阅读说明：本技术 用于收集血浆的系统和方法 (Systems and methods for collecting plasma ) 是由 M·拉古萨 于 2018-05-22 设计创作，主要内容包括：一种用于收集血浆的方法,包含确定供血者的重量和血细胞比容,以及将静脉通路装置插入至所述供血者中。然后,所述方法通过连接至血液成分分离装置的抽吸管线从所述供血者抽取血液,并且将抗凝剂引入至所抽吸的血液中。所述血液成分分离装置将血液分离成血浆成分和第二血液成分,并且所述血浆成分被从所述血液成分分离装置收集至血浆收集容器中。然后,所述方法可以计算(1)所收集的血浆成分中的抗凝剂的百分比,以及(2)所述血浆收集容器内所收集的纯血浆的体积。纯血浆的体积可以至少部分地基于抗凝剂的所计算的百分比。所述方法可以继续直至在所述血浆收集容器内收集到目标体积的纯血浆。(A method for collecting plasma comprising determining a weight and hematocrit of a donor and inserting a venous access device into the donor. The method then draws blood from the donor through a suction line connected to a blood component separation device and introduces anticoagulant into the drawn blood. The blood component separation device separates blood into a plasma component and a second blood component, and the plasma component is collected from the blood component separation device into a plasma collection container. The method may then calculate (1) the percentage of anticoagulant in the collected plasma components, and (2) the 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. The method may continue until a target volume of pure plasma is collected in the plasma collection container.)

1. A method for collecting plasma, comprising:

(a) determining a weight of the donor;

(b) determining the hematocrit of the donor;

(c) inserting a venous access device into the donor;

(d) drawing whole blood from the donor through the venous access device and a suction line connected to a blood component separation device;

(e) introducing an anticoagulant into the drawn whole blood through an anticoagulant line;

(f) separating the drawn whole blood into a plasma component and at least a second blood component using the blood component separation device;

(g) collecting the plasma component from the blood component separation device and collecting the plasma component into a plasma collection container;

(h) calculating the percentage of anticoagulant in the collected plasma fraction;

(i) calculating a volume of pure plasma collected within the plasma collection container based at least in part on the calculated percentage of anticoagulant in the collected plasma components; and

(j) continuing steps (d) through (i) until a target volume of pure plasma is collected in the plasma collection container.

2. The method of claim 1, further comprising:

determining a change in volume within an anticoagulant container, the calculated percentage of anticoagulant in the collected plasma based at least in part on the change in volume within the anticoagulant container.

3. The method of claim 1, further comprising:

determining a volume of anticoagulant introduced into the whole blood based on a number of revolutions of an anticoagulant pump, the calculated percentage of anticoagulant in the collected plasma based at least in part on the number of revolutions of the anticoagulant pump.

4. The method of claim 1, further comprising:

determining a volume of anticoagulant within the blood component separation device, the calculated percentage of anticoagulant in the collected plasma based at least in part on the volume of anticoagulant within the blood component separation device.

5. The method of claim 1, further comprising:

monitoring a volume of the collected plasma constituent within the plasma collection container, the calculated volume of the collected pure plasma within the plasma collection device based at least in part on the monitored volume of the collected plasma constituent.

6. The method of claim 1, further comprising:

monitoring a weight of the collected plasma constituent within the plasma collection container, the calculated volume of pure plasma collected within the plasma collection device based at least in part on the monitored weight of the collected plasma constituent.

7. The method of claim 1 wherein step (b) comprises monitoring the volume of red blood cells collected within the blood separation device, the determined hematocrit of the donor being 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 drawn from the donor.

8. The method of claim 1, wherein the target volume of pure plasma is based at least in part on the weight of the donor.

9. The method of claim 1, wherein the percentage of anticoagulant in the collected plasma constituent comprises at least a portion of the anticoagulant introduced into the drawn blood and at least a portion of the volume of anticoagulant added during the priming step.

10. The method of claim 1, further comprising:

after collecting at least a portion of the target volume of pure plasma, returning the second blood component to the donor through a return line.

