U.S. patent application number 10/833313 was filed with the patent office on 2004-10-07 for total system for contrast delivery.
This patent application is currently assigned to Medrad, Inc.. Invention is credited to Evans, Russell Morrison III, Uber, Arthur E. III.
Application Number | 20040199075 10/833313 |
Document ID | / |
Family ID | 22508701 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040199075 |
Kind Code |
A1 |
Evans, Russell Morrison III ;
et al. |
October 7, 2004 |
Total system for contrast delivery
Abstract
An apparatus and method enabling the injection of fluid media
into a plurality of patients is provided, including a fluid supply
source providing multiple doses, a metering device for measuring
the doses, a pressurizing device to effect injection, a
contamination prevention device disposed between the fluid source
and the patient and, when desired, an electronic control device to
integrate operation of the apparatus and process.
Inventors: |
Evans, Russell Morrison III;
(Natrona Heights, PA) ; Uber, Arthur E. III;
(Pittsburgh, PA) |
Correspondence
Address: |
PILLSBURY WINTHROP, LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Assignee: |
Medrad, Inc.
Indianola
PA
|
Family ID: |
22508701 |
Appl. No.: |
10/833313 |
Filed: |
April 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10833313 |
Apr 28, 2004 |
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10095127 |
Mar 11, 2002 |
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6731971 |
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10095127 |
Mar 11, 2002 |
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09266727 |
Mar 12, 1999 |
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6442418 |
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09266727 |
Mar 12, 1999 |
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08919742 |
Aug 28, 1997 |
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5885216 |
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08919742 |
Aug 28, 1997 |
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08534081 |
Sep 22, 1995 |
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5806519 |
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08534081 |
Sep 22, 1995 |
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08144462 |
Oct 28, 1993 |
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Current U.S.
Class: |
600/431 |
Current CPC
Class: |
A61M 2205/6072 20130101;
A61M 5/16827 20130101; Y10S 128/12 20130101; A61M 5/007 20130101;
Y10S 128/13 20130101 |
Class at
Publication: |
600/431 |
International
Class: |
A61B 006/00 |
Claims
What is claimed is:
1. A method of delivering fluid media to a plurality of patients,
comprising: delivering a first fluid medium through a reusable
fluid path; delivering the first fluid medium through a per-patient
disposable fluid path; disconnecting the per-patient disposable
fluid path from the reusable fluid path; disposing the per-patient
disposable fluid path; and connecting a second per-patient
disposable fluid path to the reusable fluid path.
2. The method of claim 1, further comprising: delivering the first
fluid medium through the reusable fluid path and the second
per-patient disposable fluid path; disconnecting the second
per-patient disposable fluid path from the reusable fluid path; and
disposing the second per-patient disposable fluid path.
3. The method of claim 1 wherein the reusable fluid path comprises
a source of the first fluid medium and a pressurizing unit.
4. The method of claim 1 wherein the per-patient disposable fluid
path comprises a valve and a tube.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional of application Ser. No. 10/095,127
filed Mar. 11, 2002, which is a continuation of application Ser.
No. 09/266,727 filed on Mar. 12, 1999, now U.S. Pat. No. 6,442,418,
which is a continuation of application Ser. No. 08/919,742, filed
on Aug. 28, 1997, now U.S. Pat. No. 5,885,216, which is a
divisional of application Ser. No. 08/534,081, filed on Sep. 22,
1995, now U.S. Pat. No. 5,806,519, which is a continuation of
application Ser. No. 08/144,462, filed on Oct. 28, 1993, abandoned,
the contents of which are incorporated herein in their
entireties.
BACKGROUND OF THE INVENTION
[0002] Contrast media are used in many medical diagnostic and
therapeutic imaging procedures. Diagnostically these include X-ray
procedures for instance, angiography, venography and urography, CT
scanning, magnetic resonance imaging (MRI), and ultrasonic imaging.
Contrast media is used during therapeutic procedures such as
angioplastic and other interventional radiologic procedures.
Because this contrast material is injected into the patient, it
must be sterile and contain a minimum of pyrogens.
