U.S. patent application number 17/309535 was filed with the patent office on 2021-12-09 for blood filtration systems.
The applicant listed for this patent is CHF Solutions, Inc.. Invention is credited to David Haskvitz, Dori Jones, David Lerner.
Application Number | 20210379264 17/309535 |
Document ID | / |
Family ID | 1000005809563 |
Filed Date | 2021-12-09 |
United States Patent
Application |
20210379264 |
Kind Code |
A1 |
Lerner; David ; et
al. |
December 9, 2021 |
Blood filtration systems
Abstract
A blood filtration system can reduce the amount of plasma
constituents (e.g., water and/or electrolytes) in the blood of the
patient, and accordingly increase the hematocrit value of the
patient. The blood filtration system (e.g., a controller, or the
like) can determine a hematocrit value of a patient. The blood
filtration system can determine a venous pressure of vasculature of
a patient. The blood filtration system can compensate for pressure
head in a component of a blood circuit (e.g., a withdrawal line of
a catheter), for example to improve the accuracy of the venous
pressure determination. The blood filtration system can determine
one or more resistance characteristics of a blood circuit for the
blood filtration system. The resistance characteristics can
correspond to a resistance to a flow of blood through a component
of the blood circuit.
Inventors: |
Lerner; David; (St. Paul,
MN) ; Haskvitz; David; (Maple Grove, MN) ;
Jones; Dori; (Riverside, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CHF Solutions, Inc. |
Eden Prairie |
MN |
US |
|
|
Family ID: |
1000005809563 |
Appl. No.: |
17/309535 |
Filed: |
June 3, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2019/069130 |
Dec 31, 2019 |
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17309535 |
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62787090 |
Dec 31, 2018 |
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62787106 |
Dec 31, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 2205/3344 20130101;
A61M 1/3431 20140204; A61M 1/3496 20130101; A61M 2230/207 20130101;
A61M 2230/30 20130101; A61M 2205/3334 20130101; A61M 1/3403
20140204; A61M 2205/3365 20130101 |
International
Class: |
A61M 1/34 20060101
A61M001/34 |
Claims
1-63. (canceled)
64. A blood filtration system for reducing one or more plasma
constituents in blood of a patient, the system comprising: a
variable-speed blood pump configured to pump blood in a withdrawal
line, through a filter, and into an infusion line, wherein: the
withdrawal line and the infusion line are configured to couple with
a catheter, and the catheter is configured for insertion into a
blood stream of the patient; a controller including processing
circuitry, wherein the controller is configured to: determine a
withdrawal line resistance characteristic of the withdrawal line
using a first pressure sensor in communication with the withdrawal
line to measure pressure in the withdrawal line, the withdrawal
line resistance characteristic corresponding to an amount of
resistance to a flow of blood through the withdrawal line, and
wherein determining the withdrawal line resistance characteristic
includes: determining a blood flow rate through the withdrawal line
using at least one blood flow rate sensor; and dividing the
measured pressure in the withdrawal line by the blood flow rate
through the withdrawal line; determine an infusion line resistance
characteristic of the infusion line using a second pressure sensor
in communication with the infusion line to measure pressure in the
infusion line, the infusion line resistance characteristic
corresponding to an amount of resistance to a flow of blood through
the infusion line; and provide a notification of one or more of the
withdrawal line resistance characteristic or the infusion line
resistance characteristic.
65. The blood filtration system of claim 64, wherein the controller
is configured to: determine a hematocrit value of the patient;
determine a hemoconcentration resistance characteristic of the
blood according to the determined hematocrit value of the patient,
wherein the withdrawal line resistance characteristic or the
infusion line resistance characteristic correspond in part to the
hemoconcentration characteristic; and determine an occlusion
resistance characteristic by subtracting the hemoconcentration
resistance characteristic from the withdrawal line resistance
characteristic or from the infusion line resistance
characteristic.
66. The blood filtration system of claim 65, wherein the
notification of the one or more of the withdrawal line resistance
characteristic or the infusion line resistance characteristic
includes the occlusion resistance characteristic.
67. The blood filtration system of claim 65, wherein the controller
is configured to provide a notification of the occlusion resistance
characteristic.
68. The blood filtration system of claim 65, wherein determining
the hematocrit value of the patient includes: controlling the speed
of the blood pump and setting a flow rate of blood through the
filter at a first blood flow rate; controlling the speed of the
blood pump and setting the flow rate of blood through the filter at
a second blood flow rate, wherein the first blood flow rate is
different than the second blood flow rate; and determining the
hematocrit at the second blood flow rate.
69. The blood filtration system of claim 64, wherein the controller
is configured to: compare the infusion line resistance or the
withdrawal line resistance to a resistance threshold; reduce a
filtration rate or increase the blood flow rate if the withdrawal
line resistance or the infusion line resistance exceeds the
resistance threshold.
70. The blood filtration system of claim 64, wherein the withdrawal
line and the infusion line are configured to be in communication
with the filter, and the filter is configured to reduce an amount
of one or more plasma constituents in blood flowing through the
filter and provide a filtrate fluid including the plasma
constituents.
71. The system of claim 70, wherein the controller is further
configured to: control the speed of a filtration pump to vary the
extraction rate of the filtrate fluid from the filter; vary the
extraction rate from a first specified extraction rate; wait for a
specified time period; monitor the withdrawal line resistance
characteristic or the infusion line resistance characteristic; and
provide a notification if the infusion line resistance
characteristic or the withdrawal line resistance characteristic
increases after the specified time period.
72. The system of claim 70, wherein the controller is configured
to: vary a filtration rate for reducing the plasma constituents in
the blood; wait for a specified time period; monitor the withdrawal
line resistance or the infusion line resistance; and operate a
harvesting pump to extract filtrate fluid from a filtrate reservoir
and inject the filtrate fluid into an inlet of the filter to dilute
the blood flowing through the filter.
73. The blood filtration system of claim 64, wherein the controller
is configured to: determine a venous pressure of the patient by
determining a pressure differential between the first pressure
sensor and the second pressure sensor; and provide a notification
when the pressure differential exceeds a pressure differential
threshold.
74. The blood filtration system of claim 73, wherein determining
the venous pressure of the patient includes compensating for a
pressure head in the withdrawal line.
75. The blood filtration system of claim 74, further comprising a
first pressure sensor in communication with the withdrawal line and
configured to measure the pressure in the withdrawal line, wherein
the first pressure sensor is located remote from a catheter tip of
the withdrawal line, and the controller is configured to determine
the venous pressure of the patient at the catheter tip by
compensating for the pressure head in the withdrawal line between
the catheter tip and the first pressure sensor.
76. The blood filtration system of claim 64, wherein determining
the infusion line resistance characteristic includes: determining a
blood flow rate through the withdrawal line using at least one
blood flow rate sensor; and dividing the measured pressure in the
withdrawal line by the blood flow rate through the withdrawal line.
Description
CLAIM OF PRIORITY
[0001] This patent application claims the benefit of priority of
Lerner et al., U.S. Provisional Patent Application Ser. No.
62/787,106, titled "BLOOD FILTRATION SYSTEMS," filed on Dec. 31,
2018 (Attorney Docket No. 4567.027PRV); and Lerner et al., U.S.
Provisional Patent Application Ser. No. 62/787,090, titled "BLOOD
FLOW ASSISTING PORTABLE ARM SUPPORT," filed on Dec. 31, 2018
(Attorney Docket No. 4567.026PRV) the benefit of priority of each
of which is claimed hereby, and each of which are incorporated by
reference herein in its entirety.
CROSS-REFERENCE TO RELATED PATENT DOCUMENTS
[0002] This patent application is also related to the application
titled "BLOOD FLOW ASSISTING PORTABLE ARM SUPPORT" by Lerner et
al., filed on Dec. 31, 2018 (Attorney Docket No. 4567.026PRV),
which is hereby incorporated by reference herein in its
entirety.
TECHNICAL FIELD
[0003] This document pertains generally, but not by way of
limitation, to medical devices.
BACKGROUND
[0004] A blood filtration system can remove blood from the blood
stream (e.g., venous circulation) of a patient and separate plasma
water and electrolytes from erythrocytes (e.g., red blood cells)
and other blood constituents by means of a filter. The system can
convey the plasma water to a reservoir (e.g., a bag) for disposal.
The balance of the plasma water, the erythrocytes, and other blood
constituents are returned to the patient's blood stream. Once blood
is withdrawn from the blood stream and makes contact with
extracorporeal components of the blood filtration system (e.g.,
tubing, the filter, or the like), a potential exists for clots to
form within the extracorporeal components, leading to an increase
in resistance within the components (e.g., the filter), and
potentially clogging (e.g., occluding) the components. While not
harmful to the patient, the increase in resistance or clotting
could necessitate replacement of one or more of the extracorporeal
components.
SUMMARY
[0005] The hematocrit value in a patient is a ratio of the red
blood cell volume to the total volume of blood in a patient, where
the total volume of blood includes the red blood cell volume and
the volume of plasma (including, but not limited to water,
proteins, and electrolytes) in the blood of the patient. In some
examples, a patient experiencing congestive heart failure can have
excess plasma volume, and accordingly a reduced hematocrit value.
For instance, the patient can have excess plasma water that
corresponding increases the plasma volume of the patient (and
lowers the hematocrit value of the patient). A blood filtration
system can reduce the amount of plasma constituents (e.g., water
and/or electrolytes) in the blood of the patient, and accordingly
increase the hematocrit value of the patient.
[0006] The present inventors have recognized, among other things,
that a problem to be solved can include improving the accuracy of a
hematocrit value determination (e.g., measurement, assessment,
evaluation, computation, or the like). Additionally, the present
inventors have recognized, among other things, that a problem to be
solved can include determining if a hematocrit value determination
is affected by movement of a patient (e.g., when a patient
transitions from a supine position to a standing position).
Further, the present inventors have recognized, among other things,
that a problem to be solved can include determining the amount of
plasma remaining in the patient.
[0007] Still further, the present inventors have recognized, among
other things, that a problem to be solved can include determining a
rate of removing plasma constituents while maintaining preferred
patient diagnostic parameters (e.g., vital signs, for instance
vascular resistance, venous pressure or the like). Still yet
further, the present inventors have recognized, among other things,
that a problem to be solved can include determining when to cease
removal of the plasma constituents from the blood stream to obtain
a preferred hematocrit value (e.g., euvolemia, or a preferred
amount of blood in the patient) in the patient. Additionally, the
present inventors have recognized, among other things, that a
problem to be solved can include reducing clogging of the
extracorporeal components of a blood filtration system.
[0008] The present subject matter can help provide a solution to
this problem, such as by providing a blood filtration system. The
blood filtration system can reduce one or more plasma constituents
in blood of a patient. The blood filtration system can include a
variable-speed blood pump that can be configured to pump blood in a
withdrawal line, through a filter, and into an infusion line. The
withdrawal line and the infusion line can be configured to couple
with a catheter, and the catheter can be configured for insertion
into a blood stream of the patient. The withdrawal line and the
infusion line can be configured to couple with the filter. The
filter can be configured to reduce an amount of one or more plasma
constituents in blood flowing through the filter and provide a
filtrate fluid including the plasma constituents. The blood
filtration system can include a variable speed filtration pump that
can be configured to extract the filtrate fluid from the
filter.
[0009] The blood filtration system can include a controller
including processing circuitry. The controller can be configured to
control the speed of the blood pump to vary the flow rate of the
blood through the filter. Additionally, the controller can be
configured to control the speed of the filtration pump to vary the
extraction rate of the filtrate fluid from the filter. Further, the
controller can be configured to determine the venous pressure of
the patient. Still further, the controller can be configured to
provide a notification of the venous pressure of the patient (e.g.,
providing a notification on a display). In some examples, the blood
filtration system can determine the venous pressure of the patient
by controlling the speed of the blood pump to stop the blood pump.
The blood filtration system can determine the venous pressure of
the patient because the blood filtration system can be in
communication with the blood stream of the patient.
[0010] Additionally, the controller can be configured to determine
a hematocrit value of the patient. In an example, determining the
hematocrit value of the patient includes controlling the speed of
the blood pump and setting the flow rate of blood through the
filter. Controlling the speed of the blood pump can improve the
accuracy of the hematocrit value determination. For instance, the
hematocrit value determination by an optical hematocrit sensor can
be affected by the flow rate of blood through the filter. In this
example, the speed of the blood pump can vary, and the determined
hematocrit value of the patient can vary according to the speed of
the blood pump. Accordingly, measuring the hematocrit value with
the blood pump at a consistent speed can improve the accuracy of
the hematocrit value determination.
[0011] Further, the controller can be configured to determine if
movement of the patient from an initial position affects the
determined hematocrit value of the patient. For instance, a sensor
can be configured to monitor movement of the patient relative to
the initial position of the patient. The controller can be
configured to provide a notification if the hematocrit
determination is affected by the movement of the patient. In an
example, the controller can provide a notification (e.g., on a
display) with a timer since the patient moved in a way that
affected the hematocrit value determination. In another example,
the controller can refrain from providing a notification of the
hematocrit value when the hematocrit value is affected by movement
of the patient (e.g., by refraining from displaying the
movement-affected hematocrit value on a display). Accordingly, the
blood filtration system can provide additional information (e.g.,
to a healthcare provider) that the hematocrit value of the patient
has been affected by movement of the patient.
[0012] Further, the controller can be configured to change a
filtration rate that the one or more plasma constituents are
extracted from the filter. For instance, the controller can control
a speed of a filtration pump to change the extraction rate of the
plasma constituents from the filter. The filtration rate can be
changed (e.g., increased or decreased) a specified of amount, and
the controller can determine the hematocrit value of the patient
(or a rate of change of the hematocrit value of the) before and
after the change in filtration rate. In some examples, the amount
of change of the filtration rate and the determined hematocrit
values before and after the change in filtration rate can be used
to determine the amount of plasma constituents remaining in a
patient. Determining the amount of plasma constituents remaining in
the patient can be used to determine how much of the plasma
constituents the blood filtration system should extract from the
patient.
[0013] Still further, the controller can be configured to control a
speed of one or more pumps to adjust a filtration fraction of the
system. The filtration fraction can include a ratio of a filtration
rate (e.g., a rate that one or more plasma constituents is
extracted from the filter) to a blood flow rate through the filter.
The controller can vary the speed of the one or more pumps (e.g.,
the filtration pump, the blood pump, or the like) to adjust the
filtration fraction. Additionally, the controller can be configured
to determine the hematocrit value, and can compare the hematocrit
value to a hematocrit threshold. The controller can be configured
to maintain the filtration fraction, for instance when the
hematocrit value equals the hematocrit threshold. Further, the
controller can be configured to adjust the filtration fraction, for
instance if the hematocrit value exceeds, or declines below, the
hematocrit threshold. In some examples, the hematocrit threshold is
a range of hematocrit values (e.g., 45 percent to 55 percent).
Controlling the filtration fraction can be used to control the rate
of removing plasma constituents while maintaining preferred patient
diagnostic parameters. Additionally, controlling the filtration
fraction can be used to reduce clogging of the extracorporeal
components of a blood filtration system. For instance, when the
hematocrit value is high (e.g., greater than 50 percent) the filter
can have an increased probability of clogging). In some examples,
the filtration fraction can be reduced (e.g., filtration rate
reduced, blood flow rate increased, or a combination thereof) to
reduce the probability of clogging in the filter.
[0014] This summary is intended to provide a summary of subject
matter of the present patent application. It is not intended to
provide an exclusive or exhaustive explanation of the invention.
The detailed description is included to provide further information
about the present patent application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the drawings, which are not necessarily drawn to scale,
like numerals can describe similar components in different views.
