U.S. patent application number 12/199166 was filed with the patent office on 2009-04-30 for air trap for a medical infusion device.
This patent application is currently assigned to DEKA Products Limited Partnership. Invention is credited to Jason A. Demers, Michael J. Wilt.
Application Number | 20090107335 12/199166 |
Document ID | / |
Family ID | 40581172 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090107335 |
Kind Code |
A1 |
Wilt; Michael J. ; et
al. |
April 30, 2009 |
AIR TRAP FOR A MEDICAL INFUSION DEVICE
Abstract
An air trap for a blood circuit and method for removing air from
blood in a dialysis unit. The air trap may include a blood inlet
supply line, a blood outlet supply line, and a container having an
approximately spherical internal wall, an inlet at a top end of the
container connected to the blood inlet supply line, and an outlet
at a bottom end of the container connected to the blood outlet
supply line. The inlet may be offset from a vertical axis of the
approximately spherical internal wall such that blood entering the
container is directed to flow in a spiral-like path. The inlet port
may be arranged to introduce blood into the container in a
direction that is approximately tangential to the approximately
spherical inner wall of the container and/or in a direction that is
approximately perpendicular to the vertical axis of the
container.
Inventors: |
Wilt; Michael J.; (Windham,
NH) ; Demers; Jason A.; (Manchester, NH) |
Correspondence
Address: |
DEKA Research and Development Corporation;c/o Wolf, Greenfield & Sacks,
P.C.
600 Atlantic Avenue
Boston
MA
02210-2206
US
|
Assignee: |
DEKA Products Limited
Partnership
Manchester
NH
|
Family ID: |
40581172 |
Appl. No.: |
12/199166 |
Filed: |
August 27, 2008 |
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12072908 |
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12199166 |
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12038474 |
Feb 27, 2008 |
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60903582 |
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60904024 |
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60904024 |
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60921314 |
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60921314 |
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60904024 |
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60921314 |
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60904024 |
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60921314 |
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Current U.S.
Class: |
95/261 ; 96/209;
96/211 |
Current CPC
Class: |
A61M 1/14 20130101; A61M
1/3627 20130101; B01D 19/00 20130101 |
Class at
Publication: |
95/261 ; 96/209;
96/211 |
International
Class: |
B01D 19/00 20060101
B01D019/00 |
Claims
1. An air trap for a blood circuit in a dialysis unit, comprising:
a blood inlet supply line; a blood outlet supply line; and a
container having an approximately spherical internal wall, an inlet
at a top end of the container connected to the blood inlet supply
line, and an outlet at a bottom end of the container connected to
the blood outlet supply line, the inlet being offset from a
vertical axis of the approximately spherical internal wall such
that blood entering the container through the inlet is directed to
flow in around the approximately spherical wall in a spiral-like
path; wherein when blood is supplied to the container via the blood
inlet supply line and blood in the container is removed from the
container via the blood outlet supply line, air in the blood
entering the container remains in the container.
2. The air trap of claim 1, wherein the container is formed by an
approximately spherical shell.
3. The air trap of claim 1, wherein the blood circuit includes a
dialyzer and the air trap receives blood via the blood inlet supply
line from the dialyzer.
4. The air trap of claim 1, further comprising: a self-sealing port
located at a top of the container.
5. The air trap of claim 4, wherein the self-sealing port is formed
by a split septum.
6. The air trap of claim 4, wherein the split septum is arranged to
permit introduction of fluid into, and withdrawal of liquid from,
the container by inserting a needleless device through the split
septum.
7. The air trap of claim 4, wherein the self-sealing port is
arranged to be self-cleaning when disinfection liquid is circulated
through the container.
8. The air trap of claim 7, wherein an inner surface of the
self-sealing port is approximately flush with the internal wall of
the container at a top of the container.
9. The air trap of claim 8, wherein the self-sealing port is
cleaned by introducing liquid into the container via the blood
outlet supply line and removing liquid from the container via the
blood inlet supply line.
10. The air trap of claim 1, wherein the inlet port is arranged to
receive air in the container when liquid is introduced into the
container via the outlet port during a priming operation.
11. The air trap of claim 1, wherein the inlet port is arranged to
introduce blood into the container in a direction that is
approximately tangential to the approximately spherical inner wall
of the container.
12. The air trap of claim 1, wherein the inlet port is arranged to
introduce blood into the container in a direction that is
approximately perpendicular to the vertical axis of the
container.
13. A method for removing air from a flow of blood in a dialysis
unit, comprising: introducing blood into an upper portion of an
approximately spherical container; causing the blood to flow in a
spiral-like path in the container; and removing the blood from a
lower portion of the approximately spherical container.
14. The method of claim 13, wherein the step of introducing
comprises: introducing blood into the container in a direction that
is approximately tangential to an approximately spherical inner
wall of the container.
15. The method of claim 13, wherein the step of introducing
comprises: introducing blood into the container in a direction that
is approximately perpendicular to the vertical axis of the
container.
16. An air trap for a blood circuit in a dialysis unit, comprising:
a blood inlet supply line; a blood outlet supply line; a container
having an approximately spherical internal wall, an inlet at a top
end of the container connected to the blood inlet supply line, and
an outlet at a bottom end of the container connected to the blood
outlet supply line, the inlet being offset from a vertical axis of
the approximately spherical internal wall such that blood entering
the container through the inlet is directed to flow in around the
approximately spherical wall in a spiral-like path; and a
self-sealing port located at a top of the container, the
self-sealing port having an inner surface that is approximately
flush with the internal wall of the container at the top of the
container, wherein when blood is supplied to the container via the
blood inlet supply line and blood in the container is removed from
the container via the blood outlet supply line, air in the blood
entering the container remains in the container, and wherein any
air in the container is substantially completely removed by
introducing liquid into the container via the blood outlet supply
line and removing liquid from the container via the blood inlet
supply line.
17. The air trap of claim 16, wherein the inlet, outlet and
internal wall of the container and the self-sealing port are
arranged to substantially eliminate stagnation regions.
Description
FIELD OF INVENTION
[0001] The present invention generally relates to hemodialysis and
similar dialysis systems, e.g., systems able to treat blood or
other bodily fluids extracorporeally.
BACKGROUND
[0002] Many factors make hemodialysis inefficient, difficult, and
expensive. These factors include the complexity of hemodialysis,
the safety concerns related to hemodialysis, and the very large
amount of dialysate needed for hemodialysis. Moreover, hemodialysis
is typically performed in a dialysis center requiring skilled
technicians. Therefore any increase in the ease and efficiency of
the dialysis process could have an impact on treatment cost or
patient outcome.
SUMMARY OF INVENTION
[0003] Aspects of the invention generally relate to hemodialysis
and similar dialysis systems. Illustrative embodiments described
herein involve, in some cases, interrelated products, alternative
solutions to a particular problem, and/or a plurality of different
uses of one or more systems and/or articles. Although the various
systems and methods described herein are described in relation to
hemodialysis, it should be understood that the various systems and
method described herein are applicable to other dialysis systems
and/or in any extracorporeal system able to treat blood or other
bodily fluids, such as hemofiltration, hemodiafiltration, etc.
[0004] In one aspect of the invention, an enclosure for containing
a portable hemodialysis unit is provided, where the hemodialysis
unit includes suitable components for performing hemodialysis
including a dialyzer, one or more pumps to circulate blood through
the dialyzer, a source of dialysate, and one or more pumps to
circulate the dialysate through the dialyzer. The enclosure may
include a housing that supports the components of the hemodialysis
unit and has a front panel at which blood circuit connections and
dialysate fluidic connections are located. For example, the front
panel may support blood line connections for patient blood access,
connections for a reagent supply, dialyzer connections for both
blood flow and dialysate, etc. Thus, in one embodiment, an operator
may complete all necessary fluid circuit connections for the blood
circuit and reagent supply at the housing front panel. The
enclosure may also include a pair of vertical, side-by-side doors
hingedly mounted to the housing at opposite sides of the front
panel so that the doors are movable between open and closed
positions. With the doors in an open position, an operator may have
access to the blood circuit connections and dialysate fluidic
connections. Also, with the doors in the closed position, access to
the patient access and dialysate fluidic connections may be
blocked, and the doors may allow for the retention of heat in the
housing suitable for disinfection during a disinfection cycle. For
example, at least one of the doors may include a seal to resist air
exchange between an interior and an exterior of housing when the
doors are in the closed position to help retain heat and/or help
resist entry of dust, dirt or other contaminants.
[0005] In one embodiment, each of the vertical, side-by-side doors
is mounted to the housing via a hinge plate that is pivotally
mounted to the door at a first end, and is pivotally mounted to the
housing at a second end opposite the first end. Thus, the doors may
be positionable at two open positions, e.g., a first open position
in which blood circuit connections and dialysate fluidic
connections are exposed and the hinge plate is adjacent the
housing, and a second open position in which the hinge plate is
positioned away from the housing. One or more retainer members may
be included to maintain the doors in an open position relative to a
corresponding hinge plate. For example, the retainer member may
include at least one magnet attached to the door or the hinge plate
that tends to keep the door in an open position relative to the
hinge plate and the housing. Also, one or more retainer members may
maintain the hinge plates in a closed position relative to the
housing, e.g., in a position close to the housing, and/or maintain
the hinge plates in an open position away from the housing.
[0006] In one embodiment, at least one of the doors may include a
container holder that is movable between a folded position and an
extended position in which the container holder is arranged to
support a container, such as reagent supply container. In addition,
or alternately, one or both of the doors may include a hook to
support a control interface for the hemodialysis unit, such as a
remote interface unit that is connected to the housing by a
communication cable. These features may make use of the dialysis
unit easier by supporting components in a convenient location.
[0007] In another embodiment, the front panel may include at least
one flanged portion to support blood lines of a blood circuit
assembly. For example, the front panel may include several flanged
sections arranged at a periphery of the front panel, such as at
lower corners and at a top edge of the front panel. Blood circuit
lines that connect to a patient may be relatively long (e.g., up to
3-4 feet or more), and may be wrapped around the periphery of the
front panel and retained in place by the flanged portions. The
flanged portions may be arranged to support the blood lines and
allow the doors to be moved to the closed position without
contacting the blood lines, e.g., to avoid pinching of the blood
lines at door hinge points.
[0008] In one embodiment, the blood circuit connections at the
front panel include arterial and venous blood line connectors for
the blood circuit, and the dialysate fluidic connections at the
front panel include a connection point for a reagent supply,
dialyzer dialysate connections, and a blood line connection point
for connecting the arterial and venous blood lines to a directing
circuit of the dialysis unit.
[0009] The hemodialysis unit may include a control interface that
is connected to the housing by a flexible cable and that is
arranged to allow a user to receive information from and provide
information to the hemodialysis unit. In one embodiment, the
enclosure may include a control interface mounting area at a top of
the enclosure where the control interface is mountable. For
example, the control interface may include a foldable leg or other
support that permits the control interface to be stood in a near
vertical orientation on the top of the housing.
[0010] In another embodiment, the enclosure may include an
electronics section that is separated and insulated from a
disinfection section that is heated to disinfect components of the
hemodialysis unit. For example, the disinfection section may
include all of the liquid circuit components, such as valves,
pumps, conduits, etc., of the various portions of the dialysis
unit. The electronics section may include motors, computers or
other data processing devices, computer memory, and/or other
temperature sensitive electronics or other components. By isolating
the electronics section from the disinfection section (at least to
some degree), components in the electronics section may be spared
exposure to the heat or other environmental conditions in the
disinfection section whether during a disinfection operation or
otherwise.
[0011] In another aspect of the invention, a portable hemodialysis
system may be arranged so that power for the fluid circuit pumps of
a dialysis unit may be provided by a modular power unit, e.g., a
unit that can be selectively connected to or disconnected from the
dialysis unit. As a result, failure of a power unit need not
necessarily disable the entire dialysis system. Instead, the power
unit may be replaced with another power unit, allowing for
treatment to continue. For example, a modular assembly for a
portable hemodialysis system may include a dialysis unit, e.g.,
including a housing that contains suitable components for
performing hemodialysis, such as a dialyzer, one or more pumps to
circulate blood through the dialyzer, a source of dialysate, and
one or more pumps to circulate the dialysate through the dialyzer.
The housing may have a front panel at which blood circuit
connections and dialysate fluidic connections are located, e.g.,
where an operator may make patient blood access connections,
connect a reagent supply, and/or connect a dialyzer. The modular
assembly may also include a power unit having a housing that
contains suitable components for providing operating power to the
pumps of the dialysis unit. The power unit may be selectively
connected to the dialysis unit and provide power to the dialysis
unit for the pumps when connected to the dialysis unit, but may be
incapable of providing power to the dialysis unit when disconnected
from the dialysis unit. The power unit may be selectively connected
to and disconnected from the dialysis unit by operation of a single
handle, e.g., an operator may turn or otherwise operate a single
handle to disconnect the power unit from the dialysis unit. In one
embodiment, the dialysis unit and the power unit are sized and
weighted to each be carried by hand by a human.
