Note: Descriptions are shown in the official language in which they were submitted.
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System and Method for Collecting Plasma
Priority
[0001] This patent application claims priority from United States Patent
Application No. 15/793,339, entitled "System and Method for Collecting
Plasma," filed
October 25, 2017, attorney docket number 130670-08003 (formerly 1611/C86), and
naming Michael Ragusa as inventor, the disclosure of which is incorporated
herein, in its
entirety, by reference.
[0002] United States Application No. 15/793,339, in turn, is a continuation-in-
part of and claims priority from all priority dates of U.S. Patent Application
No.
15/608,183, entitled "System and Method for Collecting Plasma," filed May 30,
2017,
attorney docket number 130670-08002 (formerly 1611/C80), and naming Michael
Ragusa as inventor, the disclosure of which is incorporated herein, in its
entirety, by
reference.
Technical Field
[0003] The present invention relates to systems and methods for blood
apheresis,
and more particularly system and methods for collecting a plasma product.
Background Art
[0004] Apheresis is a procedure in which individual blood components can be
separated and collected from whole blood temporarily withdrawn from a subject.
Typically, whole blood is withdrawn through a needle inserted into a vein of
the subjects
arm and into a cell separator, such as a centrifugal bowl. Once the whole
blood is
separated into its various components, one or more of the components (e.g.,
plasma) can
be removed from the centrifugal bowl. The remaining components can be returned
to the
subject along with optional compensation fluid to make up for the volume of
the removed
component. The process of drawing and returning continues until the quantity
of the
desired component has been collected, at which point the process is stopped. A
central
feature of apheresis systems is that the processed but unwanted components are
returned
to the donor. Separated blood components may include, for example, a high
density
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component such as red blood cells, an intermediate density component such as
platelets
or white blood cells, and a lower density component such as plasma.
[0005] Many jurisdictions have regulations regarding the amount of whole blood
and/or blood components that can be removed from a donor. For example, the
U.S. Food
and Drug Administration ("the FDA") sets both an upper limit on the volume of
plasma
that may be collected (e.g., 800 ml for an adult weighing more than 175
pounds) as well
as an upper limit on the total collection volume (e.g., 880 ml for an adult
weighing more
than 175 pounds). Prior art plasma collection systems are unable to determine
the total
volume of plasma that has been collected (e.g., because the product collected
is a mixture
of plasma and anticoagulant) and, therefore collect based on the total
collection volume,
even if the total volume of plasma that has been collected is below the limit
prescribed by
the FDA. Additionally, prior art collection systems do not tailor the amount
of plasma
collected to the individual (e.g., other than what weight group they fall
into) and,
therefore, the percentage of the patient's plasma that is collected varies
widely from
patient to patient (e.g., only 23% percent of the plasma is collected for some
patients and
29% - or greater ¨ of the plasma is collected for others).
Summary of the Invention
[0006] In accordance with some embodiments of the present invention, a method
for collecting plasma includes determining the weight and hematocrit of a
donor, and
inserting a venous-access device into the donor. Once the venous access device
is
inserted, the method may withdraw whole blood from the donor through the
venous-
access device and a draw line that is connected to a blood component
separation device.
The method may then introduce anticoagulant into the withdrawn whole blood
through an
anticoagulant line and separate, using the blood component separation device,
the
withdrawn whole blood into a plasma component and at least a second blood
component.
Once separated, the plasma component may be collected from the blood component
separation device and into a plasma collection container. During processing,
the method
may calculate (1) a percentage of anticoagulant in the collected plasma
component, and
(2) a volume of pure plasma collected within the plasma collection container.
The volume
of pure plasma may be based, at least in part, on the calculated percentage of
anticoagulant in the collected plasma component. The method may continue the
process
(e.g., withdrawing whole blood, introducing anticoagulant into the whole
blood,
separating the blood, collecting the plasma, and calculating the percentage of
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anticoagulant and volume of pure plasma) until a target volume of pure plasma
is
collected within the plasma collection container.
[0007] In some embodiments, the method may determine a change in volume
within an anticoagulant container, and the calculated percentage of
anticoagulant in the
collected plasma may be based, at least in part, on the change in volume
within the
anticoagulant container. Additionally or alternatively, the method may
determine a
volume of anticoagulant introduced into the whole blood based on a number of
rotations
of an anticoagulant pump. In such embodiments, the calculated percentage of
anticoagulant in the collected plasma may be based, at least in part, on the
number of
rotations of the anticoagulant pump. The method may also determine a volume of
anticoagulant within the blood component separation device, and the calculated
percentage of anticoagulant in the collected plasma may be based, at least in
part, on the
volume of anticoagulant within the blood component separation device.
[0008] In further embodiments, the method may monitor the volume and/or
weight of the plasma component collected within the plasma collection
container (e.g.,
using a weight sensor), and the calculated volume of pure plasma collected
within the
plasma collection device may be based, at least in part, on the monitored
volume and/or
weight of the collected plasma component. Additionally or alternatively,
determining the
hematocrit of the donor may include monitoring a volume of red blood cells
collection
within the blood separation device. In such embodiments, the determined
hematocrit of
the donor may be based, at least in part, on the monitored volume of red blood
cells
collected within the blood separation device and the volume of whole blood
withdrawn
from the donor.
[0009] The target volume of pure plasma may be based, at least in part, on the
weight of the donor. The percentage of anticoagulant in the collected plasma
component
may include at least a portion of the anticoagulant introduced into the
withdrawn blood
and at least a portion of a volume of anticoagulant that is added to the
system during a
priming step. After collecting at least a portion of the target volume of pure
plasma, the
method may return the second blood component to the donor through a return
line.
[0010] In accordance with additional embodiments, a system for collecting
plasma includes a venous-access device for drawing whole blood from a subject
and
returning blood components to the subject, and a blood component separation
device for
separating the drawn blood into a plasma component and a second blood
component. The
blood component separation device has an outlet and is configured to send the
plasma
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component to a plasma container. The system may also include a blood draw line
fluidly
connected to the venous-access device and an anticoagulant line connected to
an
anticoagulant source. The blood draw line transports drawn whole blood to the
blood
component separation device, and the flow through the blood draw line may be
controlled
by a blood draw pump. The anticoagulant line may introduce anticoagulant into
the
drawn whole blood.