[0003] Presently, most contrast is provided in sterilized glass
bottles, ranging in size from 20 ml to 200 ml. Plastic packages are
also available. Non-ionic X-ray contrast media is expensive, on the
order of $1/ml. Ionic contrast media costs about $0.10/ml. Non-ion
contrast has fewer complications but because of the cost, it is not
universally used. MRI contrast costs about $5/ml. All the
containers are single use, which means that once a bottle is
opened, it should be used for that patient or thrown away, although
a multi-use 1,000 ml bottle has been recently approved by the
FDA.
[0004] A hospital must purchase and stock many concentrations in
multiple bottle sizes to provide the right amount of the right
concentration for a specific procedure, while minimizing the
wastage of contrast remaining in any opened bottles.
[0005] This multitude of sizes and concentrations increases costs
throughout the contrast supplier chain. Manufacturers need to make
many batches with various concentrations, and package each in many
sized bottles. They must have inventories of each on hand to
quickly meet the customer's request. Each concentration and size
entails an added regulatory burden.
[0006] In the hospital, there are additional costs due to the work
purchasing the various brands and sizes, storage space is required
for stocking, cabinets are required in each procedure room; and
time is required to make sure the right numbers of each bottle are
kept in each room. Frustration, waste and/or less than optimal
studies can occur if this complex logistics chain fails at any
point.
[0007] To illustrate the problem, consider a manufacturer who makes
5 concentrations of contrast, packages them in bottles of 10, 25,
50, 75, 100, 150 and 200 ml. The manufacturer now has 35 different
products to get approval for, schedule production for, maintain
sufficient stock of, and finally, ship to his customers.
[0008] Presently, most hospitals utilize a standard protocol for a
given set of indications. For instance, for a CT scan of the liver,
the protocol may call for 130 ml of contrast injected at 3 ml/s.
This protocol is used for a wide variety of patient weights and
physical conditions. One goal of this standardization is to
minimize errors. Another is to decrease the likelihood of having to
repeat the procedure, with the problem of additional radiation and
contrast dose to the patient.
[0009] However, there are costs associated with this method. Many
patients may get more contrast than they need for an image to be
diagnostic. Overdosing wastes contrast, but there is no way with
the present contrast supply and delivery system to remedy this,
without stocking many more sizes of bottles and working harder to
fill syringes. Other patients may have studies that are less than
optimum. They do not receive enough contrast. The contrast that
isn't used doesn't cost anything, but there is a much greater
chance of having to repeat the whole procedure, with a much greater
cost than a few milliliters of contrast. Again, using many bottle
sizes and a cumbersome filling procedure is the only solution
presently available.
[0010] In angiography, there are no set protocols to the same
extent as in CT, because patient size determines vessel size which
in turn determines the volume and flow rate needed. This means that
a fixed amount of contrast cannot be prepared ahead of time with
any confidence that more won't be needed during the procedure or
that a significant amount won't remain and be wasted at the end of
the procedure. To avoid delays while working on the patient, the
technician loads more than the average amount used, with the
realization that some is likely to be wasted, and there still is a
chance that a delay will occur when more has to be loaded.
[0011] Another problem this system addresses is the volume and cost
of items which must be disposed of after each patient. To save
contrast, several small glass bottles may be opened per patient.
One or more plastic syringes, and various tubing arrangements are
used. There is a cost to purchase and a cost to dispose of each of
these items.
[0012] The problems arising from the use of a multiplicity of
concentrations and container sizes was addressed in German DE
4121568A1. In this disclosure, there is provided a supply tank of
contrast agent that could contain from about 0.1 to as much as 100
liters. The device also included a similar tank that contained a
diluent so that the composition of the resulting mixture could be
varied to form a variety of concentrations. The abstract in the
German patent utilizes a bulk mechanical mixer with sequential flow
and so it would not seem to provide for the production of
continuously variable concentrations. Nor, and importantly, is
there any description of means to prevent cross-contamination when
the apparatus is used on a plurality of patients.
[0013] Machines for mixing IV solutions also do not connect
directly to the patient. Generally, the controls require that the
operator know which fluid is in which position and that he choose
the mixing ratios. In U.S. Pat. No. 4,341,153, medication is
diluted and delivered to a syringe. There are no means described
for connection to a patient, there is no mixing means and only
sequential flows are described.