[0012] In one embodiment, the pumps of the dialysis unit are
pneumatic pumps and the power unit provides pneumatic power to the
dialysis unit. For example, the power unit may provide air pressure
and/or vacuum to the dialysis unit to power the pumps. The power
unit may include one or more air pressure pumps and/or air vacuum
pumps, and the dialysis unit may include a plurality of valves to
control application of pneumatic power to the pumps. To aid with
use of the hemodialysis system in the home, the power unit and
dialysis unit electrical power requirements may be provided by
standard residential electrical power, e.g., approximately 110 V,
15 amp electrical power. The dialysis unit may provide electrical
power to the power unit, and the power unit may use the electrical
power to generate operating power for the pumps.
[0013] In another aspect of the invention, a blood circuit assembly
for a dialysis unit may be arranged to allow the replacement of
most or all blood circuit components in a single operation. For
example, the blood circuit assembly may include an organizing tray,
a pair of pneumatic pumps mounted to the organizing tray for
circulating blood received from a patient through a circuit
including a dialyzer unit and returned to the patient, an air trap
mounted to the organizing tray arranged to remove air from blood
circulating in the circuit, a pair of dialyzer connections arranged
to connect to the inlet and outlet of a dialyzer unit, and a pair
of blood line connectors, one inlet blood line connector for
receiving blood from the patient and providing blood to the
pneumatic pumps and the other outlet blood line connector for
returning blood to the patient.
[0014] In one embodiment, an anticoagulant connection is provided
for engaging with an anticoagulant source and providing
anticoagulant into the blood circuit. For example, the
anticoagulant connection may include a pump for pumping
anticoagulant from the anticoagulant source, such as heparin from a
vial of heparin, to the circuit. The anticoagulant connection may
include a vial holder arranged to hold two or more differently
sized vials, and a spike to pierce the vial. In one embodiment, the
pair of pneumatic pumps, the anticoagulant connection, and the
anticoagulant pump are part of a pump cassette.
[0015] In another embodiment, the blood circuit assembly may be
selectively mounted to and removed from a dialysis unit. To aid in
handling of the blood circuit assembly, the organizing tray may
include a pair of handles arranged for gripping by a user. The
organizing tray may also include openings adjacent each of the
handles for receiving retaining tabs on a dialysis unit that engage
with the blood circuit assembly and retain the blood circuit
assembly on the dialysis unit.
[0016] In one embodiment, the inlet blood line connector is
connected to an inlet for the pump cassette, an outlet for the pump
cassette is connected to a dialyzer inlet connector, a dialyzer
outlet connector is connected to an inlet of the air trap, and an
outlet of the air trap is connected to the outlet blood line
connector. The inlet of the air trap may be located above the
outlet of the air trap when the blood circuit assembly is mounted
to a dialysis unit, e.g., to aid in trapping of air circulating in
the circuit during treatment. The blood line connectors may be
arranged for a threaded luer-type connection to a patient access,
as well as be arranged for a press-in type connection to the
dialysis unit. Such an arrangement may make it easier for an
operator to connect the blood line connectors to the dialysis unit
after treatment (e.g., for later disinfection and/or priming of the
blood circuit) while allowing the connectors to engage with
standard luer-type connectors at a patient blood access.
[0017] In one embodiment, the organizing tray may include circuit
tube engagement members having a hole or slot through which a
respective circuit tube passes. The engagement members may engage
with the respective circuit tube to allow the circuit tube to be
pulled and stretched for engagement with an occluder of the
dialysis unit. For example, the circuit tubes of the blood circuit
assembly may include silicone tubing that has to be stretched (and
thereby reduced in diameter) to engage with an occluder. The
circuit tube engagement members may resist the pull of an operator
on the tubes, allowing the tubes to be stretched and placed in
engagement with the occluder.
[0018] In another aspect of the invention, a method for replacing a
blood circuit assembly of a dialysis unit includes grasping a pair
of handles on an organizing tray of a blood circuit assembly that
is mounted to a dialysis unit, disengaging locking tabs of the
dialysis unit from the blood circuit assembly to free the blood
circuit assembly from the dialysis unit, and pulling on the handles
on the organizing tray of the blood circuit assembly to remove the
blood circuit assembly from the dialysis unit. Disengagement of the
locking tabs may be performed by flexing the locking tabs away from
each other such that each locking tab is moved toward a nearest one
of the handles. After removal of the blood circuit assembly, a
replacement blood circuit assembly may be provided, openings in the
organizing tray of the replacement blood circuit assembly may be
aligned with the locking tabs so that each locking tab is received
into a respective opening, and the organizing tray may be pushed
relative to the dialysis unit such that the locking tabs engage
with the replacement blood circuit assembly to mount the
replacement blood circuit assembly to the dialysis unit. Mounting
the replacement blood circuit assembly may also involve connecting
control ports on the dialysis unit to mating ports on the assembly
so that fluid control signals may be provided for pumps and valves
of the blood circuit assembly. Other blood circuit connections may
be made, such as inlet and outlet connections for the dialyzer, and
the blood line connectors may be connected to receive dialysate
into the blood circuit.
[0019] In another aspect of the invention, an air trap for a blood
circuit in a dialysis unit includes a blood inlet supply line, a
blood outlet supply line, and a container having an approximately
spherical internal wall, an inlet at a top end of the container
connected to the blood inlet supply line, and an outlet at a bottom
end of the container connected to the blood outlet supply line. The
inlet may be offset from a vertical axis of the approximately
spherical internal wall such that blood entering the container
through the inlet is directed to flow in around the approximately
spherical wall in a spiral-like path. Such flow in the container
may help to remove air bubbles from the blood as it flows from the
inlet to the outlet, with any removed air remaining near the top of
the container. The inlet port may be arranged to introduce blood
into the container in a direction that is approximately tangential
to the approximately spherical inner wall of the container and/or
in a direction that is approximately perpendicular to the vertical
axis of the container.
[0020] In one embodiment, a self-sealing port may be located at a
top of the container, e.g., in the form of a split septum that is
arranged to permit introduction of fluid into, and withdrawal of
liquid from, the container by inserting a needleless device through
the split septum. The self-sealing port may be arranged to be
self-cleaning when disinfection liquid is circulated through the
container, e.g., the port may be suitably exposed to flowing
disinfection liquid to remove debris and/or heat material on the
port to achieve desired disinfection.
[0021] In another aspect of the invention, a tube securing
arrangement of a blood circuit assembly includes a organizing tray
that supports components of a blood circuit assembly and includes a
pair of tube engagement members each having a hole, a pair of
patient inlet and outlet lines arranged to connect with patient
access points for receiving liquid from and/or providing liquid to
the patient, and a pair of stops on the patient inlet and outlet
lines, respectively. The patient inlet and outlet lines may each
pass through a hole of a respective tube engagement member so that
the stop engages with the tube engagement member. With this
arrangement, the tube engagement members may resist pulling and
stretching of the inlet and outlet lines when engaging the lines
with an occluder. The tube engagement members may be flexible to
allow a user to press inwardly on the engagement member and seat
the respective inlet or outlet line in the occluder, yet resist
downward pulling of the line.
[0022] In another aspect of the invention, a hemodialysis system
includes a dialyzer mount arranged to support a plurality of
differently sized and/or shaped dialyzer units and to accommodate
different distances between dialysate connections on the dialyzer
units. The dialyzer mount, which may be located on a front panel of
the dialysis unit, may include a pair of flange portions that are
each arranged to engage with a respective dialysate quick-connect
fitting connected to a dialysate port of the dialyzer. Each flange
portion may be arranged to engage with a groove on the quick
connect fitting that is located between a portion of the base of
the quick connect fitting and a slide element of the quick connect
fitting. For example, the dialyzer mount may include a pair of
keyhole features with each keyhole feature having an upper
insertion area sized to receive a portion of the base of the
quick-connect fitting inserted into the upper insertion area, and a
lower flanged portion having a width that is smaller than an
overall a width of the base of the quick-connect fitting and that
engages with a groove on the quick connect fitting. The lower
flanged portion may include a pair of opposite flanges that engage
with the groove and allow the quick-connect fitting to slide along
the flanges.
[0023] In one embodiment, the bottom keyhole feature may include an
adjustable support that is moveable in a vertical direction. For
example, the adjustable support may be movable along the opposed
flanges. Thus, the adjustable support may be fixable in a plurality
of different positions on the flanges to support the weight of the
dialyzer. In one arrangement, the adjustable support includes a "U"
shaped member and at least one thumb screw that may be tightened to
fix the "U" shaped member in place.
[0024] In another aspect of the invention, a blood line connector
for a blood circuit of a hemodialysis unit may have the ability to
make two different types of fluid tight connections, e.g., a
screw-type connection with a luer connector at a patient access and
a press-in type connection with a dialysate circuit of the
hemodialysis unit. For example, the blood line connector may
include a tube connection end arranged to sealingly engage with a
blood circuit tube, and a patient access connection end with a
frustoconical member having an internally threaded portion arranged
to engage with an externally threaded patient access, and a pair of
locking arms extending rearwardly from the frustoconical member.
The locking arms may each have a finger depression portion and a
barbed portion, and may be arranged to engage with a mating
connector on the dialysis unit at the barbed portions to lock the
frustoconical member in sealing engagement with the mating
connector when making a press-in type connection. The barbed
portions may disengage from the mating connector when the finger
depression portions are urged toward each other. In one embodiment,
the patient access connection end may include a central tube
extending from the center of the frustoconical member. The
internally threaded portion of the frustoconical member and the
central tube may be arranged to mate with a female luer-type
patient access connector or any other suitable screw-type
connection.
[0025] In another aspect of the invention, a method for operating a
dialysis unit includes connecting blood line connectors of arterial
and venous blood lines for a dialysis unit to patient access
connectors in communication with a patient blood system. In one
embodiment, the patient access connectors may require a
corresponding blood line connector to establish a threaded
engagement with the patient access connector, thereby forming a
luer or screw-type connection between the blood line connectors and
the patient access connectors. The dialysis unit may be operated to
withdraw blood from a patient access connector and into an arterial
blood line, subject the withdrawn blood to a dialysis process to
produce treated blood, and return the treated blood to the patient
via the venous blood line and the other patient access connector.
Thereafter, the blood line connectors may be disconnected from the
patient access connectors by unscrewing the blood line connectors
from a corresponding patient access connector, and the blood line
connectors may be connected to a directing circuit of the dialysis
unit. The blood line connectors may be connected to the directing
circuit by a press-in connection with a corresponding connection
point on the dialysis unit, e.g., by pushing the blood line
connectors into the connection points to establish the press-in
connection.
[0026] In another aspect of the invention, a reagent supply
arrangement for a hemodialysis system may be arranged to provide
two or more reagent materials for use in preparing a dialysate and
may include a connector arranged to help prevent the connection of
a reagent material to the wrong port. For example, the reagent
supply may include an E-prong connector having three parallel
prongs with two outer prongs arranged in a common plane and a
center prong arranged above the common plane, a first supply line
for a first reagent connected in fluid communication with one of
the outer prongs, a second supply line for a second reagent
connected in fluid communication with the other of the outer
prongs, a liquid line connected in fluid communication with the
center prong, and a container for housing the first reagent having
an inlet connected to the liquid line and an outlet connected to
the first supply line for the first reagent. The E-prong connector
may help prevent the improper connection of the first and second
supply lines to the dialysis unit, e.g., because the central prong
being located out of the plane of the two outer prongs ensure
connection of the E-prong connector in only one way to the dialysis
unit.
[0027] In one embodiment, the container includes a bicarbonate
material suitable for use in generating a dialysate for the
hemodialysis system. The liquid line may be a water supply line
that provides water to the container, allowing the water to mix
with the bicarbonate (which may be in powder or other solid form)
and flow to the first supply line. The second supply line may be an
acid supply line that includes a connector and provides acid
material to the E-prong connector. The reagent supply may also
include an acid bag spike that is removably engaged with the
connector of the acid supply line. The acid bag spike may include a
spike member and a pair of spring clips at an end of the acid bag
spike opposite the connector of the acid supply line, allowing the
acid bag spike to be fluidly connected with an acid bag or other
acid source.
[0028] In another aspect of the invention, a method for operating a
hemodialysis system includes providing a dialysis unit having an
enclosure containing suitable components for performing
hemodialysis including a dialyzer, one or more pumps to circulate
blood through the dialyzer, a source of dialysate, and one or more
pumps to circulate the dialysate through the dialyzer. The
enclosure may include a housing that supports the components and
has a front panel at which blood circuit connections and dialysate
fluidic connections are made. A reagent supply may be provided
including an E-prong connector, a first supply line for a first
reagent connected in fluid communication with one of the outer
prongs, a second supply line for a second reagent connected in
fluid communication with the other of the outer prongs, a liquid
line connected in fluid communication with the center prong, and a
container for housing the first reagent having an inlet connected
to the liquid line and an outlet connected to the first supply line
for the first reagent. The E-prong connector may be engaged with a
connection point at the front panel of the dialysis unit, thereby
allowing the dialysis unit to provide water to the liquid line of
the reagent supply, and allowing the dialysis unit to receive the
first and second reagents from the first and second supply
lines.
