
the backflow and does not address the accuracy of the final mixture
ratio.
[0009] While manual and automated injectors are known in the
medical field, improved fluid delivery systems having a fluid path
that promotes turbulent mixing of two or more fluids introduced
into a mixing chamber continue to be in demand in the medical
field. Additionally, improved fluid transfer sets having a fluid
path with a mixing device adapted for thorough fluid mixing are
also desired in the medical field. Moreover, the medical field
continues to demand improved medical devices and systems used to
supply fluids to patients during medical procedures such as
angiography, computed tomography, ultrasound, and NMR/MRI.
BRIEF SUMMARY
[0010] While various embodiments of a flow mixing device are
described in detail herein, one embodiment may include a housing
having a proximal end opposite a distal end, a first fluid port
provided at the proximal end of the housing for receiving a first
injection fluid, and a second fluid port provided at the proximal
end of the housing for receiving a second injection fluid. A mixing
chamber may be disposed within the housing between the proximal and
distal ends, the mixing chamber being in fluid communication with
the first and second fluid ports for mixing the first and second
injection fluids. A third fluid port may be provided at the distal
end of the housing and in fluid communication with the mixing
chamber for discharging a mixed solution of the first and second
injection fluids. A turbulent flow inducing member may be disposed
within the mixing chamber for promoting turbulent mixing of the
first and second injection fluids. The flow mixing device may
include a third fluid port for receiving a third injection fluid.
The first fluid port and the second fluid port may be substantially
parallel with a longitudinal axis of the housing. The first fluid
port and the second fluid port may be radially offset from a
longitudinal axis of the housing.
[0011] In accordance with another embodiment, the turbulent flow
inducing member may include a flow dispersion device having at
least one deflection member extending over at least a portion of
one of the first and second fluid ports for deflecting the fluid
flow of the first injection fluid or the second injection fluid
from a substantially longitudinal direction to a direction having a
radial component. The turbulent flow inducing member may include
two deflection members, wherein the first deflection member extends
over at least a portion of the first fluid port for deflecting the
first injection fluid radially outward with respect to a
longitudinal axis of the mixing chamber, and wherein the second
deflection member extends over at least a portion of the second
fluid port for deflecting the second injection fluid radially
outward with respect to the longitudinal axis of the mixing
chamber.
[0012] In accordance with another embodiment, the turbulent flow
inducing member may include at least one turbine wheel having a
plurality of rotating blades oriented substantially perpendicular
to a direction of fluid flow through the mixing chamber, the at
least one turbine wheel being rotatable with respect to a
longitudinal axis of the mixing chamber for scattering the first
and second injection fluids within the mixing chamber.
[0013] In accordance with another embodiment, the turbulent flow
inducing member may include a plurality of mixing balls having a
diameter larger than a diameter of a smallest of the first, second,
and third fluid ports, and wherein the mixing balls are agitated
within the mixing chamber by the first and second injection
fluids.
[0014] In accordance with another embodiment, the turbulent flow
inducing member may include a porous filter having a plurality of
open cell elements disposed within at least a portion of the mixing
chamber.
[0015] In accordance with another embodiment, the turbulent flow
inducing member may include a disc disposed across a portion of the
mixing chamber in a radial direction, the disc having a plurality
of recesses extending radially inward from an outer circumference
of the disc and at least one opening extending through a central
portion of the disc.
[0016] In accordance with another embodiment, the turbulent flow
inducing member may include a tubular insert fixed within the
mixing chamber and at least one hydrofoil element extending across
an interior of the tubular insert substantially parallel to a
direction of fluid flow through the mixing chamber. The at least
one hydrofoil element may have a leading edge oriented toward the
proximate end, a trailing edge oriented toward the distal end, an
upper chord extending between the leading edge and the trailing
edge, and a lower chord extending between the leading edge and the
trailing edge opposing the upper chord.
[0017] In accordance with another embodiment, the turbulent flow
inducing member may include a plurality of tubular flow dispersion
members fixed relative to the housing to define the mixing chamber,
each of the plurality of flow dispersion members having a plurality
of wings extending radially inward from an interior sidewall of the
flow dispersion members. The plurality of wings may be spaced apart
at equal intervals around the inner circumference of each flow
dispersion member, and wherein adjacent flow dispersion members are
radially aligned such that the plurality of wings of one flow
dispersion member are angularly offset with regard to the plurality
of wings of the other flow dispersion member.
[0018] In accordance with another embodiment, the turbulent flow
inducing member may include two sinusoidal fluid paths extending
through the mixing chamber, and wherein the two sinusoidal fluid
paths intersect at a plurality of intersection points within the
mixing chamber.
[0019] In another embodiment, the housing may have a first portion
and a second portion joined together at a seam extending around an
outer perimeter of the housing between the proximal and distal
ends. The seam may include a projection provided on one of the
first portion and the second portion and a corresponding groove on
the other of the first portion and the second portion for receiving
the projection within the groove. The mixing chamber may have a
spiral sidewall.
[0020] In accordance with another embodiment, the turbulent flow
inducing member may include a first arcuate tube in fluid
communication with the first fluid port and a second arcuate tube
in fluid communication with the second fluid port, wherein the
first and second arcuate tubes are curved radially inward toward a
central axis of the mixing chamber, and wherein fluid mixing at a
juncture between the first and second arcuate tubes is influenced
by a Coanda effect.
[0021] In a further embodiment, a fluid path set may have a first
fluid line having a proximal end and a distal end, where the
proximal end of the first fluid line is fluidly connectable to a
source of a first injection fluid. The fluid path set may also
include a second fluid line having a proximal end and a distal end,
where the proximal end of the second fluid line is fluidly
connectable to a source of a second injection fluid. A flow mixing
device may be in fluid communication with the distal ends of the
first and second fluid lines at a proximal end of the flow mixing
device. The flow mixing device may include a housing having a
proximal end opposite a distal end, a first fluid port provided at
the proximal end of the housing for receiving a first injection
fluid, and a second fluid port provided at the proximal end of the
housing for receiving a second injection fluid. A mixing chamber
may be disposed within the housing between the proximal and distal
ends, the mixing chamber being in fluid communication with the
first and second fluid ports for mixing the first and second
injection fluids. A third fluid port may be provided at the distal
end of the housing and in fluid communication with the mixing
chamber for discharging a mixed solution of the first and second
injection fluids. A turbulent flow inducing member may be disposed
within the mixing chamber for promoting turbulent mixing of the
first and second injection fluids. The flow mixing device may
include a third fluid port for receiving a third injection
fluid.
[0022] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a flow dispersion
device having at least one deflection member extending over at
least a portion of one of the first and second fluid ports for
deflecting the fluid flow of the first injection fluid or the
second injection fluid from a substantially longitudinal direction
to a direction having a radial component. The turbulent flow
inducing member may include two deflection members, wherein the
first deflection member extends over at least a portion of the
first fluid port for deflecting the first injection fluid radially
outward with respect to a longitudinal axis of the mixing chamber,
and wherein the second deflection member extends over at least a
portion of the second fluid port for deflecting the second
injection fluid radially outward with respect to the longitudinal
axis of the mixing chamber.
[0023] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include at least one turbine
wheel having a plurality of rotating blades oriented substantially
perpendicular to a direction of fluid flow through the mixing
chamber, the at least one turbine wheel being rotatable with
respect to a longitudinal axis of the mixing chamber for scattering
the first and second injection fluids within the mixing
chamber.
[0024] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a plurality of
mixing balls having a diameter larger than a diameter of a smallest
of the first, second, and third fluid ports, and wherein the mixing
balls are agitated within the mixing chamber by the first and
second injection fluids.
[0025] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a porous filter
having a plurality of open cell elements disposed within at least a
portion of the mixing chamber.
[0026] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a disc disposed
across a portion of the mixing chamber in a radial direction, the
disc having a plurality of recesses extending radially inward from
an outer circumference of the disc and at least one opening
extending through a central portion of the disc.
[0027] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a tubular insert
fixed within the mixing chamber and at least one hydrofoil element
extending across an interior of the tubular insert substantially
parallel to a direction of fluid flow through the mixing chamber.
The at least one hydrofoil element may have a leading edge oriented
toward the proximate end, a trailing edge oriented toward the
distal end, an upper chord extending between the leading edge and
the trailing edge, and a lower chord extending between the leading
edge and the trailing edge opposing the upper chord.
[0028] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a plurality of
tubular flow dispersion members fixed relative to the housing to
define the mixing chamber, each of the plurality of flow dispersion
members having a plurality of wings extending radially inward from
an interior sidewall of the flow dispersion members. The plurality
of wings may be spaced apart at equal intervals around the inner
circumference of each flow dispersion member, and wherein adjacent
flow dispersion members are radially aligned such that the
plurality of wings of one flow dispersion member are angularly
offset with regard to the plurality of wings of the other flow
dispersion member.
[0029] In accordance with another embodiment, the turbulent flow
inducing member may include two sinusoidal fluid paths extending
through the mixing chamber, and wherein the two sinusoidal fluid
paths intersect at a plurality of intersection points within the
mixing chamber.
[0030] In another embodiment of the fluid path set, the housing of
the fluid mixing device may have a first portion and a second
portion joined together at a seam extending around an outer
perimeter of the housing between the proximal and distal ends. The
seam may include a projection provided on one of the first portion
and the second portion and a corresponding groove on the other of
the first portion and the second portion for receiving the
projection within the groove. The mixing chamber may have a spiral
sidewall.
[0031] In accordance with another embodiment of the fluid path set,
the turbulent flow inducing member may include a first arcuate tube
in fluid communication with the first fluid port and a second
arcuate tube in fluid communication with the second fluid port,
wherein the first and second arcuate tubes are curved radially
inward toward a central axis of the mixing chamber, and wherein
fluid mixing at a juncture between the first and second arcuate
tubes is influenced by a Coanda effect.
[0032] In a further embodiment, a method of mixing a drug solution
may include the steps of delivering a first injection fluid to a
flow mixing device, delivering a second injection fluid to the flow
mixing device, mixing the first and second injection fluids inside
a mixing chamber of the flow mixing device, and delivering a mixed
solution of the first and second injection fluids from the flow
mixing device. The mixing chamber of the flow mixing device may
include a turbulent flow inducing member for promoting turbulent
mixing of the first and second injection fluids.
[0033] In accordance with a further embodiment, a method for
capacitance volume correction in a multi-fluid delivery system may
include pressurizing a first expandable body having a first
injection fluid by reducing the volume in the first expandable body
with movement of a first pressurizing element and pressurizing a
second expandable body having a second injection fluid by reducing
the volume in the second expandable body with movement of a second
pressurizing element. The method may further include controlling an
acceleration of the first pressurizing element relative to the
acceleration of the second pressurizing element as a function of
relative velocities of the first and second pressurizing elements
and a capacitance correction factor for correcting for volume
expansion of the first and second expandable bodies. Movement of
the first and second pressurizing elements may be controlled with
an algorithm. The first expandable body may be pressurized to a
first pressure, and the second expandable body may be pressurized
to a second pressure. In one embodiment, the first pressure may be
higher than the second pressure. The capacitance correction factor
may be a function of the volume in the first and second expandable
bodies, and a pressure inside the first and second expandable
bodies. The velocity of the first pressurizing member may be higher
than the velocity of the second pressurizing member.