11. A system for collecting plasma, comprising:

a venous access device for drawing whole blood from a subject and returning blood components to the subject;

a blood component separation device for separating the drawn blood into a plasma component and a second blood component, the blood component separation device having an outlet and being configured to deliver the plasma component to a plasma container;

a blood suction line fluidly connected to the venous access device and configured to convey the suctioned whole blood to the blood component separation device, flow through the blood suction line being controlled by a blood suction pump;

an anticoagulant line connected to an anticoagulant source, the anticoagulant line configured to introduce anticoagulant into the aspirated whole blood; and

a controller configured to control operation of the centrifuge bowl and the blood draw pump, the controller configured to (1) calculate a percentage of anticoagulant in the collected plasma constituent, and (2) calculate a volume of pure plasma collected within the plasma container based at least in part on the percentage of anticoagulant in the collected plasma constituent, the controller configured to stop the blood draw pump when a target volume of pure plasma is collected within the plasma container.

12. The system of claim 11, wherein the percentage of anticoagulant in the collected plasma component is based at least in part on a volume of anticoagulant added to the aspirated whole blood and a hematocrit of the subject.

13. The system of claim 11, further comprising:

an anticoagulant source weight sensor configured to measure a weight of the anticoagulant source, the controller further configured to monitor a change in volume within an anticoagulant container based on the measured weight of the anticoagulant source, the calculated percentage of anticoagulant in the collected plasma based at least in part on the change in volume within the anticoagulant source.

14. The system of claim 11, wherein the controller is configured to monitor a number of revolutions of an anticoagulant pump to determine a volume of anticoagulant introduced into the whole blood, the calculated percentage of anticoagulant in the collected plasma based at least in part on the number of revolutions of the anticoagulant pump.

15. The system of claim 11, further comprising:

an optical sensor located on the blood component separation device and configured to monitor contents of the blood component separation device and determine whether a volume of anticoagulant remains within the blood component separation device, the calculated percentage of anticoagulant in the collected plasma based at least in part on the volume of anticoagulant within the blood component separation device.

16. The system of claim 11, further comprising:

a plasma container weight sensor configured to monitor a volume of the collected plasma constituent within the plasma container, the calculated volume of pure plasma collected within the plasma collection device based at least in part on the monitored volume of the collected plasma constituent.

17. The system of claim 11, further comprising:

a plasma container weight sensor configured to monitor a weight of the collected plasma constituent within the plasma container, the calculated volume of pure plasma collected within the plasma collection device based at least in part on the monitored weight of the collected plasma constituent.

18. The system of claim 11, further comprising:

an optical sensor located on the blood component separation device and configured to monitor a volume of red blood cells collected within the blood component separation device, the controller configured to determine the hematocrit of the subject based at least in part on the monitored volume of red blood cells collected within the blood component separation device and a volume of whole blood drawn from the donor.

19. The system of claim 11, wherein the target volume of pure plasma is based at least in part on the weight of the donor.

20. A system according to claim 11, wherein the percentage of anticoagulant in the collected plasma constituent comprises at least a portion of the anticoagulant introduced into the drawn blood and at least a portion of the volume of anticoagulant added during the priming step.

Technical Field

The present invention relates to systems and methods for apheresis, and more particularly, to systems and methods for collecting plasma products.

Background

Apheresis is a procedure in which various blood components can be separated and collected from whole blood that is temporarily drawn from a subject. Typically, whole blood is drawn through a needle inserted into a vein and cell separator (such as a centrifugal bowl) of the subject's arm. Once the whole blood is separated into its various components, one or more components (e.g., plasma) may be removed from the centrifugal drum. The remaining components may be returned to the subject with an optional compensation fluid to make up the volume of the removed components. The process of pumping and returning continues until the desired amount of the component has been collected, at which point the process is stopped. The main feature of the separation system is to return the processed but unwanted components to the donor. The separated blood components may contain, for example, high density components, such as red blood cells; medium density components such as platelets or leukocytes; and low density components such as plasma.