[0029] Other advantages and novel features of the present invention
will become apparent from the following detailed description of
various non-limiting embodiments of the invention when considered
in conjunction with the accompanying figures. In cases where the
present specification and a document incorporated by reference
include conflicting and/or inconsistent disclosure, the present
specification shall control. If two or more documents incorporated
by reference include conflicting and/or inconsistent disclosure
with respect to each other, then the document having the later
effective date shall control.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Aspects of the invention are described with reference to
illustrative embodiments, which are described with reference to the
drawings in which like numerals reference like elements, and
wherein:
[0031] FIG. 1 is a schematic representation of fluid handling
components of a hemodialysis system in an illustrative
embodiment;
[0032] FIG. 2 shows a schematic fluid flow diagram for the dialysis
system of FIG. 1;
[0033] FIG. 3 is a schematic fluid flow diagram for the blood flow
circuit of the FIG. 2 embodiment;
[0034] FIG. 4 is a schematic fluid flow diagram for the balancing
circuit of the FIG. 2 embodiment;
[0035] FIG. 5 is a schematic fluid flow diagram for the directing
circuit of the FIG. 2 embodiment;
[0036] FIG. 6 is a schematic fluid flow diagram for the mixing
circuit of the FIG. 2 embodiment;
[0037] FIG. 7 is a right front perspective view of a hemodialysis
system in an illustrative embodiment;
[0038] FIG. 8 is a left rear perspective view of the hemodialysis
system of FIG. 7;
[0039] FIG. 9 is a front view of the hemodialysis system of FIG.
7;
[0040] FIG. 10 is a right front perspective view of the view of the
hemodialysis system of FIG. 7 with the doors in a first open
position;
[0041] FIG. 11 is a top view of the hemodialysis system of FIG.
10;
[0042] FIG. 12 is a front view of the hemodialysis system of FIG.
10;
[0043] FIG. 13 is a right side view of the hemodialysis system of
FIG. 10;
[0044] FIG. 14 is a right front perspective view of the view of the
hemodialysis system of FIG. 7 with the doors in a second open
position;
[0045] FIG. 15 is a top view of the hemodialysis system of FIG.
14;
[0046] FIG. 16 is a front view of the hemodialysis system of FIG.
14;
[0047] FIG. 17 is a front view of the hemodialysis system of FIG. 7
with the doors in an open position exposing a front panel of the
system;
[0048] FIG. 18 is a front view of a blood circuit assembly for use
with the system of FIG. 7;
[0049] FIG. 19 right perspective view of a organizing tray for the
blood circuit assembly of FIG. 18;
[0050] FIG. 20 is a left rear perspective view of the blood circuit
assembly of FIG. 18;
[0051] FIG. 21 shows a left front perspective view of the front
panel of the system of FIG. 7;
[0052] FIG. 22 shows a front view of the front panel of the system
of FIG. 7;
[0053] FIG. 23 shows a front view of the front panel of the system
of FIG. 7 with a pair of mounting features for the dialyzer;
[0054] FIG. 24 shows a side view of a dialyzer with quick-connect
fittings attached to the dialysate inlet/outlet ports of the
dialyzer;
[0055] FIG. 25 shows a right perspective view of a reagent supply
for use with the system of FIG. 7;
[0056] FIG. 26 shows a perspective view of an E-prong connector for
the reagent supply of FIG. 25 and a corresponding connection point
at the front panel of the hemodialysis system;
[0057] FIG. 27 shows a perspective view of a pair of blood line
connectors for the blood circuit assembly and a corresponding
connection point at the front panel of the hemodialysis system;
and
[0058] FIG. 28 shows a side view of a blood line connector and
connection point of FIG. 27.
DETAILED DESCRIPTION
[0059] Various aspects of the invention are generally directed to
new systems for hemodialysis and the like, such as hemofiltration
systems, hemodiafiltration systems, plasmapheresis systems, etc.
Accordingly, although the various systems and methods described
herein are described in relation to hemodialysis, it should be
understood that the various systems and method described herein are
applicable to other dialysis systems and/or in any extracorporeal
system able to treat blood or other bodily fluids, such as
plasma.
[0060] As discussed below, a hemodialysis system typically includes
a blood flow path and a dialysate flow path. It should be noted
that within such flow paths, the flow of fluid is not necessarily
linear, and there may be any number of "branches" within the flow
path that a fluid can flow from an inlet of the flow path to an
outlet of the flow path. Examples of such branching are discussed
in detail below. In the blood flow path, blood is drawn from a
patient, and is passed through a dialyzer, before being returned to
the patient. The blood is treated by the dialyzer, and waste
molecules (e.g., urea, creatinine, etc.) and water are passed from
the blood, through a semi-permeable membrane in the dialyzer, into
a dialysate solution that passes through the dialyzer by the
dialysate flow path. In various embodiments, blood may be drawn
from the patient from two lines (e.g., an arterial line and a
venous line, i.e., "dual needle" flow), or in some cases, blood may
be drawn from the patient and returned through the same or catheter
needle (e.g., the two lines or lumens may both be present within
the same needle, i.e., a form of "dual lumen" flow). In still other
embodiments, a "Y" site or "T" site is used, where blood is drawn
from the patient and returned to the patient through one patient
connection having two branches (one being the fluid path for the
drawn blood, the second the fluid path for the return blood, i.e.,
a form of "single needle" flow). The patient may be any subject in
need of hemodialysis or similar treatments, including non-human
subjects, such as dogs, cats, monkeys, and the like, as well as
humans.
[0061] In the dialysate flow path, fresh dialysate is prepared and
is passed through the dialyzer to treat the blood from the blood
flow path. The dialysate may also be equalized for blood treatment
within the dialyzer (i.e., the pressure between the dialysate and
the blood are equalized), often exactly, or in some embodiments, at
least within about 1% or about 2% of the pressure of the blood. In
some cases, it may be desirable to maintain a greater pressure
difference (either positive or negative) between the blood flow
path and dialysate flow path. After passing through the dialyzer,
the used dialysate, containing waste molecules (as discussed
below), is discarded in some fashion. The dialysate in some cases
may be re-circulated in a "multi-pass" arrangement, which may be
beneficial in capturing larger molecules having low mobility across
the dialyzer. In some cases, the dialysate is heated prior to
treatment of the blood within the dialyzer using an appropriate
heater, such as an electrical resistive heater. The dialysate may
also be filtered to remove contaminants, infectious organisms,
debris, and the like, for instance, using an ultrafilter. The
ultrafilter may have a pore size chosen to prevent species such as
these from passing therethrough. For instance, the pore size may be
less than about 0.3 micrometers, less than about 0.2 micrometers,
less than about 0.1 micrometers, or less than about 0.05
micrometers, etc. The dialysate is used to draw waste molecules
(e.g., urea, creatinine, ions such as potassium, phosphate, etc.)
and water from the blood into the dialysate through osmosis or
convective transport, and dialysate solutions are well-known to
those of ordinary skill in the art.
[0062] The dialysate typically contains various ions such as
sodium, chloride, bicarbonate, potassium and calcium that are
similar in concentration to that of normal blood. In some cases,
the bicarbonate, may be at a concentration somewhat higher than
found in normal blood. Typically, the dialysate is prepared by
mixing water from a water supply with one or more ingredients: an
"acid" (which may contain various species such as acetic acid,
dextrose, NaCl, CaCl, KCl, MgCl, etc.), sodium bicarbonate
(NaHCO.sub.3), and/or sodium chloride (NaCl). The preparation of
dialysate, including using the appropriate concentrations of salts,
osmolarity, pH, and the like, is well-known to those of ordinary
skill in the art. As discussed in detail below, the dialysate need
not be prepared at the same rate that the dialysate is used to
treat the blood. For instance, the dialysate can be made
concurrently or prior to dialysis, and stored within a dialysate
storage vessel or the like.
[0063] Within the dialyzer, the dialysate and the blood typically
are separated by a semi-permeable membrane. Typically, the
semipermeable membrane is formed from a polymer such as cellulose,
polyarylethersulfone, polyamide, polyvinylpyrrolidone,
polycarbonate, polyacrylonitrile, or the like, which allows the
transport of ions or small molecules (e.g., urea, water, etc.), but
does not allow bulk transport or convection during treatment of the
blood. In some cases (such as high-flux dialyzers), even larger
molecules, such as beta-2-microglobulin, may pass through the
membrane. In some cases, for example, ions and molecules may pass
through the dialyzer by convective flow if a hydrostatic pressure
difference exists across the semi-permeable membrane.
[0064] It should be noted that, as used herein, "fluid" means
anything having fluidic properties, including but not limited to,
gases such as air, and liquids such as water, aqueous solution,
blood, dialysate, etc.
[0065] FIG. 1 shows a schematic block diagram of fluid circuitry
for a hemodialysis system that incorporates various aspects of the
invention. In this illustrative embodiment, the dialysis system 5
includes a blood flow circuit 141 that draws blood from a patient,
passes the blood through a dialyzer 14, and returns the treated
blood to the patient. A balancing circuit or an internal dialysate
circuit 143 receives dialysate from an ultrafilter 73, passes the
dialysate through the dialyzer 14, and receives used dialysate from
the dialyzer 14. A directing circuit or an external dialysate
circuit 142 provides fresh dialysate to the ultrafilter 73, and
receives used dialysate from the internal dialysate circuit 143
(which may be directed to a drain 31). The directing circuit 142
can also receive water from a water supply 30 and pass it to a
mixing circuit 25. The mixing circuit 25 forms dialysate using
water from the directing circuit 142 and reagent ingredients 49,
such as citric acid, salt and a bicarbonate, that may be received
from a renewable source. The mixing circuit 25 may prepare
dialysate, for example, on an as-needed basis, during and/or in
advance of dialysis. New dialysate prepared by the mixing circuit
25 may be provided to the directing circuit 142, which may provide
the dialysate to the ultrafilter 73, as described above. The
directing circuit 142 may include a heater to heat the dialysate to
a suitable temperature and/or to heat fluid in the system for
disinfection. Conduits 67 (shown in dotted line) may be connected
between the blood flow circuit 141 and the directing circuit 142,
e.g., for disinfection of the hemodialysis system.
[0066] FIG. 2 is a schematic diagram showing a more detailed
circuit arrangement for the dialysis system 5 shown in FIG. 1. It
should be understood, of course, that FIG. 2 is only one possible
embodiment of the general hemodialysis system of FIG. 1, and in
other embodiments, other fluid circuits, modules, flow paths,
layouts, etc. are possible. Examples of such systems are discussed
in more detail below, and also can be found in the following, each
of which is incorporated herein by reference: U.S. application Ser.
No. 12/072,908, filed Feb. 27, 2008, U.S. Provisional Application
60/903,582, filed Feb. 27, 2007, U.S. Provisional Application
60/904,024, filed Feb. 27, 2007, U.S. patent application Ser. No.
11/871,680, filed Oct. 12, 2007, U.S. patent application Ser. No.
11/871,712, filed Oct. 12, 2007, U.S. patent application Ser. No.
11/871,787, filed Oct. 12, 2007, U.S. patent application Ser. No.
11/871,793, filed Oct. 12, 2007, or U.S. patent application Ser.
No. 11/871,803, filed Oct. 12, 2007.
[0067] The blood flow circuit 141 includes an anticoagulant supply
11 and a blood flow pump 13 which pumps blood from a patient
through a dialyzer 14 and returns the blood to the patient. The
anticoagulant supply 11, although shown in the path of blood
flowing towards the dialyzer, may be instead located in another
suitable location. e.g., any location upstream or downstream from
blood flow pump 13. The balancing circuit 143 includes two
dialysate pumps 15, which pump dialysate into the dialyzer 14, and
a bypass pump 35. The flow of blood through the blood flow circuit
141 in some cases, is synchronized with the flow of dialysate in
the dialysate flow path. In an embodiment, the flow of dialysate
into and out of the dialyzer 14 and the balancing circuit 143 is
balanced volumewise using balancing chambers in the balancing
circuit 143. The directing circuit 142 includes a dialysate pump
159, which pumps dialysate from a dialysate tank 169 through a
heater 72 and/or the ultrafilter 73 to the balancing circuit 143.
The directing circuit 142 also receives waste fluid from balancing
circuit 143 and directs it to a drain 31. In some cases, the blood
flow circuit 141 can be connected via conduits 67 to the directing
circuit 142, e.g., for disinfection, as discussed below. Dialysate
in the dialysate tank 169 is provided by the mixing circuit 25,
which produces the dialysate using water from a water supply 30
provided via the directing circuit 142 and dialysate ingredients 49
(e.g., bicarbonate and acid). A series of mixing pumps 180, 183,
184 are used to mix the various components and produce the
dialysate.
[0068] FIG. 3 shows a close-up view of the blood flow circuit 141
in this illustrative embodiment. Under normal operation, blood
flows from a patient through arterial line 203 via blood flow pump
13 to the dialyzer 14 (the direction of flow during normal dialysis
is indicated by arrows 205; in some modes of operation, however,
the flow may be in different directions, as discussed below).
Optionally, an anticoagulant may be introduced into the blood via
anticoagulant pump 80 from an anticoagulant supply. After passing
through dialyzer 14 and undergoing dialysis, the blood returns to
the patient through venous line 204, optionally passing through an
air trap and/or a blood sample port 19. The pump 13 may include,
for instance, pumps 23 that are actuated by a control fluid.