[0034] In another embodiment, a method for capacitance volume
correction in a multi-fluid delivery system may include the steps
of pressurizing a first syringe having a first injection fluid to a
first pressure by reducing the volume in the first syringe with
movement of a first piston at a first acceleration and pressurizing
a second syringe having a second injection fluid to the first
pressure by reducing the volume in the second syringe with movement
of a second piston at a second acceleration different from the
first acceleration. The acceleration of the first piston relative
to the acceleration of the second piston may be a function of a
capacitance correction factor for correcting volume expansion of
the first and second syringes. The capacitance correction factor
may be a function of the volume in the first and second syringes,
and the first pressure.
[0035] These and other features and characteristics of the fluid
path set with a turbulent mixing chamber, as well as the methods of
manufacture and functions of the related elements of structures and
the combination of parts and economies of manufacture, will become
more apparent upon consideration of the following description and
the appended claims with reference to the accompanying drawings,
all of which form a part of this specification, wherein like
reference numerals designate corresponding parts in the various
figures. It is to be expressly understood, however, that the
drawings are for the purpose of illustration and description only
and are not intended as a definition of the limits of the
invention. As used in the specification and the claims, the
singular form of "a", "an", and "the" include plural referents
unless the context clearly dictates otherwise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a perspective view of a fluid delivery system
according to one embodiment.
[0037] FIG. 2 is a perspective view of a fluid delivery system
according to another embodiment.
[0038] FIG. 3 is a top perspective view of a fluid path for use in
a fluid delivery system.
[0039] FIG. 4 is a top perspective view of a flow mixing device in
accordance with a first embodiment.
[0040] FIG. 5 is an exploded perspective view of the flow mixing
device shown in FIG. 4.
[0041] FIG. 6A is a cross-sectional view of the flow mixing device
taken along line A-A shown in FIG. 4.
[0042] FIG. 6B is a cross-sectional view of the flow mixing device
taken along line B-B shown in FIG. 4.
[0043] FIG. 6C is a cross-sectional view of the flow mixing device
taken along line C-C shown in FIG. 4.
[0044] FIG. 7 is an exploded perspective view of a flow mixing
device in accordance with a second embodiment.
[0045] FIG. 8A is a cross-sectional view of an assembled flow
mixing device taken along line A-A shown in FIG. 7.
[0046] FIG. 8B is a cross-sectional view of an assembled flow
mixing device taken along line B-B shown in FIG. 7.
[0047] FIG. 8C is a cross-sectional view of an assembled flow
mixing device taken along line C-C shown in FIG. 7.
[0048] FIG. 8D is a cross-sectional view of an assembled flow
mixing device taken along line D-D shown in FIG. 7.
[0049] FIG. 9 is an exploded perspective view of the flow mixing
device in accordance with a third embodiment.
[0050] FIG. 10 is a cross-sectional view of an assembled flow
mixing device taken along line A-A shown in FIG. 9.
[0051] FIG. 11 is a cross-sectional view of a flow mixing device in
accordance with a fourth embodiment.
[0052] FIG. 12 is a cross-sectional view of a flow mixing device in
accordance with a fifth embodiment.
[0053] FIG. 13 is an exploded perspective view of a flow mixing
device in accordance with a sixth embodiment.
[0054] FIG. 14 is a cross-sectional view of an assembled flow
mixing device taken along line A-A shown in FIG. 13.
[0055] FIG. 15 is a top perspective view of a flow mixing device in
accordance with a seventh embodiment.
[0056] FIG. 16 is an exploded perspective view of the flow mixing
device shown in FIG. 15.
[0057] FIG. 17A is a cross-sectional view of an assembled flow
mixing device taken along line A-A shown in FIG. 15.
[0058] FIG. 17B is a cross-sectional view of an assembled flow
mixing device taken along line B-B shown in FIG. 15.
[0059] FIG. 17C is a cross-sectional view of an assembled flow
mixing device taken along line C-C shown in FIG. 15.
[0060] FIG. 18A is a cross-sectional view of a flow mixing device
in accordance with an eighth embodiment.
[0061] FIG. 18B is a cross-sectional view of the flow mixing device
shown in FIG. 18A.
[0062] FIG. 18C is a cross-sectional view of the flow mixing device
shown in FIG. 18A.
[0063] FIG. 19 is an exploded perspective view of a flow mixing
device in accordance with a ninth embodiment.
[0064] FIG. 20A is a cross-sectional view of the flow mixing device
taken along line A-A shown in FIG. 19.
[0065] FIG. 20B is a cross-sectional view of an assembled flow
mixing device taken along line B-B shown in FIG. 19.
[0066] FIG. 21 is a top perspective view of a flow mixing device in
accordance with a tenth embodiment.
[0067] FIG. 22 is an exploded perspective view of the flow mixing
device shown in FIG. 21.
[0068] FIG. 23 is a cross-sectional view of an assembled flow
mixing device taken along line A-A shown in FIG. 21.
[0069] FIG. 24 is a top perspective view of a flow mixing device in
accordance with an eleventh embodiment.
[0070] FIG. 25 is an exploded perspective view of the flow mixing
device shown in FIG. 24.
[0071] FIG. 26 is a top view of a first portion of the flow mixing
device shown in FIG. 25.
[0072] FIG. 27 is a top perspective view of a flow mixing device in
accordance with a twelfth embodiment.
[0073] FIG. 28A is a cross-sectional view of the flow mixing device
taken along line A-A shown in FIG. 27.
[0074] FIG. 28B is a cross-sectional view of the flow mixing device
taken along line B-B shown in FIG. 27.
[0075] FIG. 29 is a top perspective view of a flow mixing device in
accordance with a thirteenth embodiment.
[0076] FIG. 30 is an exploded perspective view of the flow mixing
device shown in FIG. 29.
[0077] FIG. 31 is a cross-sectional view of the flow mixing device
taken along line A-A shown in FIG. 29.
[0078] FIG. 32 is a graph of capacitance volume relative to
injection pressure for a plurality of fill volumes of first and
second injection fluids.
[0079] FIG. 33 is a graph of backflow volume relative to injection
ratios of a first injection fluid and a second injection fluid.
[0080] FIG. 34 is a graph of backflow volume relative to injection
pressure for a single injection profile.
[0081] FIG. 35 is a velocity graph of pistons driving first and
second injection fluids during an injection procedure.
[0082] FIG. 36 is a modified velocity graph of pistons driving
first and second injection fluids during an injection
procedure.
[0083] FIG. 37 is an enlarged portion of the graph shown in FIG.
36.
[0084] FIG. 38 is a graph of backflow volume relative to injection
pressure for a plurality of injection profiles.
DETAILED DESCRIPTION
[0085] For purposes of the description hereinafter, spatial
orientation terms, as 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 components, devices, and
features illustrated in the accompanying drawing figures and
described herein are simply exemplary and should not be considered
as limiting.
[0086] FIG. 1 is a perspective view of a fluid delivery system 100
having a flow mixing device 200 according to one embodiment. The
fluid delivery system 100 is adapted for delivering fluids to a
patient during a medical injection procedure. For example, the
fluid delivery system 100 may be used during an angiographic
procedure to inject contrast solution and common flushing agents,
such as saline, into the body of a patient. An example of such a
fluid injection or delivery system is disclosed in U.S. patent
application Ser. No. 09/982,518, filed on Oct. 18, 2001, now issued
as U.S. Pat. No. 7,094,216 on Aug. 22, 2006 (hereinafter "the '216
patent"), and assigned to the assignee of the present application,
the disclosure of which is incorporated herein by reference in its
entirety. Additional examples of fluid delivery systems are
disclosed in the following references: U.S. patent application Ser.
No. 10/825,866, filed on Apr. 16, 2004, now issued U.S. Pat. No.
7,556,619 on Jul. 7, 2009 (hereinafter "the '619 patent"); U.S.
Pat. No. 8,337,456 to Schriver et al., issued Dec. 25, 2012; U.S.
Pat. No. 8,147,464 to Spohn et al., issued Apr. 3, 2012; and, U.S.
patent application Ser. No. 11/004,670, now published as U.S.
2008/0086087 on Apr. 10, 2008, each of which are assigned to the
assignee of the present application and the disclosures of which
are incorporated herein by reference in their entireties. The flow
mixing device 200 is generally adapted to interface with one or
more components of the fluid delivery system 100 to aid in the
mixing of the fluids, particularly contrast solution and saline
solution in the case of angiographic procedures, to be delivered to
the patient.
[0087] The fluid delivery system 100 generally includes a powered
fluid injector 102 that is adapted to support and actuate a syringe
104 storing a first injection fluid for injection to a patient
during a medical procedure, such as an angiographic procedure. The
fluid delivery system 100 further includes a second injection fluid
that may be mixed with the first injection fluid prior to being
delivered to a patient. The injector 102 is generally used to
supply the first and second injection fluids under pressure to the
fluid path set 108 and, ultimately, the patient. The injector 102
may be controlled by a hand controller 114 to supply the first and
second injection fluids at discrete and preselected flow rates
based on the physical inputs to the hand controller 114.
[0088] The following operational discussion of the flow mixing
device 200 will be with exemplary reference to an angiographic
procedure involving the fluid delivery system 100 and how the flow
mixing device 200 contributes to the homogeneous mixing of the
first injection fluid and the second injection fluid from the fluid
delivery system 100. In typical angiographic procedures, the first
injection fluid is contrast solution and the second injection fluid
or flushing agent is saline. The contrast solution typically has
higher viscosity and specific gravity compared to saline. One of
ordinary skill in the art will appreciate that, depending on the
medical procedure, various other medical fluids can be used as the
first injection fluid and the second injection fluid.
[0089] The injector 102 is operatively associated with a fluid
control module 106. The fluid control module 106 may be adapted for
controlling the operation of the fluid delivery system 100 by
allowing the user to manually select the injection parameters, or
select a pre-defined injection protocol. Alternatively, this
functionality may reside with an external control unit or with the
powered injector 102. In either case, the fluid control module 106
controls the injection pressure and the ratio of the first
injection fluid relative to the second injection fluid. The fluid
control module 106 is generally adapted to support a fluid path set
108 that is generally adapted to fluidly connect the syringe 104 to
a source of first injection fluid (contrast solution) 112. The
fluid path set 108 is further connected to a source of second
injection fluid (saline) 110 which is supplied to the patient via
the same catheter as the contrast solution. The flow mixing device
200 is disposed within the fluid path set 108 and is adapted for
mixing the fluids from the syringe 104 and the source of saline
110. The flow of the contrast solution from the syringe 104 and the
saline is regulated by the fluid control module 106 which controls
the various valves and flow regulating structures in the fluid path
set 108 to regulate the delivery of contrast solution and saline to
the patient based on user selected injection parameters, such as
total injection volume and ratio of contrast solution and saline.