[0014] U.S. Pat. No. 4,610,790 describes in great detail how to
make sterile water a for diluting medications. Making diluted
fluids is mentioned in little detail. U.S. Pat. No. 4,783,273
describes the use of sterilizing filters to assure the sterility of
bulk fluids. Concentration monitors are also described. A serious
drawback is the use of chemical sterilants.
[0015] In none of the references mentioned above is a mechanism
described which can be used to sequentially or simultaneously
inject contrast into several patients while minimizing the chance
of cross-contamination. Nor is there any mention of information
integrity or information transfer so that the proper procedures are
followed with the diluted medications.
OBJECTS OF THE INVENTION
[0016] It is a principal object of this invention to provide an
improved apparatus for injecting a contrast medium sequentially
into a plurality of patients while minimizing the chance of
cross-contamination.
[0017] It is another object of this invention to provide a contrast
medium apparatus in which the degree of concentration of the
contrast medium can be continuously varied.
[0018] It is another object of this invention to provide an
apparatus for producing contrast medium in which the medium can
either be injected directly into the patient or can be loaded into
containers and then injected by means of an injecting
apparatus.
[0019] Other objects and advantages of this invention will be, in
part, obvious and, in part, explained by reference to the
accompanying specification and the drawings in which:
DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 diagrammatically shows an apparatus and a system for
making constant changes in contrast solution strength and for
injecting the fluid or the medium directly into the patient while
minimizing the chance of patient-to-patient
cross-contamination;
[0021] FIG. 2 is an illustration similar to FIG. 1 showing one
method for filling dose containers and subsequently, putting the
dose containers in an injector head for use with a patient.
DESCRIPTION OF THE INVENTION
[0022] It is a goal of this invention to enable delivery of only
the amount of contrast needed to a patient, with minimal contrast
waste. A companion goal is to be able to deliver whatever volume of
contrast is needed, when it is needed, without the arbitrary
limitation of syringe or mixing chamber size. The bulk containers
can hold more fluid than would be given to one patient, so its size
is not a limit.
[0023] This is accomplished by changing the way contrast is
packaged and delivered to the patient. Bulk contrast bottles would
be manufactured and distributed to the hospital in only a few
number of sizes. A given procedure room would only stock one size
of bottle. The bulk contrast could only be available in a single
high concentration, the highest used in current procedures, or it
may be available in a limited number of different concentrations.
Two bottle sizes times two concentrations is only four variations
that a manufacturer would potentially have to deal with.
[0024] It is possible to eliminate the multiplicity of
concentrations by providing bulk diluent and having a contrast
delivery system able to dilute the most concentrated contrast to
any concentration which the doctor desires. The diluent may be
sterile water if the contrast is hyperosmolar, it may be saline if
the contrast is iso-osmolar, or it may be a contrast specific
diluent which preserves specific desirable properties of the
contrast during dilution, such as pH. It may be most convenient if
contrast and diluent are available as a pair from the manufacturer.
Diluent is so inexpensive that its waste is not a problem. It is
essential that sterility is preserved and that all materials be
compatible with the contrast material in use. Pharmaceutical
companies are experienced and have developed considerable expertise
in materials selection.
[0025] In the present disclosure, all embodiments employ an
electronic control system which provides the proper fluid flows
according to the instructions of the operator. The operator can
either input information on the concentrations in the various
containers, or the control system can read a bar code or other code
on the bulk container which informs it of the volume and
concentration in that bulk container. Also, there can be sensors
which inform the control system when a bulk container empties, or
the control system can keep track of the volume removed and
anticipate when it will run out. Anticipation is preferred because
an operator can then be informed during programming of the need to
add fluid, rather than start a procedure and then run out.
[0026] There is a benefit to having back-up monitors for these
important parameters. If the system anticipates when fluid runs
out, there can still be fluid assurance sensors, in case a
technician installs a partially used bottle. Especially when the
contrast is being delivered to a patient, there needs to be a fluid
assurance sensor to prevent the problem of air embolism. While
concentration is not as critical, an improper concentration can
necessitate repeat procedure. A sensor measuring
electro-conductivity could be used for both concentration
monitoring and fluid assurance. There are commercially available
ultrasonic sensors designed to detect the presence or absence of
fluid in a line. For example, U.S. Pat. No. 4,981,467 discloses
such a detector.