[0069] For example, in one embodiment, the blood flow pump 13 may
comprise two (or more) pod pumps 23. Each pod pump, in this
particular example, may include a rigid chamber with a flexible
diaphragm or membrane dividing each chamber into a pumping
compartment and control compartment. There may be four entry/exit
valves for these compartments, two for the pumping compartment and
two for the control compartment. The valves for the control
compartment of the chambers may be two-way proportional valves, one
connected to a first control fluid source (e.g., a high pressure
air source), and the other connected to a second control fluid
source (e.g., a low pressure air source) or a vacuum source. The
fluid valves can be opened and closed to direct fluid flow when the
pod pumps 23 are operating. Non-limiting examples of pod pumps are
described in U.S. Provisional Application 60/792,073, filed Apr.
14, 2006, or in U.S. patent application Ser. No. 11/787,212, filed
Apr. 13, 2007, each incorporated herein by reference. If more than
one pod pump is present, the pod pumps may be operated in any
suitable fashion, e.g., synchronously, asynchronously, in-phase,
out-of-phase, etc. For instance, in some embodiments, the two-pump
pumps can be cycled out of phase to affect the pumping cycle, e.g.,
one pump chamber fills while the second pump chamber empties. A
phase relationship anywhere between 0.degree. (the pod pumps fill
and empty in unison) and 180.degree. (one pod pump fills as the
other empties) can be selected in order to impart any desired
pumping cycle. A phase relationship of 180.degree. may yield
continuous flow into and out of the set of pod pumps. This is
useful, for instance, when continuous flow is desired, e.g., for
use with dual needle or dual lumen catheter flow. Setting a phase
relationship of 0.degree., however, may be useful in some cases for
single needle/single lumen flow or in other cases. In a 0.degree.
relationship, the pod pumps will first fill from the needle, then
deliver blood through the blood flow path and back to the patient
using the same needle. In addition, running at phases between
0.degree. and 180.degree. can be used in some cases, to achieve a
push/pull relationship (hemodiafiltration or continuous back flush)
across the dialyzer.
[0070] An anticoagulant (e.g., heparin, or any other suitable
anticoagulant) may be contained within a vial 11 (or other
anticoagulant supply, such as a tube or a bag), and blood flow
circuit 141 may include a spike 201 (which, in one embodiment, is a
needle) that can pierce the seal of the vial. The spike 201 may be
formed from plastic, stainless steel, or another suitable material,
and may be a sterilizable material in some cases, e.g., the
material may be able to withstand sufficiently high temperatures
and/or radiation so as to sterilize the material.
[0071] An anticoagulant pump 80, which can act as a metering
chamber in some cases, can be used to control the flow of
anticoagulant into the blood circuit. The anticoagulant pump 80 may
be a pod pump or a membrane-based metering pump, and/or may be
actuated by a control fluid, such as air. For example, the
anticoagulant pump 80 may include a rigid chamber with a flexible
diaphragm dividing the chamber into a pumping compartment and a
control compartment. One valve for the control compartment of the
chamber may be connected to a first control fluid source (e.g., a
high pressure air source), and the other valve connected to a
second control fluid source (e.g., a low pressure air source) or a
vacuum source. Valves for the pumping compartment of the chamber
can be opened and closed in coordination with the control
compartment, thus controlling the flow of anticoagulant into the
blood. In one set of embodiments, air provided through a filter 81
may also be introduced into the blood flow path by the
anticoagulant pump 80, e.g., to provide air into the vial 11 after
or before anticoagulant is withdrawn from the vial.
[0072] Fluid Management System ("FMS") measurements may be used to
measure the volume of fluid pumped through a pump chamber during a
stroke of the membrane, or to detect air in the pumping chamber.
FMS methods are described in U.S. Pat. Nos. 4,808,161; 4,826,482;
4,976,162; 5,088,515; and 5,350,357, which are hereby incorporated
herein by reference in their entireties. In one illustrative
embodiment, the volume of liquid delivered by an anticoagulant
pump, a dialysate pump, or other membrane-based fluid pump is
determined using an FMS algorithm in which changes in chamber
pressure are used to calculate a volume measurement at the end of a
fill stroke and at the end of a delivery stroke. The difference
between the computed volumes at the end of fill and delivery
strokes may be used to determine the actual stroke volume. This
actual stroke volume can be compared to an expected stroke volume
for the particular sized chamber. If the actual and expected
volumes are significantly different, the stroke has not properly
completed and an error message can be generated.
[0073] The blood flow circuit 141 may also include an air trap 19
to remove air bubbles that may be present within the blood flow
path. In some cases, the air trap 19 is able to separate any air
that may be present from the blood due to gravity, and/or may
include a port for sampling blood.
[0074] FIG. 4 shows a close-up view of the balancing circuit 143 in
the FIG. 2 embodiment. In the balancing circuit 143, dialysate
flows from the optional ultrafilter 73 into a dialysate pump 15. In
this embodiment, the dialysate pump 15 includes two pod pumps 161,
162, two balancing chambers 341, 342, and a pump 35 for bypassing
the balancing chambers 341, 342. The balancing chambers 341, 342
may be constructed such that they are formed from a rigid chamber
with a flexible diaphragm dividing the chamber into two separate
fluid compartments, so that entry of fluid into one compartment can
be used to force fluid out of the other compartment and vice versa.
Non-limiting examples of pumps that can be used as pod pumps and/or
balancing chambers are described in U.S. Provisional Application
60/792,073, filed Apr. 14, 2006, or in U.S. patent application Ser.
No. 11/787,212, filed Apr. 13, 2007.
[0075] In one embodiment, balancing of flow in the internal
dialysate circuit works as follows. A set of pneumatically operated
valves 211, 212, 213, 241, 242 has its operation synchronized and
controlled together, where valves 211, 212, 213 are ganged and
valves 241 and 242 are ganged, and a second set of pneumatically
operated valves 221, 222, 223, 231, 232 similarly have its
operation synchronized and controlled together, where valves 221,
222, 223 are ganged, and valves 231 and 232 are ganged. At a first
point of time, the first set of valves 211, 212, 213, 241, 242 is
opened while the second set of valves 221, 222, 223, 231, 232 is
closed. Fresh dialysate flows into balancing chamber 341 while used
dialysate flows from dialyzer 14 into pod pump 161. Fresh dialysate
does not flow into balancing chamber 342 since valve 221 is closed.
As fresh dialysate flows into balancing chamber 341, used dialysate
within balancing chamber 341 is forced out and exits balancing
circuit 143 (the used dialysate cannot enter pod pump 161 since
valve 223 is closed). Simultaneously, pod pump 162 forces used
dialysate present within the pod pump into balancing chamber 342
(through valve 213, which is open; valves 242 and 222 are closed,
ensuring that the used dialysate flows into balancing chamber 342).
This causes fresh dialysate contained within balancing chamber 342
to exit the balancing circuit 143 into dialyzer 14. Also, pod pump
161 draws in used dialysate from dialyzer 14 into pod pump 161.
[0076] Once pod pump 161 and balancing chamber 341 have filled with
dialysate, the first set of valves 211, 212, 213, 241, 242 is
closed and the second set of valves 221, 222, 223, 231, 232 is
opened. Fresh dialysate flows into balancing chamber 342 instead of
balancing chamber 341, as valve 212 is closed while valve 221 is
now open. As fresh dialysate flows into balancing chamber 342, used
dialysate within the chamber is forced out and exits balancing
circuit, since valve 213 is now closed. Also, pod pump 162 now
draws used dialysate from the dialyzer into the pod pump, while
used dialysate is prevented from flowing into pod pump 161 as valve
232 is now closed and valve 222 is now open. Pod pump 161 forces
used dialysate contained within the pod pump (from the previous
step) into balancing chamber 341, since valves 232 and 211 are
closed and valve 223 is open. This causes fresh dialysate contained
within balancing chamber 341 to be directed into the dialyzer 14
(since valve 241 is now open while valve 212 is now closed). At the
end of this step, pod pump 162 and balancing chamber 342 have
filled with dialysate. This puts the state of the system back into
the configuration at the beginning of this description, and the
cycle is thus able to repeat, ensuring a constant flow of dialysate
to and from the dialyzer 14. In an embodiment, the fluid (e.g.
pneumatic) pressures on the control side of the balancing chamber
valves are monitored to ensure they are functioning (e.g., opening
and closing) properly.
[0077] As a specific example, a vacuum (e.g., 4 p.s.i. of vacuum)
can be applied to the port for the first set of valves, causing
those valves to open, while positive pressure (e.g., 20 p.s.i. of
air pressure) is applied to the second set of valves, causing those
valves to close (or vice versa). The pod pumps each urge dialysate
into one of the volumes in one of the balancing chambers 341, 342.
By forcing dialysate into a volume of a balancing chamber, an equal
amount of dialysate is squeezed by the diaphragm out of the other
volume in the balancing chamber. In each balancing chamber, one
volume is occupied by fresh dialysate heading towards the dialyzer
and the other volume is occupied by used dialysate heading from the
dialyzer. Thus, the volumes of dialysate entering and leaving the
dialyzer are kept substantially equal.
[0078] The bypass pump 35 can direct the flow of dialysate from the
dialyzer 14 through balancing circuit 143 without passing through
either of pod pumps 161 or 162. In this embodiment, the bypass pump
35 is a pod pump, similar to those described above, with a rigid
chamber and a flexible diaphragm dividing each chamber into a fluid
compartment and a control compartment. This pump may be the same or
different from the other pod pumps and/or metering pumps described
above. When control fluid is used to actuate the bypass pump 35,
the additional drop in pressure on the exiting (spent) dialysate
side of the dialyzer causes additional ultrafiltration of fluid
from the blood in the dialyzer. This may cause a net efflux of
fluid from the patient's blood, through the dialyzer, and
ultimately to drain. Such a bypass may be useful, for example, in
reducing the amount of fluid a patient has, which is often
increased due to the patient's inability to excrete excess fluid
(primarily water) through the kidneys. As shown in FIG. 4, the
bypass pump 35 may be controlled by a control fluid (e.g., air),
irrespective of the operation of pod pumps 161 and 162. This
configuration may allow for easier control of net fluid removal
from a patient, without having to operate the inside dialysate
pumps either out of balance or out of phase with the blood pumps in
order to achieve such fluid withdrawal from the patient.
[0079] To achieve balanced flow across the dialyzer, the blood flow
pump, the pumps of the balancing circuit, and the pumps of the
directing circuit (discussed below) may be operated to work
together to ensure that flow into the dialyzer is generally equal
to flow out of the dialyzer. If ultrafiltration is required, the
ultrafiltration pump (if one is present) may be run independently
of some or all of the other blood and/or dialysate pumps to achieve
the desired ultrafiltration rate.
[0080] To prevent outgassing of the dialysate, the pumps of the
balancing circuit may be kept at pressures above atmospheric
pressure. In contrast, however, the blood flow pump and the
directing circuit pumps use pressures below atmosphere to pull the
diaphragm towards the chamber wall to complete a fill stroke.
Because of the potential of fluid transfer across the
semi-permeable membrane of the dialyzer and because the pumps of
the balancing circuit run at positive pressures, the balancing
circuit pumps may be able to use information from the blood flow
pump(s) in order to synchronize the delivery strokes of the
balancing circuit chambers to the dialyzer with the delivery
strokes of the blood pumps.
[0081] In one set of embodiments, when running in such a balanced
mode, if there is no delivery pressure from the blood flow pump,
the balancing circuit pump diaphragm will push fluid across the
dialyzer into the blood and the alternate pod of the balancing
circuit will not completely fill. For this reason, the blood flow
pump reports when it is actively delivering a stroke. When the
blood flow pump is delivering a stroke the inside dialysate pump
operates. When the blood flow pump is not delivering blood, the
valves that control the flow from the dialyzer to the inside
dialysate pumps (and other balancing valves ganged together with
these valves, as previously discussed) may be closed to prevent any
fluid transfer from occurring from the dialysate side to the blood
side. During the time the blood flow pump is not delivering, the
inside dialysate pumps are effectively frozen, and the inside
dialysate pump delivery stroke resumes once the blood flow pump
starts delivering again. The inside dialysate pump fill pressure
can be set to a minimal positive value to ensure that the pump
operates above atmosphere at minimal impedance. Also, the inside
dialysate pump delivery pressure can be set to the blood flow pump
pressure to generally match pressures on either side of the
dialyzer, minimizing flow across the dialyzer during delivery
strokes of the inside dialysate pump.
[0082] In another embodiment, the inside dialysate pump delivers
dialysate to the dialyzer at a pressure slightly above the pressure
at which blood is delivered to the dialyzer. This ensures that a
full balance chamber of clean dialysate gets delivered to the
dialyzer. On the return side, the inside dialysate pump can fill
with spent dialysate from the dialyzer at a slightly lower pressure
than the outlet pressure on the blood side of the dialyzer,
ensuring that the receiving dialysate pump chamber can fill. This
in turn ensures that there is enough dialysate available to
complete a full stroke in the balancing chamber. Flows across the
semi-permeable membrane caused by these differential pressures will
tend to cancel each other; and the pumping algorithm otherwise
attempts to match the average pressures on the dialysate and blood
sides of the dialyzer.