The fluid path set 108 further connects the syringe 104 to a
catheter (not shown) which is associated with the patient for
supplying the contrast solution and saline to the patient.
[0090] FIG. 2 illustrates an alternative embodiment of fluid
delivery system 100a having a powered fluid injector 102a adapted
to interface with two syringes 104a, 104b which may be fluidly
connected to a source of first injection fluid (not shown) and a
source of second injection fluid (not shown) or any two desired
medical fluids. Injector 102a is desirably at least a dual-syringe
injector, wherein two fluid delivery syringes are oriented in a
side-by-side relationship and which are separately actuated by
respective piston elements associated with the injector 102a. Fluid
path set 108a may be interfaced with injector 102a in a similar
manner to that described previously in connection with fluid
delivery system 100 described with reference to FIG. 1. In
particular, the injector 102a is operatively associated with a
fluid control module 106a. The fluid control module 106a is
generally adapted to support a fluid path set 108a that is
generally adapted to fluidly connect to the first syringe 104a
having a first injection fluid, such a contrast solution. The fluid
path set 108a is further connected to the second syringe 104b
having a second injection fluid, such as saline. The flow mixing
device 200 is disposed within the fluid path set 108a and is
adapted for mixing the fluid flow from the first and second syringe
104a, 104b. The flow of the first injection fluid from the first
syringe 104a and the second injection fluid from the second syringe
104b is regulated by a fluid control module 106a which controls the
various valves and flow regulating structures to regulate the
delivery of first and second medical fluids to the patient based on
user selected injection parameters, such as total injection volume
and ratio of contrast solution and saline. The fluid path set 108a
further connects to a catheter (not shown) which is associated with
the patient for supplying the first and second medical fluids to
the patient. A suitable multi-syringe fluid injector for use with
the above-described system is described in U.S. patent application
Ser. No. 13/386,765, filed on Jan. 24, 2012, which published as
U.S. Patent Application Publication No. 2012/0123257, and is
assigned to the assignee of the present application, the disclosure
of which is incorporated herein by reference in its entirety. Other
relevant multi-fluid delivery systems are found in U.S. patent
application Ser. No. 10/159,592, filed on May 30, 2002 (published
as U.S. 2004/0064041), U.S. patent application Ser. No. 10/722,370,
filed Nov. 25, 2003 (published as U.S. 2005/0113754), and
International Patent Application No. PCT/US2012/037491, filed on
May 11, 2012 (published as WO 2012/155035), all of which are
assigned to the assignee of the present application, and the
disclosures of which are incorporated herein by reference.
[0091] In another embodiment, a manually-controlled fluid delivery
system (not shown) may be provided. Similar to power-operated fluid
delivery systems described with reference to FIGS. 1-2, a
manually-controlled fluid delivery system may include a first
injector adapted to actuate a first syringe storing a first
injection fluid, such as a contrast medium, for injection to a
patient during a medical procedure. The manually-controlled fluid
delivery system may also include a second injector adapted to
actuate a second syringe storing a second injection fluid, such as
saline. A fluid path set is provided for delivering and mixing the
first injection fluid and the second injection fluid in a desired
ratio prior to being delivered to a patient. An exemplary
manually-controlled fluid delivery system is disclosed in U.S.
patent application Ser. No. 13/755,883, filed Jan. 31, 2013,
assigned to the assignee of the present application, the disclosure
of which is incorporated herein by reference.
[0092] With reference to FIG. 3, fluid path set 108 is shown
removed from the fluid delivery system. The fluid path set 108
includes a first fluid line 116 in fluid communication at its
proximal end with the source of the first injection fluid and a
second fluid line 118 in fluid communication at its proximal end
with the source of the second injection fluid. First and second
fluid lines 116, 118 act as fluid conduits for delivering the first
and second injection fluid, respectively, from the source of each
respective fluid. Distal ends of each of the first and second fluid
lines 116, 118 are in fluid communication with the flow mixing
device 200. First and second injection fluids flow into the mixing
device 200 and mix in the mixing device 200. In one embodiment, a
contrast medium having a high specific gravity is delivered under
pressure to the mixing device 200 through the first fluid line 116
and a saline solution having a lower specific gravity relative to
the contrast medium is delivered under pressure to the mixing
device 200 through the second fluid line 118. Then, the mixed
solution of the first and second injection fluid is passed through
a third fluid line 120 in fluid connection at its proximal end with
a distal end of the flow mixing device 200. A distal end of the
third fluid line 120 is desirably connected to a catheter by a
connector 122 to deliver the mixed solution of the first and second
injection fluid to the patient. The connector 122 may be bonded to
the third fluid line 120 by a conventional UV bonding technique.
Alternatively, the connector 122 may be coupled to the third fluid
line 120 by an over-molding technique. While FIG. 3 illustrates the
connector 122 being provided on the third fluid line 120, the
connector 122 may be provided on any one or all of the first,
second, and third fluid lines 116, 118, 120, respectively. One or
more valves 124 may be provided within the fluid path set 108 to
selectively block the passage of first and/or second injection
fluid through the fluid path set 108. For example, a one-way valve
may be provided on one or both of the first and second fluid lines
116, 118, respectively, to prevent the first or second injection
fluid to flow back into the source of the first and second
injection fluid. Alternatively, or in addition, the one-way valve
may be provided on the third fluid line 120 to prevent the mixed
solution of the first and second injection fluids to flow back into
the flow mixing device 200. In one embodiment, the one or more
valves 124 may be provided directly on the flow mixing device
200.
[0093] With reference to FIGS. 4, 5, and 6A-6C, a flow mixing
device 200a is illustrated in accordance with a first embodiment.
Flow mixing device 200a includes a housing 202a having a proximal
end 204a opposite a distal end 205a. The proximal end 204a of the
housing 202a includes a first fluid port 206a and a second fluid
port 208a (shown in FIG. 6A) which are connected or connectable to
respective first fluid line 116 and second fluid line 118 (not
shown). The proximal end 204a of the housing 202a may include a
connector (not shown) for connecting the first and second fluid
lines 116, 118 to the flow mixing device 200a. The distal end 205a
of the housing 202a includes a third fluid port 210a which is
connected or connectable to the third fluid line 120. The distal
end 205a of the housing 202a may include a connector (not shown)
for connecting the flow mixing device 200a to the third fluid line
120 or to a catheter.
[0094] The housing 202a of the flow mixing device 200a defines a
mixing chamber 212a (shown in FIG. 6A) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212a is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids and produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212a is also
adapted to eliminate zones of stagnant fluid flow. The housing 202a
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202a during the injection procedure. For example, the
housing 202a is adapted to retain its shape without appreciable
expansion in volume at an injection pressure of 1200 psi.
[0095] With specific reference to FIG. 5, and with continuing
reference to FIG. 4, the housing 202a of the flow mixing device
200a includes a first portion 214a and second portion 216a. The
first portion 214a of the housing 202a has a substantially conical
proximal end 218a and a substantially cylindrical distal end 220a.
A collar 222a surrounds the base of the conical proximal end 218a
of the first portion 214a. The second portion 216a includes a
flange 224a that corresponds to the collar 222a of the first
portion 214a to receive the flange 224a within the collar 222a. In
another embodiment, the collar 222a is provided on the second
portion 216a, while the flange 224a is provided on the first
portion 214a of the housing 202a. In one preferred and non-limiting
embodiment, the first and second portions 214a, 216a are
permanently coupled together by gluing, ultrasonic welding, an
interference fit connection, or other mechanical securing
arrangement.
[0096] With reference to FIGS. 6A-6C, and with continuing reference
to FIG. 5, the first and second fluid ports 206a, 208a extend
through the second portion 216a and are in fluid communication with
the mixing chamber 212a through first and second fluid orifices
226a, 228a, respectively. First and second fluid ports 206a, 208a
are substantially parallel to each other. In other embodiments,
first and second fluid ports 206a, 208a may be angled relative a
longitudinal axis of flow mixing device 200a such that fluid flow
of the first and second injection fluids converges or diverges
relative to the longitudinal axis. In one exemplary embodiment, a
contrast medium may be supplied through the first fluid port 206a
and saline may be supplied through the second fluid port 208a.
Fluid flowing through the first and second fluid ports 206a, 208a
passes through the first and second fluid orifices 226a, 228a
having a reduced cross-section relative to the first and second
fluid ports 206a, 208a. First and second fluid orifices 226a, 228a
have equal diameters. In another embodiment, the diameter of the
first fluid orifice 226a may be larger or smaller relative to the
diameter of the second fluid orifice 228a. First and second
injection fluids mix within the mixing chamber 212a to form a mixed
solution. The mixed solution is discharged from the mixing chamber
212a through a third fluid orifice 230a provided at a distal end of
the first portion 214a of the housing 202a. The third fluid orifice
230a is in fluid communication with the third fluid port 210a that
discharges the mixed fluid from the mixing device 200a through a
fluid conduit (not shown).
[0097] As best shown in FIGS. 6A and 6B, the mixing chamber 212a is
defined within the interior of the first portion 214a. The mixing
chamber 212a has a generally conical shape that narrows from the
proximal end 218a to the distal end 220a such that a
cross-sectional shape of the mixing chamber 212a is substantially
circular (FIG. 6C). Alternatively, the cross-sectional shape of the
mixing chamber 212a may be an ellipse or any other shape formed
from a curved line. In another embodiment, the mixing chamber 212a
may have a first portion that narrows from the proximal end 218a to
the distal end 220a and a substantially cylindrical portion that
extends therefrom.
[0098] With continuing reference to FIGS. 6A-6C, second portion
216a includes a fluid flow dispersion device 238a having a stem
240a and two deflection members 242a, 244a. The stem 240a is
positioned between the first and second fluid orifices 226a, 228a
and extends in a longitudinal direction toward the distal end 220a
of the first portion 214a. Deflection members 242a, 244a extend
radially outward from the stem 240a. A transitional portion between
a longitudinally-extending stem 240a and the radially-extending
deflection members 242a, 244a is curved to gradually transition the
flow of the first and second injection fluid from a substantially
longitudinal direction to a substantially radial direction with
respect to a central axis of the mixing chamber. A radial space
246a is provided between the terminal end of each deflection member
242a, 244a and the sidewall of the mixing chamber 212a. First and
second injection fluids are deflected to flow from a substantially
longitudinal direction to a substantially radial direction by the
deflection members 242a, 244a and are forced to flow through the
radial space 246a. The rapid change in the flow direction of the
first and second injection fluids promotes turbulent mixing of the
first injection fluid and the second injection fluid within the
mixing chamber 212a.