[0011] Additionally, the system may include a controller that controls the
operation of the centrifuge bowl. The controller may also calculate (1) a
percentage of
anticoagulant in the collected plasma component, and (2) a volume of pure
plasma
collected within the plasma container. The volume of pure plasma may be based,
at least
in part, upon the percentage of anticoagulant in the collected plasma
component. The
controller may stop the blood draw pump when a target volume of pure plasma
(e.g.,
based, at least in part, on the weight of the donor) is collected within the
plasma
container. In some embodiments, the percentage of anticoagulant in the
collected plasma
component may be based, at least in part, on the volume of anticoagulant added
to the
drawn whole blood and the subject's hematocrit.
[0012] The system may also include an anticoagulant source weight sensor that
measures the weight of the anticoagulant source. The controller may monitor
the change
in volume within the anticoagulant container based on the measured weight of
the
anticoagulant source, and the calculated percentage of anticoagulant in the
collected
plasma may be based, at least in part, on the change in volume within the
anticoagulant
source. Additionally or alternatively, the controller may monitor the number
of rotations
of an anticoagulant pump to determine a volume of anticoagulant introduced
into the
whole blood. In such embodiments, the calculated percentage of anticoagulant
in the
collected plasma may be based, at least in part, on the number of rotations of
the
anticoagulant pump.
[0013] In some embodiments, the system may include an optical sensor located
on the blood component separation device. The optical sensor may monitor the
contents
of the blood component separation device and determine if a volume of
anticoagulant
remains within the blood component separation device. The calculated
percentage of
anticoagulant in the collected plasma may be based, at least in part, on the
volume of
anticoagulant within the blood component separation device.
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[0014] In additional embodiments, the system may also include a plasma
container weight sensor that monitors a volume and/or weight of the plasma
component
collected within the plasma collection container. The calculated volume of
pure plasma
collected within the plasma collection container may be based, at least in
part, on the
monitored volume and/or weight of collected plasma component. The system may
also
have an optical sensor located on the blood component separation device. The
optical
sensor may monitor the volume of red blood cells collected within the blood
separation
device. The controller may then determine the subject's hematocrit based, at
least in part,
upon on the monitored volume of red blood cells collected within the blood
separation
device and the volume of whole blood withdrawn from the donor. The percentage
of
anticoagulant in the collected plasma component may include at least a portion
of the
anticoagulant introduced into the withdrawn blood and at least a portion of a
volume of
anticoagulant added to the system during a priming step.
[0015] In accordance with additional embodiments, a method for collecting
plasma determines the weight, height, and hematocrit of a donor, and
calculates a donor
plasma volume based, at least in part, on the weight, height and hematocrit of
the donor.
The method then calculates a target plasma collection volume based, at least
in part, on
the calculated donor plasma volume and a target percentage of plasma (e.g.,
between 26.5
and 29.5 percent of the donor's plasma volume), and withdraws whole blood from
the
donor through the venous-access device and a first line that is connected to a
blood
component separation device. As the whole blood is withdrawn, the method may
introduce anticoagulant into the withdrawn whole blood through an
anticoagulant line.
[0016] The blood component separation device separates the withdrawn whole
blood into a plasma component and at least a second blood component, and the
method
may collect the plasma component from the blood component separation device
and into
a plasma collection container. During processing, the method may calculate a
volume of
pure plasma collected within the plasma collection container. The method
continues the
withdrawing, introduction of anticoagulant, separating, collecting, and
calculating steps
until the volume of pure plasma collected within the plasma collection
container equals
the target plasma collection volume.
[0017] In some embodiments, after collecting at least a portion of the target
plasma collection volume, the method may return the contents of the blood
component
separation device to the donor through the first line. Additionally or
alternatively, the
method may calculate an intravascular deficit based, at least in part on, the
volume of
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pure plasma collected and the volume of the contents of the blood component
separation
device that are returned to the donor. The method may also return a volume of
saline to
the donor to obtain a target intravascular deficit. The target intravascular
deficit may be
between -250 and 500 milliliters (e.g., it may be 0 milliliters or 250
milliliters).The donor
plasma volume may be calculated based, at least in part, on the donor's body
mass index
that, in turn, is calculated based on the donor's weight and height.
[0018] In further embodiments, the method may include calculating a percentage
of anticoagulant in the collected plasma component. In such embodiments, the
volume of
pure plasma may be based, at least in part, on the calculated percentage of
anticoagulant
in the collected plasma component. The calculated percentage of anticoagulant
in the
collected plasma may be based, at least in part, on a change in volume within
the
anticoagulant container, the number of rotations of the anticoagulant pump,
and/or the
volume of anticoagulant within the blood component separation device. The
method may
determine the change in volume within the anticoagulant container, the volume
of
anticoagulant introduced into the whole blood, and/or the volume of
anticoagulant within
the blood component separation device. The percentage of anticoagulant in the
collected
plasma component may include at least a portion of the anticoagulant
introduced into the
withdrawn blood and at least a portion of a volume of anticoagulant added
during a
priming step.
[0019] In some embodiments, the method may include monitoring a volume or
and/or weight of the plasma component collected within the plasma collection
container.
In such embodiments, the calculated volume of pure plasma collected within the
plasma
collection device may be based, at least in part, on the monitored volume
and/or weight
of collected plasma component. To determine the donor's hematocrit, the method
may
monitor the volume of red blood cells collected within the blood separation
device. The
hematocrit of the donor may be based, at least in part, on the monitored
volume of red
blood cells collected within the blood separation device and the volume of
whole blood
withdrawn from the donor.
[0020] In accordance with still further embodiments, a system for collecting
plasma includes a venous-access device for drawing whole blood from a subject
and
returning blood components to the subject, and a blood component separation
device for
separating the drawn blood into a plasma component and a second blood
component. The
blood component separation device may have an outlet and may send the plasma
component to a plasma container. The system may also have a first line and an
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anticoagulant line. The first line may be fluidly connected to the venous-
access device
and may (1) transport drawn whole blood to the blood component separation
device and
(2) return fluid within the blood component separation device to the subject.
The flow
through the first line may be controlled by a first pump. The anticoagulant
line may be
connected to an anticoagulant source and may introduce anticoagulant into the
drawn
whole blood.
