U.S. patent application number 10/383458 was filed with the patent office on 2003-08-28 for support devices for surgical systems.
Invention is credited to Fallen, David M., Long, Stuart G., Martinet, Alphonse.
Application Number | 20030163078 10/383458 |
Document ID | / |
Family ID | 26797619 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030163078 |
Kind Code |
A1 |
Fallen, David M. ; et
al. |
August 28, 2003 |
Support devices for surgical systems
Abstract
A device for supporting and displaying interrelated medical
components, such as cardiopulmonary bypass circuit components. The
device includes a rigid or flexible chassis having openings therein
for receiving the components. A plurality of retainers, such as
straps, hooks, or tabs, are provided adjacent the openings for
releasably securing the components therein. The chassis may be
formed of a thin, flexible polymer sheet having tabs cut therein
and adapted to be bent out of the plane of the sheet for securely
retaining the various components. The pre-arrangement of the
components in close proximity greatly simplifies the task of
setting up a particular medical circuit, and reduces the potential
for error. For cardiopulmonary bypass circuits, the support device
enables the tubing lengths to be reduced, thus reducing the prime
volume of the circuit. The chassis is provided with apertures for
mounting on rods in the operating room, which rods may extend from
the operating table. Handles are also provided on the chassis for
conveniently transporting the components or circuit. The compact
nature of the chassis and components thereon simplifies and reduces
the cost of packaging and shipping. In addition, disposal of a used
circuit is facilitated by the provision of a clean bag around the
entire system. A pumpless cardioplegia delivery system is also
provided.
Inventors: |
Fallen, David M.;
(Asheville, NC) ; Long, Stuart G.; (Lake Forest,
CA) ; Martinet, Alphonse; (Placentia, CA) |
Correspondence
Address: |
EDWARD LIFESCIENCES CORPORATION
ONE EDWARDS WAY
IRVINE
CA
92614
US
|
Family ID: |
26797619 |
Appl. No.: |
10/383458 |
Filed: |
March 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10383458 |
Mar 6, 2003 |
|
|
|
09390381 |
Sep 3, 1999 |
|
|
|
60100852 |
Sep 18, 1998 |
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Current U.S.
Class: |
604/6.01 ;
604/6.15 |
Current CPC
Class: |
A61M 1/3666 20130101;
A61M 1/367 20130101; A61M 2209/082 20130101; A61M 1/3667 20140204;
A61M 1/3664 20130101 |
Class at
Publication: |
604/6.01 ;
604/6.15 |
International
Class: |
A61M 037/00 |
Claims
What is claimed is:
1. A support device for surgical systems, comprising: a chassis
adapted to support and display in a predetermined arrangement a
plurality of interrelated surgical system components.
2. The support device of claim 1, wherein the chassis comprises a
body having a plurality of openings therein for supporting and
displaying the surgical system components.
3. The support device of claim 2, wherein the body is rigid.
4. The support device of claim 2, wherein the body is planar.
5. The support device of claim 2, wherein the body is flexible.
6. The support device of claim 5, wherein the body is generally
planar.
7. The support device of claim 6, wherein the chassis includes the
generally planar body and a plurality of flanges provided at the
periphery of the planar body for stabilizing the flexible body.
8. The support device of claim 2, wherein the body is formed of a
polymer.
9. The support device of claim 8, wherein the polymer is
non-brittle and non-abrasive.
10. The support device of claim 2, wherein the body is formed of a
polymer sheet and the openings are cut therein.
11. The support device of claim 10, further including a plurality
of tabs formed by cuts in the polymer sheet, the tabs being
bendable from the plane of the planar body and being adapted to
releasably retain the surgical system components.
12. The support device of claim 11, wherein at least some of the
cuts are directed away from the openings so that any tears that may
occur between the tabs and the body are propagated away from the
openings.
13. The support device of claim 1, wherein the surgical system is a
cardiopulmonary bypass circuit, and the chassis includes customized
openings for supporting at least a blood reservoir, an oxygenator,
and a blood filter.
14. The support device of claim 13, wherein the chassis comprises a
generally planar body and is reversible so that the blood
reservoir, oxygenator, and blood filter may be supported and
displayed in the openings from either side of the planar body.
15. The support device of claim 13, wherein the chassis includes
channels formed between the openings so that the blood reservoir,
oxygenator, and blood filter may be interconnected by tubes
positioned in the channels.
16. The support device of claim 1, further including a plurality of
retainers provided on the chassis for supporting the surgical
system components.
17. The support device of claim 16, wherein the retainers comprise
straps.
18. The support device of claim 16, wherein the retainers comprise
hooks.
19. The support device of claim 16, wherein the retainers comprise
hook and loop fasteners.
20. The support device of claim 16, wherein the retainers comprise
tabs formed in the chassis.
21. The support device of claim 20, wherein the tabs are flexible
and may be bent away from the chassis.
22. The support device of claim 21, wherein the chassis comprises a
planar body, and wherein the tabs are formed by cuts in the planar
body that are bendable from the plane of the planar body about
living hinges and are adapted to releasably retain the surgical
system components.
23. The support device of claim 1, wherein the the plurality of
interrelated surgical components is adhesively bonded to the
chassis.
24. The support device of claim 1, wherein the plurality of
interrelated surgical components is integrally formed into the
chassis.
25. The support device of claim 1, wherein the chassis comprises a
wire grid and the plurality of interrelated surgical components is
supported by the wire grid using suitable retainers.
26. A pre-assembled surgical system, comprising: a plurality of
interrelated surgical system components; and a chassis, wherein the
surgical system components are supported and displayed by the
chassis in a predetermined arrangement.
27. The pre-assembled surgical system of claim 26, wherein the
surgical system is a circuit, and further including a plurality of
tubes for interconnecting the surgical system components, at least
some of the tubes initially being disconnected in the pre-assembled
surgical system.
28. The pre-assembled surgical system of claim 26, wherein the
chassis comprises a plurality of openings for receiving the
surgical system components.
29. The pre-assembled surgical system of claim 28, further
including a plurality of retainers provided on the chassis adjacent
the openings for retaining the surgical system components.
30. The pre-assembled surgical system of claim 29, wherein the
retainers comprise flexible tabs formed in the chassis adapted to
be bent away from the chassis.
31. The pre-assembled surgical system of claim 30, wherein the
chassis comprises a planar body, and wherein the tabs are formed by
cuts in the planar body.
32. The pre-assembled surgical system of claim 26, wherein the
surgical system is a cardiopulmonary bypass circuit including a
venous blood reservoir sealed for vacuum-assisted venous drainage,
the system further including a bracket for receiving the chassis
and having at least one occluder adapted to regulate flow into
portions of the bypass circuit.
33. The pre-assembled surgical system of claim 32, wherein there
are at least two occluders, and the occluders are adjustable
electronic occluders which control flow where needed in both
positive and negative pressure areas of the system.