[0099] With reference to FIGS. 7-8D, a flow mixing device 200b is
illustrated in accordance with a second embodiment. The housing
202b of the flow mixing device 200b is substantially similar to the
housing 202a of the flow mixing device 200a described above.
Reference numerals 200b-230b in FIG. 7 are used to illustrate
identical components as reference numerals 200a-230a in FIGS. 4-5.
As the previous discussion regarding the flow mixing device 200a
generally shown in FIGS. 4-6C is applicable to the embodiment shown
in FIGS. 7-8D, only the relevant differences between these systems
are discussed hereinafter.
[0100] With specific reference to FIGS. 8A-8D, second portion 216b
includes two deflection members 242b, 244b extending radially
outward over first and second fluid orifices 228a, 228b in mutually
opposing directions. First injection fluid is directed in one
radial direction by the first deflection member 242b, while the
second injection fluid is directed in the opposite radial direction
by the second deflection member 244b. A radial space 246b is
provided between the terminal end of each deflection member 242b,
244b and the sidewall of the mixing chamber 212b. First and second
injection fluids are deflected to flow in a substantially radial
direction by the deflection members 242b, 244b in opposite
directions and forced to flow through the radial space 246b. The
rapid change in the flow direction promotes turbulent mixing of the
first injection fluid and the second injection fluid within the
mixing chamber 212b once the first and second injection fluids are
recombined downstream of the deflection members 242b, 244b.
[0101] With reference to FIGS. 9-10, a flow mixing device 200c is
illustrated in accordance with a third embodiment. Flow mixing
device 200c includes a housing 202c having a proximal end 204c
opposite a distal end 205c. The proximal end 204c of the housing
202c includes a first fluid port and a second fluid port which are
connected or connectable to respective first fluid line 116 and
second fluid line 118. The proximal end 204c of the housing 202c
may include a connector (not shown) for connecting the first and
second fluid lines 116, 118 to the flow mixing device 200c. The
distal end 205c of the housing 202c includes a third fluid port
210c which is connected or connectable to the third fluid line 120
(not shown in FIGS. 9-10). The distal end 205c of the housing 202c
may include a connector (not shown) for connecting the flow mixing
device 200c to the third fluid line 120 or to a catheter.
[0102] With reference to FIG. 10, the housing 202c of the flow
mixing device 200c includes a first portion 214c and second portion
216c. The first portion 214c of the housing 202c has a
substantially conical proximal end 218c and a substantially
cylindrical distal end 220c. A collar 222c surrounds the base of
the first portion 214c. The second portion 216c includes a flange
224c that corresponds to the collar 222c of the first portion 214c
to receive the flange 224c within the collar 222c. In another
embodiment, the collar 222c is provided on the second portion 216c,
while the flange 224c is provided on the first portion 214c of the
housing 202c. In one preferred and non-limiting embodiment, the
first and second portions 214c, 216c are permanently coupled
together by gluing, ultrasonic welding, an interference fit
connection, or other mechanical securing arrangement.
[0103] The housing 202c of the flow mixing device 200c defines a
mixing chamber 212c (shown in FIG. 10) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212c is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution.
[0104] With continuing reference to FIG. 10, the first and second
fluid ports 206c, 208c extend through the second portion 216c and
are in fluid communication with the mixing chamber 212c through
first and second fluid orifices 226c, 228c, respectively. First and
second fluid ports 206c, 208c are substantially parallel to each
other. In other embodiments, first and second fluid ports 206c,
208c may be angled relative a longitudinal axis of flow mixing
device 200c such that fluid flow of the first and second injection
fluids converges or diverges relative to the longitudinal axis. In
one exemplary embodiment, a contrast medium may be supplied through
the first fluid port 206c and saline may be injected through the
second fluid port 208c. Fluid flowing through the first and second
fluid ports 206c, 208c passes through the first and second fluid
orifice 226c, 228c having a reduced cross-section relative to the
first and second fluid ports 206c, 208c. First and second fluid
orifices 226c, 228c have equal diameters. In another embodiment,
the diameter of the first fluid orifice 226c may be larger or
smaller relative to the diameter of the second fluid orifice 228c.
First and second injection fluids mix within the mixing chamber
212c to form a mixed solution. The mixed solution is discharged
from the mixing chamber 212c through a third fluid orifice 230c
provided at a distal end of the first portion 214c of the housing
202c. The third fluid orifice 230c is in fluid communication with a
third fluid port 230c that discharges the mixed fluid from the
mixing device 200c through the fluid conduit (not shown).
[0105] As best shown in FIG. 10, the mixing chamber 212c is defined
within the interior of the first portion 214c. The mixing chamber
212c has a generally conical shape that narrows from the proximal
end 218c to the distal end 220c, such that a cross-sectional shape
of the mixing chamber 212c is substantially circular.
Alternatively, the cross-sectional shape of the mixing chamber 212c
may be an ellipse or any other shape formed from a curved line. In
another embodiment, the mixing chamber 212c may have a first
portion that narrows from the proximal end 218c to the distal end
220c and a substantially cylindrical portion that extends
therefrom.
[0106] The second portion 216c includes a fluid flow dispersion
device 238c having a central hub 240c and a turbine wheel 241c
rotatable around the central hub 240c, as shown more fully in FIG.
9. The central hub 240c is located between the first and second
fluid orifices 226c, 228c and extends in a longitudinal direction
toward the distal end 220c of the first portion 214c. Turbine wheel
241c is rotatably disposed on the central hub 240c and is retained
in a longitudinal direction by a cap 243c. Turbine wheel 241c
includes a plurality of rotor blades 245c extending radially
outward from a central portion of the turbine wheel 241c. Each
rotor blade 245c is angled with respect to a longitudinal axis of
the mixing chamber 212c such that first and second injection fluids
exiting from first and second fluid orifices 226c, 228c are
deflected in a radial direction. Fluid exiting from the first and
second fluid orifices 226c, 228c strikes the rotor blades 245c and
causes the turbine wheel 241c to rotate. Rotation of the turbine
wheel 241c causes a scattering of the first and second fluids
within the mixing chamber 212c to promote a homogeneous mixing of
the fluids.
[0107] With reference to FIG. 11, a flow mixing device 200d is
illustrated in accordance with a fourth embodiment. The housing
202d of the flow mixing device 200d is substantially similar to the
housing 202a of the flow mixing device 200a described above.
Reference numerals 200d-230d in FIG. 11 are used to illustrate
identical components as reference numerals 200a-230a in FIGS. 4-5.
As the previous discussion regarding the flow mixing device 200a
generally shown in FIGS. 4-6C is applicable to the embodiment shown
in FIG. 11, only the relevant differences between these systems are
discussed hereinafter.
[0108] With reference to FIG. 11, the mixing chamber 212d is
defined within the interior of the first portion 214d. The mixing
chamber 212d has a generally cylindrical shape having a
substantially circular cross-section. Alternatively, the
cross-sectional shape of the mixing chamber 212d may be an ellipse
or any other shape formed from a curved line. In another
embodiment, the mixing chamber 212d may have a first portion that
narrows from the proximal end 218d to the distal end 220d to define
a conical profile.
[0109] The mixing chamber 212d has a plurality of mixing balls 213d
disposed within. Each mixing ball 213d is substantially spherical
and has a diameter that is larger than the diameter of the smallest
of the first, second, and third fluid orifices 226d, 228d, 230d,
respectively, in order to eliminate blocking of the fluid ports.
Desirably, each of the plurality of mixing balls 213d has a
diameter sufficiently large to avoid complete occlusion of the
first, second, and third fluid orifices 226d, 228d, 230d. As the
first and second injection fluids enter the mixing chamber 212d,
the mixing balls 213d are agitated by the fluid flow and move about
the mixing chamber 212d. In an embodiment where the housing 202d is
transparent, the mixing balls 213d provide a visual indication of
injection and mixing. In a purge cycle, the position of the mixing
balls 213d within the mixing chamber 212d is indicative of whether
the purge is completed. In a further embodiment, the mixing balls
213d may provide an audible indication of injection as the mixing
balls 213d bounce off of the walls of the mixing chamber 212d and
produce noise.
[0110] With reference to FIG. 12, a flow mixing device 200e is
illustrated in accordance with a fifth embodiment. The flow mixing
device 200e is substantially similar to the flow mixing device 200d
described above. Reference numerals 200e-230e in FIG. 12 are used
to illustrate identical components as reference numerals 200d-230d
in FIG. 11. As the previous discussion regarding the flow mixing
device 200d is applicable to the embodiment shown in FIG. 11, only
the relevant differences between these systems are discussed
hereinafter.
[0111] Whereas the flow mixing device 200d includes a plurality of
mixing balls 213d disposed within the mixing chamber 212d, the flow
mixing device 200e includes a porous filter material filing at
least a portion of the mixing chamber 212e. In particular, an
open-cell filter element 213e fills the mixing chamber 212e and
creates a fluid path restriction which forces the first and second
injection fluids to mix while passing through the pores. In one
embodiment, the filter element 213e is provided only on one lateral
side of the mixing chamber 212e in order to increase a pressure
drop of one of the first or second injection fluids.
[0112] With reference to FIG. 13, a flow mixing device 200f is
illustrated in accordance with a sixth embodiment. Flow mixing
device 200f includes a housing 202f having a proximal end 204f
opposite a distal end 205f. The proximal end 204f of the housing
202f includes a first fluid port 206f and a second fluid port 208f
which are connected or connectable to respective first fluid line
116 and second fluid line 118. The proximal end 204f of the housing
202f may include a connector (not shown) for connecting the first
and second fluid lines 116, 118 to the flow mixing device 200f. The
distal end 205f of the housing 202f includes a third fluid port
210f which is connected or connectable to the third fluid line 120.
The distal end 205f of the housing 202f may include a connector
(not shown) for connecting the flow mixing device 200f to the third
fluid line 120 or to a catheter.
[0113] The housing 202f of the flow mixing device 200f defines a
mixing chamber 212f (shown in FIG. 14) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212f is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212f is also
adapted to eliminate zones of stagnant fluid flow. The housing 202f
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202f during the injection procedure. For example, the
housing 202f is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0114] With reference to FIG. 14, the second portion 216f includes
a first fluid port 206f for receiving a first injection fluid
through a first fluid conduit (not shown) and a second fluid port
208f for receiving a second injection fluid through a second fluid
conduit (not shown). First and second fluid ports 206f, 208f extend
through the second portion 216f and are in fluid communication with
the mixing chamber 212f through first and second fluid orifices
226f, 228f, respectively. First and second fluid ports 206f, 208f
are substantially parallel to each other. In other embodiments,
first and second fluid ports 206f, 208f may be angled relative to a
longitudinal axis of flow mixing device 200f such that fluid flow
of the first and second injection fluids converges or diverges
relative to the longitudinal axis. In one exemplary embodiment, a
contrast medium may be supplied through the first fluid port 206f
and saline may be injected through the second fluid port 208f.