[0021] The system may also include a controller that controls the operation of
the
centrifuge bowl and the first pump. The controller may calculate (1) a donor
plasma
volume, (2) a target plasma collection volume, and (3) a volume of pure plasma
collected
within the plasma container. The donor plasma volume may be based, at least in
part, on
a weight and height of the donor and a hematocrit of the donor. The target
plasma
collection volume may be based, at least in part, on the calculated donor
plasma volume
and a target percentage of plasma. The volume of pure plasma collected within
the
plasma container may be based, at least in part, upon a percentage of
anticoagulant in the
collected plasma component. The controller may stop the first pump when the
calculated
volume of pure plasma collected within the plasma collection container equals
the target
plasma collection volume.
[0022] In further embodiments, the controller may return, after collecting at
least
a portion of the target plasma collection volume, fluid remaining within the
blood
component separation device via the first line. Additionally or alternatively,
the controller
may calculate an intravascular deficit based, at least in part on, the volume
of pure plasma
collected and the volume of the contents of the blood component separation
device
returned to the donor. The system may also include a saline line that fluidly
connects to a
saline source and the blood component separation device. The controller may
return a
volume of saline to the donor to obtain a target intravascular deficit (e.g.,
between -250
and 500 milliliters).
[0023] The controller may calculate the donor's body mass index based, at
least
in part, on the weight and height of the donor. The donor plasma volume may,
in turn, be
calculated based, at least in part, on the donor's body mass index. The target
percentage
of plasma may be between 26.5 and 29.5 percent (e.g., 28.5 percent) of the
donor's
plasma volume.
[0024] In additional embodiments, the controller may calculate the percentage
of
anticoagulant in the collected plasma component, for example, based on the
volume of
anticoagulant added to the drawn whole blood, and the subject's hematocrit.
The system
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may also include an anticoagulant source weight sensor that measures the
weight of the
anticoagulant source. The controller may then monitor a change in volume
within the
anticoagulant container based on the measured weight of the anticoagulant
source. The
calculated percentage of anticoagulant in the collected plasma may be based,
at least in
part, on the change in volume within the anticoagulant source. Additionally or
alternatively the controller may monitor a number of rotations of the
anticoagulant pump
to determine the volume of anticoagulant introduced into the whole blood. In
such
embodiments, the calculated percentage of anticoagulant in the collected
plasma may be
based, at least in part, on the number of rotations of the anticoagulant pump.
[0025] The system may also include an optical sensor and/or a plasma container
weight sensor. The optical sensor may be located on the blood component
separation
device and may monitor the contents of the blood component separation device
to
determine if a volume of anticoagulant remains within the blood component
separation
device. The calculated percentage of anticoagulant in the collected plasma may
then be
based, at least in part, on the volume of anticoagulant within the blood
component
separation device. The plasma container weight sensor may monitor a volume
and/or
weight of the plasma component collected within the plasma container. The
calculated
volume of pure plasma collected within the plasma collection device may then
be based,
at least in part, on the monitored volume and/or weight of collected plasma
component.
The optical sensor may also monitor the volume of red blood cells collected
within the
blood separation device, and the controller may determine the subject's
hematocrit based,
at least in part, upon on the monitored volume of red blood cells collected
within the
blood separation device and the volume of whole blood withdrawn from the
donor. The
percentage of anticoagulant in the collected plasma component may include at
least a
portion of the anticoagulant introduced into the withdrawn blood and at least
a portion of
a volume of anticoagulant added during a priming step.
Brief Description of the Drawings
[0026] The foregoing features of the invention will be more readily understood
by
reference to the following detailed description, taken with reference to the
accompanying
drawings, in which:
[0027] Fig. 1 schematically shows a perspective view of a blood processing
system in accordance with some embodiments of the present invention.
[0028] Fig. 2 schematically shows a top view of the blood processing system of
Figure 1, in accordance with some embodiments of the present invention;
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[0029] Fig. 3 schematically shows a disposable set installed within the blood
processing system of Figure 1, in accordance with some embodiments of the
present
invention.
[0030] Fig. 4 is a flowchart depicting a method of collecting plasma, in
accordance with embodiments of the present invention.
[0031] Fig. 5 is a flowchart depicting an alternative method of collecting
plasma,
in accordance with further embodiments of the present invention.
Detailed Description of Specific Embodiments
[0032] Illustrative embodiments of the present invention provide blood
processing
systems and methods for collecting a target volume of pure plasma. The system
and
method calculate a percentage of anticoagulant collected within a plasma
collection
container (e.g., in addition to the plasma that is collected within the
container) based on
the amount of anticoagulant added to the system and the hematocrit of the
donor. The
system/method may then calculate the volume of pure plasma (e.g., plasma
without
anticoagulant) that has been collected within the container. Further
embodiments may
tailor the volume of plasma collected based on the donor's plasma volume and a
target
percentage of plasma to collect. Details of the illustrative embodiments are
discussed
below.
[0033] As shown in Figures 1 and 2, the blood processing system 100 includes a
cabinet 110 that houses the main components of the system 100 (e.g., the non-
disposable
components). Within the cabinet 110, the system 100 may include a first/blood
pump 232
that draws whole blood from a subject, and a second/anticoagulant pump 234
that pumps
anticoagulant through the system 100 and into the drawn whole blood.
Additionally, the
system 100 may include a number of valves that may be opened and/or closed to
control
the fluid flow through the system 100. For example, the system 100 may include
a donor
valve 120 that may open and close to selectively prevent and allow fluid flow
through a
donor line 218 (e.g., an inlet line; Fig. 3), and a plasma valve 130 that
selectively
prevents and allows fluid flow through an outlet/plasma line 222 (Fig. 3).
Some
embodiments may also include a saline valve 135 that selectively prevents and
allows
saline to flow through a saline line 223.
[0034] To facilitate the connection and installation of a disposable set and
to
support the corresponding fluid containers, the system 100 may include an
anticoagulant
pole 150 on which the anticoagulant solution container 210 (Fig. 3) may be
hung, and a
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saline pole 160 on which a saline solution container 217 (Fig. 3) may be hung
(e.g., if the
procedure being performed requires the use of saline). Additionally, in some
applications,
it may be necessary and/or desirable to filter the whole blood drawn from the
subject for
processing. To that end, the system 100 may include blood filter holder 170 in
which the
blood filter (located on the disposable set) may be placed.