34. A method of setting up a cardiopulmonary bypass circuit,
comprising: obtaining a pre-assembled cardiopulmonary bypass
circuit, including a plurality of bypass components supported and
displayed on a chassis and a plurality of tubes for interconnecting
the bypass circuit components, at least some of the tubes initially
being disconnected in the pre-assembled bypass circuit; and
interconnecting the bypass circuit components using the tubing.
35. The method of claim 34, further comprising: priming the system;
and temporarily removing one or more of the bypass components from
the chassis as needed during priming of the system.
36. The method of claim 35, wherein the chassis has openings
therein customized to fit each of the bypass components, and
retainers are provided for releasably retaining the bypass
components in the openings, the method further comprising:
releasing the retainers to temporarily remove the bypass components
as needed from the chassis during priming; and using the retainers,
re-attaching the bypass components that were temporarily
removed.
37. The method of claim 36, wherein the chassis comprises a
generally planar, polymer body, and retainers are tabs cut in the
body and adapted to pivot out of the plane of the body about living
hinges.
38. A method of disposing of a surgical circuit, comprising:
depositing a chassis having a plurality of used components mounted
thereon in a clean bag, and transporting the bag to an infectious
waste disposal container.
39. The method of claim 38, wherein the surgical system components
are supported and displayed by the chassis in a predetermined
arrangement.
40. The method of claim 39, wherein the chassis comprises a
plurality of openings for receiving the surgical system components,
and further including a plurality of retainers provided on the
chassis adjacent the openings for retaining the surgical system
components.
41. The method of claim 38, wherein the chassis includes a handle
for transport, and the clean bag and chassis are configured so that
the handle can remain outside of the clean bag while the bag
surrounds the rest of the chassis and components thereon.
42. The method of claim 41, further including an adjustable closure
on the clean bag for closing about the chassis and components
thereon while the handle remains outside, the closure being adapted
to be subsequently loosened and re-closed with the handle inside
the clean bag.
43. A method of cardiopulmonary bypass including cardioplegia
delivery, comprising: impelling blood using a pump through an
oxygenator, some of the oxygenated blood being directed through a
filter to an arterial return line, and some of the oxygenated blood
being directed to an input of a cardioplegia heat exchanger; mixing
cardioplegia solution with the oxygenated blood within the
cardioplegia heat exchanger; and impelling the mixed cardioplegia
solution and oxygenated blood using the pump through the
cardioplegia heat exchanger to a cardioplegia delivery line.
44. A cardiopulmonary bypass system, comprising: a pump; an
oxygenator having an inlet connected to receive blood from the
pump; a filter connected to receive oxygenated blood from the
oxygenator; an arterial return line connected to receive oxygenated
blood from the filter; a cardioplegia heat exchanger connected to
receive oxygenated blood from the oxygenator; a cardioplegia
delivery line connected to receive fluid from the cardioplegia heat
exchanger; a cardioplegia solution supply connected to the
cardioplegia heat exchanger; and wherein the pump impels the
cardioplegia solution and oxygenated blood through the cardioplegia
heat exchanger to the cardioplegia delivery line.
Description
RELATED APPLICATION
[0001] The present application claims the benefit of priority under
35 U.S.C. section 119 (e) from provisional application serial No.
60/100,852, filed Sep. 18, 1998, entitled "SYSTEMS AND METHODS FOR
PERFORMING EXTRACORPOREAL BYPASS PROCEDURES".
FIELD OF THE APPLICATION
[0002] The present invention relates to devices and methods for
supporting operating room systems and, more typically, to devices
and methods for supporting surgical circuits in a convenient and
easily accessible format. The invention is particularly well-suited
to enable pre-assembling of cardiopulmonary bypass circuits.
BACKGROUND OF THE INVENTION
[0003] Effective circulation and control of the patient's blood are
essential to successful heart surgery. This is of particular
importance in procedures where the patient is on cardiopulmonary
bypass for a significant period of time during surgery. In most
modem bypass procedures, blood is oxygenated, treated, and
recirculated through the patient by establishing an extracorporeal
cardiopulmonary bypass (CPB) circuit in which the blood is
mechanically forced by a blood pump through a variety of processing
or blood modifying components. A plurality of blood pumps are
typically used throughout the CPB circuit to direct the flow of
blood through the various CPB circuit components. Generally, the
CPB circuit removes blood from the patient, oxygenates the blood,
and then returns the blood to the patient. Critics of heart surgery
techniques cite a number of drawbacks for procedures that rely on
known extracorporeal bypass platforms or circuits.
[0004] One well-known drawback of current CPB circuits is the
hemolytic effect the multiple mechanical pumps and other
instruments in the circuit may have on the blood. For example, a
CPB circuit has as many as six pumps for arterial delivery,
cardioplegia delivery, cardiotomy suction, left ventricular or
aortic root venting, assisted venous drainage, and
hemoconcentration. These pumps are typically occlusive roller-type
pumps which sequentially pinch and release tubing to affect the
desired flow.
[0005] Another drawback with current CPB circuits is the potential
for detrimental blood/air interfaces in the long segments of tubing
used for cardiotomy suction and venting. Any time blood and air
meet and are transported through tubing together, foaming may
occur. This foaming results in destruction of clotting factors
contained in whole diluted blood circulated through the CPB
circuit. This, in turn, results in the release of substances that
initiate a cascade of events leading to further dysfunction of
platelets, proteins, and eventually organ function in the form of
an inflammatory response.
[0006] A further drawback of known CPB circuits and procedures is
the extended amount of time required by a cardiac perfusionist to
set up the circuit prior to performing the procedure. The
components of a bypass circuit are typically individually packaged,
free-standing units which need to be connected together prior to
each surgical procedure. Specifically, the circuit elements must
first be located, assembled, and attached to appropriate sterilized
circuit tubing. Then, the entire circuit must be flushed out with
an inert gas and then primed with a biocompatible fluid, such as
blood or saline. The time expenditure increases the cost associated
with such surgeries.
[0007] Additionally, perfusionists preferably use long lengths of
tubing between components to allow for the exchange of bypass
components should one of them fail. Furthermore, long lengths of
tubing are required to connect venting cannulas and suction tips
located in the operative field to blood pumps which then propel the
patient's blood to the cardiotomy reservoir for processing and
return to the patient. The excess tubing creates excess tubing
volume that must be accounted for by using additional blood or
saline when the system is being primed. However, it is in the
patient's best interest to retain the maximum volume of blood
within the body, and excessive dilution of the blood can be
harmful. Therefore, the need of the perfusionist for long tubing
lengths may not be in the best interest of the patient.
[0008] Because of the drawbacks associated with conventional CPB
circuits, there is a need for improved methods and apparatuses for
performing extracorporeal bypass procedures. In particular, there
is a need for an improved CPB circuit that reduces trauma to the
blood being processed, reduces the time spent by a perfusionist
during setup, provides for reliable access to the vasculature,
minimizes the risk of infection to the patient by reducing the
number of handmade connections required during assembly and setup,
and desirably requires only minor modifications to present
procedures.