[0083] It is generally beneficial to keep the blood flow as
continuous as possible during therapy, as stagnant blood flow can
result in blood clots. In addition, when the delivery flow rate on
the blood flow pump is discontinuous, the balancing pump may pause
its stroke more frequently, which can result in discontinuous
and/or low dialysate flow rates. However, the flow through the
blood flow pump can be discontinuous for various reasons. For
instance, pressure may be limited within the blood flow pump, e.g.,
to +600 mmHg and/or -350 mmHg to provide safe pumping pressures for
the patient. For instance, during dual needle flow, the two pod
pumps of the blood flow pump can be programmed to run 180.degree.
out of phase with one another. If there were no limits on pressure,
this phasing could always be achieved. However to provide safe
blood flow for the patient these pressures are limited. If the
impedance is high on the fill stroke (due to a small needle, very
viscous blood, poor patient access, etc.), the negative pressure
limit may be reached and the fill flow rate will be slower then the
desired fill flow rate. Thus the delivery stroke must wait for the
previous fill stroke to finish, resulting in a pause in the
delivery flow rate of the blood flow pump. Similarly, during single
needle flow, the blood flow pump may be run at 0.degree. phase,
where the two blood flow pump pod pumps are simultaneously emptied
and filled. When both pod pumps are filled, the volumes of the two
pod pumps are delivered. In an embodiment, the sequence of
activation causes a first pod pump and then a second pod pump to
fill, followed by the first pod pump emptying and then the second
pod pump emptying. Thus the flow in single needle or single lumen
arrangement may be discontinuous.
[0084] One method to control the pressure saturation limits would
be to limit the desired flow rate to the slowest of the fill and
deliver strokes. Although this would result in slower blood
delivery flow rates, the flow rate would still be known and would
be more continuous, which would allow for more accurate and
continuous dialysate flow rates. Another method to make the blood
flow rate more continuous in single needle operation would be to
use maximum pressures to fill the pods so the fill time would be
minimized. The desired deliver time could then be set to be the
total desired stroke time minus the time that the fill stroke took.
However, the less continuous the blood flow, the more the dialysate
flow rate may have to be adjusted upward during blood delivery to
the dialyzer to make up for the time that the dialysate pump is
stopped when the blood flow pump is filling. If this is done with
the correct timing, an average dialysate flow rate taken over
several strokes can still match the desired dialysate flow
rate.
[0085] FIG. 5 shows a close up of the directing circuit 142 in the
FIG. 2 embodiment. In this embodiment, the directing circuit 142
can provide dialysate from a dialysate tank 169 via a dialysate
pump 159 to a heater 72 and the ultrafilter 73. The heater 72 may
be used to warm the dialysate to body temperature, and/or a
temperature such that the blood in the blood flow circuit is heated
by the dialysate, and the blood returning to the patient is at body
temperature or higher. In some cases, the heater 72 may be
connected to a control system such that dialysate that is
incorrectly heated (i.e., the dialysate is too hot or too cold) may
be recycled (e.g., back to the dialysate tank 169) or sent to drain
instead of being passed to the dialyzer. The heater 72 may also be
used, in some embodiments, for disinfection or sterilization
purposes. For instance, water may be passed through the
hemodialysis system and heated using the heater such that the water
is heated to a temperature able to cause disinfection or
sterilization to occur, e.g., temperatures of at least about
70.degree. C., at least about 80.degree. C., at least about
90.degree. C., at least about 100.degree. C., at least about
110.degree. C., etc.
[0086] The flow of dialysate through the directing circuit 142 may
be controlled (at least in part) by operation of the dialysate pump
159. In addition, the dialysate pump 159 may control flow through
the balancing circuit 143. For instance, as discussed above, fresh
dialysate from the directing circuit 142 flows into balancing
chambers 341 and 342 of balancing circuit 143. The dialysate pump
159 may be used as a driving force to cause the fresh dialysate to
flow into these balancing chambers. In one set of embodiments,
dialysate pump 159 includes a pod pump, e.g., similar to those
described above.
[0087] The dialysate may also be filtered to remove contaminants,
infectious organisms, pathogens, pyrogens, debris, and the like,
for instance, using an ultrafilter 73. The ultrafilter 73 may be
positioned in any suitable location in the dialysate flow path, for
instance, between the directing circuit and the balancing circuit,
e.g., as shown, and/or the ultrafilter 73 may be incorporated into
the directing circuit or the balancing circuit. If an ultrafilter
is used, its pore size may be chosen to prevent species such as
these from passing through the filter.
[0088] In some cases, the ultrafilter 73 may be operated such that
waste from the filter (e.g., the retentate stream) is passed to a
waste stream, such as waste line 39 in FIG. 5. In some cases, the
amount of dialysate flowing into the retentate stream may be
controlled. For instance, if the retentate is too cold (i.e.,
heater 72 is not working, or heater 72 is not heating the dialysate
to a sufficient temperature, the entire dialysate stream (or at
least a portion of the dialysate) may be diverted to waste line 39,
and optionally, recycled to dialysate tank 169 using line 48. Flow
from the filter 73 may also be monitored for several reasons, e.g.,
using temperature sensors (e.g., sensors 251 and 252), conductivity
sensors (for confirming dialysate concentration, e.g., sensor 253),
or the like. An example of such sensors is discussed below; further
non-limiting examples can be seen in a U.S. patent application Ser.
No. 12/038,474, filed Feb. 27, 2008.
[0089] The ultrafilter and the dialyzer may provide redundant
screening methods for the removal of contaminants, infectious
organisms, pathogens, pyrogens, debris, and the like. Accordingly,
any contaminant would have to pass through both the ultrafilter and
the dialyzer before reaching a patient's blood. Even in the event
that either the ultrafilter or dialyzer integrity fails, the other
may still be able to maintain dialysate sterility and prevent
contaminants from reaching the patient's blood.
[0090] The directing circuit 142 may also be able to route used
dialysate coming from a balancing circuit to a drain, e.g., through
waste line 39 to drain 31. The drain may be, for example, a
municipal drain or a separate container for containing the waste
(e.g., used dialysate) to be properly disposed of. In some cases,
one or more check or "one-way" valves (e.g., check valves 215 and
216) may be used to control flow of waste from the directing
circuit 142 and from the system 5. Also, in certain instances, a
blood leak sensor (e.g., sensor 258) may be used to determine if
blood is leaking through the dialyzer 14 into the dialysate flow
path. In addition, a liquid sensor can be positioned in a
collection pan at the bottom of the hemodialysis unit to indicate
leakage of either blood or dialysate, or both, from any of the
fluid circuits.
[0091] The directing circuit 142 may receive water from a water
supply 30, e.g., from a container of water such as a bag, and/or
from a device able to produce water, e.g., a reverse osmosis
device. In some cases, the water entering the system is set at a
certain purity, e.g., having ion concentrations below certain
values. The water entering into the directing circuit 142 may be
passed on to various locations, e.g., to a mixing circuit 25 for
producing fresh dialysate and/or to waste line 39. In some cases,
valves to the drain 31 and various recycle lines are opened, and
conduits 67 may be connected between directing circuit 142 and
blood flow circuit 141, such that water is able to flow
continuously around the system. If heater 72 is also activated, the
water passing through the system will be continuously heated, e.g.,
to a temperature sufficient to disinfect the system.
[0092] FIG. 6 shows a close-up view of the mixing circuit 25 in the
illustrative embodiment of FIG. 2. Water from the directing circuit
142 flows into the mixing circuit 25 due to action of a pump 180.
In this embodiment, the pump 180 includes one or more pod pumps,
similar to those described above. In some cases, a portion of the
water is directed to reagent ingredients 49, e.g., for use in
transporting the ingredients, such as the bicarbonate 28, through
the mixing circuit 25. In some cases, sodium chloride and/or the
sodium bicarbonate 28 may be provided in a powdered or granular
form, which is mixed with water provided by the pump 180.
Bicarbonate from bicarbonate source 28 is delivered via bicarbonate
pump 183 to a mixing line 186, which also receives water from the
directing circuit 142. Acid from an acid source 29 (which may be in
a liquid form) is also pumped via an acid pump 184 to the mixing
line 186. The ingredients 49 (water, bicarbonate, acid, NaCl, etc.)
are mixed in mixing chamber 189 to produce dialysate, which then
flows out of mixing circuit 25 to the directing circuit 142.
Conductivity sensors 178 and 179 are positioned along mixing line
186 to ensure that as each ingredient is added to the mixing line,
it is added at proper concentrations. The volumes delivered by the
water pump 180 and/or the other pumps may be directly related to
the conductivity measurements, so the volumetric measurements may
be used as a cross-check on the composition of the dialysate that
is produced. This may ensure that the dialysate composition remains
safe even if a conductivity measurement becomes inaccurate during a
therapy.
[0093] FIG. 7 shows a perspective view of a hemodialysis system 5
that incorporates various aspects of the invention. In accordance
with one aspect of the invention, the system 5 includes a dialysis
unit 51 and a power unit module 52 that are shown joined together.
In this embodiment, the dialysis unit 51 has a housing that
contains suitable components for performing hemodialysis, such as a
dialyzer, one or more pumps to circulate blood through the
dialyzer, a source of dialysate, and one or more pumps to circulate
the dialysate through the dialyzer. For example, the dialysis unit
51 may include the mixing circuit 25, blood flow circuit 141, the
balancing circuit 143 and the directing circuit 142 as described
above. The dialysis unit 51 may also include all blood circuit
connections and dialysate fluidic connections needed for operation
of the system 5. Patient access and other connections may be
revealed by opening side-by-side vertical doors 53 via a handle 54
at a front side of the dialysis unit 51 housing. In this
embodiment, the dialysis unit 51 includes a control interface 55
(attached to the housing by a flexible cable in this embodiment)
that a user may use to control operation of the dialysis unit 51.
The control interface 55 may include a display screen with a touch
sensitive overlay to allow touch control and interaction with a
graphical user interface presented on the screen. The control
interface 55 may also include other features, such as push buttons,
a speaker, a microphone for receiving voice commands, a digital
camera, and so on. The back side of the control interface 55 may
include a retractable "kick-stand" (not shown) that allows the
control interface 55 to be positioned on top of the dialysis unit
51 housing. Deploying the retractable "kick-stand" permits the
control interface 55 to be placed in a near-vertical position to
allow proper viewing of the display screen.
[0094] The power unit 52 housing may contain suitable components
for providing operating power to the dialysis unit 51, e.g.,
pneumatic pressure/vacuum to power the pumps, valves and other
components of the dialysis unit 51. "Pneumatic," as used herein,
means using air or other gas to move a flexible diaphragm or other
member. (It should be noted that air is used by way of example
only, and in other embodiments, other control fluids, such as
nitrogen (N.sub.2), CO.sub.2, water, an oil, etc., may be used). As
discussed above, the pumps and valves of the dialysis unit 51 may
operate on pneumatic power, and thus the power unit 52 may provide
one or more pneumatic sources for use by the dialysis unit 51. In
this way, the dialysis unit 51 need not necessarily be arranged to
generate and/or store the necessary pneumatic power needed, but
instead may rely on the power unit module 52. The power unit 52 may
include one or more pneumatic pumps to generate desired air
pressure and/or vacuum, one or more accumulators or other devices
to store pneumatic power, valves, conduits and/or other devices to
control flow of pneumatic power in the power unit 52, as well as a
controller having suitable components, such as a programmed general
purpose data processor, memory, sensors (e.g., to detect pressure,
temperature, etc.), relays, actuators, and so on.
[0095] In one embodiment, the pneumatic power (e.g., air under
suitable pressure/vacuum) may be supplied by the power unit 52 to
the dialysis unit 51 via one or more supply tanks or other pressure
sources. For instance, if two tanks are used in the power unit 52,
one supply tank may be a positive pressure reservoir, and in one
embodiment, has a set point of 750 mmHg (gauge pressure) (1 mmHg is
about 133.3 pascals). The other supply tank can be a vacuum or
negative pressure reservoir, and in one embodiment, has a set point
of -450 mmHg (gauge pressure). This pressure difference may be
used, for instance, between the supply tanks and the required pod
pump pressure to allow for accurate control of the variable valves
to the pod pumps. The supply pressure limits can be set based on
maximum pressures that can be set for the patient blood flow pump
plus some margin to provide enough of a pressure difference for
control of the variable valves. Thus, in some cases, the two tanks
may be used to supply pressures and control fluids for all of the
dialysis unit 51 functions.
[0096] In one embodiment, the power unit 52 may include two
independent compressors to service the supply tanks. Pressure in
the tanks can be controlled using any suitable technique, for
instance, with a simple "bang-bang" controller (a controller that
exists in two states, i.e., in an on or open state, and an off or
closed state), or with more sophisticated control mechanisms,
depending on the embodiment. As an example of a bang-bang
controller, for the positive tank, if the actual pressure is less
than a set point, the compressor servicing the positive tank is
turned on. If the actual pressure is greater than a set point, the
compressor servicing the positive tank is turned off. The same
logic may be applied to the vacuum tank and control of the vacuum
compressor with the exception that the sign of the set point term
is reversed. If the pressure tanks are not being regulated, the
compressor is turned off and the valves are closed.
[0097] Tighter control of the pressure tanks can be achieved by
reducing the size of the hysteresis band, however this may result
in higher cycling frequencies of the compressor. If very tight
control of these reservoirs is required, the bang-bang controller
could be replaced with a proportional-integral-derivative ("PID")
controller and using pulse width modulation ("PWM") signals on the
compressors. Other methods of control are also possible.