[0035] As discussed in greater detail below, apheresis systems 100 in
accordance
with embodiments of the present invention withdraw whole blood from a subject
through
a venous access device 206 (Fig. 3) using the blood pump 232. As the system
100
withdraws the whole blood from the subject, the whole blood enters a blood
component
separation device 214, such as a Latham type centrifuge (other type of
separation
chambers and devices may be used, such as, without limitation, an integral
blow-molded
centrifuge bowl, as described in U.S. Patent Nos. 4,983,158 and 4,943,273,
which are
hereby incorporated by reference). The blood component separation device 214
separates
the whole blood into its constituent components (e.g., red blood cells, white
blood cell,
plasma, and platelets). Accordingly, to facilitate operation of the separation
device 214,
the system 100 may also include a well 180 in which the separation device 214
may be
placed and in which the separation device 214 rotates (e.g., to generate the
centrifugal
forces required to separate the whole blood).
[0036] To allow the user/technician to monitor the system operation and
control/set the various parameters of the procedure, the system 100 may
include a user
interface 190 (e.g., a touch screen device) that displays the operation
parameters, any
alarm messages, and buttons which the user/technician may depress to control
the various
parameters. Additional components of the blood processing system 100 are
discussed in
greater detail below (e.g., in relation to the system operation).
[0037] FIG. 3 is a schematic block diagram of the blood processing system 100
and a disposable collection set 200 (with an inlet disposable set 200A and an
outlet
disposable set 200B) that may be loaded onto/into the blood processing system
100, in
accordance with the present invention. The collection set 200 includes a
venous access
device 206 (e.g., a phlebotomy needle) for withdrawing blood from a donor's
arm 208, a
container of anti-coagulant 210, a centrifugation bowl 214 (e.g., a blood
component
separation device), a saline container 217, and a final plasma collection bag
216. The
blood/inlet line 218 couples the venous access device 206 to an inlet port 220
of the bowl
214, the plasma/outlet line 222 couples an outlet port 224 of the bowl 214 to
the plasma
collection bag 216, and a saline line 223 connects the outlet port 224 of the
bowl 214 to
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the saline container 217. An anticoagulant line 225 connects the anti-
coagulant container
210 to the inlet line 218. In addition to the components mentioned above and
as shown in
Figure 3, the blood processing system 100 includes a controller 226, a motor
228, and a
centrifuge chuck 230. The controller 226 is operably coupled to the two pumps
232 and
234, and to the motor 228, which, in turn, drives the chuck 230. The
controller 226 may
be operably coupled to and in communication with the user interface 190.
[0038] In operation, the disposable collection set 200 (e.g., the inlet
disposable set
200A and the outlet disposable set 200B) may be loaded onto/into the blood
processing
system 100 prior to blood processing. In particular, the blood/inlet line 218
is routed
through the blood/first pump 232 and the anticoagulant line 225 from the anti-
coagulant
container 210 is routed through the anticoagulant/second pump 234. The
centrifugation
bowl 214 may then be securely loaded into the chuck 230. Once the bowl 214 is
secured
in place, the technician may install the outlet disposable set 200B. For
example the
technician may connect a bowl connector 300 to the outlet 224 of the bowl 214,
install
the plasma container 216 into the weight senor 195, run the saline line 223
through valve
135, and run the plasma/outlet line 222 through valve 130 and the line sensor
185. Once
the disposable set 200 is installed and the anticoagulant and saline
containers 210/217 are
connected, the system 100 is ready to begin blood processing.
[0039] Figure 4 is a flowchart depicting an exemplary method of collecting
plasma in accordance with various embodiments of the present invention. Prior
to
connecting the donor to the blood processing device 100, it is beneficial (and
perhaps
necessary in some instances) to obtain/determine some information regarding
the donor,
namely, the donor's weight (Step 410) and hematocrit (Step 415). Not only does
this
information help determine if the individual is a viable donor and the volumes
of blood
components that may be withdrawn/collected (e.g., per the FDA guidelines), the
hematocrit may be used during processing to help collect a target volume of
plasma. The
technician may obtain/determine the donor's weight by weighing the donor
(e.g., on a
scale). To obtain/determine the donor's hematocrit, the technician may draw a
blood
sample from the donor and test the sample of blood. Additionally or
alternatively, as
discussed in greater detail below, the system may determine the hematocrit
during blood
processing. For example, the blood processing device 100 may include a
hematocrit
sensor (not shown) that determines the hematocrit of the blood flowing into
the blood
processing device 100 and/or the system 100 may determine the hematocrit based
on a
volume of red blood cells collected within the bowl 214.
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[0040] Once the lines 222/223 are in place and the technician has determined
the
donor's weight and/or hematocrit (if needed), the user/technician may insert
the venous
access device 206 into the donor's arm 208 (Step 420). Next, the controller
226 activates
the two pumps 232, 234 and the motor 228. Operation of the two pumps 232, 234
causes
whole blood to be drawn from the donor (step 425), anticoagulant from
container 210 to
be introduced into the drawn whole blood (step 430), and the now
anticoagulated whole
blood to be delivered to the inlet port 220 of the bowl 214.
[0041] It should be noted that the anticoagulant line 225 may also include a
bacteria filter (not shown) that prevents any bacteria in the anticoagulant
source 210, the
anticoagulant, or the anticoagulant line 225 from entering the system 100
and/or the
subject. Additionally, the anticoagulant line 225 may include an air detector
140 that
detects the presence of air within the anticoagulant. The presence of air
bubbles within
any of the system 100 lines can be problematic for the operation the system
100 and may
also be harmful to the subject if the air bubbles enter the blood stream.
Therefore, the air
detector may be connected to an interlock that stops the flow within the
anticoagulant line
225 in the event that an air bubble is detected (e.g., by stopping the
anticoagulant pump
234), thereby preventing the air bubbles from entering the subject.
[0042] As the anti-coagulated whole blood is withdrawn from the subject and
contained within the blood component separation device 214, the blood
component
separation device 214 separates the whole blood into several blood components
(Step
435). For example, the blood component separation device 214 may separate the
whole
blood into a first, second, third, and, perhaps, fourth blood component. More
specifically,
the blood component separation device 214 (and the centrifugal forces created
by rotation
of the separation device 214) can separate the whole blood into plasma,
platelets, red
blood cells ("RBC"), and, perhaps, white blood cells ("WBC"). The higher
density
component, i.e., RBC, is forced to the outer wall of the bowl 214 while the
lower density
plasma lies nearer the core. A buffy coat is formed between the plasma and the
RBC.