Like numerals having different letter suffixes can represent
different instances of similar components. The drawings illustrate
generally, by way of example, but not by way of limitation, various
embodiments discussed in the present document.
[0016] FIG. 1 shows a schematic view of an example of a first blood
filtration system.
[0017] FIG. 2 shows a schematic view of an example of a second
blood filtration system.
[0018] FIG. 3 shows a flowchart of a first method for preserving a
filter for a blood filtration system.
[0019] FIGS. 4A-4H show a schematic view of an example of a third
blood filtration system.
[0020] FIG. 5 shows a schematic view of a fourth blood filtration
system.
[0021] FIG. 6 shows a flowchart for a second method for preserving
a filter for a blood filtration system.
[0022] FIG. 7 shows a schematic view of a fifth blood filtration
system.
[0023] FIGS. 8A-8B shows a schematic view of a sixth blood
filtration system.
[0024] FIG. 9 shows a schematic view of a seventh blood filtration
system.
[0025] FIG. 10 shows a schematic view of an eighth blood filtration
system.
[0026] FIGS. 11A-11B are photographs of line protectors for a blood
filtration system.
[0027] FIG. 12 is a block diagram illustrating an example of a
machine upon which one or more embodiments can be implemented.
[0028] FIG. 13 shows a graph of a filtration fraction of a blood
filtration system versus a hematocrit level of a patient.
[0029] FIG. 14 shows a method for determining venous pressure of a
patient with a blood filtration system.
DETAILED DESCRIPTION
[0030] FIG. 1 shows a schematic view of an example of a first blood
filtration system 100. The blood filtration system 100 can be
configured to reduce one or more plasma constituents (e.g., water,
proteins, electrolytes, or the like) in blood of a patient. The
blood filtration system 100 can include a controller 102. The
controller 102 can include processing circuitry, for instance an
integrated circuit. As described herein, the controller 102 can be
configured to control one or more components of the blood
filtrations system 100.
[0031] The blood filtration system 100 can include a withdrawal
line 104 and can include an infusion line 106. The lines 104, 106
can be configured to couple with a catheter 108, and the lines 104,
106 can transmit blood within the blood filtration system 100. In
an example, the catheter 108 can be inserted into a blood stream of
the patient, for instance the catheter 108 can be inserted into a
basilic vein, cephalic vein, brachial vein, the axillary vein, the
subclavian vein, the brachiocephalic vein, or the like. Blood can
flow into the catheter 108, into the withdrawal line 104, through
other components of the system 100, through the infusion line 106,
into the catheter 108, and back into the blood stream of the
patient. The line 104 can be separate from the line 106. The lines
104, 106 can be in communication with the catheter 108. For
example, the catheter 108 can include one or more lumens, for
example a withdrawal lumen in communication with the line 104 and
an infusion lumen in communication with the line 106.
[0032] The lines 104, 106 can be configured to couple with a filter
110, for instance the lines 104, 106 can include one or more
fittings that facilitate coupling the lines 104, 106 with the
filter 110. In an example, the withdrawal line 104 can couple with
a filter inlet port 111A, and the infusion line 106 can couple with
a filter outlet port 111B. The filter 110 can be configured to
reduce an amount of one or more plasma constituents (e.g., water,
electrolytes, or the like) in blood flowing through the filter 110
and provide a filtrate fluid including the one or more plasma
constituents. As described herein, blood can flow through the lines
104, 106 to and from the catheter 108. The lines 104, 106 can be
coupled with the filter and blood can flow from the withdrawal line
104, through the filter 110, and into the infusion line 106.
[0033] The blood filtration system can include a blood pump 112,
and the blood pump 112 can be configured to pump (e.g., convey,
drive, push, or the like) blood through the blood filtration system
100. In an example, the blood pump 112 can be a peristaltic pump,
and the blood pump 112 can engage with the withdrawal line 104 to
pump blood through the withdrawal line 104 and into the filter 110.
The controller 102 can be configured to operate the blood pump 112
to vary a speed of the blood pump 112 and accordingly vary the flow
rate of blood through the blood filtration system 100 (e.g., the
withdrawal line 104, the filter 110, the infusion line 106, or the
like).
[0034] Referring again to FIG. 1, the blood filtration system 100
can include a filtration line 114 and a filtration pump 116. The
filtration line 114 can be configured to couple with the filter 110
(e.g., with a fitting), for instance the filtration line 114 can
couple with a filtrate fluid port 111C. The filter 110 can be
configured to transmit the filtrate fluid (including one or more
plasma constituents) to extracted by the filter 110 to the filtrate
fluid port 111C.
[0035] The filtration pump 116 can pump extracted filtrate fluid
from the filter 110, and into a filtrate fluid reservoir 118 (e.g.,
a bag, container, bladder, or the like). In some examples, the
filtration pump 116 can be a peristaltic pump that engages with the
filtration line 114 to pump the filtrate fluid through the filtrate
fluid line 114. The controller 102 can be configured to vary a
speed of the filtration pump 116 and accordingly vary the flow rate
of filtrate fluid through the blood filtrate system 100 (e.g., the
filtration line 114).
[0036] In some examples, the blood filtration system 100 can
include one or more access ports 120, for instance a first access
port 120A, a second access port 120B, and a third access port 120C.
The access ports 120 can facilitate the extraction of blood from
the blood filtration system 100, or injection of substances (e.g.,
a blood thinner, for instance heparin or the like) into the blood
within the blood filtration system 100. In an example, the access
ports 120A, 120B can be in communication with the withdrawal line
104, and the access port 120C can be in communication with the
infusion line 106.
[0037] A valve 122 (e.g., a mechanical check valve, or
electronically controlled valve) can be positioned between the
access ports 120A, 120B, and the valves 122 can be configured to
allow blood to flow unidirectionally within the withdrawal line 104
(e.g., flowing from the catheter 108 to the filter 110). In this
example, a substance can be injected into the withdrawal line 104
at the access port 120B, and blood can be withdrawn from the access
port 120A. Because the valve 122 facilitates unidirectional flow
within the withdrawal line 104, the blood including the substance
will not be withdrawn from the access port 120A, for instance
because the access port 120A is upstream of the access port 120B).
In an example, heparin can be infused into the access port 120B and
blood is drawn from the access port 120A to measure blood clotting
time parameters of a patient. Because the blood is drawn from the
access port 120A, the withdrawn blood does not include heparin, and
the blood clotting time parameter determination is not affected by
the heparin injection at the access port 120B. Accordingly, the
performance of blood filtration system 100 is thereby improved.
[0038] As shown in FIG. 1, the blood filtration system 100 can
include one or more sensors 124 (e.g., transducer, accelerometer,
or the like), for instance a first sensor 124A, a sensor 124B, and
a sensor 124C. The first sensor 124A can determine (e.g., measure,
calculate, obtain, provide, or the like) the pressure within the
withdrawal line 104, the second sensor 124B can determine the
pressure within the infusion line 106, and the third sensor 124C
can determine the pressure within the filtration line 114. The
sensors 124 can include a fourth sensor 124D (e.g., a position
sensor, or the like) and a fifth sensor 124E (e.g., blood flow
rate, or the like), and the sensor 124E can determine the blood
flow rate through the system 100 (e.g., a component of the blood
circuit 140, for example the withdrawal line 104).
[0039] The controller 102 can determine a venous pressure of the
patient (e.g., a pressure of a vein that is in communication with
the catheter 108). As described herein, the controller 102 can
operate the blood pump 112 and control the speed of the blood pump
112. In an example, the controller 102 can vary the speed of the
blood pump 112, and stop the blood pump 112 so that there is no
blood flow through the blood filtration system 100. Accordingly,
pressure in the lines 104, 106 can reach equilibrium with the
venous pressure of the patient. As described herein, the sensors
124A, 124B can determine the pressure in the lines 104, 106.
Accordingly, when the blood pump 112 is stopped, the controller 102
and sensors 124A, 124B can determine the venous pressure of the
patient.
[0040] In some examples, the controller 102 can provide a
notification of the venous pressure of the patient. In an example,
the controller 102 can cooperate with a display (e.g., a screen,
for instance an LCD display) to display the determined venous
pressure of the patient (e.g., providing the determined venous
pressure on a display included in a housing for the system
100).
[0041] In another example, the controller 102 can determine a
pressure differential between the sensors 124A, 124B. The
controller 102 can compare the pressure differential to a pressure
differential threshold. In this example, if the pressure
differential exceeds the pressure differential threshold, the
controller 102 can provide a notification. In an example, the
withdrawal line 104, can become blocked (e.g., compressed, twisted,
or the like, for instance by a patient leaning on the withdrawal
line), and the pressure in the withdrawal line 104 can be greater
than the pressure of the infusion line 106.
[0042] The pressure differential between the lines 104, 106 can
exceed a pressure differential threshold, and the controller 102
can provide a notification that the pressure differential threshold
has been exceeded. For instance, the controller 102 can provide a
signal to a display to display a message that the withdrawal line
104 is blocked. In another example, the controller 102 can provide
a signal to an audio device (e.g., a speaker, a buzzer, or the
like) to generate an audio signal that notifies a patient (or a
healthcare provider) that the withdrawal line is blocked.
Accordingly, the patient or a healthcare provider can remedy the
blockage of the withdrawal line 104 and restore proper blood flow
in the blood filtration system 100.
[0043] As described herein, the blood filtration system (e.g., the
system 100) can determine the venous pressure of a patient. For
example, the sensors 124A, 124B can determine the pressure in the
lines 104, 106, and the controller 102 can be in communication with
the sensors 124A, 124B to determine the venous pressure of the
patient. The blood filtration system 100 can compensate for
pressure head (e.g., static pressure head, static head, the
pressure exerted by, or the like) in one or more of the lines 104,
106. For example, the controller 102 can compensate for the
pressure head in the lines 104, 106 due to gravitational forces due
to a change in elevation (e.g., height, distance, offset or the
like) between a catheter tip 130 of the catheter 108 and the one or
more of the sensors 124A, 124B that determine the pressure in the
lines 104, 106. In some approaches, a ruler is used to determine
the elevation difference between the catheter tip 130 and the
sensors 124A, 124B.
[0044] In an example, the catheter tip 130 can have a different
elevation than the sensors 124A, 124B. For instance, the catheter
tip 130 can be located in vasculature of a limb of a patient (e.g.,
in a vein in an arm of the patient, or the like), for example to
withdraw or infuse blood into the vasculature. The sensors 124A,
124B can include position sensors that determine the elevation
where the sensors 124A, 124B are located (e.g., the elevation where
the sensors 124A, 124B determines the pressure in the lines 104,
106). The catheter tip 130 can have a different elevation (e.g., as
determined by the sensor 123D) than the sensors 124A, 124B. In an
example, the patient can be located on a bed and blood filtration
system 100 (including the sensors 124A, 124B) can be located at a
different elevation (e.g., on a cart, side table, or the like).
Accordingly, the system 100 can determine the difference in
elevation between the catheter tip 130 and the elevation where the
sensors 124A, 124B are located, for example to compensate for
pressure head in the lines 104, 106.
[0045] The difference in elevation between the sensors 124A, 124B
and the catheter tip 130 can affect the pressure determination by
the sensors 124A, 124B in the lines 104, 106, for instance due to
pressure head in the lines 104, 106. The system 100 can compensate
for pressure head in the lines 104, 106 when determining the venous
pressure of the patient. For example, the system 100 can include a
fourth sensor 124D, for example an accelerometer. The sensor 124D
can determine one or more of position, velocity, acceleration,
jerk, or the like. The sensor 124D can be coupled to the catheter
108, and the sensor 124D can be remote from the catheter tip 130.
The sensor 124D can be communication with the controller 102, and
the controller can determine an elevation difference between the
catheter tip 130 and other components of the system 100 (e.g., the
sensors 124A, 124B) using the sensor 124D. For example, the system
100 can include one or more accelerometers that provide the
elevation of components of the system 100 (e.g., the sensors 124A,
124B), and the system 100 can determine elevation difference
between components of the system 100 based on differences in
gravitational forces measured by the accelerometers.
[0046] The controller 102 can compensate for the pressure head in
the lines 104, 106 by determining the pressure head in the lines
104, 106 and using the determined head pressure when determining
the venous pressure of the patient (e.g., at the catheter tip 130).
For example, the catheter tip 130 can be elevated with respect to
the sensors 124A, 124B. The sensors 124A, 124B can determine the
pressure in the lines 104, 106, and the pressure in the lines 104,
106 can correspond (at least partially) with the venous pressure in
the vasculature where the catheter tip 130 is located. The pressure
head in the lines 104, 106 due to the difference in elevation
between the tip and the sensors 124A, 124B can affect the pressure
determination of the sensors 124A, 124B. For instance, when the
catheter tip 130 is located at a higher elevation than the sensors
124A, 124B, the pressure head in the lines 104, 106 can cause the
sensors 124A, 124B to determine a pressure that is higher than the
actual venous pressure at the catheter tip 130 (e.g., because the
pressure head increases the pressure above the actual venous
pressure due to the elevation difference between components of the
system 100). Accordingly, the system 100 can determine the pressure
head in the lines 104, 106, and the system 100 can compensate for
the pressure head in the lines 104, 106 when determining the venous
pressure of the patient (e.g., at the catheter tip 130).
[0047] The blood filtration system 100 can determine density of
blood in the vasculature of the patient, for example to improve the
accuracy of the pressure head determination. For example, the
pressure head in the lines 104, 106 can be determined using the
density of blood multiplied by the standard gravity (e.g., 9.8
meters per second-squared) and multiplied by the elevation
difference between the sensors 124A, 124B. Accordingly, the density
of blood can affect the determination of the pressure head in the
lines 104, 106 by the controller 102.
[0048] The controller 102 can determine the density of blood in the
vasculature of the patient, for example to improve the pressure
head determination for the lines 104, 106. In an example, the
density of the blood can be determined using a hematocrit value of
the blood of the patient (e.g., as determined by the hematocrit
sensor 126). Accordingly, the pressure head determination by the
controller 102 can be improved using density of the blood.
[0049] The system 100 can include a blood circuit 140, and the
blood circuit 140 can include one or more components of the system
100. For example, the blood circuit 140 can include (but is not
limited to) the withdrawal line 104, the infusion line 106, the
catheter 108, the filter 110, the filtration line 114, the filtrate
fluid reservoir 118. The blood circuit 140 can include components
of the system that are in communication with a biological fluid of
the patient.
[0050] The system 100 can include an activation key 150, and the
activation key 150 can be in communication with the controller 102,
for example to provide information about the blood circuit 140 to
the controller 102. The activation key 150 can include (but is not
limited to) an electronic device (e.g., a radio frequency
identification tag, memory card, or the like) that interconnects
with the system 100 (e.g., wirelessly, or with wires,
interconnects, or the like). For example, the activation key 150
can include a radio frequency identification tag, and the system
100 can communicate with the activation key when the blood circuit
140 is located proximate to the system 100. The activation key 150
can store information provided by the system 100, for example usage
information related to the blood circuit 140.
[0051] In an example, the activation key 150 can be coupled with a
portion of the blood circuit 140 (e.g., the activation key 150 can
be coupled with the filter 110). The activation key 150 can be
unique to (e.g., paired with, tied to, associated with, or the
like) an individual one of the blood circuit 140 to provide
information to the system 100 about the individual one of the blood
circuit 140. For example, the activation key 150 can provide the
controller 102 with circuit characteristics of the blood circuit
140. The circuit characteristics can include (but are not limited
to) dimensions (e.g., size, length, diameter, or the like) of the
lines 104, 106; dimensions of the filter 110; types of filters
(e.g., a first filter intended for use with a child or a second
filter intended for use with an adult, or the like); dimensions of
the catheter 108; or the like.