Fluid flowing through the first and second fluid ports 206f, 208f
passes through the first and second fluid orifices 226f, 228f
having a reduced cross-section relative to the first and second
fluid ports 206f, 208f. First and second fluid orifices 226f, 228f
have equal diameters. In another embodiment, the diameter of the
first fluid orifice 226f may be larger or smaller relative to the
diameter of the second fluid orifice 228f. First and second
injection fluids mix within the mixing chamber 212f to form a mixed
solution. The mixed solution is discharged from the mixing chamber
212f through a third fluid orifice 230f provided at a distal end of
the first portion 214f of the housing 202f. The third fluid orifice
230f is in fluid communication with the third fluid port 210f that
discharges the mixed fluid from the mixing device 200f through a
fluid conduit (not shown).
[0115] The mixing chamber 212f is defined within the interior of
the first portion 214f. The mixing chamber 212f has a generally
conical shape having a substantially circular cross-section.
Alternatively, the cross-sectional shape of the mixing chamber 212f
may be an ellipse or any other shape formed from a curved line.
[0116] As best shown in FIG. 13, a disc 237f is provided between
the first portion 214f and the second portion 216f. The disc 237f
is disposed inside the mixing chamber 212f between the proximal end
218f and the distal end 220f of the first portion 214f. The disc
237f has a generally circular shape adapted to fit inside the
mixing chamber 212f. Desirably, the disc 237f is adapted to be
fixed inside the mixing chamber 212f and extend substantially
perpendicular to a longitudinal axis of the mixing chamber 212f.
The disc 237f includes a plurality of recesses 239f extending
radially inward from the outer circumference of the disc 237f. When
positioned inside the mixing chamber 212f, the recesses 239f define
a fluid passage 241f through which mixed solution can pass.
Additionally, the disc 237f includes a central opening 243f
extending through the thickness of the disc 237f. As is well known
from the fundamental principles of fluid dynamics, a velocity
profile of a fluid traveling through a circular conduit has a
maximum velocity value at the center of the conduit and a minimum
velocity value at the sidewall of the conduit. A stagnation point
exists at the surface of the conduit, where the fluid is brought to
rest by the conduit and its local velocity is zero. In order to
modify the velocity profile of the first and second injection
fluids such that they mix inside the mixing chamber 212f to create
a mixed solution, disc 237f restricts the fluid such that the fluid
flow closest to the sidewall of the mixing chamber 212f is less
restricted than the fluid flow closer to the center of the mixing
chamber 212f. The fluid passages 241f provided around the perimeter
of the disc 237f do not cause a restriction in the fluid where
fluid flow is at its lowest value, while the body of the disc 237f
acts as a barrier to reduce the velocity profile of the fastest
moving fluid. The central opening 243f prevents an excess buildup
of backup pressure by allowing fluid to pass therethrough. The
fluid obstruction caused by the disc 237f causes a turbulent flow
downstream of the disc 237f to promote homogeneous mixing of the
first and second injection fluids.
[0117] With reference to FIGS. 15-17C, a flow mixing device 200g is
illustrated in accordance with a seventh embodiment. Flow mixing
device 200g includes a housing 202g having a proximal end 204g
opposite a distal end 205g. The proximal end 204g of the housing
202g includes a first fluid port 206g and a second fluid port 208g
(shown in FIG. 17B) which are connected or connectable to
respective first fluid line 116 and second fluid line 118. The
proximal end 204g of the housing 202g may include a connector (not
shown) for connecting the first and second fluid lines 116, 118 to
the flow mixing device 200g. The distal end 205g of the housing
202g includes a third fluid port 210g which is connected or
connectable to the third fluid line 120. The distal end 205g of the
housing 202g may include a connector (not shown) for connecting the
flow mixing device 200g to the third fluid line 120 or to a
catheter.
[0118] The housing 202g of the flow mixing device 200g defines a
mixing chamber 212g (shown in FIG. 17B) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212g is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212g is also
adapted to eliminate zones of stagnant fluid flow. The housing 202g
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202g during the injection procedure. For example, the
housing 202g is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0119] With specific reference to FIGS. 17A-17C, the second portion
216g includes a first fluid port 206g for receiving a first
injection fluid through a first fluid conduit (not shown) and a
second fluid port 208g for receiving a second injection fluid
through a second fluid conduit (not shown). First and second fluid
ports 206g, 208g extend through the second portion 216g and are in
fluid communication with the mixing chamber 212g through first and
second fluid orifices 226g, 228g, respectively. First and second
fluid ports 206g, 208g are substantially parallel to each other. In
other embodiments, first and second fluid ports 206g, 208g may be
angled relative a longitudinal axis of flow mixing device 200g such
that fluid flow of the first and second injection fluids converges
or diverges relative to the longitudinal axis. In one exemplary
embodiment, a contrast medium may be supplied through the first
fluid port 206g and saline may be injected through the second fluid
port 208g. Fluid flowing through the first and second fluid ports
206g, 208g passes through the first and second fluid orifice 226g,
228g having a reduced cross-section relative to the first and
second fluid ports 206g, 208g. First and second fluid orifices
226g, 228g have approximately equal diameters. In another
embodiment, the diameter of the first fluid orifice 226g may be
larger or smaller relative to the diameter of the second fluid
orifice 228g. First and second injection fluids mix within the
mixing chamber 212g to form a mixed solution. The mixed solution is
discharged from the mixing chamber 212g through a third fluid
orifice 230g provided at a distal end of the first portion 214g of
the housing 202g. The third fluid orifice 230g is in fluid
communication with the third fluid port 210g that discharges the
mixed fluid from the mixing device 200g through a fluid conduit
(not shown).
[0120] The mixing chamber 212g is defined within the interior of
the first portion 214g. The mixing chamber 212g has a generally
cylindrical shape having a substantially circular cross-section.
Alternatively, the cross-sectional shape of the mixing chamber 212g
may be an ellipse or any other shape formed from a curved line. The
mixing chamber 212g may have a first portion that narrows from the
proximal end 218g to the distal end 220g to define a conical
profile.
[0121] With continuing reference to FIGS. 17A-17C, and referring
back to FIG. 16, flow mixing device 200g includes a flow dispersion
insert 237g disposed between the first portion 214g and the second
portion 216g. The flow dispersion insert 237g is adapted for being
received within a cavity of the first portion 214g. The flow
dispersion insert 237g has a substantially tubular structure with
two pins 239g extending longitudinally outward from a distal end of
a sidewall of the flow dispersion insert 237g. Each of the pins
239g is received in a corresponding pin hole 241g provided on a
stop surface 243g at a distal end of the cavity of the first
portion 214g. Pins 239g are adapted for engaging the pin holes 241g
to prevent rotation of flow dispersion insert 237g relative to
first portion 214g of the housing 202g. As best shown in FIG. 17A,
the flow dispersion insert 237g includes a hydrofoil element 245g
extending across a central portion of the interior of the tubular
structure of the flow dispersion insert 237g. The hydrofoil element
245g includes a leading edge 247g located at the proximate end and
a trailing edge 249g at the distal end of the flow dispersion
insert 237g. The hydrofoil element 245g further includes an upper
chord 251g extending between the leading edge 247d and the trailing
edge 249g, and a lower chord 253g extending between the leading
edge 247g and the trailing edge 249g opposite the upper chord 251g.
Upper and lower chords 251g, 253g define the cross-sectional
profile of the hydrofoil element 245g and define the flow
characteristics of the fluid passing across the hydrofoil element
245g. As is well known from hydrodynamics principles, a convex
profile of the upper chord 251g will cause a fluid stream to
accelerate over the upper surface of the hydrofoil element 245g,
thereby creating a condition of low fluid pressure. On the other
hand, a flat or concave profile of the lower chord 253g will cause
a fluid stream to decelerate over the lower surface of the
hydrofoil element 245g, thereby creating a condition of high fluid
pressure. As fluid traveling across the upper chord 251g joins the
fluid traveling across the lower chord 253g at the trailing edge
249g, vortices shed off of the trailing edge 249g result in
turbulent fluid flow distally of the trailing edge 249g to promote
a homogeneous mixing of the first and second injection fluids
inside the mixing chamber 212g. In the embodiment shown in FIG.
17B, first and second fluid orifices 226g, 228g are substantially
parallel to the leading edge 247g of the hydrofoil element 245g. In
another embodiment, first and second fluid orifices 226g, 228g may
be oriented perpendicularly relative to the leading edge 247g of
the hydrofoil element 245g.
[0122] With reference to FIGS. 18A-18C, a flow mixing device 200h
is illustrated in accordance with an eighth embodiment. The flow
mixing device 200h is substantially similar to the flow mixing
device 200g described above. Reference numerals 200h-230h in FIGS.
18A-18C are used to illustrate identical components as reference
numerals 200g-230g in FIGS. 15-17C. Whereas the flow mixing device
200g includes only one hydrofoil element 245g, the flow mixing
device 200h includes a plurality of hydrofoils. In particular, with
reference to FIGS. 18A-18C, flow mixing device 200h includes a flow
dispersion insert 237h disposed between the first portion 214h and
the second portion 216h. The flow dispersion insert 237h is adapted
for being received within a cavity of the first portion 214h. The
flow dispersion insert 237h has a substantially tubular structure
with two pins 239h extending longitudinally outward from a distal
end of a sidewall of the flow dispersion insert 237h. Each of the
pins 239h is received in a corresponding pin hole 241h provided on
a stop surface 243h at a distal end of the cavity of the first
portion 214h. Pins 239h are adapted for engaging the pin holes 241h
to prevent rotation of flow dispersion insert 237h relative to
first portion 214h of the housing 202h. As best shown in FIG. 18A,
the flow dispersion insert 237h includes two hydrofoil elements
245h, 245h' extending across a central portion of the interior of
the tubular structure of the flow dispersion insert 237h. The
hydrofoil elements 245h, 245h' are offset from each other such that
fluid may pass therebetween. The hydrofoil elements 245h, 245h'
include a leading edge 247h, 247h' located at the proximate end and
a trailing edge 249h, 249h' at the distal end of the flow
dispersion insert 237h. The hydrofoil elements 245h, 245h' further
include an upper chord 251h, 251h' extending between the leading
edge 247h, 247h' and the trailing edge 249h, 249h', and a lower
chord 253h, 253h' extending between the leading edge 247h, 247h'
and the trailing edge 249h, 249h' opposite the upper chord 251h,
251h'. Upper cords 251h, 251h' and lower chords 253h, 253h' define
the cross-sectional profile of the hydrofoil elements 245h, 245h'
and define the flow characteristics of the fluid passing across the
hydrofoil elements 245h, 245h'. Hydrofoil elements 245h, 245h' may
be arranged such that (a) the leading edge 247h of the first
hydrofoil element 245h is aligned substantially parallel with the
leading edge 247h' of the second hydrofoil element 245h', (b) the
upper chord 251h of the first hydrofoil element 245h is adjacent to
the upper chord 251h' of the second hydrofoil element 245h', (c)
the lower chord 253h of the first hydrofoil element 245h is
adjacent to the lower chord 253h' of the second hydrofoil element
245h', or (d) the upper chord 251h of the first hydrofoil element
is adjacent to the lower chord 253h' of the second hydrofoil
element 245h'. As is well known from hydrodynamics principles, a
convex profile of the upper chord 251h, 251h' will cause a fluid
stream to accelerate over the upper surface of the hydrofoil
element 245h, 245h', thereby creating a condition of low fluid
pressure. On the other hand, a flat or concave profile of the lower
chord 253h, 253h' will cause a fluid stream to decelerate over the
lower surface of the hydrofoil element 245h, 245h', thereby
creating a condition of high fluid pressure. As fluid traveling
across the upper chord 251h, 251h' joins the fluid traveling across
the lower chord 253h, 253h' at the trailing edge 249h, 249h',
vortices shed off of the trailing edge 249h, 249h' result in
turbulent fluid flow distally of the trailing edge 249h, 249h' to
promote a homogeneous mixing of the first and second injection
fluids inside the mixing chamber 212h. In the embodiment shown in
FIG. 18B, first and second fluid orifices 226h, 228h are
substantially parallel to the leading edges 247h, 247h' of the two
hydrofoil elements 245h, 245h'. In another embodiment, first and
second fluid orifices 226h, 228h may be oriented perpendicularly
relative to the leading edges 247h, 247h' of the two hydrofoil
elements 245h, 245h'.