SUMMARY OF THE INVENTION
[0009] The present invention also provides improved systems,
methods, and kits for creating and establishing a bypass circuit
for use in a variety of extracorporeal procedures such as
cardiopulmonary bypass and the like. The improved system of the
present invention advantageously allows a user to assemble the
system prior to the bypass procedure with minimal setup time. In
particular, the present invention provides methods and apparatuses
that combine the advantages of putting a patient on cardiopulmonary
bypass with the advantages of reduced blood damage (e.g., minimal
hemodilution, minimal hemolysis, and preservation of clotting
factors).
[0010] A further aspect of the present invention is a system
provided in a package that can be adapted to use traditional bypass
circuit components. The system preferably reduces the total amount
of blood and foreign surface contact, thus reducing the potential
for foaming which may destroy clotting factors in the blood.
Although the present invention provides advantages in the context
of practically all bypass procedures, the invention finds
particular use with minimally invasive surgical techniques to
minimize patient trauma due to surgery and post-operative effects
related to blood bypass.
[0011] The present invention also lends itself well in the role of
a backup support system for "beating heart" coronary artery bypass
procedures known by the acronyms OP-CAB or MID-CAB. These
procedures utilize extracorporeal bypass support only in the event
of patient instability. The circuit is made available in the
operating room, but may not be used. This requires the perfusionist
to set up the pump system and dedicate a bypass system prior to the
patient need in the event bypass is required, which increases the
cost dramatically. Alternatively, the components are made
available, and the perfusionist must rapidly connect them into a
working system under great pressure. The latter solution increases
the patient risk and stress on the medical personnel. In contrast,
the present invention permits the entire circuit to be made
available in the operating room to be ready at a moments notice,
but still remain in the original packaging so that if it is not
needed, it is not expended.
[0012] In one aspect, the present invention provides a support
device for surgical systems including a chassis adapted to support
and display in a predetermined arrangement a plurality of
interrelated surgical system components. The chassis may comprise a
generally planar body having a plurality of openings therein for
supporting and displaying the surgical system components.
Preferably, the planar body is flexible and includes a plurality of
tabs formed by cuts therein. The tabs are bendable from the plane
of the planar body and are adapted to releasably retain the
surgical system components.
[0013] In another aspect, the present invention provides a
pre-assembled surgical system comprising a plurality of
interrelated surgical system components and a chassis. The surgical
system components are supported and displayed by the chassis in a
predetermined arrangement. If the surgical system is a circuit,
such as cardiopulmonary bypass circuit, the system further includes
a plurality of tubes for interconnecting the system components. At
least some of the tubes are initially disconnected in the
pre-assembled system. The chassis desirably includes a plurality of
openings for receiving the surgical system components, and a
plurality of retainers provided on the chassis adjacent the
openings for retaining the components in the openings.
[0014] In a further aspect, a method of setting up a
cardiopulmonary bypass circuit is provided by the present
invention. The method includes a pre-assembled cardiopulmonary
bypass circuit including a plurality of bypass components supported
and displayed on a chassis. A plurality of tubes interconnect the
bypass circuit components, at least some of the tubes initially
being disconnected in the pre-assembled bypass circuit. The method
includes interconnecting the bypass circuit components using the
tubing.
[0015] In a still further aspect, a method of disposing of a
surgical circuit is disclosed by present invention. The method
includes depositing a chassis having a plurality of used components
mounted thereon in a clean bag, and transporting the bag to an
infectious waste disposal container.
[0016] According to a further aspect of the present invention, an
apparatus for use in an extracorporeal bypass procedure comprises a
cassette or chassis adapted to have a plurality of mounting
elements on which a plurality of bypass components can be affixed.
The chassis may be molded from generally strong, lightweight
surgical grade materials such as plastic, polymers, and the like.
The chassis, which is generally rectangular in shape, will
preferably be oriented vertically during use. It should be
understood, however, that the chassis may be of different
configurations and/or may be adapted for use in other orientations.
The chassis will preferably allow the bypass circuit to be primed
with less than 1000 cc of fluid, preferably about 800 cc of
fluid.
[0017] The chassis of the present invention will preferably include
a plurality of mounting elements, such as recesses, to which the
bypass components can be affixed. If recesses are used, the bypass
components are fitted within the recesses. The recesses generally
allow for at least partial insertion of the component into the
chassis so that some portion of the component remains outside the
chassis. This facilitates visual inspection of the operation of
these components and also allows for handling, de-airing, and
replacement of components as desired. The mounting elements on the
chassis allow bypass components to be vertically stacked or
otherwise arranged to promote the shortest connections between
components and also provide cascading or gravity-assisted flow of
fluid. Additionally, the use of the chassis further reduces space
occupied by equipment in an already crowded surgical
environment.
[0018] Channels molded into the chassis may be provided to
facilitate the connection of components. The chassis may also come
as a pre-assembled bypass circuit with bypass components such as
the venous reservoir and tubing integrally molded or formed within
the chassis. Problems related to the sterilization process, such as
heat-kinked lines or component shifting during transportation, will
be greatly reduced or eliminated through the use of the chassis
according to the present invention. The chassis may come
pre-sterilized, assembled, and pre-connected to comprise a priming
circuit or loop, thus reducing setup time from a traditional 20-40
minutes down to about 10 minutes or less, and more preferably about
5 minutes. This is particularly advantageous when rapid set-up of a
CPB circuit may be needed to support "beating heart"
procedures.
[0019] According to a further aspect of the present invention, an
apparatus for use in extracorporeal procedures comprises a blood
circuit defining a flow path having at least one inlet from which
blood arrives from the patient, and at least one outlet where
oxygenated blood is return to the patient. The flow path is coupled
to least one vacuum source adapted to remove blood from the
patient. The flow path may contain a plurality of actuatable
occluders to control positive and negative pressures between
specific components coupled together by the flow path.
[0020] In one aspect, the flow path comprises a plurality of inlet
lines leading from the patient to a cardiotomy reservoir and a
venous line leading from the patient to a venous reservoir. The
cardiotomy reservoir, in turn, may be coupled to the venous
reservoir as desired. In this embodiment, the venous reservoir is
fluidly coupled to an arterial pump which is coupled to an
oxygenator. The output of the oxygenator is typically forked to
have an arterial line and cardioplegia line both leading to the
patient. An arterial filter and an air detector device may be
located along the arterial line. An additional pump and a
cardioplegia heat exchanger may optionally be located within the
cardioplegia line. Preferably, a one-way valve (retroguard) is
located between the venous reservoir and the arterial pump to
prevent undesired back flow. Additionally, flows to the cardiotomy
reservoir and the venous reservoir are preferably independently
controlled by vacuum sources. By using a vacuum source instead of
pumps, the level of hemolysis over the course of a surgery may be
reduced.