[0098] Other pressure sources may be used in other embodiments, and
in some cases, more than one positive pressure source and/or more
than one negative pressure source may be used. For instance, more
than one positive pressure source may be used that provides
different positive pressures (e.g., 1000 mmHg and 700 mmHg), which
may be used to minimize leakage. For example, high positive
pressure can be used to control valves, whereas lower positive
pressures can be used to control pumps. This limits the amount of
pressure that can potentially be sent to the dialyzer or to the
patient, and helps to keep actuation of the pumps from overcoming
the pressures applied to adjacent valves. A non-limiting example of
a negative pressure is -400 mmHg. In some cases, the negative
pressure source may be a vacuum pump, while the positive pressure
pump may be an air compressor.
[0099] Moreover, the power unit 52 may be selectively connectable
to the dialysis unit 51, e.g., to allow different power units 52 to
be interchanged. For example, the dialysis unit 51 may be arranged
to work with different types of power units 52, such as power units
52 that use electrical power to generate the pneumatic power
supply, as well as power units 52 that use stored pneumatic power
(e.g., pressurized air stored in one or more high pressure tanks).
Thus, a power unit 52 may be interchanged for another unit 52, in
case of failure or other requirements. For example, it may be
desired to use the system 5 in an area where noise generation is
unacceptable, such as when nearby people are sleeping. In this
case, it may be desirable to use a power unit 52 that uses stored
pneumatic power, rather than a unit 52 that generates pneumatic
power by running pumps or other noise generating equipment. As
shown in FIG. 8, the power unit 52 may be disconnected from the
dialysis unit 51 by manipulating a handle 521. For example, turning
the handle 521 may unlock the power unit 52 from the dialysis unit
51, disengaging not only mechanical connections between the
housings, but also power and/or communications connections between
the two. An interface (not shown) between the dialysis unit 51 and
the power unit 52 may permit the units to exchange pneumatic power
(from the power unit 52 to the dialysis unit 51) as well as
electrical power, control communications, and other. The dialysis
unit 51 may have connection points for electrical power (e.g.,
standard 115V, 15 amp power found in most home power outlets),
external communication (such as Ethernet, or any other suitable
connection suitable for communication), a water supply, and so on.
The dialysis unit 51 may provide electrical power or other
connections to the power unit 52, if desired.
[0100] The dialysis unit 51 may include a controller to control
flow of control fluid for various components of the system 5, as
well as perform other desired functions. In some cases, the control
fluid may be held at different pressures within the various tubes
or conduits. For instance, some of the control fluid may be held at
positive pressure (i.e., greater than atmospheric pressure), while
some of the control fluid may be held at negative pressures (less
than atmospheric pressure). In addition, in certain embodiments,
the controller may have components that are kept separate from the
various liquid circuits. This configuration has a number of
advantages. For example, in one embodiment, the liquid circuits in
the dialysis unit 51 may be heated to disinfection temperatures
and/or exposed to relatively high temperatures or other harsh
conditions (e.g., radiation) to effect disinfection, while
electronic components of the controller may not be exposed to such
harsh conditions, and may even be kept separate by an insulating
wall (e.g., a "firewall") or the like. That is, the dialysis unit
housing may have two or more compartments, e.g., one compartment
with electronic and other components that may be sensitive to heat
or other conditions, and another compartment with liquid circuit
components that are heated or otherwise treated for
disinfection.
[0101] Thus, in some embodiments, the system 5 may include a "cold"
section (which is not heated), and a "hot" section, portions of
which may be heated, e.g., for disinfection purposes. The cold
section may be insulated from the hot section through insulation.
In one embodiment, the insulation may be molded foam insulation,
but in other embodiments can be any type of insulation, including
but not limited to a spray insulation, an air space, insulation cut
from sheets, etc. In one embodiment, the cold section includes a
circulation system, e.g., a fan and/or a grid to allow air to flow
in and out of the cold box. In some cases, the insulation may be
extended to cover access points to the "hot" section, e.g., doors,
ports, gaskets, and the like. For instance, when the "hot" section
is sealed, the insulation may completely surround the "hot" section
in some cases.
[0102] Non-limiting examples of components that may be present
within the "cold" section include power supplies, electronics,
power cables, pneumatic controls, or the like. In some cases, at
least some of the fluids going to and from the "hot" section may
pass through the "cold" section; however, in other cases, the
fluids may pass to the "hot" section without passing through the
"cold" section.
[0103] Non-limiting examples of components that may be present
within the "hot" section include cassettes (if present), fluid
lines, temperature and conductivity sensors, blood leak sensors,
heaters, other sensors, switches, emergency lights, or the like. In
some cases, some electrical components may also be included in the
"hot" section. These include, but are not limited to, a heater. In
one embodiment, the heater can be used to heat the hot box itself,
in addition to fluid. In some embodiments, the heater 72 heats the
entire "hot" section to reach a desired temperature.
[0104] In accordance with an aspect of the invention, the dialysis
unit 51 housing may include vertical side-by-side doors that can be
opened to expose all mechanical interface points for blood flow
circuitry and connections for dialysate circuitry, i.e., all
connection points for patient blood connections and
acid/bicarbonate connections, that must be made by a user to use
the dialysis unit 51. FIG. 9 shows a front view of the dialysis
unit 51 with the vertical side-by-side doors 53 in a closed state.
In this arrangement, the doors 53 may block access to connection
points for patient blood connections and acid/bicarbonate
connections as well as seal the interior of the unit housing so as
to allow heat retention suitable for disinfection. The seal
provided by the doors 53 may be hermetic, preventing or
substantially resisting any air exchange between the housing
interior and an exterior environment, or may be of a somewhat
lesser quality yet still allow for disinfection.
[0105] In this embodiment, the doors 53 are connected to the
dialysis unit 51 housing by a dual hinge arrangement such that the
doors 53 can be opened to two different states of opening. FIGS.
10-13 show the doors 53 in a first state of opening. In this state,
the doors 53 expose all user-made connections for the blood circuit
connections and for the dialyzer circuitry, including the dialyzer
14 itself and for reagent materials, such as consumable
acid/bicarbonate materials. This position also exposes several
other features, such as holders 531 for an acid/bicarbonate
container (not shown) and hooks 532 that may be used to hold any
suitable item, such as the control interface 55, which may be hung
by its handle on one of the hooks 532. (See also FIG. 7 which shows
a hook 532 on the front of the left door 53 which may be folded out
to receive the control interface 55 or other item.) The holders 531
in this embodiment may be folded down from their position shown in
the figures (i.e., folded up and into recesses in the doors 53) so
as to extend horizontally from the doors 53. The holders 531 have a
"C" shaped receiving section to receive and hold an
acid/bicarbonate container, but of course could be shaped or
otherwise arranged in any suitable way.
[0106] FIGS. 14-16 show the doors 53 in a second state of opening
in which a hinge plate 533 for each door 53 is pivoted outward and
away from the dialysis unit housing 51. The hinge plates 533, which
in this embodiment extend vertically along almost the entire height
of the dialysis unit housing 51, are pivotally attached to the
doors 53 at a first, outer end, and are pivotally attached at a
second inner end to the dialysis unit housing 51. (Of course, it
should be understood that the hinge plates 533 could be arranged
and/or positioned differently, e.g., at the top and bottom of the
doors 53 as is found in many refrigerator door arrangements, each
plates 533 may include two or more portions that are vertically
separated from each other, etc.) Magnets 534 attached to the hinge
plates 533 may interact with corresponding magnets (or other
suitable components, such as a steel elements) attached to the
dialysis unit housing 51 so as to attract the hinge plates 533
toward the dialysis unit housing 51, thus tending to keep the hinge
plates 533 in the position shown in FIGS. 10-13. (Of course, the
magnets 534 could be positioned on the unit housing, and the hinge
plates 533 could have suitable elements (such as pieces of steel)
that are attracted to the magnets 534.) The doors 53 in this
embodiment also include magnets attached near the hinge plates 533
so that when the doors 53 are opened to the first state as shown in
FIGS. 10-13, the magnets interact with corresponding magnets in the
hinge plates 533 to help keep the doors 53 in an open position
relative to the hinge plate 533. These magnets will also help
maintain the relative position of the doors 53 and the hinge plates
533 when the hinge plates 533 are opened to the second state shown
in FIGS. 13-16.
[0107] Although magnets are used in this illustrative embodiment as
part of a retainer member to help the doors 53 and/or hinge plates
533 stay in a particular state of opening or closing, other
arrangements for a retainer member are possible. For example, the
hinge connection between the doors 53 and the hinge plates 533
and/or the connection between the hinge plates 533 and the housing
51 may include a detent arrangement that serves to resiliently hold
the door 53 or hinge plate 533 in a particular position relative to
the other part (the hinge plate or housing, respectively). In
another embodiment, one or more springs may be used to help
maintain the doors 53 in an open position relative to the hinge
plates 533. In yet another embodiment, the hinge plates 533 may
have a friction or interference fit with a portion of the housing
51 that tends to maintain the hinge plates 533 in the closed
position (adjacent the housing). Accordingly, a retainer member
that functions to help maintain a door 53 in a particular position
relative to its hinge plate 533, and/or that functions to help
maintain a hinge plate 533 in a particular position relative to the
housing 51, may take any one of a number of possible
arrangements.
[0108] In accordance with another aspect of the invention, opening
of the doors to the dialysis unit housing may reveal all of the
user-made connections for blood circuit connections and dialysate
fluidic connections needed for operation of the system 5. For
example, as shown in FIG. 17, with the doors 53 in an open position
(either the first or second state of opening) a front panel 511 of
the dialysis unit 51 may be exposed. In this embodiment, the front
panel 511 carries several items or connection points that must be
accessed by a user. For example, the dialyzer 14, which must be
periodically replaced, is mounted to the front panel 511. The
dialyzer 14 must be connected not only to the blood flow circuit
141, but also the balancing circuit 143. Also, a connection point
512 for an acid/bicarbonate source 49 is located at a lower end of
the front panel 511. It is at this connection point 512 that a user
may connect a source of consumable reagent ingredients 49 used by
the dialysis unit 51 in making dialysate. An occluder 513 is also
mounted on the front panel 511. The occluder 513 receives tubes of
the blood flow circuit and controls the open/closed state of the
tubes based on system operation. The function of the occluder 513
is discussed in more detail in U.S. application Ser. No.
12/198,947, filed Aug. 27, 2008 (under Attorney Docket Number
D0570.70020US00 (G28)) and below. In short, the occluder 513 allows
flow through the arterial and venous lines of the blood flow
circuit unless there is a system problem, such as a leak, pump
failure, overpressure situation, etc. In such case, the occluder
513 automatically closes the blood lines to prevent all flow to or
from the patient. Also exposed on the front panel 511 are blood
line connection points 514 for connecting the arterial and venous
blood lines 203, 204 of the blood flow circuit 141 with the
directing circuit 142 (as explained above with reference to FIGS. 2
and 3, the blood flow circuit 141 may be connected to the directing
circuit 142). This connection is normally made at the end of
treatment to allow the system to clean and disinfect the blood flow
circuit 141. The front panel 511 also has a set of control ports
515 that mate with corresponding control ports on the blood pump
portion of the blood flow circuit 141. The control ports 515
provide controlled levels of air pressure and/or vacuum to control
the open/closed state of valves and to power the pumps of the blood
flow circuit 141.
[0109] Also exposed on the front panel 511 is a user control panel
510. The user control panel 510 includes one or more buttons
permitting the user to bypass the graphical user interface on
control interface 55, providing an alternate method to control
certain functions (e.g., critical functions) during hemodialysis.
This may be important, for example, if the control interface 55
should ever fail during a dialysis treatment session. Non-limiting
examples of critical functions can include a "stop dialysis" or
"pause dialysis" command and an "infuse dialysate solution"
command.
[0110] FIG. 17 does not show the arterial and venous lines 203, 204
for the blood flow circuit 141 because in this embodiment and in
accordance with another aspect of the invention, the blood flow
circuit 141 is formed as a blood circuit assembly that is removable
from the front panel 511 of the dialysis unit 51, and the blood
circuit assembly is not mounted on the front panel 511 in FIG. 17.
FIG. 18 shows a front view of the blood circuit assembly 17 in this
embodiment along with the dialyzer 14. The blood circuit assembly
17 includes various components discussed above, for example with
reference to FIG. 3, that are mounted to a blood circuit organizing
tray 171. The arterial and venous lines 203 and 204 (e.g.,
including lengths of flexible silicone tubing) are terminated with
blood line connectors that, in one aspect of the invention, are
arranged to provide a plug-in or press-in connection with the blood
line connection points 514 as well as provide a screw-type
connection used with standard patient access points (e.g., luer
type patient access connectors). The arterial line 203 leads to an
inlet at the top of the blood pump 13, which includes two pod pumps
23, valves and other components for controlling blood flow.