Many jurisdictions have regulations on the amount of whole blood and/or blood components that may be removed from a donor. For example, the united states food and drug administration ("FDA") sets an upper limit on the volume of plasma that can be collected (e.g., 800ml for adults weighing more than 175 pounds) and an upper limit on the total collected volume (e.g., 880ml for adults weighing more than 175 pounds). The prior art plasma collection systems are not capable of determining the total volume of plasma that has been collected (e.g., because the collected product is a mixture of plasma and anticoagulant), and therefore are not capable of collecting based on the total collection volume even though the total volume of plasma that has been collected is below the limits set by the U.S. food and drug administration.

Disclosure of Invention

According to some embodiments of the present invention, a method for collecting plasma includes determining a 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 draw whole blood from the donor through the venous access device and a suction line connected to a blood component separation device. The method may then introduce anticoagulant into the drawn whole blood through the anticoagulant line and separate the drawn whole blood into a plasma component and at least a second blood component using the blood component separation device. Once separated, the plasma component may be collected from the blood component separation device into a plasma collection container. During processing, the method may calculate (1) the percentage of anticoagulant in the collected plasma components, and (2) the 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., drawing whole blood, introducing anticoagulant into whole blood, separating blood, collecting plasma, and calculating the percentage of anticoagulant and the volume of pure plasma) until a target volume of pure plasma is collected within the plasma collection container.

In certain 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 the volume of anticoagulant introduced into the whole blood based on a number of revolutions of an anticoagulant pump. In such embodiments, the calculated percentage of anticoagulant in the collected plasma may be based at least in part on a number of revolutions 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.

In further embodiments, the method may monitor the volume and/or weight of the collected plasma constituent within the plasma collection container (e.g., using a weight sensor), and the calculated volume of the collected pure plasma within the plasma collection device may be based at least in part on the monitored volume and/or weight of the collected plasma constituent. Additionally or alternatively, determining the donor's hematocrit may include monitoring the volume of red blood cell 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 drawn from the donor.

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 drawn blood and at least a portion of the volume of anticoagulant added to the system during the 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.

According to further embodiments, a system for collecting plasma includes a venous-access device for drawing whole blood from a subject and returning a blood component 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 deliver the plasma component to a plasma container. The system may also include a blood aspiration line fluidly connected to the venous access device and an anticoagulant line connected to an anticoagulant source. The blood suction line delivers the whole blood drawn to the blood component separation device and flow through the blood suction line may be controlled by a blood suction pump. The anticoagulant line may introduce anticoagulant into the aspirated whole blood.

Additionally, the system may include a controller that controls operation of the centrifuge bowl. The controller may also calculate (1) a percentage of anticoagulant in the collected plasma constituent, and (2) a volume of pure plasma collected within the plasma container. The volume of pure plasma may be based at least in part on a percentage of anticoagulant in the collected plasma constituent. The controller may stop the blood draw pump when a target volume of pure plasma is collected within the plasma container (e.g., based at least in part on the donor's weight). In certain 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 aspirated whole blood and the hematocrit of the subject.

The system may also include an anticoagulant source weight sensor that measures a weight of the anticoagulant source. The controller may monitor a 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 revolutions 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 a number of revolutions of the anticoagulant pump.

In certain 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 whether 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 a volume of anticoagulant within the blood component separation device.

In further embodiments, the system may further comprise a plasma container weight sensor that monitors the volume and/or weight of the plasma constituent 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 plasma constituent collected. 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 hematocrit of the subject 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 drawn from the donor. The percentage of anticoagulant in the collected plasma component may include at least a portion of the anticoagulant introduced into the drawn blood and at least a portion of the volume of anticoagulant added to the system during the priming step.

Drawings

The foregoing features of the invention will be more readily understood by reference to the following detailed description and by reference to the accompanying drawings, in which:

fig. 1 schematically illustrates a perspective view of a blood processing system according to certain embodiments of the present invention.