[0123] With reference to FIGS. 19-20B, a flow mixing device 200i is
illustrated in accordance with a ninth embodiment. Flow mixing
device 200i includes a housing 202i having a proximal end 204i
opposite a distal end 205i. The proximal end 204i of the housing
202i includes a first fluid port 206i and a second fluid port 208i
(shown in FIG. 20A) which are connected or connectable to
respective first fluid line 116 and second fluid line 118. The
proximal end 204i of the housing 202i may include a connector (not
shown) for connecting the first and second fluid lines 116, 118 to
the flow mixing device 200i. The distal end 205i of the housing
202i includes a third fluid port 210i which is connected or
connectable to the third fluid line 120. The distal end 205i of the
housing 202i may include a connector (not shown) for connecting the
flow mixing device 200i to the third fluid line 120 or to a
catheter.
[0124] The housing 202i of the flow mixing device 200i defines a
mixing chamber 212i (shown in FIG. 20A) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212i is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212i is also
adapted to eliminate zones of stagnant fluid flow. The housing 202i
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202i during the injection procedure. For example, the
housing 202i is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0125] With specific reference to FIGS. 20A-20B, the first and
second fluid ports 206i, 208i extend through the second portion
216i and are in fluid communication with the mixing chamber 212i
through first and second fluid orifices 226i, 228i, respectively.
First and second fluid ports 206i, 208i are substantially parallel
to each other. In other embodiments, first and second fluid ports
206i, 208i may be angled relative a longitudinal axis of flow
mixing device 200i such that fluid flow of the first and second
injection fluids converges or diverges relative to the longitudinal
axis. In one exemplary embodiment, a contrast medium may be
supplied through the first fluid port 206i and saline may be
injected through the second fluid port 208i. Fluid flowing through
the first and second fluid ports 206i, 208i passes through the
first and second fluid orifice 226i, 228i having a reduced
cross-section relative to the first and second fluid ports 206i,
208i. First and second fluid orifices 226i, 228i have equal
diameters. In another embodiment, the diameter of the first fluid
orifice 226i may be larger or smaller relative to the diameter of
the second fluid orifice 228i. First and second injection fluids
mix within the mixing chamber 212i to form a mixed solution. The
mixed solution is discharged from the mixing chamber 212i through a
third fluid orifice 230i provided at a distal end of the first
portion 214i of the housing 202i. The third fluid orifice 230i is
in fluid communication with the third fluid port 210i that
discharges the mixed fluid from the mixing device 200i through a
fluid conduit, such as the third fluid line 120 connected to a
catheter, as discussed above with reference to FIG. 3.
[0126] With reference to FIGS. 19 and 20A, flow mixing device 200i
includes a plurality of flow dispersion inserts 237i disposed
between the first portion 214i and the second portion 216i. The
flow dispersion inserts 237i are adapted for being received within
a cavity of the first portion 214i. The flow dispersion inserts
237i have a substantially tubular structure with two pins 239h
extending longitudinally outward from a distal end of a sidewall of
the flow dispersion insert 237i and two pin holes 241i extending
into the sidewall of the flow dispersion insert at the proximal end
thereof. Each of the pins 239i is received in the corresponding pin
hole 241i provided on the adjacent flow dispersion insert 237i. The
pins 239i of the flow dispersion insert closest to the distal end
of the first portion 214i is received inside a stop surface 243i at
a distal end of the first portion 214i. Pins 239i are adapted for
engaging the pin holes 241i to prevent rotation of flow dispersion
insert 237i relative to first portion 214i of the housing 202i.
[0127] With continuing reference to FIG. 20A, each flow dispersion
insert 237i has a substantially cylindrical exterior adapted to be
received inside the first portion 214i. Each flow dispersion insert
237i further includes a hollow interior. Collectively, the hollow
interiors of the plurality of flow dispersion inserts 237i define
the mixing chamber 212i. Each flow dispersion insert includes a
plurality of wings 245i that extend radially inward from the inside
sidewall of the flow dispersion insert 237i. The wings 245i are
spaced apart at equal intervals about the inner circumference of
the flow dispersion insert 237i. For example, the embodiment
illustrated in FIG. 20A includes four wings 245i spaced apart at
90.degree. intervals. Adjacent flow dispersion inserts 237i are
desirably rotated with respect to each other such that wings 245i
of one flow dispersion insert 237i are angularly offset with regard
to the adjacent flow dispersion insert 237i. In the embodiment
shown in FIG. 20A, the three flow dispersion inserts 237i are
provided, where the first and last flow dispersion inserts 237i are
positioned such that the wings 245i on these inserts are in angular
alignment with respect to the longitudinal axis extending through
the mixing chamber 212i. The middle flow dispersion insert 237i is
angularly offset with regard to the first and last flow dispersion
inserts 237i such that the wings 245i on the middle insert are
offset with regard to the first and last flow dispersion inserts
237i. While FIG. 20A illustrates three flow dispersion inserts
237i, one of ordinary skill in the art would appreciate that any
number of flow dispersion inserts 237i can be provided. The wings
245i in each flow dispersion insert 237i create an obstruction in
the fluid path through the mixing chamber 212i to generate a
turbulent fluid flow through the mixing chamber 212i.
[0128] With reference to FIGS. 21-23, a flow mixing device 200j is
illustrated in accordance with a tenth embodiment. Flow mixing
device 200j includes a housing 202j having a proximal end 204j
opposite a distal end 205j. The distal end 205j of the housing 202j
may include a connector (not shown) for connecting the flow mixing
device 200j to the third fluid line 120 or to a catheter. The
housing 202j of the flow mixing device 200j defines a mixing
chamber 212j (shown in FIG. 22) where first and second injection
fluids mix to form a mixed solution. The mixing chamber 212j is
adapted for providing a homogeneous mixing flow under turbulent
conditions to promote a thorough mixing of the first and second
injection fluids to produce a substantially homogeneous mixed
solution. Additionally, the mixing chamber 212j is also adapted to
eliminate zones of stagnant fluid flow. The housing 202j is
desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202j during the injection procedure. For example, the
housing 202j is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0129] With specific reference to FIG. 22, the housing 202j
includes a first portion 214j and a second portion 216j joined
together at a seam 217j extending around the outer perimeter of the
lateral sides of the first and second portions 214j, 216j. The seam
217j defines a seal between the first and second portions 214j,
216j to prevent fluid leakage from the mixing device 200j. The seam
217j includes a groove 219j provided on one of the first or second
portions 214j, 216j of the housing 202j, and a corresponding
projection 221j on the other of the first or second portions 214j,
216j such that the projection 221j is received inside the groove
219j. The first portion 214j and the second portion 216j are joined
at the seam 217j by, for example, ultrasonic welding, UV bonding,
or other joining techniques.
[0130] The housing 202j includes a first fluid port 206j for
receiving a first injection fluid through a first fluid conduit
(not shown) and a second fluid port 208j for receiving a second
injection fluid through a second fluid conduit (not shown). First
and second fluid ports 206j, 208j extend through the first and
second portions 214j, 216j of the housing 202j and are in fluid
communication with the mixing chamber 212j through first and second
fluid orifices 226j, 228j, respectively. First and second fluid
ports 206j, 208j are substantially parallel to each other. In other
embodiments, first and second fluid ports 206j, 208j may be angled
relative to a longitudinal axis of flow mixing device 200j such
that fluid flow of the first and second injection fluids converges
or diverges relative to the longitudinal axis. In one exemplary
embodiment, a contrast medium may be supplied through the first
fluid port 206j and saline may be injected through the second fluid
port 208j. Fluid flowing through the first and second fluid ports
206j, 208j passes through the first and second fluid orifices 226j,
228j having a reduced cross-section relative to the first and
second fluid ports 206j, 208j. First and second fluid orifices
226j, 228j have equal diameters. In another embodiment, the
diameter of the first fluid orifice 226j may be larger or smaller
relative to the diameter of the second fluid orifice 228j. First
and second injection fluids mix within the mixing chamber 212j to
form a mixed solution. The mixed solution is discharged from the
mixing chamber 212j through a third fluid orifice 230j provided at
a distal end of the first portion 214j of the housing 202j. The
third fluid orifice 230j is in fluid communication with the third
fluid port 210j that discharges the mixed fluid from the mixing
device 200j through a fluid conduit (not shown).
[0131] With continued reference to FIG. 22, mixing chamber 212j is
defined by two sinusoidal fluid paths 213j extending through the
longitudinal length of the mixing chamber 212j. Each sinusoidal
fluid path 213j is substantially circular in cross section (FIG.
23). The sinusoidal fluid paths 213j intersect at a plurality of
intersection points 215j spaced apart at regular intervals over the
longitudinal length of the mixing chamber 212j. At each
intersection point 215j, fluid flow is combined from the portion of
the sinusoidal fluid paths 213j upstream of the intersection point
215j and divided prior to continuing downstream of the intersection
point 215j. The repeated combining and dividing fluid flow promotes
turbulent mixing inside the mixing chamber 212j to produce a
thoroughly mixed solution of the first and second injection
fluids.