The buffy coat is made up of an inner layer of platelets, a transitional layer
of platelets
and WBC and an outer layer of WBC. The plasma is the component closest to the
outlet
port and is the first fluid component displaced from the bowl 214 via the
outlet port 224
as additional anticoagulated whole blood enters the bowl 214 through the inlet
port 220.
[0043] As shown in Figure 3, the system 100 may also include an optical sensor
213 that may be applied to a shoulder portion of the bowl 214. The optical
sensor
monitors each layer of the blood components as they gradually and coaxially
advance
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toward the core from the outer wall of the bowl 214. The optical sensor 213
may be
mounted in a position (e.g., within the well 180) at which it can detect the
buffy coat
and/or the red blood cells reaching a particular radius, and the steps of
drawing the whole
blood from the subject/donor and introducing the whole blood into the bowl 12
may be
altered and/or terminated in response to the detection.
[0044] Additionally, in some embodiments, the optical sensor 213 may be used
to
determine the hematocrit of the donor during processing. For example, as the
bowl 214
fills with red blood cells and the optical sensor 213 detects the layer of red
blood cells,
the system 100 (e.g., the controller) can determine the volume of red blood
cells within
bowl 214 based on the location of the red blood cell layer and the fixed/known
bowl
volume. The system 100 may then calculate the donor hematocrit based on the
volume of
red blood cells within the bowl and the volume of whole blood that has been
processed to
that point.
[0045] Once the blood component separation device 214 has separated the blood
into the various components, one or more of the components can be removed from
the
blood component separation device 214. For instance, the plasma may be removed
to a
plasma container 216 (e.g., a plasma bottle) through line 222 (Step 440). As
noted above,
some embodiments of the system 100 may include a weight sensor 195 (Fig. 1)
that
measures the amount of plasma collected. The plasma collection process may
continue
until a target volume of pure plasma (discussed in greater detail below) is
collected within
the plasma collection container 216. Although not shown, if the blood
processing system
100 and/or the disposable set 200 include platelet, red blood cell, and/or
white blood cell
bags, each of the bags/containers may include similar weight sensors (e.g.,
load cells).
[0046] In some embodiments, the system 100 may also include a line sensor 185
(mentioned above) that can determine the type of fluid (e.g., plasma,
platelets, red blood
cells etc.) exiting the blood component separation device 214. In particular,
the line
sensor 185 consists of an LED which emits light through the blood components
leaving
the bowl 214 and a photo detector which receives the light after it passes
through the
components. The amount of light received by the photo detector is correlated
to the
density of the fluid passing through the line. For example, if plasma is
exiting the bowl
214, the line sensor 185 will be able to detect when the plasma exiting the
bowl 214
becomes cloudy with platelets (e.g., the fluid existing the bowl 214 is
changing from
plasma to platelets). The system 100 may then use this information to either
stop the
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removal of blood components from the bowl 214, stop drawing whole blood from
the
subject, or redirect the flow by, for example, closing one valve an opening
another.
[0047] It is important to note that during processing, the osmolarity of the
red
blood cells prevents the anticoagulant introduced into the whole blood from
entering/remaining with the red blood cells (e.g., within the bowl 214).
Rather, the
anticoagulant mixes with the plasma component. Therefore, the anticoagulant
exits the
bowl 214 with the plasma and is collected within collection container 216
along with the
plasma. In other words, the weight of the product measured by the weight senor
195 is the
weight of the plasma, as well as any anticoagulant that is mixed with the
plasma ¨ the
weight provided by the weight sensor 195 is not the weight of pure plasma.
[0048] Additionally, whole blood contains a variable amount of plasma, as
determined by the donor's hematocrit. The hematocrit for typical donors can
vary from
38% to 54%, which means that for 100 ml of whole blood, the volume of plasma
can vary
from 36 to 62 ml. Furthermore, the amount of anticoagulant added to the
withdrawn
whole blood is fixed (e.g., it does not depend on the hematocrit of the
donor), meaning
that the percentage of anticoagulant in the collected plasma may vary from
9.7% to
12.7% for donor hematocrits between 38% to 54%, respectively. Therefore, not
only does
the volume measured by the weight sensor 195 include the volume of
anticoagulant, that
volume of anticoagulant may vary from donor to donor based on the hematocrit.
[0049] As mentioned above, some embodiments of the present invention continue
the blood processing/separation procedure until a target volume of pure plasma
(e.g.,
plasma only ¨ without the volume of any anticoagulant mixed with the plasma
included
in the target volume) is collected within the plasma collection container 216.
To that end,
some embodiments of the present invention may calculate the volume of pure
plasma
within the plasma collection container 216. For example, the technician or the
system 100
(e.g., the controller) may calculate the percentage of anticoagulant within
the collected
plasma (Step 455) (e.g., the plasma contained within the plasma collection
container 216)
based on the amount of anticoagulant added/metered into the whole blood and
the
hematocrit of the donor. The technician and/or system can calculate the
percentage of
anticoagulant according to the following equation, where AC is the amount of
anticoagulant added to the system 100. As noted above, because the osmolarity
of the red
blood cells prevents the anticoagulant from mixing with it, essentially all of
the
anticoagulant exits the bowl 214 and is collected within the plasma collection
container
216 along with the plasma.
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1
/oAC =
1+ (AC ¨ 1)(1 ¨ Hap)
[0050] The amount of anticoagulant that is added to the system 100 can be
determined in a number of ways. For example, the system 100 can base the
amount of
anticoagulant (e.g., the value of "AC" in the above equation) on the
predetermined ratio
of anticoagulant per unit of anticoagulated whole blood. In some embodiments,
the value
of "AC" may be the inverse of the predetermined ratio (e.g., "AC" would be 16
if the
ratio of anticoagulant to anticoagulated whole blood was 1:16). Additionally
or
alternatively, the technician/system 100 can monitor the volume of
anticoagulant added to
the system. In such embodiments, the technician/system can monitor the volume
of
anticoagulant added to the system 100 based on the number of rotations of the
anticoagulant pump (e.g., each rotation of the anticoagulant pump introduces a
set
volume of anticoagulant into the system 100) and/or based on the change in
weight of the
anticoagulant container 210 as measured by a weight sensor (discussed in
greater detail
below).