Associated with the blood pump 13 are an air filter 81, an
anticoagulant pump 80 (not shown), and an anticoagulant supply 11
(such as a vial of heparin). (Details regarding the blood pump 13
in this illustrative embodiment may be found in U.S. patent
application Ser. No. 11/871,680, filed Oct. 12, 2007, entitled
"Pumping Cassette"; U.S. patent application Ser. No. 11/871,712,
filed Oct. 12, 2007, entitled "Pumping Cassette"; U.S. patent
application Ser. No. 11/871,787, filed Oct. 12, 2007, entitled
"Pumping Cassette"; U.S. patent application Ser. No. 11/871,793,
filed Oct. 12, 2007, entitled "Pumping Cassette"; and U.S. patent
application Ser. No. 11/871,803, filed Oct. 12, 2007, entitled
"Cassette System Integrated Apparatus.") Blood output from the
blood pump 13 (the outlet is located at a bottom of the pump 13)
flows to an inlet of the dialyzer 14 (at the top of the dialyzer
14), and out of the dialyzer (the dialyzer blood outlet is located
at the bottom of the dialyzer 14) to the inlet of the air trap 19.
The outlet of the air trap 19 is connected to the venous blood line
204. Connections to the inlet and outlet blood ports of the
dialyzer 14 are made with typical screw-type connections.
[0111] In accordance with another aspect of the invention, the air
trap 19 is placed in the blood flow path after the blood exits the
dialyzer and before it is returned to the patient. In an
embodiment, air trap 19 can have a spherical or spheroid-shape
container (i.e., a container having an approximately spherical
inner wall), and have its inlet port located near the top and
offset from the vertical axis of the container, and an outlet at a
bottom of the container. (The vertical axis of the container is
arranged in a vertical direction passing through the top and bottom
"poles" of the approximately spherical container.) With the inlet
port offset from the vertical axis (in this case set back toward
the tray 171), blood is introduced into the container in a
direction that is approximately perpendicular to the vertical axis
of the container and that is approximately tangential to the
spherical inner wall of the container. The curved shape of the
inside wall of the trap can thus direct the blood to circulate
along the inside wall as the blood gravitates to the bottom of the
container (e.g., in a spiral like fashion), facilitating the
removal of air bubbles from the blood. Air present in the blood
exiting the outlet of the dialyzer 14 will enter at the top of the
air trap 19 and remain at the top of the container as blood flows
out the outlet at the bottom and to the venous blood line 204. By
locating the inlet port near the top of trap 19, it is also
possible to circulate blood through the trap with minimal or no air
present within the container (as a "run-full" air trap. The ability
to avoid an air-blood interface for routine circulation of blood in
the trap can be advantageous. Placing the inlet port at or near the
top of the container also allows most or all of the air present in
the trap to be removed from the trap by reversing the flow of fluid
through the blood tubing (i.e. from the bottom to the top of the
trap 19, exiting through the inlet port of the trap 19).
[0112] In an embodiment, a self-sealing port, such as a
self-sealing stopper with a split septum or membrane, or another
arrangement, is located at the top of the trap, allowing the
withdrawal of air from the container (e.g., by syringe). The
blood-side surface of the self-sealing membrane can be situated
nearly flush with the top of the interior of the trap, in order to
facilitate cleaning of the self-sealing port during disinfection,
e.g., by reversing flow through the air trap using a dialysate or
other cleaning fluid. Also, the inlet, outlet and internal wall of
the container and the self-sealing port may be arranged to
substantially eliminate stagnation regions, i.e., allow for few or
no regions where blood can stagnate or clot. The self-sealing port
can also serve as a blood sampling site, and/or to allow the
introduction of liquids, drugs or other compounds into the blood
circuit. A sealed rubber-type stopper can be used if access with a
needle is contemplated. Using a self-sealing stopper with split
septum permits sampling and fluid delivery using a needleless
system.
[0113] FIG. 19 shows the organizing tray 171 for the blood circuit
assembly 17 without the various blood circuit assembly 17
components mounted. In accordance with one aspect of the invention,
the organizing tray 171 includes handles 172 (in this embodiment,
finger pulls) that a user can grip when mounting/dismounting the
blood circuit assembly 17 to the front panel 511. Inward of the
handles 172 are openings 173 that allow spring tabs on the front
panel 511 to pass through and engage with the organizing tray 171
and/or the blood pump 13 cassette to hold the blood circuit
assembly 17 in place on the front panel 511. In accordance with
another aspect of the invention, the organizing tray 171 includes
blood line engagement members 174 that each have a C-shaped recess
or other hole through which a corresponding blood line 203, 204
passes. (In this context, a "hole" includes a recess like that
shown in FIG. 19, a throughbore that has a continuous wall, e.g.,
as may be made by a drill, or other suitable opening.) As described
in more detail below, the blood line engagement members 174 are
used when mounting the blood lines 203, 204 in the occluder 513. In
short, when mounting the blood lines 203, 204 in the occluder 513,
the blood lines 203, 204 must be pulled and stretched downwardly
(so as to reduce the outside diameter of the line) while being
pushed horizontally into slots for the occluder 513. The blood line
engagement members 174 function to both resist downward pulling on
the blood lines 203, 204 (e.g., each line 203, 204 may include a
stop ring above the respective engagement member 174 that cannot be
pulled through the recess in the engagement member 174) as well as
permit the user to press inwardly on the engagement member 174 to
seat the lines 203, 204 in the occluder slots. The engagement
members 174 are formed integrally with the organizing tray 171 so
that a "living hinge" or relatively flexible portion of the
organizing tray is positioned between the engagement member 174 and
the main body of the organizing tray 171. This arrangement allows
the engagement members 174 to be pushed inwardly relative to the
organizing tray 171 as the connection portion between the
engagement members 174 and the organizing tray main body
flexes.
[0114] FIG. 20 shows a rear view of the blood circuit assembly 17
with the organizing tray 171 removed. This view shows the rear side
of the blood pump 13 section with control ports exposed. These
control ports mate with corresponding ports 515 on the front panel
511 (see FIG. 17) so that pneumatic control (e.g., suitable air
pressure or vacuum) can be applied to the pumps and valves to
control their operation and flow through the blood circuit assembly
17. FIG. 20 also shows the offset of the inlet port of the air trap
19, i.e., the inlet port at the top of the air trap 19 is arranged
to the rear of the vertical axis of the generally spherical
container portion of the air trap 19.
[0115] FIG. 21 shows a perspective view of the front panel 511 of
the dialysis unit 51 with the blood circuit assembly 17 mounted to
the front panel 511 without the organizing tray 171. (Normally, the
blood circuit assembly 17 would include the organizing tray 171,
but the tray 171 is not shown in the example so as to more clearly
show components at the front panel 511.) On opposite sides of the
blood pump 13 cassette, the front panel 511 has spring tabs 516
that extend forwardly and resiliently engage with the blood pump
cassette and/or the organizing tray 171 to retain the blood circuit
assembly 17 in place. The tabs 516 may include a barb or other
feature to help retain the blood circuit assembly 17 in place. The
spring tabs 516 may be flexed outwardly to release their hold on
the blood circuit assembly 17, allowing its removal. However, in
the absence of an outwardly directed force on the spring tabs 516,
the tabs 516 will remain engaged with the blood circuit assembly
17. FIG. 22 shows a front view of the front panel 511 with the
organizing tray 171 of the blood circuit assembly 17 included. To
remove the blood circuit assembly 17 from the front panel 511, a
user may place index fingers behind the handles 172 while
simultaneously placing thumbs on the inner side of the spring tabs
516 (the sides nearest the blood pumps 23) and flexing the spring
tabs 516 outwardly and away from the pumps 23. This causes the
spring tabs 516 to release the blood circuit assembly 17, e.g.,
disengagement of barbs on the tabs 516 from the blood pump 13
and/or the organizing tray 171. Of course, to remove the blood
circuit assembly 17, other connections must be removed, including
connections to the dialyzer 14 and the blood line connection points
514, as well as removal of the lines 203, 204 from the occluder
513. When mounting the blood circuit assembly 17 to the front panel
511, the organizing tray 171 may be grasped at the handles 172 and
properly aligned, e.g., so that the spring tabs 516 are aligned to
pass through the openings 173 and the control ports of the blood
pump 13 cassette are aligned with the corresponding ports 515 on
the front panel 511. The blood circuit assembly 17 may then be
simply pushed into place, so that the spring tabs 516 engage with
the organizing tray 171 and/or the blood pump cassette. Other
connections can then be made, such as connections to the dialyzer
14, mounting of the blood lines 203, 204 with the occluder 513,
etc.
[0116] FIG. 21 also shows the slots 517 that hold the blood lines
203, 204 for leading into the occluder 513. The slots 517 define a
channel that is slightly smaller than the outside diameter of the
blood lines 203, 204 so that the lines 203, 204 tend to remain in
the slots 517 after placement in the slots. This helps to ensure
proper association of the lines with the occluder 513. Once the
blood circuit assembly 17 is mounted on the spring tabs 516, the
user may then engage the blood lines 203, 204 with the slots 517 by
stretching the lines 203, 204 downward (with the engagement members
174 on the organizing tray 171 engaging the stop ring or other
feature on the respective line 203, 204 and resisting the downward
pull) and pushing the lines 203, 204 into a corresponding slot. The
lines 203, 204 can be pushed into place by pressing inwardly on the
engagement members 174, which as described above, are flexible and
bend inwardly relative to the organizing tray 171. The lines 203,
204 can then be routed through the occluder 513.
[0117] In accordance with another aspect of the invention, the
front panel 511 includes a blood line wrap feature around the
periphery of the front panel 511. In this illustrative embodiment,
the front panel 511 includes flanged portions 518 along the top
edge and at lower corners of the front panel 511. This allows a
user to wrap the blood lines 203, 204 around the periphery of the
front panel 511 by placing the lines 203, 204 in a channel defined
by the flanged portions 518. The lines 203, 204 may be wrapped in a
clockwise direction, starting from a point near the bottom of the
dialyzer 14, and ending at a point near the lower right corner of
the front panel 511. The blood lines 203, 204 may then be connected
at the blood line connection points 514, e.g., to allow
disinfecting fluid to be circulated through the blood lines 203,
204. As a result, the blood lines 203, 204 can be neatly retained
on the front panel 511, allowing easy access to other components on
the front panel 511 and allowing the user to close the doors 53
with minimal concern for pinching the blood lines 203, 204 between
the doors 53 and the dialyzer unit housing 51. Alternatively, the
blood lines 203, 204 may be first connected at the blood line
connection points 514, and then wrapped in a clockwise direction,
starting from a point near the bottom of the dialyzer 14, and
ending at a point near the lower right corner of the front panel
511. This ensures that the blood lines are properly distributed
along the flanged portions 518 to reach the connection points 514.
Vertical fences 519 may also be provided along the left and right
sides of the front panel 511 to help keep the blood lines 203, 204
in a desired position and away from the hinge plates 533 and other
possible pinch points.
[0118] In accordance with another aspect of the invention, the
front panel 511 of the dialysis unit 51 (or other suitable
component) may be arranged to accommodate a variety of differently
sized and/or shaped dialyzer units 14. Different patients, and in
some cases even the same patient over time, may be prescribed
different dialyzers so as to provide different treatment
conditions. Thus, the dialysis unit 51 is preferably arranged to
operate with multiple different types of dialyzers 14. In many
cases, different dialyzers 14 have different dimensions, such as
the overall diameter and/or length of the dialyzer unit. In this
illustrative embodiment as shown in FIG. 23, the front panel 511
includes a dialyzer mount with a pair of "keyhole" features 520
that are arranged to engage with a respective dialysate
quick-connect fitting on the dialyzer 14. Each keyhole feature 520
includes an upper insertion area 520a sized to receive a portion of
the quick-connect fitting and a lower flanged portion 520b that has
a width that is smaller than an overall diameter of the
quick-connect fitting and that engages with a grooved area of the
quick-connect fitting. So as to aid in understanding of these
features, FIG. 24 shows a dialyzer 14 with quick connect fittings
14a attached at dialysate inlet and outlet ports of the dialyzer
14. (Blood inlet and outlet ports are located at the extreme top
and bottom of the dialyzer 14 shown in FIG. 24.) The quick connect
fittings 14a shown are of a standard type, and most, if not all,
dialyzers 14 have dialysate inlet/outlet ports that are arranged to
engage with the standard quick connect fittings 14a. The quick
connect fittings 14a each include a slide element 14b that is moved
to the right (as shown in FIG. 24) relative to a base 14c to allow
the fitting 14a to be engaged with a dialysate port on the dialyzer
14. When the slide element 14b is moved to allow the fitting 14a to
be attached to the dialyzer 14, a groove 14d is closed. However,
once the fitting 14a is properly seated on the inlet/outlet port of
the dialyzer 14, the slide element 14b may be released, allowing a
spring (not shown) to move the slide to the left as shown in FIG.
24, reestablishing the groove 14d to the condition shown in FIG.
24. Thus, when the quick connect fitting 14a is properly engaged
with the dialyzer 14, the groove 14d will be present as shown in
FIG. 24.
[0119] To mount the dialyzer 14 to the keyhole features 520, the
quick connect fittings 14a may be partially inserted into the upper
insertion area 520a of the top and bottom keyhole features,
respectively, so that the groove 14d of each fitting 14a is aligned
with a flange of the lower flanged portion 520b of the keyhole
features 520. (Note that the upper insertion area 520 of the bottom
keyhole feature 520 may be made longer than that shown in FIG. 23
to allow the accommodation of a wider range of dialyzer lengths.)