[0027] In the present instance, there are two classes of
embodiments, the first being those that are directly connected to
the patient and secondly, those which fill a dose container which
is then moved to an injector for delivery to a patient. The first
of these embodiments is shown in FIG. 1 where numeral 10 indicates
a source of contrast medium which is in the form of a bulk
container. Numeral 11 represents a similar container that is used
to hold a supply of diluent, in the event that it is desired to
reduce the concentration of the contrast medium contained within
source 10. The containers may be rigid or flexible glass or a fluid
compatible plastic such as polypropylene. If the containers are
rigid, one of many known methods is used to vent the container with
sterile air. A non-vented collapsible container is preferred to
avoid air entry. A metering pump 12 draws contrast from the
contrast supply source 10 at the proper flow rate. A second
metering pump 13 draws diluent (when desired) from the bulk
reservoir 11 within which the supply of diluent is contained. A
preferred metering pump is a precision peristaltic pump with
santoprene tubing. A wall design similar to that of U.S. Pat. No.
5,230, 614 would minimize the pulsatite flow characteristics. As
the fluids are removed from the containers 10 and 11, they are
heated by means of the heaters 14 and 15 so that they approximate
body temperature. The heating, of course, decreases the viscosity
of the contrast and makes the fluid more comfortable for the
patient. (Rather than in-line heaters, the bulk containers could be
heated.)
[0028] Upon leaving the metering pumps 12 and 13, the fluids meet
as they are joined and flow through a static mixer 20 that contains
helical vanes. The company ConProTec makes many sizes and lengths,
some with polypropylene vanes and a case. These static mixers are
designed for mixing fluids with very different viscosities and
varying dilution ratios. The exact length and diameter to be used
will depend to some degree upon the viscosity of the contrast,
dilution ranges, and flow rates. The flow is next through a
concentration monitor 23. With metering pumps, this is optional but
serves a useful verification function signaling if an incorrect mix
occurs. Or, the metering pumps could be replaced by valves and the
concentration monitor could continuously monitor and be part of the
feed back control of the valves. The monitor measures a property
which changes with concentration, such as electrical conducting,
optical refraction index, rotation of polarized light, attenuation
of sound, speed of sound, density, viscosity, or pressure drop
through a fixed section. The mixture next flows through a back-flow
prevention valve 21 which can be either a spring-loaded ball valve
or a duck bill valve. This is an important feature of the overall
device since it helps prevent cross-contamination when the device
is used on another patient. By including valve 21 in the system, it
is possible for fluid to flow only in one direction and there is no
chance that contaminated fluid can be drawn back into the bulk
fluid reservoirs from the patient's body.
[0029] Next, the fluid flows through a fluid assurance detector 22
which may be an ultrasonic detector so that the presence or absence
of air in the fluid can be determined. Since these types of devices
cannot detect small air bubbles, by being located before the
pressurization pump 25, bubbles will be as large as possible. The
fluid assurance detector helps minimize the chance that a broken
line or human error can inject air into the patient.
[0030] Up until this point, the flow of the liquid has been at
relatively low pressures. To inject the fluid through the connector
tube 27 and catheter into the patient, relatively high pressures
are needed: 300 psi for CT, up to 1200 psi for angiography, and 300
psi for MRI. Ultrasound contrast is presently not stable at high
pressures, but its viscosity is similar to that of water so high
pressures are not necessary. Presently this procedure is done by a
powerful syringe pump, but these have the draw back that they can
only inject one syringe full at a time. In the present embodiment,
the pressurizing pump is a gear pump, with the housing and gears
made from TPX. The parts could optionally be polycarbonate or
Teflon coated polycarbonate. This gives the clarity needed to check
for bubbles, and the drug compatibility of Teflon. The shaft of the
gear pump is connected to an electric motor with a spline or other
coupling mechanism so that the pump head can be removed and
disposed of when required. Depending upon the fluid path which
leads to the gear pump and the turbulence within the pump, enough
mixing could take place that the static vane mixer could be
eliminated. Fassbender in U.S. Pat. No. 3,349,713 teaches how a
gear pump can be modified to accomplish the mixing of fluids of
different viscosities. Because of the widely varying flow rate,
this is not possible for all applications, but some would benefit
by the elimination of the mixing element and the incorporation of
its function into the pump.