[0051] Once the technician/system 100 has calculated the percentage of
anticoagulant within the plasma collection container 216, the
technician/system 100 may
then use this information to calculate the volume of pure plasma within the
plasma
collection container 216 (Step 465). For example, the technician/system 100
may
determine the volume of anticoagulant within the container (based on the
percentage of
anticoagulant within the container 216) and subtract this volume from the
total volume of
fluid within the container 216 as measured by the weight sensor 195. The
system 100
may continue to monitor the volume of pure plasma collected within the
container 216
and continue processing whole blood (e.g., continue performing Steps 425, 430,
435, 440,
455, 460 and 465) until a target volume of pure plasma is collected within the
plasma
collection container 216 (Step 470) (e.g., 800 mL for an adult donor weighing
more than
175 pounds or other limit prescribed by the FDA or similar governing body).
[0052] Once the system 100 has collected the target volume of pure plasma
within
the plasma collection container 216, the system 100 can return the remaining
components
(e.g., the components remaining within the bowl 214) to the subject (Step
475). For
example, when all the plasma has been removed and the bowl 214 is full of RBCs
(and
any other blood component not collected), the controller 226 stops the draw of
whole
blood from the subject and reverses the direction of the blood/first pump 232
to draw the
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RBCs (and other components) from the bowl 214 directly back to the subject.
Alternatively, if the system 100 is so equipped, the system may return the
components to
the subject via a dedicated return line.
[0053] In addition to the non-collected blood components (e.g., the components
remaining in the bowl 214), the system 100 may also return saline to the
patient/subject.
The saline may be used as a compensation fluid to make up for the volume of
the blood
component (e.g., plasma) that was removed and collected, and is not being
returned to the
patient. To that end, during the return step (e.g., Step 475), the saline
valve 135 may be
opened to allow saline from the saline container 217 to flow through the
saline line 223
and into the bowl 214 (via outlet 224), where it can be returned to the
patient/donor with
or after the remaining blood components.
[0054] It should be noted that some embodiments may perform some additional
and optional steps to help determine the volume of pure plasma within the
plasma
collection container 216. For example, as mentioned above, some embodiments
may
monitor the change in weight of the anticoagulant container 210 (e.g., as
measured by a
weight sensor/load cell on the anticoagulant container 210) (step 445). This
measurement
provides an indication of the volume of anticoagulant that has been added to
the system
100, and may be used help determine the percentage of anticoagulant within the
plasma
collection container 216. Additionally or alternatively, some embodiments may
similarly,
monitor the change in weight and/or volume of the plasma and anticoagulant
collected
within the plasma collection container 216 (e.g., via weight sensor 195) (step
450). This
measurement may be used to calculate of the total volume of pure plasma
collected
within the plasma collection container 216 (e.g., to obtain the total weight
from which to
subtract the calculated volume of anticoagulant).
[0055] Some embodiments may also (optionally) monitor the volume of
anticoagulant remaining in the bowl 214 (step 460) (e.g., anticoagulant that
did not mix
with the plasma and/or otherwise remained in the bowl). For example, the
system 100
may utilize the optical sensor on the bowl 214 to determine whether any
anticoagulant
remains within the bowl 214. If it does, the method 400/system 100 may modify
the
calculation of the amount of pure plasma collected within the plasma
collection container
(e.g., either increase the calculated amount or decreased the calculated
amount), based on
the volume of anticoagulant remaining within the bowl 214.
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[0056] The various embodiment of the present invention described above provide
numerous benefits over prior art plasma collection systems. In particular, as
noted above,
prior art plasmapheresis devices end plasma collection based on a total volume
of
anticoagulated plasma (e.g., pure plasma plus the added anticoagulant).
Although this is
the easiest method because it requires only that the product collection
container be
weighed, the amount of true product ¨ the pure plasma ¨ is dependent on the
donor's
hematocrit. In other words, prior art systems will collect more plasma from
low
hematocrit donors than from high hematocrit donors because of the variation of
the
percentage of anticoagulant in the product. Various embodiments of the present
invention
address the issues of prior art systems by collecting a standard volume (e.g.,
a target
volume) of pure plasma from each donor. As noted above, embodiments of the
present
invention accomplish this by using knowledge of the donor's hematocrit and the
amount
of anticoagulant collected within the plasma collection container 216 (e.g.,
by counting
pump rotations and/or using scale/weight sensors, etc.) to determine the
percentage of
anticoagulant in the product. Additionally, by stopping the plasma collection
process
based on a volume of pure plasma collected, embodiments of the present
invention are
able to collect a greater volume of plasma as compared to prior art systems
that stop
based on a plasma/anticoagulant mixture.
[0057] Figure 5 shows an alternative method for collecting plasma, using the
system (or similar system) shown within Figures 1-3, that bases the total
volume of
plasma to collect on the individual donor (e.g., based on their height,
weight, hematocrit,
blood volume and/or plasma volume). In a manner similar to that described
above for the
method shown in Figure 4, prior to connecting the donor to the blood
processing device
100, the system/method may obtain/determine some information regarding the
donor,
namely, the donor's weight and height (Step 505) and hematocrit (Step 510).
For
example, the technician may obtain/determine the donor's weight by weighing
the donor
(e.g., on a scale) and the donor's height by measuring the donor. To
obtain/determine the
donor's hematocrit (e.g., in a manner similar to that described above), the
technician may
test a blood sample or the system may determine the hematocrit during blood
processing
using a hematocrit sensor and/or based on the volume of red blood cells
collected within
the bowl 214.
[0058] Using the donor height and weight, and the hematocrit, the system
100/method 500 may calculate the donor's plasma volume (e.g., the volume of
plasma
within the donor's blood) (Step 515). For example, the system 100/method 500
may
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calculate the donor/subject's body mass index ("BMI") using the donor's height
and
weight (e.g., BMI = weight/height2), and then the total blood volume within
the
donor/subject using the calculated BMI (e.g., see Lemmens et al., Estimating
Blood
Volume in Obese and Morbidly Obese Patients, Obesity Surgery, 2006:16, 773-
776, the
subject matter incorporated herein by reference). The total blood volume may
be
calculated using the following equation:
[0059] InBV = 70
1_
v BMIp/22
[0060] In the above equation, InBV is the indexed blood volume (e.g., the
donor's
total blood volume), BMIp is the patient's BMI (e.g., kg/ m2), 22 is the BMI
value (e.g.,
also in kg/m2) for an ideal body weight (IBW), and 70 is the total blood
volume (in
mL/kg) for a donor at their ideal weight (BMI = 22 kg/ m2). Once the system
100 has
calculated the total blood volume within the donor/subject, the system 100
(e.g., the
controller) may then determine/calculate the volume of plasma within the
donor's blood
(Step 515) based, for example, on the donor's hematocrit.