[0021] A further understanding of the nature advantages of the
invention will become apparent by reference to the remaining
portions of the specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective view of a cardiopulmonary bypass
system including a component support device of the present
invention;
[0023] FIG. 2 is a perspective view of one embodiment of a
component support device of the present invention;
[0024] FIG. 3 is a perspective view of another embodiment of a
component support device of the present invention and exemplary CPB
components supported thereby;
[0025] FIG. 4 is an elevational view of an exemplary bracket for
use with the component support device of the present invention;
[0026] FIG. 5 is a top plan view of the bracket of FIG. 4;
[0027] FIG. 6 is a schematic view of various components and
connecting tubing of a CPB circuit;
[0028] FIG. 7 is a perspective view of a workstation used in the
system of FIG. 1;
[0029] FIG. 8 is a perspective view of another workstation used in
the system of FIG. 1;
[0030] FIGS. 9-12 are plan views of various control panels of the
workstation shown in FIG. 7;
[0031] FIG. 13 is a front perspective view of a cardiopulmonary
bypass circuit supported and displayed by a further embodiment of
the support device of the present invention including a flexible,
planar body;
[0032] FIG. 14 is a rear perspective view of another embodiment of
the support device including a flexible, planar body showing a
number of cardiopulmonary bypass circuit components received in
openings therein;
[0033] FIG. 15 is a front perspective view of the support device of
FIG. 14 showing the bypass circuit components without
interconnecting tubes;
[0034] FIG. 16 is an isolated perspective view of FIG. 15 showing a
cardioplegia heat exchanger releasably retained by tabs bent out of
a planar body of support device;
[0035] FIG. 17 is a plan view of an unassembled support device,
seen assembled in FIGS. 14 and 15;
[0036] FIG. 18 is a perspective view of cardiopulmonary bypass
circuit mounted on the device of the present invention and enclosed
within a clean bag for easy disposal;
[0037] FIG. 19 is a schematic diagram of a prior art CPB circuit
with cardioplegia pumping; and
[0038] FIG. 20 is a schematic diagram of a CPB circuit of the
present invention with pump-less cardioplegia delivery.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] The present invention is related to improved methods,
apparatuses, and kits for supporting a number of interconnected, or
related, medical components in a convenient and easily accessible
manner. In particular, a component support device is disclosed on
which a plurality of related medical components may be mounted in
close proximity. The support device is especially useful for
mounting components in a medical circuit, such as a cardiopulmonary
bypass (CPB) circuit as illustrated. However, the support device is
also useful for mounting components in other circuits, such as for
dialysis. Moreover, the support device is useful for mounting
unconnected but related medical components used in a single medical
procedure. Therefore, the inventive aspects described herein should
not be construed as applicable only in the context of CPB circuits,
or circuits in general.
[0040] In the context of CPB circuits, the present invention may be
adapted to use a variety of safety devices such as arterial line
air detection, venous reservoir level detection, over pressure
alert/alarm systems, an arterial line retrograde flow prevention
valve, and vacuum relief valves for all vent and cardiotomy section
lines. In other words, the various components shown in described
herein should not be construed as the only type of components which
can be conveniently mounted on the support device of the present
invention. Furthermore, the specific mounting features of the
support device useful for mounting the specific components shown
could be modified to mount other components of the same type. For
example, the mounting features for the particular oxygenator or
reservoir shown could be modified to receive other oxygenators or
reservoirs.
[0041] The terms "cassette," "frame," or "chassis," and other such
terms are all used interchangeably herein to refer to any component
support devices having the properties of supporting and displaying
surgical components in a secure and convenient manner. For example,
the chassis may be a backing plate having recessed cavities or
openings in which devices may be press-fit. Alternatively, the
chassis may be an enclosure, cassette, or housing of some type in
which the medical components are internally mounted. The chassis
may itself be coupled to a mounting bracket or other similar device
to facilitate positioning within the operating theater.
Alternatively, the chassis may be a wire grid or slat-like frame to
which the medical components may be attached by tying, or otherwise
connecting them.
[0042] Referring to FIG. 1, one embodiment of a CPB system 20 of
the present invention includes a cassette or chassis 22 containing
components of an exemplary bypass circuit 24. The system 20 also
includes a control workstation 26 and an accessory workstation 28
to provide required operational support elements and accessories
for the components of the bypass circuit 24 in the chassis 22. In
other embodiments, these workstations may be combined to further
reduce the size occupied by the system 20.
[0043] Referring now to Figures 1 and 2, the chassis 22 is
typically constructed from strong, lightweight materials such as
plastic, fiberglass, or other similar expedient. As seen in FIG. 2,
the chassis 22 is mounted in a bracket 30 which slidably receives
the chassis and positions it near the control workstation 26. It
should be understood that the bracket 30 may be coupled to the
chassis 22 using other techniques such as hooks, clips, or similar
connectors. The bracket 30 may also be integrally formed with the
chassis 22 and mounted to the control workstation 26 via arm 32. In
a further embodiment, the chassis 22 may be adapted for mounting on
the operating table to minimize tubing lengths required to bring
and return blood between the bypass circuit 24 and the patient. The
chassis 22 may initially be mounted near the control workstation 26
to prepare the bypass circuit 24, and then may be hooked onto the
side, or on another location, of the operating table once bypass is
desired. As the only connections between the chassis 22 and control
workstation 26 are typically just electrical and vacuum lines, such
lines can be easily extended as desired without significantly
effecting the operation of the system 20.
[0044] Referring again to FIG. 2, in one embodiment the chassis 22
is a molded frame or template having a plurality of openings,
recesses, and channels to hold individual components of the bypass
circuit 24. It should be understood that the location of components
or component openings in the chassis 22 may be configured in many
different ways to suit the needs of a particular surgical
situation, or medical circuit. Preferably, the openings or
components of the chassis 22 will be located to minimize tubing
lengths used, reduce floor space occupied by the bypass components,
and minimize stagnant flow in the bypass circuit 24. The openings
also act as an assembly template so that the risk of errors during
assembly is reduced. The recesses and openings further minimize
manufacturing problems such as heat-kinked lines during
sterilization or component shifting during transportation, because
the chassis 22 will effectively secure the components relative to
one other. In other words, the spacing between the components is
maintained at all times such that the tubing lines are minimized
and extend directly without kinking between the components.
[0045] Due to the optimum and constant spacing between components,
the prime volume for a bypass circuit 24 using the chassis 22 is
minimized. In one preferred embodiment, the prime volume is about
800 cubic centimeters (cc), significantly lower than the prime
volume in conventional systems.
[0046] The chassis 22, as shown in FIG. 2, has an opening 34 for a
venous reservoir, an opening 38 for an arterial pump, an opening 40
for an oxygenator, an opening 42 for an arterial filter, an opening
44 for a bubble or air detector, and an optional opening 46 for a
cardioplegia pump. The openings may contain mounting elements such
as hooks 48, or may be designed to be recesses into which
components can be press fit. The openings may also contain
connecting elements such as hook and loop fasteners, adhesives, and
the like to secure components to the chassis 22. A plurality of
channels 50 help define a flow path between components as indicated
by arrows 52. The chassis 22 of FIG. 2 is optionally disposable
once the bypass components have been removed. In a preferred
embodiment, however, as explained below, the entire assembly of the
chassis 22 and the bypass components mounted thereon is disposable
as a unit.