With the grooves 14d aligned with the flanges, the dialyzer 14 may
be lowered so that the quick connect fittings 14a are fully
received into the lower flanged portions 520b of the keyhole
features 520.
[0120] In accordance with another aspect of the invention, one or
both of the keyhole features 520 may be adjustable so that the
weight of the dialyzer 14 is shared by both lower flanged portions
520b of the keyhole features 520. For example, in this illustrative
embodiment, the bottom keyhole feature 520 has part of the lower
flanged portion 520b adjustable in vertical position relative to
the top keyhole feature 520. In this way, the portion of the lower
flanged portion 520b may be adjusted in vertical position so that,
with the top quick connect fitting 14a supported by the flanged
portion 520b of the top keyhole feature 520, the movable portion of
the flanged portion 520b of the bottom keyhole feature can be
moved, e.g., upwardly, so that the bottom quick connect fitting 14a
is also supported by the flanged portion 520b. Thus, the weight of
the dialyzer 14 can be shared by both keyhole features 520. The
flanged portion 520b may be made adjustable in any suitable way. In
this embodiment, the flanged portion 520b has a "U" shaped member
520c that is vertically slidable along the vertical flanges and can
be fixed in place by tightening a set of thumb screws. The "U"
shaped member 520c may engage the quick connect fitting 14a so that
the "U" shaped member 520c supports the weight (at least in part)
of the dialyzer 14.
[0121] Although in the embodiment above, the dialyzer 14 is
supported by keyhole features in the front panel 511, a support
arrangement for the dialyzer may be configured in other ways. For
example, the upper insertion area 520a is not necessarily required.
Instead, only flange portions (e.g., in the shape of a "U" shaped
flange having opposed flange portions) may be provided to engage
the dialyzer quick connect fittings. The flange portions may be
offset from the front surface of the front panel 511 to provide
clearance for the fitting and allow the flange portions to engage
with the grooves of the quick connect fittings. Also, the flange
portions need not be provided in a vertical orientation as shown,
but instead may be oriented at an angle to the vertical, e.g., in a
horizontal arrangement. The flange portions may have a detent,
catch, or other feature to help maintain the dialyzer in place as
well.
[0122] In accordance with another aspect of the invention, a
bicarbonate, acid and/or other reagent supply device may be
selectively associated with the dialysis unit. As described above,
the dialysis unit 51 requires a supply of certain chemicals to
generate dialysate and/or other materials needed for system
operation. FIG. 25 shows a reagent supply 49 used to provide acid,
bicarbonate and/or other materials to the dialysis unit 52. (FIG.
21 shows the reagent supply 49 attached to the acid/bicarbonate
connection point 512 on the front panel 511.) The reagent supply 49
in this illustrative embodiment includes an E-prong connector 491
that is arranged to mate with the acid/bicarbonate connection point
512. As with other connections made by the user at the front panel
511, e.g., including the blood line connections at the connection
point 514, the mating connectors may be color coded or otherwise
marked to help ensure proper connections are made. For example, the
E-prong connector 491 and the acid/bicarbonate connection point 512
may be colored orange, while the arterial line 203 and its mating
connection at the connection point 514 may be colored red, and the
venous line 204 and its mating connection at the connection point
514 are colored blue. Leading from the E-prong connector 491 are a
bicarbonate supply line 492, a water supply line 493 and an acid
supply line 494. (See FIG. 6 and the accompanying description
regarding the function of these lines.) The water supply line 493
provides water to a bicarbonate supply 28 (which in this embodiment
is a 750 g Altracart Bicarbonate cartridge (#500750A) sold by
Baxter International Inc. that includes a powdered bicarbonate
material, but may be any suitable supply), which provides
bicarbonate to the dialysis unit 51 via the bicarbonate supply line
492. In this embodiment, the acid supply line 494 leads to an acid
bag spike 495, which may be used to pierce and draw a suitable acid
from a IV-type bag or other container. In this embodiment, the acid
bag spike 495 includes a spike member 495a and a pair of spring
clips 495b. The spring clips 495b are joined together at center
portions by a connecting bar such that the spring clips 495b and
the connecting bar form an "H" shape and allow the spring clips
495b to be pivoted relative to each other when proximal ends of the
spring clips 495b are squeezed toward each other. The spring clips
495b may be arranged to engage with a connector element on an acid
bag (or other acid supply, not shown) so that the spike member 495a
remains engaged with the bag until a user disengages the clips
495b. For example, distal ends of the clips 495b may include barbs
that engage with the acid supply, and the clips may be disengaged
from the acid supply by squeezing proximal ends of the clips 495b
together to disengage the barb elements at the distal ends of the
clips 495b from the acid supply. The acid bag spike 495 may also
include a valve 495c (in this case, a pinch clamp) to open/close
the line of the acid bag spike 495. In accordance with one aspect
of the invention, the acid bag spike 495 may be replaced
(disconnected from the acid supply line 494 at a cap connector 496)
with another component, such as an acid jug straw (not shown) or
other arrangement. When used with a jug straw, the cap connector
496 may be engaged with an acid jug opening such that the cap
connector 496 covers the opening, like a cap. Alternatively, the
jug straw can terminate in a spike, which then has the ability to
penetrate a self-sealing (e.g. rubber) membrane covering the
opening of the acid jug. Thus, different types of components may be
attached to the acid supply line 494 depending on the acid supply
arrangement (such as a jug, bottle, bag, or other).
[0123] FIG. 26 shows a close up view of the E-prong connector 491
and the corresponding connection point 512 at the front panel 511.
The E-prong connector 491 has three parallel prongs (corresponding
to the bicarbonate and acid supply lines 492 and 494 and the water
supply line 493) that that engage with corresponding receiving
holes in the connection point 512. The E-prong connector 491 and
receiving holes in the connection point 512 are arranged so that a
center lumen (the water supply line 493) is arranged above, or
otherwise out of, a common plane of the two outer lumens (the
bicarbonate and acid supply lines 492 and 494). In this way, it is
ensured that the bicarbonate and acid supply lines 492 and 494 are
properly connected since the E-prong connector 491 cannot be
engaged with the connection point 512 unless appropriately
oriented. The E-prong connector 491 includes a pair of spring tabs
491a that can be engaged with corresponding slots 512a in the
connection point 512, e.g., when the prongs are properly seated in
receiving holes of the connection point 512. With the tabs 491a
engaged in the slots 512a, the E-prong connector 491 cannot be
easily removed from the connection point 512, helping reduce the
likelihood of an accidental disconnection. The E-prong connector
491 may be disconnected by pressing the tabs 491a toward each other
so that barbs at the distal ends of the tabs 491a disengage from
the slots 512a. The connection point 512 has similar spring tabs
512b which allow the connection point 512 to be connected to and
disconnected from the front panel 511.
[0124] In accordance with another aspect of the invention, a
disinfect connector (not shown) engages with connection point 512
for use during a disinfection procedure. The disinfect connector
has three parallel prongs having a similar orientation as the
E-prong connector 491, so that the prongs may engage with the
receiving holes in connection point 512. The channels in the prongs
of the disinfect connector terminate within a common chamber within
the disinfect connector. Thus, during a disinfect procedure, the
bicarbonate flow line, acid flow line and water flow line are all
interconnected, permitting disinfection of each of these flow lines
during the disinfect procedure. (This is shown as a dashed inverted
"T" line at 49 in FIG. 6).
[0125] In accordance with another aspect of the invention, the
blood lines 203, 204 are equipped with a connector that enables two
types of connections to be made. One type of connection is a
plug-in or press-in connection by which the connector can be pushed
into a receiving lumen and a leakfree connection made without
requiring rotation of the connector or the receiving lumen. A
second type of connection is a screw-type connection by which a
leakfree connection can be made by a threaded engagement of the
connector with a complementary element. For example, FIGS. 27 and
28 show a perspective view and a side view of a blood line
connector 202 that is used with the blood lines 203, 204 and that
can engage with the blood line connection point 514 on the front
panel 511. The connector 202 includes a tube connection end 202a
that connects to the corresponding blood line 203, 204, and a
patient access connection end 202b that is arranged to connect to
both a patient access as well as the connection point 514 to
establish a leakfree connection. At the patient access connection
end 202b, the connector 202 includes a frustoconical member 202c
that has an internally threaded portion arranged to engage with an
externally threaded patient access. For example, the frustoconical
member 202c may be part of a male-type luer connector that includes
the central tube 202e extending from the center of the
frustoconical member 202c. When making the luer connection, the
tube 202e may extend into a female luer connector at the patient
access and the threaded portion on the interior of the
frustoconical member 202c may engage with a thread on the female
luer connector of the patient access (whether arterial or venous).
Such luer connections are standard when connecting blood lines to a
patient access. However, the connector 202 may also be engaged with
the connection point 514 by simply pushing the patient access
connection end 202b into a receiving hole of the connection point
514. When making this connection, the exterior of the frustoconical
member 202c may engage with a suitable seat, or other surface or
element in the connection point 514 (such as a valve seat, O-ring,
or other) so that a seal is formed between the frustoconical member
202c and the connection point 514. The central tube 202e may also,
or instead, be used to engage with the connection point 514 to
establish a suitable seal. Locking arms 202d that extend rearwardly
from the frustoconical member 202c may engage with holes 514a in
the connection point 514 (e.g., barbed portions on the arms 202d
may engage with the holes 514a) to help maintain the connector 202
in the receiving hole of the connection point 514. The connector
202 may be released by pressing the arms 202d toward each other
(e.g., by pressing on finger depression portions at the distal ends
of the arms 202d), thereby disengaging the barbs from the holes
514a, and withdrawing the connector 202. Note that the connection
point 514 may include spring tabs 514b to allow the connection
point 514 to be selectively engaged/disengaged at the front panel
511. The connectors 202 may be made in any suitable way, such as by
molding of plastic as a single unitary part.
[0126] The following are each incorporated herein by reference in
their entireties: U.S. Provisional Patent Application Ser. No.
60/903,582, filed Feb. 27, 2007, entitled "Hemodialysis System and
Methods"; U.S. Provisional Patent Application Ser. No. 60/904,024,
filed Feb. 27, 2007, entitled "Hemodialysis System and Methods";
U.S. patent application Ser. No. 11/787,213, filed Apr. 13, 2007,
entitled "Heat Exchange Systems, Devices and Methods"; U.S. patent
application Ser. No. 11/787,212, filed Apr. 13, 2007, entitled
"Fluid Pumping Systems, Devices and Methods"; U.S. patent
application Ser. No. 11/787,112, filed Apr. 13, 2007, entitled
"Thermal and Conductivity Sensing Systems, Devices and Methods";
U.S. patent application Ser. No. 11/871,680, filed Oct. 12, 2007,
entitled "Pumping Cassette"; U.S. patent application Ser. No.
11/871,712, filed Oct. 12, 2007, entitled "Pumping Cassette"; U.S.
patent application Ser. No. 11/871,787, filed Oct. 12, 2007,
entitled "Pumping Cassette"; U.S. patent application Ser. No.
11/871,793, filed Oct. 12, 2007, entitled "Pumping Cassette"; and
U.S. patent application Ser. No. 11/871,803, filed Oct. 12, 2007,
entitled "Cassette System Integrated Apparatus." In addition, the
following are incorporated by reference in their entireties: U.S.
Pat. No. 4,808,161, issued Feb. 28, 1989, entitled
"Pressure-Measurement Flow Control System"; U.S. Pat. No.
4,826,482, issued May 2, 1989, entitled "Enhanced Pressure
Measurement Flow Control System"; U.S. Pat. No. 4,976,162, issued
Dec. 11, 1990, entitled "Enhanced Pressure Measurement Flow Control
System"; U.S. Pat. No. 5,088,515, issued Feb. 18, 1992, entitled
"Valve System with Removable Fluid Interface"; and U.S. Pat. No.
5,350,357, issued Sep. 27, 1994, entitled "Peritoneal Dialysis
Systems Employing a Liquid Distribution and Pumping Cassette that
Emulates Gravity Flow." Also incorporated herein by reference are a
U.S. patent application entitled "Sensor Apparatus Systems, Devices
and Methods," filed on even date herewith (Docket No. F63, now Ser.
No. 12/038,474), and a U.S. patent application entitled "Cassette
System Integrated Apparatus," filed on even date herewith (Docket
No. F62).
[0127] While several embodiments of the present invention have been
described and illustrated herein, those of ordinary skill in the
art will readily envision a variety of other means and/or
structures for performing the functions and/or obtaining the
results and/or one or more of the advantages described herein, and
each of such variations and/or modifications is deemed to be within
the scope of the present invention. More generally, those skilled
in the art will readily appreciate that all parameters, dimensions,
materials, and configurations described herein are meant to be
exemplary and that the actual parameters, dimensions, materials,
and/or configurations will depend upon the specific application or
applications for which the teachings of the present invention
is/are used. Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many
equivalents to the specific embodiments of the invention described
herein. It is, therefore, to be understood that the foregoing
embodiments are presented by way of example only and that, within
the scope of the appended claims and equivalents thereto, the
invention may be practiced otherwise than as specifically described
and claimed.
[0128] The indefinite articles "a" and "an," as used herein in the
specification and in the claims, unless clearly indicated to the
contrary, should be understood to mean "at least one."
* * * * *