[0061] As mentioned above, the embodiment shown in Figure 5 bases the volume
of plasma to collect on the individual donor. To that end, once the system
100/method
500 has determined the donor's plasma volume, the system 100/method 500 may
then
calculate the target volume of plasma to collect (Step 520). For example, the
system
100/method 500 may multiply the total plasma volume within the patient by a
target
percentage of plasma to collect to obtain the target plasma volume to collect
(e.g., if the
total plasma volume is 2700 ml and the target percentage to collect is 28.5%,
then the
target plasma volume to collect is 769.5 m1). The target percentage of plasma
to collect
may depend on the application and/or the donor, and may be input directly into
the
system 100 (e.g., using the user interface 190) or may be preset from the
factory. In some
embodiments, the target percentage may be between 26.5 and 30%, and preferably
may
be 28.5%. However, in other embodiments, the target percentage may be below
26.5% or
above 30%.
[0062] Once the lines 222/223 are in place and the system 100/method 500 has
calculated the target plasma volume, the user/technician may insert the venous
access
device 206 into the donor's arm 208 (Step 525). Next, in a manner similar to
that
described above for the method shown in Figure 4, the controller 226 activates
the two
pumps 232, 234 and the motor 228. Operation of the two pumps 232, 234 causes
whole
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blood to be drawn from the donor (step 530), anticoagulant from container 210
to be
introduced into the drawn whole blood (step 535), and the now anticoagulated
whole
blood to be delivered to the inlet port 220 of the bowl 214.
[0063] As the anti-coagulated whole blood is withdrawn from the subject and
introduced into the blood component separation device 214, the blood component
separation device 214 separates the whole blood into the respective blood
components
(e.g., into plasma, platelets, RBC, and, perhaps, WBC) (Step 540). As
discussed above,
the higher density component, i.e., RBC, is forced to the outer wall of the
bowl 214 and
the plasma is the component closest to the outlet port and, therefore, is the
first fluid
component displaced from the bowl 214 via the outlet port 224 as additional
anticoagulated whole blood enters the bowl 214 through the inlet port 220.
During
separation and processing, the optical sensor 213 monitors each layer of the
blood
components as they gradually and coaxially advance toward the core from the
outer wall
of the bowl 214, and the steps of drawing the whole blood from the
subject/donor and
introducing the whole blood into the bowl 12 may be altered and/or terminated
in
response to the detection. Additionally, as discussed above, the optical
sensor 213 may be
used to determine the hematocrit of the donor during processing (e.g., if it
is not known
and/or determined prior to the start of processing).
[0064] Once the blood component separation device 214 has separated the blood
into the various components, the plasma may be removed to a plasma container
216 (e.g.,
a plasma bottle) through line 222 (Step 545). As noted above, some embodiments
of the
system 100 may include a weight sensor 195 (Fig. 1) that measures the amount
of plasma
collected. The plasma collection process may continue until the target plasma
collection
volume (discussed in greater detail below) is collected within the plasma
collection
container 216. If equipped with the line sensor 185, the system 100 may then
use the
information from the sensor 185 to either stop the removal of blood components
from the
bowl 214, stop drawing whole blood from the subject, or redirect the flow by,
for
example, closing one valve an opening another.
[0065] As mentioned above, some embodiments of the present invention continue
the blood processing/separation procedure until a target plasma collection
volume is
collected. In order to ensure that this volume does not include the volume of
any
anticoagulant collected within the container 216, the target plasma collection
volume
should only include the volume of pure plasma (e.g., plasma only ¨ without the
volume of
any anticoagulant mixed with the plasma included in the target volume). To
that end and
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in a manner similar to that described above, some embodiments of the present
invention
may calculate the volume of pure plasma within the plasma collection container
216. To
determine the volume of pure plasma, the technician or the system 100 (e.g.,
the
controller) may calculate the percentage of anticoagulant within the collected
plasma
(Step 560) (e.g., the plasma contained within the plasma collection container
216) based
on the amount of anticoagulant added/metered into the whole blood and the
hematocrit of
the donor (see equation provided above). The amount of anticoagulant that is
added to the
system 100 can be determined in any of the ways mentioned above (e.g., based
on the
predetermined ratio of anticoagulant per unit of anticoagulated whole blood,
by
monitoring the volume of anticoagulant added to the system, etc.).
[0066] Once the technician/system 100 has calculated the percentage of
anticoagulant within the plasma collection container 216, the
technician/system 100 may
then use this information to calculate the volume of pure plasma within the
plasma
collection container 216 (Step 570). For example, as discussed above, the
technician/system 100 may determine the volume of anticoagulant within the
container
(based on the percentage of anticoagulant within the container 216) and
subtract this
volume from the total volume of fluid within the container 216 as measured by
the weight
sensor 195. The system 100 may continue to monitor the volume of pure plasma
collected
within the container 216 and continue processing whole blood (e.g., continue
performing
Steps 530, 535, 540, 545, 560, 570 and, possibly, steps 550, 555 and 565)
until the
volume of pure plasma collected within the plasma collection container 216
reaches the
target plasma volume (Step 575) (e.g., as calculated based on the individual
plasma
volume of the donor and the target percentage of plasma to collect).
[0067] Once the system 100 has collected the target plasma volume within the
plasma collection container 216, the system 100 can return the remaining
components
(e.g., the components remaining within the bowl 214) to the subject (Step 580)
by
stopping the draw of whole blood from the subject and reversing the direction
of the
blood/first pump 232 to draw the RBCs (and other components) from the bowl 214
and
back to the subject (e.g., directly via the blood/inlet line 218 or, if so
equipped, via a
dedicated return line.
[0068] It is important to note that, because the system 100/method 500 collect
and
do not return some of the blood components (e.g., the plasma), the volume of
fluid that is
returned to the donor/subject is less than the volume that was removed. This,
in turn,
creates an intravascular deficit that is equal to the amount of plasma
collected (e.g., the
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volume of whole blood removed from the donor minus the volume of plasma
collected/not returned). In instances in which the intravascular deficit is
too large, the
donor is at risk of fainting when the procedure is complete and they get up to
leave the
facility. To reduce the intravascular deficit (and the risk of donor injury),
as noted above,
some embodiments of the present invention return saline to the patient/subject
(Step 585).