[0047] As seen in FIG. 3, the bypass components may also be
integrally formed into the chassis 22. This further simplifies set
up of the bypass circuit 24 since many of the desired components
are prepackaged when removed from the box. Integrally forming the
chassis 22 and the bypass components also provides certain cost
efficiencies because some components, such as various reservoirs,
do not need to be separately molded. The integrated configuration
of FIG. 3 may also eliminate the need for polyvinyl chloride (PVC)
tubing along most of the fluid pathway, except for using tubing and
quick disconnects to couple certain components to the bypass
circuit 24.
[0048] With reference to FIGS. 4 and 5, the bracket 30 used to
support the chassis 22 may also contain elements used in the bypass
circuit 24. For example, the bracket 30 of FIG. 4 includes a venous
occluder 60 and pinch clamp assembly 62 used to regulate flow into
portions of the bypass circuit 24 in the chassis 22 when using
various vacuum sources for blood drainage. In some embodiments, the
bracket 30 may also have a support 64 for an air detector, a
support 66 for a centrifugal driver, and a support 68 for a
cardioplegia pump. Specifically, these certain elements on the
chassis 22 will be remotely driven by a driver or motor mounted on
the bracket. For example, if a cardioplegia pump is utilized, it
will be remotely driven and the roller pump head or centrifugal
pump driver assembly will be mounted on the bracket 30. To attach
the bracket 30 to the control workstation 26, connectors 70 and
wire harnesses 72 are provided with the bracket. As seen in the top
view of FIG. 5, slots 74 defined by the bracket 30 slidably receive
the chassis 22.
[0049] With reference now to FIGS. 1 and 6, an exemplary embodiment
of a bypass circuit 24 for use with the chassis 22 will be
described. As seen in FIG. 1, the inlets into the bypass circuit 24
include the venous drainage line 80 and additional suction and vent
lines 82. These lines 80 and 82 bring blood from the patient into a
venous reservoir 84 and a cardiotomy reservoir 86. The drainage
from the patient is assisted by least one vacuum source 88 (FIG.
6). In the embodiment of FIG. 1, the vacuum source has vacuum lines
90 and 92 connected to the respective reservoirs to generate the
desired pressure differential. The vacuum from each line 90 and 92
is regulated by vacuum regulators 94 and 96 (FIGS. 1 and 7).
[0050] Occluders 98 and 100 provided on the drainage lines 80 and
82 control flow from the patient. These occluders 98, 100 are
preferably adjustable electronic occluders which control flow where
needed in both positive and negative pressure areas of the system
20. For example, a positive pressure occluder controls cardioplegia
blood flow while a negative pressure control point would regulate
the aortic root (AO root) vent system. The use of these vacuum
sources advantageously reduces the need for a centrifugal pump on
the venous line and eliminates the need for three (3) roller pumps
used in conventional pump systems for drainage of venting systems
and cardiotomy suction. The vacuum sources do not have as much
mechanical interaction with the blood and thus will reduce
hemolysis over conventional systems.
[0051] As illustrated in FIG. 6, a retroguard valve 102 located
between the vacuum-assisted venous reservoir 84 and an arterial
centrifugal pump 104 (or as seen at 403 in FIG. 13) isolates the
negative pressure in the venous reservoir from an oxygenator 106. A
plurality of quick-disconnect devices 108 located along the tubing
110 allows for exchange of bypass circuit components should one of
them fail. The tubing is typically between about {fraction (3/16)}
inches and 1/2 inches in diameter and made from PVC or a
polytetrafluoroethylene (PTFE) equivalent. The quick-disconnect
devices 108 are optionally straight connectors with ribs or barbs
on each side with a positive locking/unlocking mechanism enabling
the device to be broken into its male and female components. A
sealing O-ring is typically an integral part of the connection
between male and female components. The devices 108 may also be
viewed as adaptive hardware which allows the present invention to
be used with currently existing bypass equipment and pump
hardware.
[0052] Blood exiting the oxygenator 106 may then flow to both an
arterial filter 112 and a cardioplegia heat exchanger 114 for
delivery back to the patient. And optional cardioplegia pump 116
(FIG. 3) may also be installed to facilitate blood delivery.
Typically, an arterial line 118 and cardioplegia delivery line 120
return blood back to the patient.
[0053] A bypass circuit 24 of the present invention performs well
at higher perfusion pressures generated during some minimally
invasive surgical procedures. Antegrade cardioplegia flow effected
by delivery of solutions through the coronary arteries is
determined to some degree by arterial line pressure. For example,
arterial line pressure of 320 mmHg has an antegrade cardioplegia
flow of 270 ml/min, with a 90 mmHg aortic root pressure. Similarly,
arterial line pressure of 150 mmHg has an antegrade cardioplegia
flow of 65 ml/min, with a 100 mmHg aortic root pressure. For
patients who exhibit great flow rates at the lower end of arterial
line pressures, bypass circuit pressure could be artificially and
temporarily increased during antegrade cardioplegia administration
to optimize cardioplegia flow. Retrograde cardioplegia flow, with
maximum flows in excess of 300 cc/min, seems unaffected by the
arterial line pressure.
[0054] Optionally, the cardiotomy reservoir 86, such as a Bentley
CATR-3500 reservoir manufactured by Baxter International Inc., can
be used for cardiotomy return and cell salvage, connected and
intermittently drained to either the venous reservoir or the cell
saver depending on the quality of the contents. At the end of the
procedure, the cardiotomy reservoir 86 can be utilized as a chest
drainage reservoir in the post-operative setting. This eliminates
the current practice of acquiring a separate chest tube drainage
reservoir at additional expense to the procedure. All reservoirs
will preferably utilize a pressure relief system, providing both
positive and negative pressure limits.
[0055] FIGS. 7 and 8 show preferred embodiments of the workstations
26 and 28. Workstation 26 contains a console 130 for arterial,
centrifugal pump control and a console 132 for cardioplegia roller
pump or centrifugal pump control if desired. Left console panel 134
controls suction and vent occluder controls, and venous line
variable occluder controls. Right console panel 136 provides safety
features such as level detection, alarm detection, CO2 flush
control, and power source-battery indicator. Perfusion information
is displayed on monitor 138. T.E.E. and DLP negative pressure
transducer information are displayed on monitors 140 and 142,
respectively. Vacuum regulators 94 and 96 regulate venous return
and cardiotomy suction and vents, respectively. Sharps containers
and the like are on workstation 28 (FIG. 8). FIGS. 9-12 illustrate
the control panels discussed above.
[0056] With reference now to FIGS. 13-18, one preferred embodiment
of the present invention is disclosed. As mentioned above, the
support device can be formed of molded plastic, a wire grid, a
rigid board with cutouts, or any number of constructions. In a
preferred embodiment, a lightweight, flexible polymer sheet is
used, with the various openings for surgical components formed by
cutouts in the sheet. There are a number of benefits derived from
using a polymer sheet, including a low manufacturing cost, low
weight, ease-of-use, and design flexibility. In one embodiment
shown, the sheet is substantially planar with all the components
been arrayed on one side. This provides the additional advantage of
permitting the sheet to be assembled with the components facing one
way or the other. In other words, the sheet is reversible to enable
the components to be displayed in either a right- or -left-handed
orientation, from the perspective of the perfusionist.