[0132] With reference to FIGS. 24-26, a flow mixing device 200k is
illustrated in accordance with an eleventh embodiment. Flow mixing
device 200k includes a housing 202k having a proximal end 204k
opposite a distal end 205k. The proximal end 204k of the housing
202k includes a first fluid port 206k and a second fluid port 208k
(shown in FIG. 25) which are connected or connectable to a
respective first fluid line 116 and second fluid line 118. First
injection fluid, such as a contrast solution, is delivered to the
first fluid port 206k through the first fluid line 116, while the
second injection fluid, such as saline, is delivered to the second
fluid port 208k. The proximal end 204k of the housing 202k may
include a connector (not shown) for connecting the first and second
fluid lines 116, 118 to the flow mixing device 200k. The distal end
205k of the housing 202k includes a third fluid port 210k which is
connected or connectable to the third fluid line 120. As the first
and second injection fluids are introduced into the housing 202k of
the flow mixing device 200k, they mix to produce a mixed solution
of the first and second injection fluid. This mixed solution flows
through the housing 202k and exits the flow mixing device 200k
through the third fluid port 210a. The distal end 205k of the
housing 202k may include a connector (not shown) for connecting the
flow mixing device 200k to the third fluid line 120 or to a
catheter.
[0133] The housing 202k of the flow mixing device 200k defines a
mixing chamber 212k (shown in FIG. 25) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212k is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212k is also
adapted to eliminate zones of stagnant fluid flow. The housing 202k
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202k during the injection procedure. For example, the
housing 202k is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0134] With reference to FIGS. 25-26, the housing 202k includes a
first portion 214k and a second portion 216k joined together at a
seam 217k extending around the outer perimeter of the lateral sides
of the first and second portions 214k, 216k. The seam 217k defines
a seal between the first and second portions 214k, 216k to prevent
fluid leakage from the mixing device 200k. The seam 217k includes a
groove 219k provided on one of the first or second portions 214k,
216k of the housing 202k, and a corresponding projection 221k on
the other of the first or second portions 214k, 216k such that the
projection 221k is received inside the groove 219k.
[0135] The housing 202k includes a first fluid port 206k for
receiving a first injection fluid through a first fluid conduit
(not shown) and a second fluid port 208k for receiving a second
injection fluid through a second fluid conduit (not shown). First
and second fluid ports 206k, 208k extend through the first and
second portion 214k, 216k of the housing 202k and are in fluid
communication with the mixing chamber 212k through first and second
fluid orifices 226k, 228k, respectively. First and second fluid
ports 206k, 208k are substantially parallel to each other. In other
embodiments, first and second fluid ports 206k, 208k may be angled
relative a longitudinal axis of flow mixing device 200k such that
fluid flow of the first and second injection fluids converges or
diverges relative to the longitudinal axis. In one exemplary
embodiment, a contrast medium may be supplied through the first
fluid port 206k and saline may be injected through the second fluid
port 208k. Fluid flowing through the first and second fluid ports
206k, 208k passes through the first and second fluid orifice 226k,
228k having a reduced cross-section relative to the first and
second fluid ports 206k, 208k. First and second fluid orifices
226k, 228k have equal diameters. In another embodiment, the
diameter of the first fluid orifice 226k may be larger or smaller
relative to the diameter of the second fluid orifice 228k. First
and second injection fluids mix within the mixing chamber 212k to
form a mixed solution. The mixed solution is discharged from the
mixing chamber 212k through a third fluid orifice 230k provided at
a distal end of the first portion 214k of the housing 202k. The
third fluid orifice 230k is in fluid communication with a third
fluid port 210k that discharges the mixed fluid from the mixing
device 200k through a fluid conduit (not shown).
[0136] The mixing chamber 212k is defined within the interior of
the first portion 214k. The mixing chamber 212k has a generally
cylindrical shape having a substantially circular cross-section.
Alternatively, the cross-sectional shape of the mixing chamber 212k
may be an ellipse or any other shape formed from a curved line. The
mixing chamber 212k may have a first portion that narrows from the
proximal end 218k to the distal end 220k to define a conical
profile.
[0137] With continued reference to FIGS. 25-26, first and second
fluid orifices 226k, 228k are in fluid communication with the
mixing chamber 212k through first and second arcuate tubes 233k,
235k. The first and second arcuate tubes 233k, 235k are curved
radially inward toward a longitudinal axis of the mixing chamber
212k such that they intersect at a juncture at the proximal end of
the mixing chamber 212k. Due to the characteristics of the Coanda
effect, a fluid jet of first or second injection fluid passing
through the first and second arcuate tubes 233k, 235k will be
attracted to the nearest surface, i.e., the surface closest to the
longitudinal axis of the mixing chamber 212k. Once the fluid jet of
the first injection fluid passes through the first arcuate tube
233k, the fluid jet will continue to flow in an arcuate manner
within the mixing chamber 212k until it collides with an inner
sidewall of the mixing chamber 212k, after which the fluid jet will
be deflected in an opposite direction, thereby defining a
sinusoidal travel path. Similarly, once the fluid jet of the second
injection fluid passes through the second arcuate tube 235k, the
fluid jet will continue to flow in an arcuate manner within the
mixing chamber 212k until it collides with an inner sidewall of the
mixing chamber 212k, after which the fluid jet will be deflected in
an opposite direction, thereby defining a sinusoidal travel path
opposite to the travel path of the first injection fluid. When the
first fluid jet intersects with the second fluid jet, turbulent
mixing of the first and second injection fluid occurs due to the
difference in a radial velocity component of each fluid jet.
[0138] With reference to FIGS. 27-28B, a flow mixing device 200l is
illustrated in accordance with an eleventh embodiment. Flow mixing
device 200l includes a housing 202l having a proximal end 204l
opposite a distal end 205l. The proximal end 2041 of the housing
202l may include a connector (not shown) for connecting the first
and second fluid lines 116, 118 to the flow mixing device 200l. The
distal end 205l of the housing 202l includes a third fluid port
210l which is connected or connectable to the third fluid line 120.
As the first and second injection fluids are introduced into the
housing 202l of the flow mixing device 200l, they mix to produce a
mixed solution of the first and second injection fluids. This mixed
solution flows through the housing 202l and exits the flow mixing
device 200l through the third fluid port 210l. The distal end 205l
of the housing 202l may include a connector (not shown) for
connecting the flow mixing device 200l to the third fluid line 120
or to a catheter.
[0139] The housing 202l of the flow mixing device 200l defines a
mixing chamber 212l (shown in FIG. 28A) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212l is adapted for providing a homogeneous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212l is also
adapted to eliminate zones of stagnant fluid flow. The housing 202l
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202l during the injection procedure. For example, the
housing 202l is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0140] As best shown in FIG. 28A, the mixing chamber 212l includes
a plurality of grooves 213l around the inner circumference of the
mixing chamber 212l. The grooves 213l extend helically through the
longitudinal length of the mixing chamber 212l to define a "gun
barrel rifling" shape. As first and second injection fluids are
delivered to the mixing chamber 212l, the grooves 213l promote a
swirling flow of the fluids along the longitudinal length of the
mixing chamber 212l.
[0141] With reference to FIGS. 29-30, a flow mixing device 200m is
illustrated in accordance with a thirteenth embodiment. Flow mixing
device 200m includes a housing 202m having a proximal end 204m
opposite a distal end 205m. The proximal end 204m of the housing
202m includes a first fluid port 206m and a second fluid port 208m
(shown in FIG. 31) which are connected or connectable to respective
first fluid line 116 and second fluid line 118. First and second
fluid ports 206m, 208m are substantially parallel to each other. In
other embodiments, first and second fluid ports 206m, 208m may be
angled relative to a longitudinal axis of flow mixing device 200m
such that fluid flow of the first and second injection fluids
converges or diverges relative to the longitudinal axis. The
proximal end 204m of the housing 202m may include a connector (not
shown) for connecting the first and second fluid lines 116, 118 to
the flow mixing device 200m. The distal end 205m of the housing
202m includes a third fluid port 210m which is connected or
connectable to the third fluid line 120. The distal end 205m of the
housing 202m may include a connector (not shown) for connecting the
flow mixing device 200m to the third fluid line 120 or to a
catheter.
[0142] The housing 202m of the flow mixing device 200m defines a
mixing chamber 212m (shown in FIG. 31) where first and second
injection fluids mix to form a mixed solution. The mixing chamber
212m is adapted for providing a homogenous mixing flow under
turbulent conditions to promote a thorough mixing of the first and
second injection fluids to produce a substantially homogeneous
mixed solution. Additionally, the mixing chamber 212m is also
adapted to eliminate zones of stagnant fluid flow. The housing 202m
is desirably formed from a medical-grade plastic material having
sufficient rigidity to prevent any substantial expansion of the
housing 202m during the injection procedure. For example, the
housing 202m is adapted to retain its shape without appreciable
expansion at an injection pressure of 1200 psi.
[0143] With reference to FIG. 31, fluid flowing through the first
and second fluid ports 206m, 208m passes through the first and
second fluid orifice 226m, 228m having a reduced cross-section
relative to the first and second fluid ports 206m, 208m. The
diameter of the first fluid orifice 226m is smaller relative to the
diameter of the second fluid orifice 228m. During fluid injection,
a first injection fluid, such as saline, is passed through the
first fluid orifice 226m. Due to a reduced diameter of the first
fluid orifice 226m relative to the second fluid orifice 228m, the
first injection fluid experiences a higher pressure drop across the
first fluid orifice 226m. The higher relative pressure drop is also
associated with a change in the Reynolds number associated with the
first injection fluid flowing through the first fluid orifice 226m
and a corresponding transition from laminar to turbulent flow. For
example, fluid flow of the first injection fluid prior to entering
the first fluid orifice 226m is associated with a Reynolds number
lower than 2300 (i.e., laminar flow). After experiencing the
pressure drop caused by the diameter reduction between the first
fluid port 206m and the first fluid orifice 226m, the Reynolds
number of the first injection fluid will be higher than 4000 (i.e.
turbulent flow). Similarly, fluid flow of the second injection
fluid prior to entering the second fluid orifice 228m is also
associated with a Reynolds number lower than 2300 (i.e., laminar
flow); however, because the second injection fluid is not subjected
to a high pressure drop due to the diameter reduction between the
second fluid port 208m and the second fluid orifice 228m, the
second injection fluid will maintain a laminar flow after passing
through the second fluid orifice 228m. An additional benefit of
reducing the diameter of the first fluid orifice 226m relative to
the second fluid orifice 228m offsets any backflow of the first
injection fluid when injecting a ratio of fluids having more than
50% of the second injection fluid that is more viscous than the
first injection fluid. By combining a turbulent flow of a first
injection fluid and a laminar flow of a second injection fluid in
the mixing chamber 212m, the mixing of the two fluids to form a
mixed solution is improved. The mixed solution is discharged from
the mixing chamber 212m through a third fluid orifice 230m provided
at a distal end of the first portion 214m of the housing 202m. The
third fluid orifice 230m is in fluid communication with the fluid
port 210m that discharges the mixed fluid from the mixing device
200m through a fluid conduit (not shown).