[0052] In some examples, the controller 102 can evaluate the
circuit characteristics provided by the activation key 150 to
operate the system 100 at a configuration specific to the circuit
characteristics of the blood circuit 140 coupled to the system 100.
In an example, a first blood circuit 140 can include a first filter
110 (e.g., a small filter) and a first activation key 150 that
includes a first set of circuit characteristics (e.g., that
correspond to a small filter). A second blood circuit 140 can
include a second filter 110, and the second filter 110 (e.g., a
large filter) can include a second set of circuit characteristics
(e.g., that correspond to a large filter). The system 100 can
determine whether the first blood circuit 140 or the second blood
circuit 140 are coupled with the system 100, for example by
evaluating the circuit characteristics stored by the activation key
150. The controller 102 can operate the system 100 according to the
first set of circuit characteristics, for example by operating the
blood pump 112 at a first blood flow rate. The controller 102 can
operate the system 100 according to the second set of circuit
characteristics, for instance by operating the blood pump 112 at a
second blood flow rate. Operating the system 100 in correspondence
with the circuit parameters provided by the activation key 150 can
improve patient safety, for example by limiting the rate that blood
is withdrawn from a patient (e.g., where the blood circuit 140 is
used with a pediatric patient that requires a reduced blood flow
rate in comparison to the blood flow rate for an adult
patient).
[0053] As described herein, the activation key 150 can be in
communication with the controller 102. The controller 102 can
provide the activation key 150 with an activated characteristic,
for example when the blood circuit 140 is connected with other
components of the system 100 (e.g., the blood pump 112). The
activated characteristic can indicate whether the blood circuit 140
has been previously used with the system 100. Providing the
activated characteristic to the activation key 150 can inhibit the
reuse of the blood circuit 140, for example to inhibit (e.g., stop,
prevent, block, or the like) the use of the blood circuit 140 (or
individual components of the blood circuit 140) with more than one
patient. In another example, the system 100 can limit the time
duration that an individual one of the blood circuit 140 can be
used with the system 100 (e.g., to limit the time that the filter
110 can be used in renal replacement therapy).
[0054] The activation key 150 can store the activated
characteristic when the activated characteristic is provided by the
controller 102. For example, the activation key 150 can include
memory, and the activation key 150 can store data corresponding to
the activated characteristic in the memory (e.g., a solid state
memory device, or the like). The system 100 can read the activated
characteristic stored by the activation key 150, for example to
determine whether the blood circuit 140 was previously coupled with
the system 100 (e.g., to inhibit more than one use of the blood
circuit 140).
[0055] When the system 100 (e.g., the controller 102) determines
whether the blood circuit 140 was previously coupled with the
system 100, the system 100 can inhibit operation of the system 100
(e.g., by inhibiting one or more functions of the system 100. For
example, the controller 102 can inhibit operation of the blood pump
112 to inhibit the system 100 from withdrawing blood from the
patient. In another example, the system 100 can provide a
notification (e.g., by displaying a message on a display, for
example an LCD screen, or the like) that the blood circuit 140 with
an activated characteristic has been coupled with the system
100.
[0056] As described herein, the system 100 can limit the time
duration that an individual one of the blood circuit 140 can be
used with the system 100. For example, the system 100 can limit a
usage time that the blood circuit 140 is used with the system 100.
In an example, the controller 102 can provide the activation key
150 with an expiration characteristic. The controller 102 can
provide the expiration characteristic after a specified time period
(e.g., 12 hours, 2 days, 3 days, or the like) from when the
controller 102 provided the activated characteristic to the
activation key 150. The activation key 150 can store one or more
usage characteristics of the blood circuit 140. For example, the
activation key 150 can store the usage time that the blood circuit
140 has been used during therapy with the system 100. In some
examples, the system 100 can provide a notification (e.g., by
transmitting a message to a mobile device, or the like) that the
usage time of the blood circuit 140 is approaching the specified
time period where the system 100 will inhibit the use of the blood
circuit 140 with the system 100 (e.g., by providing the expiration
characteristic to the activation key 150). The notification can
notify a health provider to change (e.g., swap, or the like) the
used blood circuit 140 with a new blood circuit 140 (e.g., when the
usage time reaches 80 percent of the specified time period).
[0057] FIG. 1 shows the blood filtration system 100 can include a
hematocrit sensor 126. In some examples, the hematocrit sensor 126
can include an optical hematocrit sensor, and the hematocrit sensor
126 can be coupled with one or more of the lines 104, 106, and the
hematocrit sensor 126 can determine a hematocrit value (e.g.,
level, or the like) of the patient. In an example, the hematocrit
sensor 126 can be located between the catheter 108 and the valve
122, for instance to monitor the hematocrit value of the patient
prior to injection of a fluid (e.g., heparin or saline) into the
blood (e.g., at the access port 120B). Accordingly, the hematocrit
value determination can be improved with the system 100.
[0058] In an example, the controller 102 can be configured to
control the speed of the blood pump 112 and set the flow rate of
blood through the filter 110 at a first blood flow rate.
Additionally, the controller 102 can be configured to control the
speed of the blood pump 112 and set the flow rate of blood through
the filter at a second blood flow rate. The first blood flow rate
can be different than the second blood flow rate. The controller
102 can determine the hematocrit at the second blood flow rate. The
controller 102 can control the speed of the blood pump 112 and set
the flow rate of blood at the first blood flow rate after
determining the hematocrit value, for example after determining the
hematocrit value at the second blood flow rate.
[0059] The controller 102 can control the speed of the blood pump
112 to measure the hematocrit value because the hematocrit value
can vary according to the speed of the blood pump 112, and
controlling the speed of the blood pump can improve the accuracy of
the hematocrit value determination. For instance, the hematocrit
value determination by the hematocrit sensor 126 can be affected by
the flow rate of blood through the filter. In this example, the
speed of the blood pump 112 can vary, and the determined hematocrit
value of the patient can vary according to the speed of the blood
pump 112. Accordingly, measuring the hematocrit value with the
blood pump 112 at a consistent speed can improve the accuracy of
the hematocrit value determination. Accordingly, varying the speed
of the blood pump 112 can account for a source of error in
determining the hematocrit value and the performance of the blood
filtration system 100 is thereby improved.
[0060] As described herein, the blood filtration system 100 can
determine a hematocrit value of a patient. The hematocrit value of
the patient can be defined by Equation (1). H=RBCV/BV, where H is
the hematocrit value, RBCV is the red blood cell volume, and BV is
the total blood volume (e.g., the RBCV plus plasma volume).
Equation (1) can be rearranged to determine the red blood cell
volume, as shown in Equation (2): BV=RBCV/H. The derivative of
Equation (2) is shown in Equation (3):
d .function. ( BV ) dt = RBCV * d .function. ( 1 H ) dt
##EQU00001##
[0061] where 1/H is an inverse of the hematocrit value. The change
of blood volume for a patient undergoing blood filtration with the
blood filtration system 200 is shown in Equation (4):
d .function. ( BV ) dt = PRR - FR ##EQU00002##
where PRR is the plasma refill rate, and FR is the filtration rate
(e.g., the rate of filtrate fluid flowing from the filter 110). The
plasma refill rate is the rate that the plasma volume changes with
respect to time, from within the body of the patient (e.g., the
flowing of plasma water into the blood stream from interstitial
spaces of the body into the venous system of the patient).
[0062] The filtration rate can be varied (e.g., changed), for
instance by varying the speed of the filtration pump 116, and the
change in filtration rate is shown in Equation (5):
.DELTA.FR=FR.sub.2-FR.sub.1
Combining Equations (3) and (4) yields Equation (6):
PRR - FR = RBCV * d .function. ( 1 H ) dt ##EQU00003##
[0063] As described herein the filtration rate (FR) can be varied,
and accordingly substituting Equation (6) into Equation (5), and
performing additional algebra yields Equation (7):
RBCV = .DELTA. .times. .times. FR d .function. ( 1 H .times.
.times. 2 ) dt - d .function. ( 1 H .times. .times. 1 ) dt
##EQU00004##
where H.sub.1 is the hematocrit value at the first filtration rate
(FR.sub.1), and H.sub.2 is the hematocrit value at the second
filtration rate (FR.sub.2). The controller 102 can be configured to
determine a red blood cell volume using Equation (7).
[0064] Substituting Equation (7) into Equation (1) yields Equation
(8):
BV .function. ( at .times. .times. t = tx ) = RBCV H t = tx
##EQU00005##
Performing algebraic manipulation of Equation (8) yields Equation
(9):
PV .function. ( at .times. .times. t = tx ) = RBCV .times. ( ( 1 Hx
) - 1 ) ##EQU00006##
where PV is the plasma volume of the patient.
[0065] The controller 102 can use Equation (9) to determine the
plasma volume of the patient, and determine when to stop filtering
the blood of the patient. In another example, the red blood cell
volume can be determined using Equation (10):
RBCV = ( FV ) * Hfinal * Hinit Hfinal - Hinit ##EQU00007##
where FV is the volume of filtrate fluid extracted from the patient
(e.g., by the filtration pump 16), H.sub.init is the hematocrit
value at the beginning of filtration therapy (e.g., when the
filtration pump 116 is started), and H.sub.final is the hematocrit
value at the end of filtration therapy (e.g., when the filtration
pump 116 is stopped). H.sub.init and H.sub.final can be determined
using the hematocrit sensor 126
[0066] Determining the red blood cell volume with the blood
filtration system 100 can reduce the need to determine the red
blood cell volume with other methodologies. For instance, a tracer
(e.g., a radioactive tracer, cardiac green, or saline, or the like)
can be injected into a blood stream of the patient. One or more
blood samples can be withdrawn from the patient to determine the
red blood cell volume. The red blood cell volume can be used to
determine the quantity of the one or more plasma constituents to
extract from the patient. In this example, the red blood cell can
be inputted into the blood filtration system, for instance at the
beginning of therapy. In another example, the controller 102 can
determine the red blood cell volume according to Equation (7) or
Equation (10). In some examples, the controller 102 is optionally
configured to set an extraction rate of filtrate fluid from the
filter 110 using the determined red blood cell volume or the
determined hematocrit value of the patient.
[0067] As described herein, the plasma refill rate is the rate that
the plasma volume changes with respect to time, from within the
body of the patient (e.g., the flowing of plasma water into the
blood stream from interstitial spaces of the body). The plasma
refill rate can affect the plasma volume determination, for
instance when using Equation (9). The plasma refill rate can be
determined using Equation (11):
PRR = FV * [ H .times. .times. 1 * H .times. .times. 2 - H .times.
.times. 1 * H .times. .times. 3 ] .tau.1 * [ H .times. .times. 1 *
H .times. .times. 2 - H .times. .times. 1 * H .times. .times. 3 ] -
.tau.2 * [ H .times. .times. 1 * H .times. .times. 3 - H .times.
.times. 2 * H .times. .times. 3 ] ##EQU00008##
where FV is the volume of filtrate fluid extracted from the patient
(e.g., by the filtration pump 116), H1 is a first hematocrit value
determination, H2 is a second hematocrit value determination, H3 is
a second hematocrit value determination, .tau.1 is the time
difference between the H1 and H2 determinations, and .tau.2 is the
time difference between the H2 and H3 determinations. H1 can be
determined at the beginning of filtration therapy (e.g., when the
filtration pump 116 is started). H2 can be determined at the end of
filtration therapy (e.g., when the filtration pump 116 is stopped).
H3 can be determined after a waiting period (e.g., one hour) where
the blood pump is operated (e.g., turned on), while the filtration
pump 116 is not operated (e.g., turned off). Accordingly, the blood
filtration system 100 can determine the plasma refill rate and use
the plasma refill rate to determine when to stop therapy of the
patient, and when the patient has reached euvolemia. The controller
102 can use one or more of Equations (1)-(11) during therapy to
determine a quantity of filtrate fluid to extract from the patient,
and determine how much plasma remains in the patient at a given
point in time. Accordingly, the controller 102 using one or more of
Equations (1)-(11) (or Equations (1)-(17) can improve the
performance of the blood filtration system (e.g., the system
100).
[0068] As described herein, Equation (1) is H=RBCV/BV, where H is
the hematocrit value, RBCV is the red blood cell volume, and BV is
the total blood volume. Equation (1) can be equivalent to:
H=RBCV/(RBCV+PV), where PV is the plasma volume. Equation (12)
facilitates the determination of the density of the blood of the
patient (e.g., whole blood, unfiltered blood, or the like):
.rho. b = mass volume = .rho. r * RBCV + .rho. p * PV RBCV + PV
##EQU00009##
[0069] where .rho..sub.b is the density of the blood of the
patient, .rho..sub.r is the density of a single blood cell,
.rho..sub.p is the density of plasma, PV is the plasma volume. In
an example, the system 100 can determine one or more of the
hematocrit value, the density of plasma .rho..sub.p, and the
density of a single blood cell .rho..sub.r. For example, the system
can determine the hematocrit value H, the density of plasma
.rho..sub.p, or the density of a single blood cell .rho..sub.r
using one or more equations or constants, including (but not
limited to) Equations (1)-(17). Performing one or more mathematical
operations on Equation (1) yields Equation (13):
(H-1)*RBCV+H*PV=0
[0070] Performing one or more mathematical operations on Equation
(12) yields Equation (14):
(.rho..sub.b-.rho..sub.r)*RBCV+(.rho..sub.b-.rho..sub.p)*PV=0
[0071] Performing one or more mathematical operations on Equations
(13) and (14), for example by simultaneously solving Equations (13)
and (14) yields Equation (15):
H = .rho. b - .rho. p .rho. r - .rho. p ##EQU00010##
[0072] The density of blood of the patient .rho..sub.b can be
determined using Equation (15), for example by performing one or
more mathematical operations on Equation (15) to yield Equation
(16):
.rho..sub.b=.rho..sub.p(1-H)+H*.rho..sub.r
[0073] Accordingly, the system 100 can determine the density of
blood of the patient .rho..sub.b, using the hematocrit value H
determination.
[0074] FIG. 1 shows the withdrawal line 104 in communication with
the sensor 124A and the infusion line in communication with the
sensor 124B. As described herein, the sensors 124A can determine
pressure in the withdrawal line 104, and the sensor 124B can
measure pressure in the infusion line 106. The sensors 124A, 124B
can be in communication with the controller 102, and the controller
102 can determine the pressure in the lines 104, 106 using the
sensors 124A, 124B.
[0075] When the controller 102 operates the blood pump 112, the
blood pump 112 generates a negative pressure in withdrawal line 104
to withdraw blood from the vasculature where the catheter tip 130
is located. The blood pump 112 can generate a positive pressure in
the infusion line 106 to infuse blood into the vasculature where
the catheter tip 130 is located. The magnitude of the pressure in
lines 104, 106 can increase to correspondingly increase the blood
flow rate within the lines 104, 106.
[0076] The blood circuit 140 (including the lines 104, 106) can
have a total resistance characteristic that corresponds to an
amount of resistance in the blood circuit 140 to the flow of blood
through one or more components of the blood circuit, for instance
the lines 104, 106 or the filter 110. One or more characteristics
can contribute to the total resistance characteristic of the lines
104, 106. For example, the resistance characteristic of the lines
104, 106 can increase due to occlusion (e.g., clotting,
obstruction, or the like) of the blood circuit 140 (e.g., in or
around the catheter 108), changes to the vasculature (e.g.,
inflammation of walls of the vasculature, compression of the
vasculature, or the like), hemoconcentration of the blood, or the
like. The resistance characteristic (e.g., transverse or
longitudinal) of the filter 110 can contribute to the total
resistance characteristic of the blood circuit 140.