[0057] In addition, those of skill in the art will understand that
the planar configuration is only one possible construction.
Alternatively, a planar sheet may be bent into three-dimensional
shapes, such as cylinders, for supporting and displaying surgical
components to face in different directions.
[0058] A cardiopulmonary bypass circuit 150 is shown in FIG. 13
supported and displayed on a component support chassis 152. The
chassis 152 is formed of sheet material defining a planar body 154
having a plurality of openings, such as opening 156 for receiving
the various bypass circuit components. The particular bypass
circuit 150 shown includes a reservoir 160, an oxygenator 162, a
cardioplegia heat exchanger 164, and an arterial filter 166. In the
operating room, the cardiopulmonary bypass circuit 150 will be
connected to a blood pumping system, such as a centrifugal pump 170
(or roller pump system as previously shown). In addition, a source
of cardioplegia solution 172 will be connected to supply solution
to the heat exchanger 164 via an intravenous pumping/metering
device 174. Some of the tubing necessary for bypass is not shown in
FIG. 13, such as the venous and cardiotomy drainage lines that
would connect to the upper portion of the reservoir 160. Likewise,
other components such as a separate cardiotomy reservoir may be
present and supported on the chassis 152. The venous drainage may
be by gravity, with the reservoir 160 positioned below the level of
the patient, or may be vacuum-assisted, in which case the height of
the reservoir 160 relative to the patient is not as important.
[0059] The component support chassis 152 comprises the planar body
154 previously mentioned, and a plurality of bent outer flanges,
such as side flange 180, for stability. The assembled configuration
is somewhat like a vertically-oriented tray. The flanges may be
bent so that the tray is rearwardly- or -forwardly-facing,
depending on what side the components are displayed. A pair of
angled slots 182 in the upper corners of the planar body 154
receive horizontal support rods 184. The pair of angled slots 182
are spaced apart such that the support rods 184 are forced apart
slightly after the chassis 152 is suspended therefrom. This helps
maintain the chassis 152 in place through the friction between the
slots 182 and support rods 184. A lower pair of apertures 186,
which may also be angled slots, is provided in the planar body 154
and receives a corresponding pair of horizontal support rods
188.
[0060] FIGS. 14 and 15 are front and rear perspective views,
respectively, of another embodiment of the component support
chassis 200 of the present invention. The chassis 200 is in many
respects similar to the chassis 152 seen in FIG. 13, although the
reader will see that the chassis 200 also includes an upper flange
202. The chassis 200 further includes a lower flange 204 and pair
of side flanges 206 bent rearwardly from a planar body 208 along
lines 210. The flanges are coupled at their adjacent ends to form
corners 212 of the chassis 200. More specifically, a coupling tab
214 is received in a coupling slot 216 at each corner 212. This
box-shaped construction renders the assembled component support
chassis 200 relatively rigid, although it is desirably constructed
of relatively thin and flexible polymer sheet material.
[0061] A preferred material for the component support chassis 200
seen in FIGS. 13-15 is sheet extruded high-density polyethylene.
The material is desirably formed to a thickness of between
1.02-2.29 mm (0.040-0.090 in), and more preferably to a thickness
of about 1.57 mm (0.062 in). If the material is formed too thick,
bending of various tabs and flanges might cause cracking, while the
material must be thick enough to support the various surgical
components when filled with fluids. Other materials may also be
used, including Teflon.RTM., Delrin.RTM., or other non-brittle,
non-abrasive polymer. Non-brittle materials enable the tabs to be
repeatedly bent without cracking. The surgical components are
typically constructed of a polycarbonate, and the chassis should be
non-abrasive to avoid scuffing or possible forming particulates
from vibratory contact with the components.
[0062] As with the earlier embodiment, the component support
chassis 200 includes a plurality of openings for receiving and
supporting various surgical components. With particular reference
to FIGS. 14-15, the chassis 200 includes an opening 220 formed in
upper right portion thereof (as seen from the front in FIG. 15)
that receives a reservoir 222. A second opening 224 receives an
oxygenator 226. A third opening 228 receives a cardioplegia heat
exchanger 230, and a fourth opening 232 receives an arterial filter
234. Each of these openings receives at least a portion of the
corresponding surgical component and, in conjunction with a
plurality of retainers formed adjacent the openings, supports the
surgical components even when full.
[0063] As mentioned, a plurality of retainers are provided in the
chassis 200 adjacent the aforementioned openings to help support
the surgical components. In a preferred embodiment, the retainers
comprise tabs formed in specific shapes for mating with the
corresponding architecture of each of the surgical components. The
tabs are desirably formed by cut lines in the planar body 208 and
are designed to bend outward from the plane of the planar body and
releasably couple with the surgical components. Therefore, those of
skill in the art will recognize that the preferred polymer sheet
material enables a plurality of tabs to be cut therein and be bent
along living hinge lines. However, the invention should not be
construed as limited to tabs pivoted about living hinges. That is,
other arrangements which rely on separate tabs hingedly coupled to
the chassis 200 are contemplated. Furthermore, the openings
themselves may be provided in the polymer sheet, and the surgical
components coupled to the chassis 200 by way of straps, hooks, or
other such expedients. In short, the illustrated chassis 200 is
only one of a number of ways of supporting and displaying
interrelated medical components.
[0064] With reference to the plan view of FIG. 17, in conjunction
with the perspective views of FIGS. 14-16, the various tabs for the
medical components illustrated will now be described. Beginning at
the upper left portion of the planar body 208, an arterial filter
tab 240 is formed adjacent the filter opening 232. An upper
cardioplegia heat exchanger tab 242 is disposed directly below the
filter tab 240. A lower cardioplegia heat exchanger tab 244 is
formed opposite the heat exchanger opening 228 from upper tab 242.
Just below tab 244 is an upper oxygenator tab 250 adjacent the
oxygenator opening 224. The oxygenator is also held in place by a
pair of a lower tabs 252. The right side tab 252 includes an
elongated tubing release tab 254 which can be partly separated from
the main tab portion along score line 256. Finally, the reservoir
222 is releasably held in place using an upper tab 260, pair of
door tabs 262, and a lower tab 264.
[0065] A number of the illustrated tabs include small apertures
therein for receiving fluid inlet or outlet ports integrally formed
with the respective surgical component, or for receiving tubing
connected to such ports. In addition, several of the tabs are
provided with apertures for receiving rigid mounting flanges
provided on the components. For example, upper oxygenator tab 250
includes a pair of apertures 270 for receiving mounting flanges 272
on the oxygenator 226. Finally, some of the tabs include finger
holes for grasping and bending the tabs from the plane of the body
208. For example, upper reservoir tab 260 includes finger holes 274
and the upper heat exchanger tab 242 includes a pair of finger
holes 280.