The saline may be used as a compensation fluid to make up for the volume of
the blood
component (e.g., plasma) removed. To that end, during the return step (e.g.,
Step 580),
the controller 226 (or the technician) may open the saline valve to allow
saline from the
saline container 217 to flow through the saline line 223 and into the bowl 214
(via outlet
224), where it can be returned to the patient/donor with or after the
remaining blood
components.
[0069] As mentioned above, the volume of plasma that is collected from the
donor varies from donor to donor (e.g., because it is based on the donor's
height, weight,
hematocrit, and blood volume). Therefore, the volume of saline that is
returned to the
donor to reduce the intravascular deficit may similarly be dependent on the
donor. To that
end, when returning the contents of the separation device and the saline
(Steps 580 and
585) to the donor, the system 100/method 500 may calculate the intravascular
deficit
(Step 590) based on the total volume of whole blood removed from the donor and
the
volume of blood components and saline that has been returned (or based on the
volume of
plasma collected and the volume of blood components and saline that have been
returned). The system 100/method 500 may continue returning saline until the
donor's
intravascular deficit reaches a target intravascular deficit (Step 595).
[0070] The target intravascular deficit may be any intravascular deficit that
reduces the donor's risk for fainting and may be the same for each donor. For
example,
the target intravascular deficit may be set to 0 mL or 250 mL for each donor.
Alternatively, like the target plasma volume to collect, the target
intravascular deficit may
be different for each donor. In other words, the target intravascular deficit
may be set to 0
mL for some donors and 250 mL for others. It should be noted that 0 and 250 mL
are
provided as examples only and other embodiments may have target intravascular
deficits
between 0 and 250, or greater than 250 mL. Additionally, in some instances, it
may be
beneficial to return more fluid to the donor than was removed/collected. In
such
instances, the target intravascular deficit may be set less than zero (e.g., -
1 to -250 mL) so
that the donor has more fluid/volume after the procedure than they did before
the
procedure.
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[0071] Like the method 400 shown in Figure 4, the method 500 may similarly
perform some additional and optional steps to help determine the volume of
pure plasma
within the plasma collection container 216. For example, some embodiments may
monitor the change in weight of the anticoagulant container 210 (e.g., as
measured by a
weight sensor/load cell on the anticoagulant container 210) (step 550). This
measurement
provides an indication of the volume of anticoagulant that has been added to
the system
100, and may be used help determine the percentage of anticoagulant within the
plasma
collection container 216. Additionally or alternatively, some embodiments may
similarly,
monitor the change in weight and/or volume of the plasma and anticoagulant
collected
within the plasma collection container 216 (e.g., via weight sensor 195) (step
555). This
measurement may be used to calculate of the total volume of pure plasma
collected
within the plasma collection container 216 (e.g., to obtain the total weight
from which to
subtract the calculated volume of anticoagulant). Also, some embodiments may
also
monitor the volume of anticoagulant remaining in the bowl 214 (step 565)
(e.g.,
anticoagulant that did not mix with the plasma and/or otherwise remained in
the bowl)
using the optical sensor on the bowl 214 to determine whether any
anticoagulant remains
within the bowl 214 and modify the calculation of the amount of pure plasma
collected
within the plasma collection container (e.g., either increase the calculated
amount or
decreased the calculated amount), based on the volume of anticoagulant
remaining within
the bowl 214.
[0072] As noted above, prior art systems that follow the current FDA nomogram
for plasma collection collect a volume of plasma product (e.g., anticoagulant
and plasma
mixed together) based solely on the weight of the donor ¨ the same volume is
collected
from every donor at the same weight. However, the total blood volume and
plasma
volume for two donors may vary greatly. For example, when comparing two donors
in
the same weight grouping according to the FDA nomogram ¨ one obese and one not
obese ¨ the obese donor will effectively have a lower blood volume that the
non-obese
donor. Furthermore, with respect to the total plasma volume, donors with high
hematocrit
will have lower plasma volumes. In other words, because the total blood volume
and total
plasma volume vary from donor to donor (even among donors that weight the
same), the
percentage of the donor's plasma that is ultimately collected may vary widely
from donor
to donor. By tailoring the plasma collection to the donor (e.g., based on the
donor's
height, weight, BMI, hematocrit, total blood volume, and/or total plasma
volume) and
collecting a predetermined percent of plasma from each donor, embodiments of
the preset
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invention are able to collect a greater volume of plasma (e.g., pure plasma)
from some
donors but less plasma from more vulnerable donors (e.g., smaller donors with
high
hematocrit, donors with lower plasma volume, etc.), as compared to systems
that do not
base the collection volume on the individual donor.
[0073] Similarly, current systems do not tailor the saline return volume to
the
patient (e.g., each donor at a given level receives the same volume of saline,
for example,
if the target plasma product volume is 800 mL, the donor will receive 500 mL
of saline).
However, because prior art systems collect based on the volume of the plasma
product
(which includes both plasma and anticoagulant) and the volume of pure plasma
that is
actually collected (and therefore, the volume removed from the donor) varies
based on
the donor hematocrit, the intravascular deficit for each donor will vary. In
other words,
the volume of saline returned to the donor may be sufficient for some, but
insufficient for
others. By tailoring the saline return to the individual donor, embodiments of
the present
invention are able to ensure that each donor has the same intravascular
deficit (if any)
once the procedure is complete. This, in turn, allows embodiments of the
present
invention to achieve isovolemia for each donor and greatly reduce any adverse
reactions
that the donor may experience (e.g., falling, fainting, light-headedness,
vasovagal
reactions, etc.).
[0074] It is also important to note that, although the various embodiments
discussed above are in relation to a blood processing system that collects
plasma, the
features discussed herein may be applied to any type of blood processing
system. For
example, the features described herein may be implemented on blood processing
systems
that collect and/or process red blood cells, platelets and/or white blood
cells.
[0075] The embodiments of the invention described above are intended to be
merely exemplary; numerous variations and modifications will be apparent to
those
skilled in the art. All such
variations and modifications are intended to be within the
scope of the present invention as defined in any appended claims.
23