[0077] An increase in the resistance characteristic of the lines
104, 106 (or other components of the blood circuit 140) can
diminish blood flow through the lines 104, 106. The diminished
blood flow due to the increase in the resistance characteristic of
the lines 104, 106 can reduce the performance of the system 100,
for example by reducing the maximum blood flow rate through the
blood circuit 140 or the rate that the one or more blood
constituents can be removed from the blood by the filter 110. The
resistance characteristic of the lines 104, 106 can increase to the
point where the blood pump 112 is unable to maintain flow within
the lines 104, 106 (e.g., because the forces resisting flow in the
lines exceeds the forces generated by the blood pump 112).
Accordingly, an increase in the resistance characteristic of the
lines 104, 106 can diminish the performance of the blood filtration
system 100.
[0078] The system 100 can determine a total resistance
characteristic for one or more components of the blood circuit 140,
for example the withdrawal line 104 and the infusion line 106. In
an example, a withdrawal line resistance characteristic can
correspond to the resistance in the withdrawal line 104 to the flow
of blood through the withdrawal line 104. The withdrawal line
resistance characteristic can correspond to the pressure in the
withdrawal line 104 divided by the actual blood flow rate of system
100 (e.g., as determined by sensor 124E). The actual blood flow
rate of the system 100 can vary from a set point that the
controller 102 operates the blood pump 112 at. For example, the
resistance characteristic of the lines 104, 106 can reduce the
actual blood flow rate through the blood circuit 140 because the
resistance to the flow of blood in the lines 104, 106 decreases the
efficiency of the blood pump 112.
[0079] The infusion line resistance characteristic can correspond
to the resistance in the infusion line 106 to the flow of blood
through the infusion line 106. The infusion line resistance
characteristic can correspond to the pressure in the infusion line
106 divided by the difference between the actual blood flow rate
and the filtration rate of the system (e.g., as determined by
controller 102 in communication with the sensors 124). An increase
in the magnitude of the resistance characteristic of the blood
circuit 140 (including the lines 104, 106) can increase the force
necessary to withdraw blood from (or infuse blood into) the patient
by the blood pump 112. The increase in the magnitude of the
resistance characteristic of the blood circuit 140 can result in
(or be an indication of) clotting in the blood circuit 140.
[0080] The hematocrit value of the patient can contribute to the
total resistance characteristic of the blood circuit 140. As
described herein, the blood filtration system 100 can determine the
hematocrit value of the patient. Hemoconcentration (e.g., an
increase in the hematocrit) of the blood of the patient can
increase the density or viscosity of the blood. Accordingly, an
increase in hematocrit of the patient can increase the resistance
of blood to flow in the blood circuit 140. The system 100 can
determine a hemoconcentration resistance characteristic using the
determined hematocrit value of the patient (or a determined venous
pressure of the patient). The hemoconcentration resistance
characteristic can correspond to the resistance to the flow of the
blood of the patient through the blood circuit 140.
[0081] In an example, the total resistance characteristic of the
lines 104, 106 can increase due to occlusion (e.g., clotting,
obstruction, or the like) of the blood circuit 140, changes to the
vasculature, hemoconcentration of the blood, or the like. The
system 100 can determine an occlusion resistance characteristic of
the lines 104, 106. The occlusion resistance characteristic can
correspond to the resistance of the flow of blood through the lines
104, 106 due to an occlusion of the circuit or changes in
vasculature of the patient. The occlusion resistance characteristic
can correspond to the difference between the withdrawal line
resistance characteristic and the hemoconcentration resistance
characteristic. The occlusion resistance characteristic can
correspond to the difference (e.g., by performing a subtraction
mathematical operation) between the infusion line resistance
characteristic and the hemoconcentration resistance characteristic.
Accordingly, the system 100 can determine what resistance
characteristics (e.g., the hemoconcentration resistance
characteristic, or the like) are contributing to the total
resistance characteristic for the blood circuit 140 (including the
lines 104, 106).
[0082] The system 100 can provide a notification of one or more of
the resistance characteristics that are determined by the system
100. For example, the system 100 can provide a notification on a
display of the withdrawal line resistance characteristic or the
infusion line resistance characteristic. In another example, the
system 100 can provide a notification of the occlusion resistance
characteristic to inform a user (e.g., a healthcare provider, or
the like) that resistance in the blood circuit 140 is due to an
occlusion or the changes in vasculature of the patient. For
example, the notification of the occlusion resistance
characteristic can allow a user to apply appropriate corrective
measures to increase the lifetime of the blood circuit 140. In an
example, the user can inject an anticoagulant to try and reduce
clotting in the blood circuit 140. In another example, the user can
manipulate the catheter 108 to reposition the catheter tip 130
relative to the vasculature of the patient (e.g., to move the
catheter tip 130 away from a wall of the vasculature).
[0083] In some examples, the system 100 provides a notification of
pressures in the blood circuit 140 (e.g., pressure in the
withdrawal line 104). The pressure in the withdrawal line 104 can
be indicative of the total resistance characteristic of the blood
circuit. However, as described herein, the total resistance
characteristic depends upon other characteristics (e.g., variables,
or the like), including (but not limited to) the occlusion
resistance characteristic and the hemoconcentration resistance
characteristic. Determining the occlusion resistance characteristic
and the hemoconcentration resistance characteristic can facilitate
diagnosis for the cause of an increase in the total resistance
characteristic of the blood circuit 140. Diagnosing the cause of
the increase in the total resistance characteristic of the blood
circuit 140 can facilitate appropriate corrective measures to
reduce the total resistance characteristic of the blood circuit
140. Accordingly, the system 100 can improve the lifetime of the
blood circuit 140, for example by reducing replacement of
components of the blood circuit 140 (e.g., the filter 112) due to
clotting.
[0084] FIG. 2 shows a schematic view of an example of a second
blood filtration system 200. The blood filtration system 200 can
include, but is not limited to, the blood pump 112, the filter 110,
the filtration line 114, and the filtration pump 116. Additionally,
the filtration system 200 can include a harvest fluid line 210, and
can include a harvesting pump 220. The harvest fluid line 210 can
be in communication with the filtrate fluid port 111C, for example,
the harvest fluid line 210 can be coupled to the filtration line
114, and the harvest fluid line 210 can receive filtrate fluid from
the filtration line 114.
[0085] In some examples, the filter 110 includes a harvesting port
111D. The harvesting port 111D can be configured to receive
filtrate fluid. In an example, the harvest fluid line 210 is
coupled with the harvesting port 111D, and the harvesting port 111D
is in communication with the filtrate fluid port 111C through the
harvest fluid line 210. The harvesting pump 220 can engage with the
harvest fluid line 210 and pump filtrate fluid from the filtrate
fluid port 111C to the harvesting port 111D. The controller 102 can
operate (e.g., activate, turn on, energize, provide a control
signal to, or the like) the harvesting pump 220 to extract filtrate
fluid from a filtrate reservoir (e.g., the filtrate fluid port
111C, the filtration line 114, or the filtrate fluid reservoir 118)
and inject the filtrate fluid into the harvesting port 111D to
dilute the blood flowing through the filter.
[0086] In some examples, the harvesting port 111D is included in
(e.g., extends from, or is in communication with) a filter body 230
of the filter 110. In another example, the harvesting port 111D is
coupled with the blood inlet port 111A. Optionally, a one-way valve
is included between the filtrate fluid port 111C and the harvesting
port 111D, for instance to inhibit blood flow within the harvest
fluid line 210 while allowing filtrate fluid to flow from the
filtrate fluid port 111C to the harvesting port 111D. As described
in greater detail herein, the harvesting port 111D can provide
filtrate fluid into the filter to dilute blood within the filter
and inhibit clotting of blood flowing through the filter.
[0087] FIG. 3 shows a flowchart of a first method 300 for
preserving a filter for a blood filtration system (e.g., the blood
filtration system 100 or the blood filtration system 200). In
describing the method 300, reference is made to one or more
components, features, functions and operations previously described
herein. Where convenient, reference is made to the components,
features, operations and the like with reference numerals. The
reference numerals provided are exemplary and are not exclusive.
For instance, components, features, functions, operations and the
like described in the method 300 include, but are not limited to,
the corresponding numbered elements provided herein and other
corresponding elements described herein (both numbered and
unnumbered) as well as their equivalents. Additionally, the method
300 can be included in instructions on a computer readable medium,
and the instructions can be carried out by the controller 102
(e.g., processing circuitry).
[0088] At operation 310 the blood flow rate can be periodically set
to a reference level (e.g., operating the blood pump 112 at the
second blood flow rate). At operation 320 the hematocrit value of
the patient can be determined (e.g., with the hematocrit sensor 126
shown in FIG. 1). A filter resistance of the filter 110 can be
determined at operation 330. In an example, the filter resistance
can be determined by determining a pressure differential between
the sensors 124A, 124B (shown in FIG. 1). The filter resistance can
be determined with the blood pump operating, for instance at the
second blood flow rate. At operation 340, a filtration fraction can
be determined according to Equation (17):
Filtration .times. .times. Fraction = Filtration .times. .times.
Flow .times. .times. Rate ( 1 - Hematocrit .times. .times. Value )
.times. ( Blood .times. .times. Flow .times. .times. Rate )
##EQU00011##
[0089] At operation 350, the hematocrit value is compared to a
hematocrit threshold (e.g., 0.50) and if the hematocrit value is
greater than the hematocrit threshold, or if the filtration
fraction is greater than a filtration fraction threshold (e.g.,
0.20), the filtration fraction can be reduced at operation 360.
Reducing the filtration fraction can be reduced, for instance, by
the controller 102. The controller 102 can be configured to control
a speed of one or more pumps to adjust the filtration fraction of
the system. The controller can vary the speed of the one or more
pumps (e.g., the filtration pump 116, the blood pump 112, or the
like) to adjust the filtration fraction
Controlling the filtration fraction can be used to control the rate
of removing plasma constituents while maintaining preferred patient
diagnostic parameters.
[0090] Additionally, controlling the filtration fraction can be
used to reduce clogging of the extracorporeal components of a blood
filtration system (e.g., the blood filtration system 100, or the
blood filtration system 200). In this example, if the hematocrit
value is less than the hematocrit threshold, or if the filtration
fraction is less than a filtration fraction threshold (e.g., 0.20),
the blood flow rate of the system can be set to a user set blood
flow rate (e.g., operating the blood pump 112 at the first blood
flow rate).
[0091] FIGS. 4A-4H show a schematic view of an example of a third
blood filtration system 400. As shown in FIG. 4A, the filtration
system 400 can include the controller 102, the withdrawal line 104,
the infusion line 106, the catheter 108, the filter 110, the blood
pump 112, the filtration line 114, the filtration pump 116, the
filtration fluid reservoir 118, and the one or more valves 122. The
valves 122 can include a check valve, pinch valve (e.g., a valve
that pinches a portion of the blood circuit 140, for instance the
lines 104, 106), electromechanical valve, or the like. The catheter
108 can be inserted into vasculature 410 of a patient (e.g., a
central venous system, peripheral venous system, basilic vein,
cephalic vein, brachial vein, the axillary vein, the subclavian
vein, the brachiocephalic vein, or the like). The blood pump 112
can be in communication with a blood reservoir 430. In an example,
the withdrawal line 104 can be in communication with a blood
reservoir line 420. The controller 102 can be configured to control
the blood pump 112 to operate the blood pump 112 in a first flow
direction to transmit blood from the patient into the blood
reservoir.
[0092] Additionally, the controller 102 can be configured to
control the blood pump 112 to transmit blood from the blood
reservoir 430 to the filter 110. For instance, the blood pump 112
can be controlled to operate the blood pump 112 in a second flow
direction. The second flow direction can be opposite to the first
flow direction. As described herein, the blood filtration system
400 can include the one or more check valves 122, for instance a
first valve 122A, a second valve 122B, a third valve 122C, and a
fourth valve 122B. The first valve 122A can allow for
unidirectional flow within the withdrawal line 104 and prevent
blood from being transmitted into the catheter 108 when the blood
pump 112 is operated in the second flow direction. Accordingly, the
valve 122A facilitates transmission of blood from the blood
reservoir 430 to the filter 110.
[0093] In some examples, the valves 122 are operated out of phase
with each other. For instance, the controller 122A can operate the
valve 122A to permit flow through the withdrawal line 104. The
controller 102 can operate the valve 122D to inhibit flow through
the infusion line 106. Accordingly, the controller 102 can operate
the valve 122A out of phase with the valve 122D. Inhibiting the
flow in one or more of the lines 104, 106 can facilitate
unidirectional flow through the system 100 (e.g., the blood circuit
140). In an example, operating the valves 122 (e.g., the valves
122A, 122D, or the like) out of phase can inhibit the flow of blood
from the infusion line 106 to the withdrawal line (or from the
withdrawal line 104 to the infusion line 106). For instance,
closing the valve 122D can facilitate withdrawal of blood from the
vasculature 410 of the patient while inhibiting flow of blood from
the infusion line 106 to the withdrawal line 104. The valve 122A
can be operated to facilitate unidirectional flow in the system
400, for example by closing the valve 122A to inhibit flow from the
withdrawal line 104 to the infusion line 106 (or from the
withdrawal line 104 to the vasculature 410 during infusion of the
blood into the vasculature 410. Accordingly, operating the valves
122 out of phase with each other can facilitate unidirectional flow
through the system 400 (or other systems described herein, for
example the system 100, or the like).
[0094] The filtration pump 116 can pump extracted filtrate fluid
from the filter 110, and into the filtrate fluid reservoir 118. In
some examples, the filtration pump 116 can be a peristaltic pump
that engages with the filtration line 114 to pump the filtrate
fluid through the filtrate fluid line 114. The controller 102 can
be configured to vary a speed of the filtration pump 116 and
accordingly vary the flow rate of filtrate fluid through the blood
filtrate system 100 (e.g., the filtration line 114).
[0095] The system 400 can facilitate the use of a single lumen
catheter 108, however the present subject matter is not so limited.
For instance, the catheter 108 can include a single passage, and
blood can be withdrawn and infused within the single passage. The
single lumen catheter facilitates increased blood flow in the
system 400. Accordingly, the increased blood flow reduces clogging
in the filter 110, thereby improving the performance of the system
400.
[0096] As shown in FIG. 4B, in some examples, the catheter 108
includes a withdrawal port 440A that can be isolated from an
infusion port 440B FIG. 4C shows that the blood filtration system
400 can include a diverter valve 450. The diverter valve 450 can be
controlled by the controller 102, for instance the controller 102
can provide a control signal to operate the diverter valve 450. The
diverter valve 450 can be operated to allow for blood to flow in
one or more directions. In an example, the diverter valve 450 can
be operated to allow blood to flow from the catheter 108 to the
blood reservoir 430, while preventing blood from being withdrawn
from other portions of the blood filtration system 400 (e.g., the
filter 110).
[0097] FIG. 4D shows another example of the blood filtration system
400. In some examples, the blood filtration system 400 does not
include the one or more check valves 122. For instance, the blood
pump 112 can withdraw blood from the catheter and transmit the
blood into the blood reservoir 430. The operating direction of the
blood pump 112 can be changed (e.g., operated in the second flow
direction) to transmit blood back into the filter 110. For
instance, the blood in the system 400 can be transmitted through
the filter 110 in a plurality of cycles. In another example, for
instance as shown in FIG. 4A, blood can be transmitted through the
filter 110 in a single cycle (e.g., in a continuous circuit). The
controller 102 can be configured to operate the filtration pump 116
during a single cycle through the filter 110, or to operate the
filtration pump 116 during one or more of the plurality of cycles
through the filter 110.