[0031] The pressurized fluid flows through a 0.2 micron
"sterilizing" filter 26. These filters are becoming a standard way
to assure sterility of the solution. Its purpose here is to prevent
migration of any bacteria from the patient into the pump. In
cooperation with the backflow valve, cross-contamination in
minimized. The sterile filter prevents bacteria from swimming up
stream and the back flow preventer stops passive pathogens from
being carried backward through the sterile filter. The fluid coming
out of the pump is sterile. The area of the sterile filter will
need to be adjusted to accommodate the flow rates of the various
procedures while maintaining a reasonable pressure drop. A flexible
connector tube 27, which is preferably sterile, carries the fluid
to the patient. These are commercially available, usually made out
of PVC. This component is disposed of after each patient so that it
does not need to have long term compatibility with contrast
medium.
[0032] At the patient, there is a three-way stopcock 30 and a hand
syringe 31. This part can be used for several things. It can be
used to aspirate blood and thus, verify good IV catheter placement
in CT. It can be used to inject other medications. It can also be
used to fill a hand syringe which can be removed and used for test
injections during angiography. With one position of the stopcock,
the fluid flows straight into the patient.
[0033] The present apparatus includes an electronic control system
(ECS) 35 to assure that the needs of the patient are met safely.
ECS 35 gets information on the contents of the bulk reservoirs 10
and 11. The preferred method is to read bar codes indicated by
numerals 10' and 11' respectively. Another way is to quiz the
operator to enter the data each time a bulk reservoir is changed,
and then store that information. The operator would read the label
on or packaged with the bulk reservoir, and enter the appropriate
data. This need only be done when a bulk reservoir is changed.
[0034] With each injection, the operator needs to tell the system
what to do. The data most similar to present practice is: 1) the
concentration desired, 2) the flow rate, and 3) the total volume to
be delivered. Present practice also includes multiple phases with
various constant flow rates during each phase. This system would
allow various contrast concentrations during each phase as
well.
[0035] However, given the capabilities of this system, a preferred
set of information is: 1) the procedure being done, and 2) the
patient weight. This way the contrast dose could be optimized for
the patient. The algorithm would have been previously provided
information on milligrams of iodine per kilogram of patient for
each procedure when the system was first installed in the hospital.
It could display concentration, flow rate and volume for operator
verification, if the operator desired. An electronic interface 36
is shown which can connect to the hospital information system to
get information on the patient, such as weight. Then the operator
would only have to input the patient number. The electronic
interface could also be connected to the imaging equipment. It
could send or receive information so that, for instance, the
operator only needs to program the CT scanner with the number of
slices and the body section, and this would be transmitted to the
contrast delivery system to be used in determining flow rates and
delays. The electronic interface would also be used to let the
scanner trigger the contrast delivery system or vice versa, after
the appropriate delays. A hard copy printer may be optionally part
of the user interface, receiving data from the ECS. This can print
a record of the actual injection for insertion into the patient
records. The output may be alphanumeric or be a graphical
representation of the injection.
[0036] The operation of delivering fluid to the patient can be
started by the operator with a start switch on the contrast
delivery system, or from the console of the scanner. There would
need to be an arming procedure similar to that of present injectors
to help assure patient safety.
[0037] In CT, usually only one injection is given, sometimes with
pauses and changes in flow rates. As the end of the injection is
reached, contrast can be conserved if the contrast flow is stopped
and the diluent flow continued so the "bolus" of diluted contrast
is flushed out of the tubing and into the patient. In angiography,
several injections may be used. It is necessary to flush only after
the last injection, although no harm, except injecting a little
extra fluid, occurs if the flush follows each injection.
[0038] Another form of waste is using contrast to prime the fluid
path which is disposed of with each patient, especially if the
concentration has not yet been decided upon. The flush or diluent
fluid is much cheaper than the contrast and of lower viscosity, so
it can be used to prime the line and make sure that all air has
been removed from the path to the patient.
[0039] The present invention envisions that the "per patient"
disposable portion of the apparatus starts just above the sterile
filter 26 and ends at the patient. This "per patient" connection
26' may be made farther upstream, with the result that more of the
fluid path is disposed of. This connection must be broken after one
patient and made before the next. After the connection to one
patient is removed, the connection for the next patient is quickly
installed and sterilized, as by means of ultraviolet illumination.