[0066] The tabs are designed to securely retain each of the
components in its respective position on the chassis 220, while
permitting easy release. During setup of a cardiopulmonary bypass
circuit, for example, the perfusionist often wishes to manipulate
various components to facilitate priming and remove air bubbles
from within. In one specific example, the upper heat exchanger tab
242 includes the finger holes 280 and an elongated slot 282 for
receiving an upper fluid inlet port 284. By tilting the heat
exchanger 230 toward the planar body 208 and grasping the finger
holes 280, the upper tab 242 can be pivoted toward the planar body,
thus releasing the heat exchanger 230 for manipulation. Likewise,
as seen in FIG. 15, the tubing release tab 254 can be pulled
outward from planar body 280, thus partly separating it along score
line 256 from the lower tab 252. The score line terminates in
tubing aperture 290, which permits the oxygenator 226 to be lifted
free of the chassis 220.
[0067] A number of score lines are formed in the planar body 208 to
enable various portions to be more easily bent and retain the bent
position. So, for example, each of the peripheral flanges bends
with respect to the planar body 208 about a score line 292.
Likewise, some of the tabs also bend about score lines, such as,
for example, all of the tabs for retaining the reservoir 222. Some
tabs, however, are designed to flex out from the plane of the
planar body 208, but exert a restoring force toward the initial
position. The upper and lower cardioplegia heat exchanger tabs 242
and 244, for example, are not scored and are biased back into the
plane of the body 208. The arterial filter tab 240 is also not
scored. These unscored tabs exert a force on the respective
components that helps hold them in place with a minimum of material
or interconnections. This minimal retaining structure thus
facilitates easy manipulation or change out of components.
[0068] It should be noted that the cut lines of some tabs are
oriented to prevent any tears from propagating toward one of the
component openings. The arterial filter tab 240, for example, has
an outer edge 294 that is angled away from the filter opening 232.
Not only is the bend region strengthened, but any tear that occurs
will be directed away from the opening 232, thus preventing failure
of the filter support.
[0069] The aforementioned specific features of the tabs are related
to the particular surgical components supported and displaying by
the chassis 220. In the illustrated embodiment, the components are
part of a cardiopulmonary bypass circuit available from Baxter
International Inc.. Those of skill in the art will recognize that
the chassis 200, and the other surgical component support devices
of the present invention, can be manufactured to receive and
support any components available on the market. Therefore, although
certain specific features of the tabs shown in FIGS. 14-16 may be
used to support components supplied by different manufacturers,
other tab designs are likely and contemplated for other medical
circuits.
[0070] In this regard, the plan view of FIG. 17 clearly shows the
simplified layout of the cut lines used to form the various
openings and tabs of the present invention. These cut lines are
preferably formed by die cutting the extruded polymer sheet. A die
cutting machine comprises a roller having a predetermined knife
pattern on its exterior. The sheet is passed underneath the
rotating roller which, by downward pressure, cuts the various
lines. Alternatively, the knife pattern could be provided on a flat
die which is stamped onto the sheet material supported by a table.
The particular die is created based on a pattern of the cut lines
stored in a computer memory. Therefore, those of skill in the art
will understand that it is a relatively simple procedure, using
computer-aided drafting technology,.to customize the various
openings and tabs for an infinite number of medical circuits, which
information is then used to form the appropriate cutting die. The
dies themselves are relatively inexpensive, on the order of about
$1000, and thus in conjunction with the inexpensive sheet material,
the present invention enables a manufacturer to rapidly set up and
produce a variety of medical component support devices in
accordance with the present invention.
[0071] The medical component support chassis seen in FIGS. 13-17
each include an oval-shaped handle 300 at an upper central
location. The handles 300 are preferably oval-shaped to reduce
stress on the fingers. The assembled circuit mounted on the
chassis, as best seen in FIG. 15 without accompanying tubing
lengths, is packaged and shipped as unit, and may be lifted from
the packaging material and mounted in the operating room, such as
seen in FIG. 13. The perfusionist then must connect various tubing
lengths between the components, and connect the separately provided
components, such as the centrifugal pump 170. Once all of the
circuit components are connected, the perfusionist then primes the
circuit by known methods. Because of the pre-assembled
configuration of the circuit, the setup time is greatly reduced.
Using separately packaged components, which have to be separately
mounted on poles and interconnected, the set up process currently
takes between 20-30 minutes. With the pre-assembled circuit of the
present invention, the setup process is reduced to about 5 minutes.
The shortened setup time can help save lives, and certainly reduces
the burden on the perfusionist.
[0072] In addition to the shortened setup time, the setup is
greatly simplified by the pre-assembled circuit configuration of
the present invention. That is, the traditional technique of
mounting separate components and connecting them with relatively
long lengths of tubing is for the most part replaced by mounting
the chassis on the support rods, and connecting the short tubing
lengths supplied. Traditionally, the lengths of tubing are
typically provided in a custom pack of components depending on the
perfusionists preference, and may even be further cut by the
perfusionist on site. Of course, the accessories such as the
centrifugal pump and cardioplegia solution must still be connected,
but the main burden of interconnecting the primary circuit
components is removed. To further facilitate ease of connection,
the tubing lengths supplied with the components on the chassis may
be color-coded with the corresponding component inlet or outlet
port.
[0073] Moreover, the risk of a sterility break from making numerous
connections on site is reduced by the pre-assembled nature of the
present system. That is, a number of the connections are already
made, with the short lengths of tubing already connected to the
components. Essentially, one-half of the component-to-component
connections are already made.
[0074] The short lengths of tubing pre-connected to various
components and shipped with the assembled system are desirable to
reduce the chance of contamination, and are sized to precisely
extend to the mating component. In this manner, there is no
guesswork for the perfusionist in determining the proper tubing
lengths. This contributes to the reduced setup time, and also has
the additional benefit of reducing the tubing lengths between the
components.
[0075] One of the primary benefits of the present invention is the
reduced prime volume in the cardiopulmonary bypass circuit. As
mentioned, pre-connected lengths of tubing are provided on various
components in the system to be interconnected with other components
at the time of setup. The interconnecting tubing lengths are thus
sized just long enough to extend between the components, which are
mounted in a predetermined relationship on the chassis, without
kinking. This eliminates any excess tubing between components.
Furthermore, the compact and portable nature of the chassis-mounted
circuit enables the circuit to be moved as unit closer to the
operating table. Indeed, the chassis may be mounted on support rods
extending from the operating table, which would further reduce the
lengths of tubing extending between the circuit and a patient.
These features, particularly when used in conjunction with
vacuum-assisted venous drainage, can reduce the entire prime volume
of a cardiopulmonary bypass circuit to less than 1500 cc, and
preferably less than 1000 cc.
[0076] FIG. 18 illustrates a clean bag 320 encompassing a chassis
322 of the present invention on which a plurality of
cardiopulmonary bypass circuit components are mounted. The chassis
322 includes an upper handle 324 having a neck portion 326. The
clean bag 320 can be closed around a neck portion 326 via a string
328 and cinch device 330.