[0098] As shown in FIG. 4E, the blood filtration system 400 can
include a single valve 122. Blood can be transmitted from the
catheter 108, through the valve 122A, and into the blood reservoir
430. The operating direction of the blood pump 112 can be reversed,
and blood can be transmitted through the filter 110 and into the
catheter 108. In some examples, and as shown in FIGS. 4F-4G, the
blood pump 112 can pump a gas (e.g., air, nitrogen, or the like) to
correspondingly pump blood into and out of the blood reservoir 430.
For instance, the blood pump 112 can decrease the gas pressure in
the blood reservoir 430, and correspondingly draw blood into the
blood reservoir from the catheter 108. The operating direction of
the blood pump 112 can be changed, and the gas pressure inside the
blood reservoir 430 can be increased. In this example, the increase
in gas pressure can correspondingly cause the blood flow from the
blood reservoir 430 and into the filter 110. In some examples the
blood filtration line 420 can be in communication with the
atmosphere, for instance through an air filter 460. The
communication of the blood filtration line 420 with the atmosphere
can facilitate the blood pump 112 changing the pressure within the
blood reservoir 430.
[0099] Further, and as described in greater detail herein, the
blood filtration system 400 can include one or more filters 110.
For example, the blood filtration system 400 can include a first
filter 110A and a second filter 110B. In this example, the filters
110A, 110B are in communication with the filtration pump 116 (or a
plurality of filtration pumps 116), and the filtration pump 116
extracts filtrate fluid from the filters 110A, 110B. In an example,
the filter 110A filters filtrate fluid from the blood of the
patient when the blood pump 112 operates in a first direction
(e.g., during withdrawal of blood from the patient). In another
example, the filter 110B filters filtrate fluid from the blood of
the patient when the blood pump operates in a second direction
(e.g., during infusion of blood into the patient). The system 100
can determine the amount of filtrate fluid removed from the blood
of a patient. For example the system 100 can be in communication
with a scale that weights the reservoir 118. In another example,
the sensors 124 can include a flow meter in communication with the
line 114 and the controller 102 determines the amount of filtrate
fluid removed from the patient with the flow meter.
[0100] FIG. 5 shows a schematic view of a fourth blood filtration
system 500. As described herein, the filter 110 can include a
filter body 230, a filter inlet port 111A, a filter outlet port
111B, and a filtrate fluid port 111C. The filter inlet port 111A,
filter outlet port 111B, and filtrate fluid port 111C can be
included in the filter body 230, and the ports 111A, 111B, 111C
facilitate coupling the filter 110 with additional components of a
blood filtration system (e.g., one or more of the blood filtration
systems 100, 200, 400).
[0101] In an example, blood can flow into the filter body 230
through the filter inlet port 111A, flow through the filter body
230, and out of the filter outlet port 111B. In an example, blood
can cycle through the filter 110 multiple times, for instance as
described with reference to FIG. 4G. The filter 110 can be
configured to reduce the amount of filtrate fluid in the blood
flowing through the filter 110, and transmit the extracted filtrate
fluid to the filtrate fluid port 111C.
[0102] As described herein, the filter 110 can include the
harvesting port 111D. In some examples, the harvesting port 111D
can be coupled to the filter inlet port 111A, and the harvesting
port 111D can be in communication with the filter inlet port 111A.
Introducing filtrate fluid into the harvesting port 111D can mix
filtrate fluid with blood entering the filter inlet port 111A, and
accordingly dilute the blood with the filtrate fluid.
[0103] In some examples, the filter 110 can include one or more
valves to inhibit the flow of fluid with respect to the filter 110.
In an example, the filter can include a filter inlet valve 505, a
filter outlet valve 510, a filtration fluid valve 520, and/or a
harvesting valve 530. The valves 505, 510 can be in communication
with the ports 111A, 111B, respectively, and can stop (e.g.,
inhibit) the flow of blood with respect to the filter 110 (e.g.,
preventing the transmission of blood into or out of the ports 111A,
111B). The valve 520 can be in communication with the port 111C,
and can stop the flow of filtrate fluid with respect to the filter
110 (e.g., preventing the transmission of blood into or out of the
port 111C). The valve 530 can be in communication with the port
111D, and can stop the flow of filtrate fluid and/or blood with
respect to the filter 110 (e.g., preventing the transmission of
filtrate fluid and/or blood into or out of the port 111D).
[0104] Additionally, the withdrawal line 104 can be in
communication with a first line valve 540, the infusion line 106
can be in communication with a second line valve 550, the filtrate
fluid line 114 can be in communication with a third line valve 560,
and the harvesting line 210 can be in communication with a fourth
line valve 570. The valves 540, 550, 560, 570 can stop the flow
with respect to the lines 104, 106, 114, 210, respectively.
[0105] The valves 505, 510, 520, 530, 540, 550, 560, 570 can
facilitate interchanging the filter 110 with a different filter
110, for instance if the filter 110 becomes clogged. For instance,
the valves 505, 510, 520, 530, 540, 550, 560, 570 can be closed,
and coupling members 580 (e.g., fittings) can be separated to
detach the lines 104, 106, 114, 210 from the filter. A replacement
filter 110 can be located proximate to the lines 104, 106, 114,
210, and the coupling members 180 can be reattached to the
replacement filter 110. The valves 505, 510, 520, 530, 540, 550,
560, 570 can be opened, and flow throughout the blood filtration
system 500 is reestablished. Accordingly, the performance of the
blood filtration system 500 is thereby improved. In some examples,
the members 580 are integral with the valves 505, 510, 520, 530,
540, 550, 560, 570.
[0106] In an example, the valves 540, 550, 560, 570 include a ball
valve. In another example, the valves 540, 550, 560, 570 include
one or more pinch valves that compresses the lines 104, 106, 114,
210 to inhibit the flow of fluid through one or more of the lines
104, 106, 114, 210. In an example, the controller 102 operates the
pinch valves to inhibit flow of fluid through the lines 104, 106,
114, and 210.
[0107] The blood filtration system 500 can include the controller
102, and the controller 102 can be configured to determine one or
more filter resistances of the filter 110. In an example, the
filter 110 can have a longitudinal resistance characteristic, and
the longitudinal resistance characteristic can include the
resistance of the flow of a fluid (e.g., blood) through a length of
the filter 110, for instance as denoted by the arrow 595A. In one
example, the controller 102 can determine the longitudinal filter
resistance characteristic by determining the pressure at an inlet
pressure sensor 590A that is in communication with the inlet port
111A of the filter 110.
[0108] As the filter 110 filters blood, the filter 110 can become
clogged, for instance due to clotting in the filter 110. As the
filter 110 becomes clogged, the longitudinal filter resistance of
the filter 110 increases, because the clogged filter increases the
amount of force necessary to pump blood through the filter 110.
Accordingly, the pressure at the inlet pressure sensor 590A can
increase.
[0109] The controller 102 can compare longitudinal filter
resistance characteristic to a filter resistance threshold, for
instance a first filter resistance threshold, and determine if the
longitudinal filter resistance characteristic exceeds the first
filter resistance threshold. In this example, when the longitudinal
filter resistance exceeds (e.g., is greater than) the first filter
resistance threshold, the controller 102 can operate (e.g., with a
control signal) a harvesting pump (e.g., the harvesting pump 220
shown in FIG. 1). Operating the harvesting pump can inject a fluid
(e.g., filtrate fluid, saline, heparin, or the like) into the port
111D, and introduce the fluid into blood flowing into the filter
110. For instance, injecting the filtrate fluid into the port 111D
can reduce the longitudinal filter resistance characteristic, for
instance by diluting blood clotted in the filter 110. The
controller 102 can be configured to operate the harvesting pump and
stop injecting filtrate fluid into the port 111D when the
longitudinal filter resistance characteristic exceeds (e.g., is
less than) a second filter resistance threshold. Accordingly, the
performance of the blood filtration system 500 is improved because
a lifetime of the filter 110 can be extended by reducing clogging
of the filter 110.
[0110] In another example, the filter 110 can have a transverse
resistance characteristic, and the transverse resistance
characteristic can include the resistance of the flow of a fluid
(e.g., filtrate fluid) through a thickness of the filter 110, for
instance as denoted by the arrow 595B. In one example, the
controller 102 can determine the transverse filter resistance
characteristic by determining the pressure at a filtration pressure
sensor 590C that is in communication with the filtrate fluid port
111C of the filter 110. As the filter 110 filters blood, the filter
110 can become clogged, for instance due to clotting in the filter
110. As the filter 110 becomes clogged, the transverse filter
resistance of the filter 110 increases, because the clogged filter
increases the amount of force necessary to extract filtrate fluid
from the filter 110 (e.g., with the filtration pump 116 shown in
FIG. 1). Accordingly, the pressure at the inlet pressure sensor
590A can increase.
[0111] The controller 102 can compare the transverse resistance
characteristic to a filter resistance threshold, for instance a
first filter resistance threshold, and determine if the transverse
resistance characteristic exceeds (e.g., is greater than) the first
filter resistance threshold. In this example, when the transverse
filter resistance exceeds the first filter resistance threshold,
the controller 102 can operate (e.g., with a control signal) a
harvesting pump (e.g., the harvesting pump 220 shown in FIG. 1).
Operating the harvesting pump can inject filtrate fluid into the
port 111D, and dilute the blood flowing into the filter 110.
Injecting the filtrate fluid into the port 111D can reduce the
transverse filter resistance characteristic, for instance by
diluting blood clotted in the filter 110. The controller 102 can be
configured to operate the harvesting pump and stop injecting
filtrate fluid into the port 111D when the transverse filter
resistance characteristic exceeds (e.g., is less than) a second
filter resistance threshold. Accordingly, the performance of the
blood filtration system 500 is improved because a lifetime of the
filter 110 can be extended by reducing clogging of the filter
110.
[0112] FIG. 6 shows a flowchart for a second method 600 for
preserving a filter for a blood filtration system. In describing
the method 600, reference is made to one or more components,
features, functions and operations previously described herein.
Where convenient, reference is made to the components, features,
operations and the like with reference numerals. The reference
numerals provided are exemplary and are not exclusive. For
instance, components, features, functions, operations and the like
described in the method 600 include, but are not limited to, the
corresponding numbered elements provided herein and other
corresponding elements described herein (both numbered and
unnumbered) as well as their equivalents. Additionally, the method
600 can be included in instructions on a computer readable medium,
and the instructions can be carried out by the controller 102
(e.g., processing circuitry).
[0113] At operation 610, a filter resistance can be determined. In
some examples, the controller 102 compares pressure at the inlet
pressure sensor 590A or the filtration pressure sensor 590C to an
outlet pressure sensor 590B or a harvesting pressure sensor 590D to
determine the filter resistances, or to improve the accuracy of the
filter resistance determinations. In an example, the transverse
filter resistance can be calculated according to the pressure
differential between the outlet pressure sensor 590B and the
filtration pressure sensor 590C, and dividing the pressure
differential by the flow rate of the filtration pump (e.g., the
filtration pump 116 shown in FIG. 1). In another example, the
longitudinal filter resistance can be calculated according to the
pressure differential between the inlet pressure sensor 590A and
the filtration pressure sensor 590C, and dividing the pressure
differential by the flow rate of the blood pump (e.g., the blood
pump 112 shown in FIG. 1).
[0114] At operation 620, the blood flow rate can be determined, for
instance by determining the operating rate of the blood pump 112,
shown in FIG. 1. At operation 630, the controller 102 can determine
if the blood flow rate is intermittent (e.g., varying, fluctuating,
or the like) and accordingly the controller 102 can operate the
filtration pump 116 (e.g., stop the filtration pump) and operate
the harvesting pump 220 (e.g., operate the harvesting pump 220 to
inject filtrate fluid into the harvesting port 111D). Additionally,
the controller can determine if one or more filter resistances are
greater than a filter resistance threshold and accordingly the
controller 102 can operate the filtration pump 116 and operate the
harvesting pump 220. Additionally, the controller 102 can monitor
the blood flow rate over time (e.g., by determining the blood flow
rate with the one or more sensors 124), and when the blood flow
rate decreases over time below a blood flow rate threshold, the
controller 102 can operate the filtration pump 116 and operate the
harvesting pump 220. Accordingly, the method 600 can reduce
clogging in the filter and improve the performance of a blood
filtration system.
[0115] FIG. 7 shows a schematic view of a fifth blood filtration
system 700. The blood filtration system can include on or more
filters 110, for instance a first filter 110A or a second filter
110B. In an example, and as shown in FIG. 7, the filters 110A, 110B
can be arranged in parallel. In another example, the filters 110A,
110B can be arranged in series. The blood filtration system can
include a first valve 710A and can include a second valve 710B. The
valves 710A, 710B can facilitate the flow of fluids (e.g., blood or
filtrate fluid) through the system 500.
[0116] In an example, the valve 710A can be configured to divert
blood flow through the filter 110A or the filter 110B. For
instance, the valve 710A can be operated (e.g., by a user, or the
controller 102, for example with a control signal) to divert the
flow of blood between the filters 110A, 110B. In another example,
the valve 710B can be operated (e.g., by a user, or the controller
102, for example with a control signal) to divert the facilitate
the extraction of filtrate fluid from the filters 110A, 110B.
[0117] FIG. 8A shows a schematic view of a sixth blood filtration
system 800. The blood filtration system 800 can include an agitator
810 coupled with the filter 110. In an example, the agitator 810
can provide vibrations to the filter 110. In an example, the
agitator 810 can include a piezoelectric element, and the agitator
810 can be operated by the controller 102 (e.g., with a control
signal, for instance a control signal in communication with a relay
that energizes the piezoelectric element). In another example, the
agitator 810 can include an ultrasound generator that in some
examples is operated by the controller 102.
[0118] The agitator 810 can reduce clogging in the filter 110, for
instance when blood clots in the filter 110. In an example, the
controller 102 can operate the agitator 810 when a filter
resistance (e.g., the longitudinal filter resistance) exceeds a
filter resistance threshold (e.g., the first filter resistance
threshold). Accordingly, the agitator 810 can improve the
performance of the blood filtration system 800, for instance by
providing a vibration to the filter 110 and thereby reducing
clotting of blood within the filter 110.
[0119] As shown in FIG. 8B, the filter 110 can have a variable
volume. In an example, a filter cap 820 can be operated (e.g.,
rotated, turned, twisted, engaged with, or the like) and the volume
of the filter 110 can correspondingly vary. For instance, operation
of the filter cap can change the dimension of an aperture 830
(e.g., by changing a dimension of an iris mechanism, a Tuohy Borst
mechanism, or the like). Changing the dimension of the aperture 830
can block one or more portions of the filter, for instance filter
fibers 840, and change the volume of the filter 110. In some
examples, the volume of the filter 110 is adjusted to meet patient
needs. For instance, a child can have its blood filtered by the
blood filtration system 800, and the volume of the filter 110 can
be adjusted to accommodate for the reduced stature of the child.
The variable volume of the filter 110 allows for a filter to have a
variable filtration capacity (e.g., the amount of filtrate fluid
that is extracted by the filter 110), and accordingly improves the
performance of the blood filtration system 800.
[0120] FIG. 9 shows a schematic view of a seventh blood filtration
system 900. The blood filtration system 900 can include a system
housing 910 that includes controls 920 (e.g., buttons) that can
change various operating parameters of the system 900, for instance
a button that operates the blood pump 112 (shown in FIG. 1). The
system housing 910 can include the controller 102, and the controls
920 can communicate with the controller 102 to operate one or more
components of the blood filtration system (e.g., the harvesting
pump 220 shown in FIG. 2).