[0144] While embodiments of a fluid path set with a flow mixing
device and methods of operation thereof were 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. For example,
any of the embodiments of the fluid path set with a flow mixing
device can be adapted to receive a third (or more) injection fluid
that is introduced into the mixing chamber of the flow mixing
device for mixing with one or both of first and second injection
fluids. Accordingly, the foregoing description is intended to be
illustrative rather than restrictive.
[0145] Having described the various embodiments of the flow mixing
device, a method of backflow compensation will now be described. In
a typical multi-fluid injection procedure, an injection fluid, such
as a contrast solution, is delivered from a contrast solution
source to the patient using a powered or manual injector. The
injected contrast solution is delivered to a desired site in a
patient's body through a catheter inserted into the patient's body,
such as the patient's groin area. Once the contrast fluid is
delivered to the desired site, that area is imaged using a
conventional imaging technique, such as angiography imagining or
scanning. The contrast solution becomes clearly visible against the
background of the surrounding tissue. However, because the contrast
solution often comprises toxic substances that may be harmful to
the patient if delivered in a high dosage or a high concentration,
it is desirable to reduce contrast dosing to the patient, while
maintaining an effective contrast amount necessary for effective
imaging. By supplementing the overall contrast solution delivery
procedure with saline, additional hydration of the patient occurs
automatically and allows the body to remove the toxicity of the
contrast solution. In addition to improved patient comfort level
and less toxicity, introduction of saline at clinically significant
pressures and flow rates also allows higher flow rates to be
achieved at lower pressure settings on the injector.
[0146] To enable effective simultaneous flow delivery of first and
second injection fluids, such as contrast solution and saline,
substantially equal pressure must be present in each delivery line.
In a powered injection system described above, it is desirable to
actuate the piston elements substantially simultaneously in
simultaneous flow delivery applications to equalize the pressure in
each line. If the injector is operated with differential pressure
in each delivery line of the fluid path set, the fluid in the lower
pressure line may be stopped or reversed until sufficient pressure
is achieved in the lower pressure line to enable flow in a desired
direction. This time delay could reduce the usefulness of the image
quality. This phenomenon is particularly evident in situations
where contrast is injected at a significantly higher ratio relative
to saline, such as 80% contrast to 20% saline injection protocol.
The flow reversal is exacerbated at high injection pressures. In
small dosage injections at a high injection pressure, flow reversal
effectively stops the delivery of saline such that 100% contrast
solution is injected, rather than the desired 80% contrast to 20%
saline ratio. Similar inaccuracies occur at various other injection
protocols, including, but not limited to 20% contrast to 80% saline
ratio.
[0147] The above-described situation of flow reversal during
powered injections at high contrast-to-saline ratio occurs due to
injection system capacitance. Total system capacitance represents
the amount of suppressed fluid (i.e., backflow volume) that is
captured in the swelling of the injector system components due to
pressure. Total system capacitance is inherent to each fluid
injection system and depends on a plurality of factors, including
injector construction, mechanical properties of materials used to
construct the syringe, piston, pressure jacket surrounding the
syringe, fluid lines delivering the contrast and saline to a flow
mixing device, etc. The amount of back or reverse flow increases
when the relative speed difference between the two pistons is
large, the simultaneous fluid flow is through a small restriction,
the speed of the total fluid injection is large, and the viscosity
of the fluid is high. The back or reverse flow can prevent
different ratios of simultaneously delivered fluid from ever
occurring in certain injections, which can be a detriment for all
two-syringe type injector systems.
[0148] In general, capacitance is directly correlative to injection
pressure and inversely correlative to volume of contrast and saline
in the syringes. For example, in one embodiment, capacitance during
an injection at 1200 psi with 150 ml of contrast and saline
remaining in the syringes is around 10 ml. In another embodiment,
the capacitance volume can be from about 5 ml to about 9 ml. With
reference to the graph shown in FIG. 32, several lines labeled A,
B, and C show an increase in system capacitance relative to an
increase in injection pressure at different syringe volumes. Line
A, which corresponds to both syringes containing contrast solution
or saline at maximum capacity. Lines B and C show the increase in
capacitance with an increase in injection pressure for syringes
having 2/3 and 1/3 of maximum fill volume, respectively.
[0149] Capacitance is also a function of the ratio at which the
first and second injection fluids, such as contrast solution and
saline, are injected. With reference to FIG. 33, an illustration of
the relative change in backflow volume relative to the change in
ratio between the contrast solution and saline is illustrated. At a
50%-50% ratio, where contrast solution and saline are injected in
equal amounts, backflow volume is minimized because the capacitance
on the contrast solution side is equal to the capacitance on the
saline side of the injection system such that substantially equal
pressures are present in each delivery line. Backflow may occur in
situations where first and second injection fluids are delivered
through long fluid conduits. However, as the injection ratio of
contrast solution and saline changes, backflow volume increases
corresponding to the increase in the ratio. As shown in FIG. 33,
backflow volume is lower for low ratios of contrast solution and
saline (i.e., higher saline concentration) than for high ratios
(i.e., higher contrast concentration) due to the contrast solution
having a significantly higher viscosity relative to saline.
[0150] With reference to FIG. 34, backflow volume is shown as a
function of injection pressure for an injection protocol having a
ratio of 80% contrast solution to 20% saline. Based on the
injection pressure, desired fluid ratio cannot be realized at low
injection volumes, where 100% of the injected fluid will be
contrast solution. Even when the saline syringe is pressurized to a
level to overcome the system capacitance, the overall fluid ratio
is higher than the desired ratio. Typically, the desired ratio is
selected by simultaneously activating the pistons and controlling
the velocity and injection time to dispense the desired quantity of
contrast solution and saline. FIG. 35 illustrates a velocity
profile of pistons driving the first and second injection fluids
(contrast solution and saline) for an 80%-20% injection protocol.
As seen from the figure, velocity for each piston is kept constant
during the injection duration, with the velocity of the piston
injecting the contrast solution (labeled A) being four times faster
than the velocity of the piston injecting the saline (labeled B).
The acceleration of each piston from rest to a steady state
velocity is identical.
[0151] A solution to the problem of eliminating backflow to
compensate for system capacitance in a high contrast-to-saline
ratio is to control the relative acceleration of the pistons in
proportion to the capacitive swelling that is occurring. Thus, the
ratio of simultaneous fluid delivery can be maintained. The
difference in acceleration between the piston controlling the
injection of the contrast solution and the piston controlling the
injection of saline is determined by the predicted capacitance
volume of the syringe with the correction factor dominated
primarily by pressure and the axial position of the syringe plunger
within the syringe barrel.
[0152] With reference to FIGS. 36-37, a velocity profile of pistons
driving the first and second injection fluids (contrast solution
and saline) for an 80%-20% injection protocol is shown where the
acceleration of the piston driving the first injection fluid
(contrast solution) from rest to a steady velocity is lower than
the acceleration of the piston driving the second injection fluid
(saline). Desirably, acceleration of the piston driving the second
injection fluid is maximized such that the piston reaches its
desired velocity in a least amount of time. The acceleration of the
piston driving the first injection fluid is controlled as a
function of relative velocities between the two pistons, the
acceleration of the piston driving the second injection fluid, and
a correction factor selected to compensate for the system
capacitance. The acceleration of the piston driving the first
injection fluid may be controlled only during the start of the
injection procedure, or during the start and end of the injection
procedure. The correction factor can be derived from empirical
testing or derived from material and shape calculations of the
fluid delivery set and the fluid injection system.
[0153] With reference to FIG. 37, a velocity profile of the two
pistons controlling the injection of first and second injection
fluids (i.e., contrast solution and saline, respectively) is shown
in the initial stage of injection prior to the time when the piston
driving the first injection fluid reaches steady state velocity
(labeled A'). The velocity profile of the piston driving the second
injection fluid is labeled as B'. Injection pressure at fluid paths
of first and second injection fluids leading from the syringes are
equalized when the areas under the velocity profiles A' and B' are
substantially equal. The area under the curve for velocity profile
A' can be calculated by the following equation: U.sub.1=1/2
V.sub.1*t, where V.sub.1 is the velocity of the piston driving the
first injection fluid and t is time. The area under the curve for
velocity profile B' can be calculated by the following equation:
U.sub.2=V.sub.2*t, where V.sub.2 is the velocity of the piston
driving the second injection fluid and t is time. The calculation
of U.sub.2 does not account for any velocity gradient from the
start of the injection procedure until a steady state velocity is
achieved because acceleration of the piston driving the second
injection fluid is maximized such that the initial slope of
velocity profile B' is essentially vertical. Based on the above
equations, the areas under the velocity profiles A' and B' are
substantially equal at a time when the velocity of the piston
driving the first injection fluid is equal to twice the velocity of
the piston driving the second injection fluid (i.e.,
V.sub.1=2*V.sub.2). Because the acceleration of the piston driving
the second injection fluid is known (i.e., the maximum acceleration
A.sub.2 that the piston can achieve), the acceleration of the
piston driving the first injection fluid can be calculated as a
function of the velocity ratio between the two pistons. The
following equation governs the acceleration value Ai of the piston
driving the first injection fluid:
A.sub.1=A.sub.2/(c*(V.sub.1/V.sub.2)), where c is a scalar
correction factor selected to compensate for the system capacitance
and minimize the backflow volume. As noted above, the correction
factor c can be derived from empirical testing based on a plurality
of different injection pressures and fill volumes of the syringes
containing the first and second injection fluids. Alternatively,
the correction factor c can be derived from material and shape
calculations of the fluid delivery set and the fluid injection
system. The correction factor controls the acceleration Ai of the
piston driving the first injection fluid in the initial stage of
fluid injection in order to compensate for the system capacitance
at a given injection pressure and the fill volume of the syringes
containing the first and second injection fluids. The difference in
acceleration between the piston controlling the injection of the
contrast solution and the piston controlling the injection of
saline is determined by the predicted capacitance volume of the
syringes with the correction factor c dominated primarily by
pressure and the fill volume of the syringe.
[0154] As shown in FIG. 38, a plurality of backflow volume curves
are shown as a function of injection pressure for uncorrected
acceleration value for the piston driving the first injection fluid
and a corrected value for correction factors c. The correction
factor is chosen to minimize or eliminate the backflow volume
across all injection pressures for a given fill volume of the
syringes containing the first and second injection fluids.
Minimizing or eliminating the backflow volume ensures that the
actual ratio of the first and second injection fluids is maintained
at all stages of the injection process.
[0155] While several embodiments were 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.
* * * * *