The present practice of making aseptic connections as discussed in
U.S. Pat. No. 5,207,642 involves inserting a spike through a
resilient member. This is common practice and is acceptable when
used on one patient although it does not provide the level of
sterility provided by ultraviolet illumination. The remainder of
the connector tube and the patient connection end can remain in the
sterile bag, ready for the patient who may come in the next hour or
in the next few days. To further enhance sterility, the remainder
of the fluid path connecting containers 10, 11; heaters 14, 15;
metering pumps 12 and 13, etc., is disposable, in which case the
"per patient" connection 26' would be moved farther upstream, as
described above, to the desired position, bearing in mind that the
disposable portion is defined as everything below the connection
26', inclusive of elements downstream of the connection 26'. For
example, if the connection 26' is positioned along the fluid path
that connects the containers, heaters or metering pumps, everything
downstream of the connection 26', e.g., pump 25, detector 22 and/or
valve 21, would be included with the disposable portion. However,
it is only recommended that the disposable portion be replaced when
the bulk contrast container is replaced. Thus, this system needs no
active sterilization mechanism nor any toxic sterilants.
[0040] It is possible for the bulk fluid containers to feed more
than one imaging suite, and thus, more than one patient at the same
time. With large enough containers, this would be desireable. Each
imaging suite would have all the components shown in FIGS. 1 or 2,
except that they would share containers 10 and 11 from which fluid
could be drawn simultaneously. Or, there could be just one central
ECS, with a user interface in each imaging suite.
[0041] It is possible to operate the device without the addition of
any diluent. In this case, the static mixer could be removed since
there will be no change in the concentration of the contrast
medium. This system provides several simplifications but does
require a departure from the normal practice that has-existed in
hospital practices until this time. In operating by this method,
the operator would put in patient weight and the procedure, the
electronic control system would calculate total volume and flow
rate and the patient weight and procedure would determine the
milligrams of Iodine per second that were needed. The contrast
delivery system would then deliver at the flow rate needed to
provide the proper mgI/s. With the removal of the limitations of
syringe and bottle size, concentration is a redundant parameter
when flow rate can be freely determined.
[0042] In the apparatus shown in FIG. 2, the fluid flows from the
static mixer to a dose container 40. When filled with the proper
amount of the desired concentration, the dose container is
separated from the filling section and installed in the injecting
section 41. This embodiment has two benefits. Cross-contamination
is more positively prevented because air intervenes between the
patient and the bulk reservoirs. The sterile filter may still be
used but ideally it and the back flow valve are less significant or
optional. Secondly, the system can utilize existing contrast
injectors which hospitals already own, thus, reducing capital
costs. It is not the preferred embodiment because it imposes
limitations based upon syringe size.
[0043] The dose container need not be physically moved from one
machine to another. It may stay in place, but the connection to the
static mixer is opened and the connection to the patient is made.
Interlocks would assure that a syringe could not be refilled after
being connected to a patient. This prevents contamination by
pathogens from the patient.
[0044] FIG. 2 shows the filling station and the injector with
separate electronic control systems. To transfer information, a
label 42 is printed and attached to the dose container. This label
is read by the contrast injector and used to set the program. In
the event that the label is not machine readable then the label can
be printed in human readable text and the operator could program
the contrast injector.
[0045] The embodiment presented above is the one preferred by the
inventors, but it is possible for someone skilled in the art to
rearrange the order of the components in the fluid path and still
accomplish the goals of this device. In particular, the first
component could be pressurizing pumps which create high enough
pressures to drive the fluid through the remainder of the system
and into the patient. Or, the bulk containers could be pressurized,
and the metering pumps could then be metering valves. Mixing could
be after the sterile filters, right before injection into the
patient. These are only a few of the reasonable permutations. It is
also a reasonable extension of this idea that more than two bulk
containers may be used. These can sequentially or simultaneously
dispense their fluid as medically necessary. They may contain
various medicines to be diluted or not. An example is heparinized
saline to prevent clotting in the catheter.
[0046] Although the present invention has been described in terms
of preferred embodiments, the present description is given by way
of example and is not intended to be limiting to the scope of the
invention described and claimed.
* * * * *