[0121] The blood filtration system 900 can include an optical
sensor 930 (e.g., a camera, an infrared camera, or the like) that
can monitor movement of the patient, for instance my observing a
patient reference point 940 (e.g., a head of the patient, a mark
included on a surface of an object secured to the patient, for
instance a blood pressure cuff, or the like). The optical sensor
930 can monitor the position of the patient reference point and the
controller 102 can be configured to determine if movement of the
patient from an initial position affects the determined hematocrit
value of the patient. The hematocrit value determination can be
affected by movement of a patient, for example when the patient
transitions from a supine position (e.g., laying down) to a
standing position.
[0122] In an example, the controller 102 can be configured to
provide a notification if the hematocrit determination is affected
by the movement of the patient. For instance, the controller 102
can provide a notification on a display 950 with a timer indicating
the time since the patient moved in a way that affected the
hematocrit value determination. In an example, the controller 102
can compare the change in position of the portion of the body of
the patient to a positional threshold and provide a notification
when the change in position exceeds the positional threshold. For
instance, the controller 102 can determine the position of the
patient reference point 940 relative to the optical sensor 930.
[0123] In yet another example, the controller 102 can operate a
speaker and change a tone according to the patient movement (e.g.,
initiate a beep if the patient moves). Additionally, the controller
102 can determine a movement value for instance a difference
between the position of the patient reference point to the initial
position. Further, the controller can compare the movement value to
a movement threshold and can provide a notification if the movement
value exceeds the movement threshold.
[0124] In another example, the controller 102 can refrain from
providing a notification of the hematocrit value when the
hematocrit value is affected by movement of the patient (e.g., by
refraining from displaying the movement-affected hematocrit value
on the display 950). Accordingly, the blood filtration system 900
can provide additional information (e.g., to a healthcare provider)
that the hematocrit value of the patient has been affected by
movement of the patient.
[0125] In yet another example, the patient reference point 940 can
include an accelerometer, and the accelerometer can be in
communication with the controller 102 (e.g., with a wired or
wireless communication pathway). The accelerometer can monitor the
movement of the patient by determining acceleration of a portion of
a body of the patient (e.g., an arm). The controller 102 can
determine if the movement of the patient from the initial position
affects the determined hematocrit value of the patient, for
instance by comparing the acceleration of the portion of the body
of the patient to an acceleration threshold.
[0126] In still yet another example, a pressure sensor in
communication with a blood stream of the patient (e.g., the first
sensor 124A or the second sensor 124B shown in FIG. 1) can monitor
a change in pressure within the blood stream of the patient. The
controller 102 can determine if the movement of the patient from
the initial position affects the determined hematocrit value of the
patient, for instance by comparing the change in pressure (e.g.,
because the patient transitioned from laying down to standing)
within the blood stream to a pressure threshold. The controller 102
can provide a notification if the change in pressure exceeds the
pressure threshold.
[0127] In some examples, the controller 102 can apply a correction
value to the determined hematocrit value of the patient according
to the movement of the patient. For instance, the correction value
can be determined by evaluating a change in the hematocrit value
according to the motion of the patient. The controller 102 can log
data associated with changes in patient position and corresponding
changes in hematocrit values to determine the correction value.
[0128] FIG. 10 shows a schematic view of an eighth blood filtration
system 1000. The blood filtration system 1000 can include a
proximal venous occlusion cuff 1010 and can include a distal venous
occlusion cuff 1020. The cuffs 1010, 1020 can engage with an arm of
the patient to encourage blood flow in the arm of the patient. In
an example, the controller 102 can operate the cuffs 1010, 1020 to
constrict the cuff 1010 or the cuff 1020. Constricting the cuffs
1010, 1020 can cause the blood pressure in the arm to increase. The
controller 102 can operate the cuff 1010 to loosen the cuff 1010,
or the 1020, which can encourage blood flow in the arm, for
instance by increasing blood flow into the catheter 108 (shown in
FIG. 1).
[0129] The controller 102 can operate the cuffs 1010, 1020 to
synchronize the cuffs 1010, 1020. In an example, the controller 102
can operate the cuffs 1010, 1020 to tighten the cuffs 1010, 1020 at
the same point in time. In another example, the controller 102 can
operate the cuffs 1010, 1020 to loosen the cuffs 1010, 1020 at the
same point in time. In yet another example, the controller 102 can
operate the cuffs 1010, 1020 to tighten the cuff 1010, while the
cuff 1020 is loosened. In still yet another example, the controller
102 can operate the cuffs 1010, 1020 to tighten the cuff 1020,
while the cuff 1010 is loosened.
[0130] FIGS. 11A-11B are photographs of line protectors 1100 for a
blood filtration system. The line protectors 1100 can be located
around lines (e.g., the lines 104, 106, 114, 210 shown in FIG. 2,
or the like) of a blood filtration system (e.g., the blood
filtration system 100, shown in FIG. 1). The protectors 1100 can
prevent compression of the lines of the blood filtration system and
accordingly ensure flow of fluid (e.g., blood or filtrate fluid)
through the lines.
[0131] FIG. 12 illustrates a block diagram of an example machine
1200 upon which any one or more of the techniques (e.g.,
methodologies) discussed herein can perform, for instance the
controller 102. Examples, as described herein, can include, or can
operate by, logic or a number of components, or mechanisms in the
machine 1200. Circuitry (e.g., processing circuitry) is a
collection of circuits implemented in tangible entities of the
machine 1200 that include hardware (e.g., simple circuits, gates,
logic, etc.). Circuitry membership can be flexible over time.
Circuitries include members that may, alone or in combination,
perform specified operations when operating. In an example,
hardware of the circuitry can be immutably designed to carry out a
specific operation (e.g., hardwired). In an example, the hardware
of the circuitry can include variably connected physical components
(e.g., execution units, transistors, simple circuits, etc.)
including a machine readable medium physically modified (e.g.,
magnetically, electrically, moveable placement of invariant massed
particles, etc.) to encode instructions of the specific operation.
In connecting the physical components, the underlying electrical
properties of a hardware constituent are changed, for example, from
an insulator to a conductor or vice versa. The instructions enable
embedded hardware (e.g., the execution units or a loading
mechanism) to create members of the circuitry in hardware via the
variable connections to carry out portions of the specific
operation when in operation. Accordingly, in an example, the
machine readable medium elements are part of the circuitry or are
communicatively coupled to the other components of the circuitry
when the device is operating. In an example, any of the physical
components can be used in more than one member of more than one
circuitry. For example, under operation, execution units can be
used in a first circuit of a first circuitry at one point in time
and reused by a second circuit in the first circuitry, or by a
third circuit in a second circuitry at a different time. Additional
examples of these components with respect to the machine 1200
follow.
[0132] In alternative embodiments, the machine 1200 can operate as
a standalone device or can be connected (e.g., networked) to other
machines. In a networked deployment, the machine 1200 can operate
in the capacity of a server machine, a client machine, or both in
server-client network environments. In an example, the machine 1200
can act as a peer machine in peer-to-peer (P2P) (or other
distributed) network environment. The machine 1200 can be a
personal computer (PC), a tablet PC, a set-top box (STB), a
personal digital assistant (PDA), a mobile telephone, a web
appliance, a network router, switch or bridge, or any machine
capable of executing instructions (sequential or otherwise) that
specify actions to be taken by that machine. Further, while only a
single machine is illustrated, the term "machine" shall also be
taken to include any collection of machines that individually or
jointly execute a set (or multiple sets) of instructions to perform
any one or more of the methodologies discussed herein, such as
cloud computing, software as a service (SaaS), other computer
cluster configurations.
[0133] The machine (e.g., computer system) 1200 can include a
hardware processor 1202 (e.g., a central processing unit (CPU), a
graphics processing unit (GPU), a hardware processor core, or any
combination thereof), a main memory 1204, a static memory (e.g.,
memory or storage for firmware, microcode, a basic-input-output
(BIOS), unified extensible firmware interface (UEFI), etc.) 1206,
and mass storage 1208 (e.g., hard drive, tape drive, flash storage,
or other block devices) some or all of which can communicate with
each other via an interlink (e.g., bus) 1230. The machine 1200 can
further include a display unit 1210, an alphanumeric input device
1212 (e.g., a keyboard), and a user interface (UI) navigation
device 1214 (e.g., a mouse). In an example, the display unit 1210,
input device 1212 and UI navigation device 1214 can be a touch
screen display. The machine 1200 can additionally include a storage
device (e.g., drive unit) 1208, a signal generation device 1218
(e.g., a speaker), a network interface device 1220, and one or more
sensors 1216, such as a global positioning system (GPS) sensor,
compass, accelerometer, or other sensor. The machine 1200 can
include an output controller 1228, such as a serial (e.g.,
universal serial bus (USB), parallel, or other wired or wireless
(e.g., infrared (IR), near field communication (NFC), etc.)
connection to communicate or control one or more peripheral devices
(e.g., a printer, card reader, etc.).
[0134] Registers of the processor 1202, the main memory 1204, the
static memory 1206, or the mass storage 1208 can be, or include, a
machine readable medium 1222 on which is stored one or more sets of
data structures or instructions 1224 (e.g., software) embodying or
utilized by any one or more of the techniques or functions
described herein. The instructions 1224 can also reside, completely
or at least partially, within any of registers of the processor
1202, the main memory 1204, the static memory 1206, or the mass
storage 1208 during execution thereof by the machine 1200. In an
example, one or any combination of the hardware processor 1202, the
main memory 1204, the static memory 1206, or the mass storage 1208
can constitute the machine readable media 1222. While the machine
readable medium 1222 is illustrated as a single medium, the term
"machine readable medium" can include a single medium or multiple
media (e.g., a centralized or distributed database, and/or
associated caches and servers) configured to store the one or more
instructions 1224.
[0135] The term "machine readable medium" can include any medium
that is capable of storing, encoding, or carrying instructions for
execution by the machine 1200 and that cause the machine 1200 to
perform any one or more of the techniques of the present
disclosure, or that is capable of storing, encoding or carrying
data structures used by or associated with such instructions.
Non-limiting machine readable medium examples can include
solid-state memories, optical media, magnetic media, and signals
(e.g., radio frequency signals, other photon based signals, sound
signals, etc.). In an example, a non-transitory machine readable
medium comprises a machine readable medium with a plurality of
particles having invariant (e.g., rest) mass, and thus are
compositions of matter. Accordingly, non-transitory
machine-readable media are machine readable media that do not
include transitory propagating signals. Specific examples of
non-transitory machine readable media can include: non-volatile
memory, such as semiconductor memory devices (e.g., Electrically
Programmable Read-Only Memory (EPROM), Electrically Erasable
Programmable Read-Only Memory (EEPROM)) and flash memory devices;
magnetic disks, such as internal hard disks and removable disks;
magneto-optical disks; and CD-ROM and DVD-ROM disks.
[0136] The instructions 1224 can be further transmitted or received
over a communications network 1226 using a transmission medium via
the network interface device 1220 utilizing any one of a number of
transfer protocols (e.g., frame relay, internet protocol (IP),
transmission control protocol (TCP), user datagram protocol (UDP),
hypertext transfer protocol (HTTP), etc.). Example communication
networks can include a local area network (LAN), a wide area
network (WAN), a packet data network (e.g., the Internet), mobile
telephone networks (e.g., cellular networks), Plain Old Telephone
(POTS) networks, and wireless data networks (e.g., Institute of
Electrical and Electronics Engineers (IEEE) 802.11 family of
standards known as Wi-Fi.RTM., IEEE 802.16 family of standards
known as WiMax.RTM.), IEEE 802.15.4 family of standards,
peer-to-peer (P2P) networks, among others. In an example, the
network interface device 1220 can include one or more physical
jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more
antennas to connect to the communications network 1226. In an
example, the network interface device 1220 can include a plurality
of antennas to wirelessly communicate using at least one of
single-input multiple-output (SIMO), multiple-input multiple-output
(MIMO), or multiple-input single-output (MISO) techniques. The term
"transmission medium" shall be taken to include any intangible
medium that is capable of storing, encoding or carrying
instructions for execution by the machine 1200, and includes
digital or analog communications signals or other intangible medium
to facilitate communication of such software. A transmission medium
is a machine readable medium.
[0137] One or more of components, features, functions, or the like
of the blood filtration systems (e.g., the blood filtration systems
100, 200, 400, 500, 700, 800, 900, 1000) described herein can be
combined into one or more combinations, or sub-combinations.
Additionally, one or more configurations of the controller 102 can
be combined into or more combinations, or sub-combinations.
Further, one or more configurations, techniques, or functions
associated with the controller 102 can be included in a machine
readable medium on which is stored one or more sets of data
structures or instructions (e.g., software) embodying or utilized
by any one or more of the techniques or functions described
herein.
[0138] FIG. 13 shows a graph of a filtration fraction of a blood
filtration system versus a hematocrit level of a patient. As
discussed herein, the hematocrit of the patient is determined
according to Equation (1), and the filtration fraction of a blood
filtration system is determined according to Equation (2). A blood
filtration system (e.g., the blood filtration system 100 shown in
FIG. 1) can include a hematocrit threshold 1300 (e.g., 50 percent,
or within a range of 45 percent to 55 percent, or the like).
Additionally, the blood filtration system can include a filtration
fraction threshold 1310. In some examples, if the hematocrit
threshold 1300, or the filtration fraction threshold 1310 are
exceeded, a filter (e.g., the filter shown in FIG. 1) can become
clogged, for instance due to blood clotting in the filter.
Accordingly, the blood filtration system can be operated (e.g., by
the controller 102) to maintain the filtration fraction below the
filtration fraction threshold 1310, and can maintain a patient
hematocrit value less than the hematocrit threshold 1300.
[0139] In an example, the filtration pump 116 (shown in FIG. 1) can
be operated to vary a speed of the filtration pump (e.g., between
10-500 milliliters per hour). The speed of the filtration pump 116
can be varied incrementally (e.g., in 5 millimeter per hour
increments). The controller 102 can operate the filtration pump 116
to vary the speed of the filtration pump 116, and accordingly
maintain the filtration fraction below the filtration fraction
threshold 1310. Additionally, the controller 102 can operate the
blood pump 112 (shown in FIG. 1) to maintain the filtration
fraction below the filtration fraction threshold 1310 (e.g., by
varying the blood flow rate through the system). Further, the
controller 102 can stop the filtration pump 116 (e.g., to stop
therapy with the blood filtration system) if the hematocrit
threshold 1300 is exceeded.
[0140] In an example, the blood filtration system can extract
filtrate fluid at a high filtration rate (e.g., 400 milliliters per
hour), as shown by a first curve 1320. As filtrate fluid is
extracted from the patient, the hematocrit level of the patient
increases, and the filtration fraction increases (because the
denominator of Equation (1) is reduced). The blood filtration
system can maintain the high filtration rate until the filtration
fraction threshold 1310 is exceeded, and the blood filtration
system can operate the filtration pump 116 at an intermediate
filtration rate (e.g., 200 milliliters per hour), as shown by a
second curve 1330. The blood filtration system can continue to
extract filtrate fluid from blood of the patient at the
intermediate filtration rate, and accordingly the hematocrit value
of the patient can continue to increase. Accordingly, the
filtration fraction continues to increase at the intermediate
filtration rate. The blood filtration system can maintain the
intermediate filtration rate until the filtration fraction
threshold 1310 is exceeded.