[0077] The clean bag 320 may be part of the pre-assembled system
packaging, and may be reused to dispose of the system after the
circuit has performed its function. That is, all of the components
in a cardiopulmonary bypass circuit must be disposed of in
infectious waste containers. Typically, with separate components,
each are separately bagged and placed in a large container to be
transported to an infectious waste dumpster in a rear of a
hospital. With the chassis 322 of the present invention and clean
bag 320, the entire circuit can be disposed of at once. That is,
the chassis 322 and circuit are deposited in the clean bag 320,
with the handle 324 extending out from the top. The entire assembly
can then be transported to the infectious waste dumpster. This
system greatly reduces the time and inconvenience in separately
packaging and disposing of potentially infectious circuit
components.
[0078] Pump-Less Cardioplegia Delivery
[0079] The present invention including a device for supporting a
plurality of cardiopulmonary bypass components in close proximity
to one another is particularly well-suited to implement pump-less
cardioplegia delivery. This is so because of the close arrangement
of the components, which minimizes the tubing needed to connect the
oxygenator and cardioplegia heat exchanger. However, the principles
of pump-less cardioplegia delivery do not depend on the particular
arrangement of components, and can be implemented in any bypass
system.
[0080] With reference to FIG. 19, a schematic cardiopulmonary
bypass system of the prior art is shown. A venous input line 350
receives blood from the patient and delivers it to a filtered
venous reservoir 352. As mentioned above, there are often a
plurality of sucker lines (not shown) positioned to aspirate
various fluids and debris from the chest cavity and deliver it to
the reservoir 352. Blood that has collected in the reservoir 352 is
then impelled by pump 354 through an oxygenator 356 (typically
incorporating a heat exchanger) an arterial filter 358, and back to
the patient through arterial line 360.
[0081] The circuit also includes a cardioplegia delivery system 362
including a cardioplegia fluid supply 364, a second pump 366, a
mixer 368, and a cardioplegia heat exchanger 370. Some of the
oxygenated blood from oxygenator 356 is impelled by pump 366 to
mixer 368 to be combined with cardioplegia solution from supply
364. This mixed blood and cardioplegia solution is then directed
through the cardioplegia heat exchanger 370 and delivered by a 1/4
inch or smaller cardioplegia delivery tubing to either a antegrade
cardioplegia catheter or a retrograde cardioplegia catheter (not
shown) for myocardial protection once the heart is isolated from
normal blood circulation. The cardioplegia heat exchanger 370 acts
as a bubble trap. The pumps 354 and 366 are typically either
occlusive-type roller pumps, or in some cases centrifugal pumps
with valves preventing backflow. The pump 366 and the mixer 368,
and additional tubing required for them, cause associated
complement activation and potential hemolysis to the system.
[0082] FIG. 20 illustrates an improved pump-less cardioplegia
delivery system 380 of the present invention. Some of the
components of the circuit shown identical to those in FIG. 19, and
will be so numbered. As before, fluid pressure generated by pump
354 impels blood through oxygenator 356, filter 358, and back to
the patient through arterial line 360. Delivery line 382 connects a
second outlet of the oxygenator 356 directly with cardioplegia heat
exchanger 370, without an additional pump. The cardioplegia
solution from supply 364 passes through an intravenous infusion
pump 384 before being directed to the cardioplegia heat exchanger
370. The cardioplegia solution and oxygenated blood mix within the
heat exchanger 370. Fluid pressure generated by pump 354 is
utilized to impel blood and cardioplegia solution through heat
exchanger 370, and through 1/4 inch or smaller cardioplegia
delivery tubing to the patient's isolated heart via a cardioplegia
catheter (not shown). This arrangement, therefore, eliminates the
need for a second roller or centrifugal pump, such as pump 366 in
FIG. 19, and separate mixer 368.
[0083] Tests have shown that adequate flow through the cardioplegia
heat exchanger 370 is obtained with an arterial line 360 pressures
of as low as 100 mmHg. The blood pressure generated by pump 354 is
scavenged from the primary return line 386 and utilized to impel
cardioplegia solution through the heat exchanger 370 and through
the tubing to the patient.
[0084] An alternative to delivering the cardioplegia solution to
the cardioplegia heat exchanger 370 would be to add the
cardioplegia solution at the antegrade or retrograde catheter
utilizing an IMED style pump and a 1/4 inch or smaller tubing, with
IV size tubing integrally attached to the 1/4 inch or smaller
tubing coming from the cardioplegia heat exchanger.
[0085] The adequacy of cardioplegia solution flow depends to some
extent on the method of cardioplegia catheter insertion. That is,
the cardioplegia catheter can be inserted retrograde, or antegrade.
Retrograde insertion involves catheterizing the coronary sinus with
a specific type of cardioplegia catheter. Antegrade insertion
involves catheterizing the aortic root or coronary ostia with a
different type of cardioplegia catheter. The types of cardioplegia
catheters and insertion methods are well known in the art.
[0086] The cardioplegia delivery pressure in the pump-less
cardioplegia system of the present invention may depend on the
arterial line pressure. Cardioplegia flow in retrograde insertion
is sufficient with most arterial line pressures provided by the
pump 354. If the arterial cannula is inserted antegrade, on the
other hand, cardioplegia flow will depend to a much greater degree
on arterial line pressure. The following table illustrates the
relationship between arterial line pressure, antegrade cardioplegia
flow, and aortic root pressure using the system shown in FIG. 20,
as tested in an animal model.
1TABLE I Antegrade Cardioplegia Flow vs. Arterial Line Pressure
Antegrade Arterial Line Pressure Cardioplegia Flow Aortic Root
Pressure 320 mmHg 270 ml/min 90 mmHg 150 mmHg 65 ml/min 100
mmHg
[0087] The system shown schematically in FIG. 20 is also
illustrated in perspective in FIG. 13. Blood from the reservoir 160
passes through tubing 400 into centrifugal pump 170, and then
through tubing 402 to oxygenator 162. A retroguard valve 403 is
provided in tubing 402 to prevent backflow or regurgitation to the
centrifugal pump 170. Oxygenator outlet tubing 404 is connected to
a Y-junction 406 that branches the flow into tubing 408 and tubing
410. Tubing 408 extends to arterial filter 166, and from there back
to the patient. Tubing 410 connects to an input of cardioplegia
heat exchanger 164. Cardioplegia solution from supply 172 is also
directed to cardioplegia exchanger 164 through intravenous infusion
pump 174. The oxygenated blood passing through tubing 410 mixes
with the cardioplegia solution within the heat exchanger 164, and
is then returned to patient by tubing 412 in communication with a
cardioplegia catheter (not shown).
[0088] While the foregoing is a complete description of the
preferred embodiments of the invention, various alternatives,
modifications, and equivalents may be used. For example, a
cardioplegia pump may be eliminated by using arterial line pressure
and a variable occlusion clamp powered by solenoids and the like to
clamp on the blood line and directly inject the arresting agents by
IMED style IV pump, thus eliminating the need for a 4:1 tubing set.
The chassis may also be integrated directly into the operating
table or some portion of the control workstation. Certain elements
such as the oxygenator can be combined with an internal
hemoconcentrator to reduce the number of individual bypass
components. It will be obvious that certain other modifications may
be practiced within the scope of the appended claims.
* * * * *