[0141] Once the filtration fraction 1310 has been exceeded at the
intermediate filtration rate, the blood filtration system can
operate the filtration pump at a low filtration rate (e.g., 50
milliliters per hour), as shown by a third curve 1340. The blood
filtration system can continue to extract filtrate fluid from blood
of the patient at the low filtration rate, and accordingly the
hematocrit value of the patient can continue to increase. The blood
filtration system can maintain the low filtration rate until the
hematocrit threshold 1300 is exceeded, and the blood filtration
system can stop the filtration pump 116 (e.g., a filtration rate of
0 milliliters per second).
[0142] Once the hematocrit threshold 1300 has been exceeded, the
blood pump 112 can continue to pump blood through the blood
filtration system, and the blood filtration system can monitor the
hematocrit value (or other health parameters of the patient) to
determine if the patient requires additional therapy (e.g.,
extraction of filtrate fluid from the blood). For instance, the
plasma refill rate of the patient can reduce the hematocrit value
of the patient, and blood filtration system can resume therapy.
[0143] FIG. 14 shows a method 1400 for determining venous pressure
of a patient with a blood filtration system (e.g., the blood
filtration system 100, or the like). In describing the method 300,
reference is made to one or more components, features, functions
and operations previously described herein. Where convenient,
reference is made to the components, features, operations and the
like with reference numerals. The reference numerals provided are
exemplary and are not exclusive. For instance, components,
features, functions, operations and the like described in the
method 1400 include, but are not limited to, the corresponding
numbered elements provided herein and other corresponding elements
described herein (both numbered and unnumbered) as well as their
equivalents. Additionally, the method 1400 can be included in
instructions on a computer readable medium, and the instructions
can be carried out by the controller 102 (e.g., processing
circuitry).
[0144] At 1410, the method 1400 can include determining a
hematocrit value of a patient, for example with the controller 102
(e.g., the controller 102 can communicate with the hematocrit
sensor 126 to determine the hematocrit value). The method 1400 can
include at 1420 that the blood pump 112 can be operated to stop a
flow of blood in the blood circuit 140 (e.g., within the lines 104,
106).
[0145] At 1430, a pressure head in a component of the blood circuit
140 (e.g., one or more of the lines 104, 106, the catheter 108, or
the like) can be compensated for when determining the venous
pressure of the patient. For example, at 1440 an elevation
difference between the catheter tip 130 and a pressure sensor
(e.g., the sensor 124A) can be determined, for example with the
system 100 (e.g., the controller 102 in communication with one or
more position sensors). In another example, at 1450 an elevation
difference between a pressure sensor (e.g., the sensor 124A) and a
position sensor (e.g., the sensor 124D) can be determined (e.g., by
determining the difference in elevation between the sensors 124A,
124D with the controller 102).
[0146] At 1460, a density of the blood of the patient can be
determined. The determined head pressure in the blood circuit can
correspond to (e.g., a variable in an equation that determines the
head pressure, associated with, contribute to, based on, or the
like) the density of the blood of the patient. Accordingly,
determining the blood density can improve the accuracy of the head
pressure compensation when determining the venous pressure of the
patient.
[0147] At 1470, the method 1400 can include determining the
pressure (e.g., with the sensors 124A, 124B) in a component of the
blood circuit 140, for example the withdrawal line 104 or the
infusion line 106. In an example, the catheter tip 130 is located
within vasculature of the patient, and the system 100 can withdraw
blood from (or infuse blood into) the vasculature of the patient.
Accordingly, when the blood pump 112 is operated to stop the flow
of blood in the blood circuit 140, the pressure in the lines 104,
106 can correspond to the pressure in the vasculature of the
patient. As a result, the system 100 can determine the venous
pressure in the vasculature of the patient with the sensors
124.
VARIOUS NOTES
[0148] Aspect 1 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a variable-speed blood pump configured to pump blood in
a withdrawal line, through a filter, and into an infusion line,
wherein: the withdrawal line and the infusion line are configured
to couple with a catheter, and the catheter is configured for
insertion into a blood stream of the patient; the withdrawal line
and the infusion line are configured to couple with the filter, and
the filter is configured to reduce an amount of one or more plasma
constituents in blood flowing through the filter and provide a
filtrate fluid including the plasma constituents; a variable speed
filtration pump configured to extract the filtrate fluid from the
filter; and a controller including processing circuitry, wherein
the controller is configured to: control the speed of the blood
pump to vary a flow rate of the blood through the filter; control
the speed of the filtration pump to vary the extraction rate of the
filtrate fluid from the filter; determine a venous pressure of the
patient; and provide a notification of the venous pressure of the
patient.
[0149] In Aspect 2, the subject matter of Aspect 1 optionally
includes wherein determining the venous pressure of the patient
includes controlling the speed of the blood pump to stop the blood
pump.
[0150] In Aspect 3, the subject matter of Aspect 2 optionally
includes a first pressure sensor in communication with the
withdrawal line and a second pressure sensor in communication with
the infusion line, wherein determining the venous pressure of the
patient includes determining a pressure differential between the
first pressure sensor and the second pressure sensor, and providing
the notification when the pressure differential exceeds a pressure
differential threshold.
[0151] In Aspect 4, the subject matter of any one or more of
Aspects 1-3 optionally include wherein the controller is configured
to determine a hematocrit value of the patient, and the controller
is further configured to set the extraction rate of filtrate fluid
from the filter using the determined hematocrit value of the
patient.
[0152] In Aspect 5, the subject matter of Aspect 4 optionally
includes wherein determining the hematocrit value of the patient
includes: controlling the speed of the blood pump and setting the
flow rate of blood through the filter at a first blood flow rate;
controlling the speed of the blood pump and setting the flow rate
of blood through the filter at a second blood flow rate, wherein
the first blood flow rate is different than the second blood flow
rate; and determining the hematocrit at the second blood flow
rate.
[0153] In Aspect 6, the subject matter of Aspect 5 optionally
includes wherein determining the hematocrit value of the patient
includes controlling the speed of the pump and setting the flow
rate of blood through the filter at the first rate after
determining the hematocrit value of the patient.
[0154] In Aspect 7, the subject matter of any one or more of
Aspects 4-6 optionally include wherein the controller is configured
to determine a red blood cell volume of the blood of the patient
using the hematocrit value of the patient.
[0155] In Aspect 8, the subject matter of Aspect 7 optionally
includes wherein determining the red blood cell volume of the blood
of the patient includes: controlling a speed of the filtration pump
by changing a filtration rate from a first filtration rate to a
second filtration rate; determining a first rate of change of an
inverse of the hematocrit value of the patient corresponding to the
hematocrit value of the patient at the first filtration rate;
determining a second rate of change of an inverse of the hematocrit
value of the patient corresponding to the hematocrit value of the
patient at the second filtration rate; and determining a difference
between the first rate of change and the second rate of change.
[0156] In Aspect 9, the subject matter of any one or more of
Aspects 7-8 optionally include wherein the controller is configured
to: determine a filtrate fluid extraction volume corresponding to a
volume of filtrate fluid extracted from the patient, wherein the
filtrate fluid extraction volume is determined using the determined
red blood cell volume; and determine a plasma refill rate of the
patient according to the determined hematocrit value of the patient
and the determined filtrate fluid extraction volume.
[0157] In Aspect 10, the subject matter of any one or more of
Aspects 1-9 optionally include wherein determining the venous
pressure of the patient includes compensating for a pressure head
in the withdrawal line or the infusion line.
[0158] In Aspect 11, the subject matter of Aspect 10 optionally
includes a first pressure sensor in communication with the
withdrawal line and configured to measure the pressure in the
withdrawal line, wherein the first pressure sensor is located
remote from a catheter tip of the withdrawal line, and the
controller is configured to determine the venous pressure of the
patient at the catheter tip by compensating for the pressure head
in the withdrawal line between the catheter tip and the first
pressure sensor.
[0159] In Aspect 12, the subject matter of any one or more of
Aspects 1-11 optionally include a blood circuit configured to
couple with the blood filtration system, the blood circuit
including the catheter, the withdrawal line, and infusion line; an
activation key coupled with a portion of the blood circuit, wherein
the activation key is in communication with the controller, and the
controller provides an activated characteristic to the activation
key when the blood circuit is coupled to the blood filtration
system.
[0160] In Aspect 13, the subject matter of Aspect 12 optionally
includes wherein the controller is configured to provide an
expiration characteristic to the activation key after a specified
time period from when the controller provided the activated
characteristic to the activation key, and providing the activation
key with the expiration characteristic inhibits operation of the
blood filtration system.
[0161] Aspect 14 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a variable-speed blood pump configured to pump blood in
a withdrawal line, through a filter, and into an infusion line,
wherein: the withdrawal line and the infusion line are configured
to couple with a catheter, and the catheter is configured for
insertion into a blood stream of the patient; a controller
including processing circuitry, wherein the controller is
configured to: determine a withdrawal line resistance
characteristic of the withdrawal line using a first pressure sensor
in communication with the withdrawal line, the withdrawal line
resistance characteristic corresponding to an amount of resistance
to a flow of blood through the withdrawal line; determine an
infusion line resistance characteristic of the infusion line using
a second pressure sensor in communication with the infusion line,
the infusion line resistance characteristic corresponding to an
amount of resistance to a flow of blood through the infusion line;
and provide a notification of one or more of the withdrawal line
resistance characteristic or the infusion line resistance
characteristic.
[0162] In Aspect 15, the subject matter of Aspect 14 optionally
includes wherein the controller is configured to: determine a
hematocrit value of the patient; determine a hemoconcentration
resistance characteristic of the blood according to the determined
hematocrit value of the patient, wherein the withdrawal line
resistance characteristic or the infusion line resistance
characteristic correspond in part to the hemoconcentration
characteristic; and determine an occlusion resistance
characteristic by subtracting the hemoconcentration resistance
characteristic from the withdrawal line resistance characteristic
or from the infusion line resistance characteristic.
[0163] In Aspect 16, the subject matter of Aspect 15 optionally
includes wherein the notification of the one or more of the
withdrawal line resistance characteristic or the infusion line
resistance characteristic includes the occlusion resistance
characteristic.
[0164] In Aspect 17, the subject matter of any one or more of
Aspects 15-16 optionally include wherein the controller is
configured to provide a notification of the occlusion resistance
characteristic.
[0165] In Aspect 18, the subject matter of any one or more of
Aspects 15-17 optionally include wherein determining the hematocrit
value of the patient includes: controlling the speed of the blood
pump and setting a flow rate of blood through the filter at a first
blood flow rate; controlling the speed of the blood pump and
setting the flow rate of blood through the filter at a second blood
flow rate, wherein the first blood flow rate is different than the
second blood flow rate; and determining the hematocrit at the
second blood flow rate.
[0166] In Aspect 19, the subject matter of any one or more of
Aspects 14-18 optionally include wherein the controller is
configured to: compare the infusion line resistance or the
withdrawal line resistance to a resistance threshold; reduce a
filtration rate or increase the blood flow rate if the withdrawal
line resistance or the infusion line resistance exceeds the
resistance threshold.
[0167] In Aspect 20, the subject matter of any one or more of
Aspects 14-19 optionally include wherein the withdrawal line and
the infusion line are configured to be in communication with the
filter, and the filter is configured to reduce an amount of one or
more plasma constituents in blood flowing through the filter and
provide a filtrate fluid including the plasma constituents.
[0168] In Aspect 21, the subject matter of Aspect 20 optionally
includes wherein the controller is further configured to: control
the speed of a filtration pump to vary the extraction rate of the
filtrate fluid from the filter; vary the extraction rate from a
first specified extraction rate; wait for a specified time period;
monitor the withdrawal line resistance characteristic or the
infusion line resistance characteristic; and provide a notification
if the infusion line resistance characteristic or the withdrawal
line resistance characteristic increases after the specified time
period.
[0169] In Aspect 22, the subject matter of any one or more of
Aspects 20-21 optionally include wherein the controller is
configured to: vary a filtration rate for reducing the plasma
constituents in the blood; wait for a specified time period;
monitor the withdrawal line resistance or the infusion line
resistance, and operate a harvesting pump to extract filtrate fluid
from a filtrate reservoir and inject the filtrate fluid into an
inlet of the filter to dilute the blood flowing through the
filter.
[0170] In Aspect 23, the subject matter of any one or more of
Aspects 14-22 optionally include wherein the controller is
configured to: determine a venous pressure of the patient by
determining a pressure differential between the first pressure
sensor and the second pressure sensor; and provide a notification
when the pressure differential exceeds a pressure differential
threshold.
[0171] In Aspect 24, the subject matter of Aspect 23 optionally
includes wherein determining the venous pressure of the patient
includes compensating for a pressure head in the withdrawal
line.
[0172] In Aspect 25, the subject matter of Aspect 24 optionally
includes a first pressure sensor in communication with the
withdrawal line and configured to measure the pressure in the
withdrawal line, wherein the first pressure sensor is located
remote from a catheter tip of the withdrawal line, and the
controller is configured to determine the venous pressure of the
patient at the catheter tip by compensating for the pressure head
in the withdrawal line between the catheter tip and the first
pressure sensor.
[0173] In Aspect 26, the subject matter of any one or more of
Aspects 14-25 optionally include wherein the controller is further
configured to determine a blood flow rate of the blood flowing
through the filter.
[0174] Aspect 27 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a controller including processing circuitry, wherein
the controller is configured to: determine a filter resistance of a
filter, wherein the filter is configured to reduce an amount of one
or more plasma constituents in blood flowing through the filter and
provide a filtrate fluid including the plasma constituents;
determine if the filter resistance of the filter exceeds a first
filter resistance threshold; operate a harvesting pump to extract
filtrate fluid from a filtrate reservoir and inject the filtrate
fluid into an inlet of the filter to dilute the blood flowing
through the filter; monitor the filter resistance of the filter;
and operate the harvesting pump to stop injecting filtrate fluid
into the inlet of the filter when the filter resistance exceeds a
second filter resistance threshold.
[0175] In Aspect 28, the subject matter of Aspect 27 optionally
includes wherein the controller is further configured to determine
a blood flow rate of the blood flowing through the filter.
[0176] In Aspect 29, the subject matter of Aspect 28 optionally
includes wherein the controller is further configured to: determine
if the blood flow rate exceeds a first flow rate threshold; operate
the harvesting pump to inject filtrate fluid into the inlet of the
filter; monitor the blood flow rate; and operate the harvesting
pump to stop injecting filtrate fluid into the inlet of the filter
when the blood flow rate exceeds a second flow rate threshold.
[0177] In Aspect 30, the subject matter of any one or more of
Aspects 27-29 optionally include wherein the controller is further
configured to: monitor a rate of change of the filter resistance;
compare the rate of change of the filter resistance to a rate of
change threshold.
[0178] In Aspect 31, the subject matter of any one or more of
Aspects 27-30 optionally include wherein the controller is
configured to: determine a withdrawal line resistance
characteristic of the withdrawal line using a first pressure sensor
in communication with the withdrawal line, the withdrawal line
resistance characteristic corresponding to an amount of resistance
to a flow of blood through the withdrawal line; determine an
infusion line resistance characteristic of the infusion line using
a second pressure sensor in communication with the infusion line,
the infusion line resistance characteristic corresponding to an
amount of resistance to a flow of blood through the infusion line;
and provide a notification of one or more of the withdrawal line
resistance characteristic or the infusion line resistance
characteristic.
[0179] In Aspect 32, the subject matter of Aspect 31 optionally
includes wherein the controller is configured to: determine a
hematocrit value of the patient; determine a hemoconcentration
resistance characteristic of the blood according to the determined
hematocrit value of the patient, wherein the withdrawal line
resistance characteristic or the infusion line resistance
characteristic correspond in part to the hemoconcentration
characteristic; and determine an occlusion resistance
characteristic by subtracting the hemoconcentration resistance
characteristic from the withdrawal line resistance characteristic
or from the infusion line resistance characteristic.
[0180] In Aspect 33, the subject matter of Aspect 32 optionally
includes wherein the notification of the one or more of the
withdrawal line resistance characteristic or the infusion line
resistance characteristic includes the occlusion resistance
characteristic.
[0181] In Aspect 34, the subject matter of any one or more of
Aspects 32-33 optionally include wherein the controller is
configured to provide a notification of the occlusion resistance
characteristic.
[0182] In Aspect 35, the subject matter of any one or more of
Aspects 32-34 optionally include wherein determining the hematocrit
value of the patient includes: controlling a speed of the blood
pump and setting a flow rate of blood through the filter at a first
blood flow rate; controlling the speed of the blood pump and
setting the flow rate of blood through the filter at a second blood
flow rate, wherein the first blood flow rate is different than the
second blood flow rate; and determining the hematocrit at the
second blood flow rate.
[0183] In Aspect 36, the subject matter of any one or more of
Aspects 31-35 optionally include wherein the controller is
configured to: compare the infusion line resistance or the
withdrawal line resistance to a resistance threshold; reduce a
filtration rate or increase a blood flow rate if the withdrawal
line resistance or the infusion line resistance exceeds the
resistance threshold.
[0184] Aspect 37 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a first sensor configured to determine a hematocrit
value of the patient; a second sensor configured to monitor
movement of the patient relative to an initial position of the
patient, a controller including processing circuitry, wherein the
controller is configured to: monitor the hematocrit value of the
patient, determine if the movement of the patient from the initial
position affects the determined hematocrit value of the patient;
and provide a notification if the hematocrit determination is
affected by the movement of the patient.
[0185] In Aspect 38, the subject matter of Aspect 37 optionally
includes wherein: the first sensor includes an accelerometer
coupled with the patient, and the accelerometer is configured to
monitor the movement of the patient by determining acceleration of
a portion of a body of the patient; and determining if the movement
of the patient from the initial position affects the determined
hematocrit value of the patient includes comparing the acceleration
of the portion of the body of the patient to an acceleration
threshold.
[0186] In Aspect 39, the subject matter of any one or more of
Aspects 37-38 optionally include wherein: the first sensor includes
an accelerometer coupled with the patient, and the accelerometer is
configured to monitor the movement of the patient by determining a
change in position of a portion of a body of the patient; and
determining if the movement of the patient from the initial
position affects the determined hematocrit value of the patient
includes comparing the change in position of the portion of the
body of the patient to a positional threshold.
[0187] In Aspect 40, the subject matter of any one or more of
Aspects 37-39 optionally include wherein: the first sensor includes
an optical sensor coupled with the blood filtration system, and the
optical sensor is configured to monitor the movement of the patient
by observing a patient reference point; and determining if the
movement of the patient from the initial position affects the
determined hematocrit value of the patient includes: determining
the position of the patient reference point relative to the optical
sensor; determining a movement value, wherein the movement value is
equal to a difference between the position of the patient reference
point to the initial position; and comparing the movement value to
a movement threshold.
[0188] In Aspect 41, the subject matter of any one or more of
Aspects 37-40 optionally include wherein: the first sensor includes
a pressure sensor in communication with a blood stream of the
patient, and the first sensor is configured to monitor a change in
pressure within the blood stream of the patient; determining if the
movement of the patient from the initial position affects the
determined hematocrit value of the patient includes comparing the
change in pressure within the blood stream with a pressure
threshold.
[0189] In Aspect 42, the subject matter of any one or more of
Aspects 37-41 optionally include wherein the controller is further
configured to apply a correction value to the determined hematocrit
value according to the movement of the patient, wherein the
correction value is determined by evaluating a change in the
hematocrit value according to motion of the patient.
[0190] In Aspect 43, the subject matter of any one or more of
Aspects 37-42 optionally include wherein the controller is
configured to determine a venous pressure of the patient using the
hematocrit value of the patient, and determining the venous
pressure of the patient includes compensating for a pressure head
in a withdrawal line or an infusion line.
[0191] In Aspect 44, the subject matter of Aspect 43 optionally
includes a first pressure sensor in communication with the
withdrawal line and configured to measure the pressure in the
withdrawal line, wherein the first pressure sensor is located
remote from a catheter tip of the withdrawal line, and the
controller is configured to determine the venous pressure of the
patient at the catheter tip by compensating for the pressure head
in the withdrawal line between the catheter tip and the first
pressure sensor.
[0192] Aspect 45 is a method for reducing one or more plasma
constituents in blood of a patient, the method comprising:
determining a red blood cell volume of the blood of the patient;
inputting the red blood cell volume into a blood filtration system
configured to a reduce an amount of one or more plasma constituents
in the blood of the patient; and determining a hematocrit value of
the patient, wherein the red blood cell volume is associated with
the hematocrit value of the patient.
[0193] In Aspect 46, the subject matter of Aspect 45 optionally
includes wherein determining the red blood cell volume of the blood
of the patient includes: injecting a tracer into a blood stream of
the patient; and withdrawing one or more blood samples from the
blood stream of the patient.
[0194] In Aspect 47, the subject matter of any one or more of
Aspects 45-46 optionally include wherein determining the red blood
cell volume of the blood of the patient includes, controlling a
speed of a filtration pump configured to extract a filtrate fluid
including one or more plasma constituents from a filter by changing
a filtration rate from a first filtration rate to a second
filtration rate; determining a first rate of change of an inverse
of the hematocrit value of the patient corresponding to the
hematocrit value of the patient at the first filtration rate;
determining a second rate of change of an inverse of the hematocrit
value of the patient corresponding to the hematocrit value of the
patient at the second filtration rate; and determining a difference
between the first rate of change and the second rate of change.
[0195] Aspect 48 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a controller including processing circuitry, wherein
the controller is configured to: monitor a hematocrit value of the
patient; control a speed of one or more pumps to adjust a
filtration fraction, wherein: the filtration fraction includes a
ratio of a filtration rate to a blood flow rate through a filter;
the filtration rate includes a rate that one or more plasma
constituents is extracted from the filter, and the blood flow rate
includes a rate that blood flows through the filter; compare the
hematocrit value to a hematocrit threshold; and maintain the
filtration fraction when the hematocrit value equals the hematocrit
threshold.
[0196] In Aspect 49, the subject matter of Aspect 48 optionally
includes wherein the controller is further configured to control a
speed of a filtration pump to adjust the filtration fraction.
[0197] In Aspect 50, the subject matter of any one or more of
Aspects 48-49 optionally include wherein the controller is further
configured to control a speed of a blood pump to adjust the
filtration fraction.
[0198] Aspect 51 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a controller including processing circuitry, wherein
the controller is configured to: monitor a longitudinal filter
resistance of a filter configured to reduce an amount of one or
more plasma constituents in blood flowing through the filter and
provide a filtrate fluid including the plasma constituents,
monitoring the longitudinal filter resistance including:
determining a first pressure differential between a blood inlet
pressure at an inlet port of the filter and a filtration fluid
pressure at a filtration fluid port of the filter; determining a
ratio of the first pressure differential to a blood flow rate of
the blood flowing through the filter.
[0199] In Aspect 52, the subject matter of Aspect 51 optionally
includes wherein the controller is further configured to: monitor a
transverse resistance of the filter, monitoring the transverse
resistance including: determine a second pressure differential
between a blood outlet pressure at a blood outlet port of the
filter and the filtration fluid pressure; determine a ratio of the
second pressure differential to a filtrate flow rate, wherein the
filtrate flow rate corresponds to a rate that filtrate fluid is
removed from the filter.
[0200] Aspect 53 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a filter configured to reduce an amount of one or more
plasma constituents in blood flowing through the filter and provide
a filtrate fluid including the plasma constituents, wherein the
filter includes: a filter body; a blood inlet port included in the
filter body and configured to couple with a withdrawal line,
wherein the withdrawal line is configured to couple with a catheter
and transmit blood from the patient; a blood outlet port included
in the filter body and configured to couple with an infusion line,
wherein the infusion line is configured to couple with the catheter
and transmit blood to the patient; and a filtrate fluid port
included in the filter body and configured to couple with a harvest
fluid line, wherein the filter is configured to transmit extracted
filtrate fluid to the filtrate fluid port.
[0201] In Aspect 54, the subject matter of Aspect 53 optionally
includes wherein the harvesting port is included in the filter
body.
[0202] In Aspect 55, the subject matter of any one or more of
Aspects 53-54 optionally include wherein the harvesting port is
coupled with the blood inlet port.
[0203] In Aspect 56, the subject matter of any one or more of
Aspects 53-55 optionally include the catheter configured for
insertion into a blood stream of the patient.
[0204] Aspect 57 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a withdrawal line configured to couple with a catheter
and transmit blood from the patient, the withdrawal line in
communication with a first valve configured to stop blood flow in
the withdrawal line; an infusion line configured to couple with the
catheter and transmit blood to the patient, the infusion line in
communication with a second valve configured to stop blood flow in
the infusion line; a filtration line configured to transmit a
filtrate fluid including the one or more plasma constituents, the
filtration line in communication with a third valve configured to
stop flow of the filtrate fluid in the filtration line; a filter
configured to reduce an amount of the one or more plasma
constituents in blood flowing through the filter and provide
filtrate fluid including the plasma constituents, the filter
including: a filter body; a blood inlet port included in the filter
body and configured to couple with a withdrawal line, the blood
inlet port in communication with a fourth valve configured to stop
flow of blood from the blood inlet port; a blood outlet port
included in the filter body and configured to couple with the
infusion line, the blood outlet port in communication with a fifth
valve configured to stop flow of blood from the blood outlet port;
and a filtrate fluid port included in the filter body and
configured to couple with the filtration line, wherein the filter
is configured to transmit the filtrate fluid to the filtrate fluid
port, and the filtrate fluid port is in communication with a sixth
valve configured to stop flow of filtrate fluid from the filtrate
fluid port.
[0205] In Aspect 58, the subject matter of Aspect 57 optionally
includes a harvesting port configured to receive filtrate fluid
from the filtrate fluid port, the harvesting port in communication
with the blood inlet port and a seventh valve, the seventh valve
configured to stop flow of filtrate fluid or blood from the
harvesting port.
[0206] Aspect 59 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a blood pump in communication with a blood reservoir; a
filtration pump configured to couple with a filter, wherein the
filter is configured to reduce an amount of one or more plasma
constituents in blood flowing through the filter and provide a
filtrate fluid including the plasma constituents; and a controller
including processing circuitry, wherein the controller is
configured to: control the blood pump to operate the blood pump in
a first flow direction to transmit blood from the patient into the
blood reservoir; control the blood pump to transmit blood from the
blood reservoir to the filter, controlling the blood pump to
transmit blood from the blood reservoir includes operating the
blood pump in a second flow direction; and control the filtration
pump to extract filtration fluid from the filter and transmit the
extracted filtration fluid to a filtrate fluid reservoir.
[0207] In Aspect 60, the subject matter of Aspect 59 optionally
includes a withdrawal line configured to couple with a catheter,
the withdrawal line including at least one check valve, the at
least one check valve configured to provide unidirectional flow of
blood within the withdrawal line.
[0208] In Aspect 61, the subject matter of Aspect 60 optionally
includes wherein the at least one check valve is configured to
prevent blood from flowing to the catheter when the blood pump
transmits blood from the blood reservoir to the filter.
[0209] In Aspect 62, the subject matter of any one or more of
Aspects 59-61 optionally include wherein the blood pump is a
peristaltic pump.
[0210] Aspect 63 is a blood filtration system for reducing one or
more plasma constituents in blood of a patient, the system
comprising: a controller including processing circuitry, wherein
the controller is configured to: control a speed of a blood pump in
communication with the controller, to vary a flow rate of blood
through a filter to reduce an amount of one or more plasma
constituents in blood flowing through the filter and provide a
filtrate fluid including the plasma constituents; control the speed
of a harvest pump to vary an extraction rate of filtrate fluid from
a filtrate reservoir; determine a venous pressure of the patient,
and provide a notification of the venous pressure of the
patient.
[0211] Aspect 64 can include or use, or can optionally be combined
with any portion or combination of any portions of any one or more
of Aspects 1 through 63 to include or use, subject matter that can
include means for performing any one or more of the functions of
Aspects 1 through 63, or a machine-readable medium including
instructions that, when performed by a machine, cause the machine
to perform any one or more of the functions of Aspects 1 through
63.
[0212] The above description includes references to the
accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention can be practiced. These
embodiments are also referred to herein as "examples." Such
examples can include elements in addition to those shown or
described. However, the present inventors also contemplate examples
in which only those elements shown or described are provided.
Moreover, the present inventors also contemplate examples using any
combination or permutation of those elements shown or described (or
one or more aspects thereof), either with respect to a particular
example (or one or more aspects thereof), or with respect to other
examples (or one or more aspects thereof) shown or described
herein.
[0213] In the event of inconsistent usages between this document
and any documents so incorporated by reference, the usage in this
document controls.
[0214] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one,
independent of any other instances or usages of "at least one" or
"one or more." In this document, the term "or" is used to refer to
a nonexclusive or, such that "A or B" includes "A but not B," "B
but not A," and "A and B," unless otherwise indicated. In this
document, the terms "including" and "in which" are used as the
plain-English equivalents of the respective terms "comprising" and
"wherein." Also, in the following claims, the terms "including" and
"comprising" are open-ended, that is, a system, device, article,
composition, formulation, or process that includes elements in
addition to those listed after such a term in a claim are still
deemed to fall within the scope of that claim. Moreover, in the
following claims, the terms "first," "second," and "third," etc.
are used merely as labels, and are not intended to impose numerical
requirements on their objects.
[0215] Geometric terms, such as "parallel", "perpendicular",
"round", or "square", are not intended to require absolute
mathematical precision, unless the context indicates otherwise.
Instead, such geometric terms allow for variations due to
manufacturing or equivalent functions. For example, if an element
is described as "round" or "generally round," a component that is
not precisely circular (e.g., one that is slightly oblong or is a
many-sided polygon) is still encompassed by this description.
[0216] Method examples described herein can be machine or
computer-implemented at least in part. Some examples can include a
computer-readable medium or machine-readable medium encoded with
instructions operable to configure an electronic device to perform
methods as described in the above examples. An implementation of
such methods can include code, such as microcode, assembly language
code, a higher-level language code, or the like. Such code can
include computer readable instructions for performing various
methods. The code can form portions of computer program products.
Further, in an example, the code can be tangibly stored on one or
more volatile, non-transitory, or non-volatile tangible
computer-readable media, such as during execution or at other times
Examples of these tangible computer-readable media can include, but
are not limited to, hard disks, removable magnetic disks, removable
optical disks (e.g., compact disks and digital video disks),
magnetic cassettes, memory cards or sticks, random access memories
(RAMs), read only memories (ROMs), and the like.
[0217] The above description is intended to be illustrative, and
not restrictive. For example, the above-described examples (or one
or more aspects thereof) can be used in combination with each
other. Other embodiments can be used, such as by one of ordinary
skill in the art upon reviewing the above description. The Abstract
is provided to comply with 37 C.F.R. .sctn. 1.72(b), to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. Also, in the
above Detailed Description, various features can be grouped
together to streamline the disclosure. This should not be
interpreted as intending that an unclaimed disclosed feature is
essential to any claim. Rather, inventive subject matter can lie in
less than all features of a particular disclosed embodiment. Thus,
the following claims are hereby incorporated into the Detailed
Description as examples or embodiments, with each claim standing on
its own as a separate embodiment, and it is contemplated that such
embodiments can be combined with each other in various combinations
or permutations. The scope of the invention should be determined
with reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled.
* * * * *