Fig. 2 schematically illustrates a top view of the blood processing system of fig. 1, according to certain embodiments of the present invention.

Fig. 3 schematically illustrates a disposable set installed in the blood processing system of fig. 1 according to certain embodiments of the present invention.

Fig. 4 is a flow chart illustrating a method of collecting plasma according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Exemplary illustrative embodiments of the present invention provide blood processing systems and methods for collecting a target volume of pure plasma. The systems and methods calculate the percentage of anticoagulant collected within the plasma collection container (e.g., in addition to the plasma collected within the container) based on the amount of anticoagulant added to the system and the donor's hematocrit. The system/method may then calculate the volume of pure plasma (e.g., plasma without anticoagulant) that has been collected within the container. Details of exemplary illustrative embodiments are discussed below.

As shown in fig. 1 and 2, the blood processing system 100 includes a housing 110 that houses the major components (e.g., non-disposable components) of the blood processing system 100. Within the housing 110, the blood processing system 100 may include a first/blood pump 232 that draws whole blood from the subject, and a second/anticoagulant pump 234 that pumps anticoagulant through the blood processing system 100 and into the drawn whole blood. Additionally, the blood processing system 100 may include a plurality of valves that may be opened and/or closed to control the flow of fluid through the blood processing system 100. For example, the blood processing system 100 may include a donor valve 120 that may be opened and closed 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 brine valve 135 that selectively prevents and allows brine flow through the brine line 223.

To facilitate connection and mounting of the disposable set and support of the corresponding fluid container, the blood processing system 100 may include an anticoagulant rod 150 on which an anticoagulant solution container 210 (fig. 3) may be hung, and a saline rod 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 certain applications, it may be necessary and/or desirable to filter whole blood drawn from a subject for processing. To this end, the blood processing system 100 may include a blood filter holder 170 in which a blood filter (located on a disposable set) may be placed.

As discussed in more detail below, the blood processing system 100 according to embodiments of the present invention draws whole blood from a subject through the venous access device 206 (fig. 3) using the blood pump 232. As the blood processing system 100 draws whole blood from a subject, the whole blood enters a blood component separation device 214, such as a lytherum (Latham) type centrifuge (other types of separation chambers and devices may be used, such as, but not limited to, integral blow-molded centrifuge drums as described in U.S. patent nos. 4,983,158 and 4,943,273, which are incorporated herein by reference). The blood component separation device 214 separates the whole blood into its constituent components (e.g., red blood cells, white blood cells, plasma, and platelets). Thus, to facilitate operation of the blood component separation device 214, the blood processing system 100 may further include a hole 180, in which the blood component separation device 214 may be placed in the hole 180 and the blood component separation device 214 rotated (e.g., to generate the centrifugal force required to separate the whole blood).

To enable the user/technician to monitor the operation of the blood processing system and control/set various parameters of the program, the blood processing system 100 may include a user interface 190 (e.g., a touch screen device) that displays operating parameters, any alarm messages, and buttons that the user/technician may press to control various parameters. Additional components of the blood processing system 100 (e.g., with respect to the operation of the blood processing system) are discussed in more detail below.

Fig. 3 is a schematic block diagram of a blood processing system 100 according to the present invention and a disposable collection device 200 (having an inlet disposable device 200A and an outlet disposable device 200B) that may be loaded onto/into the blood processing system 100. The collection apparatus 200 includes a venous access device 206 (e.g., phlebotomy needle) for drawing blood from a donor's arm 208, an anticoagulant container 210, a centrifuge drum 214 (e.g., a blood component separation device), a saline container 217, and a final plasma collection bag 216. A blood/inlet line 218 couples venous access device 206 to inlet port 220 of drum 214, a plasma/outlet line 222 couples outlet port 224 of drum 214 to plasma collection bag 216, and a saline line 223 connects outlet port 224 of drum 214 to saline container 217. Anticoagulant line 225 connects anticoagulant container 210 to inlet line 218. In addition to the components mentioned above and shown in fig. 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 two pumps 232 and 234 and to a motor 228, which in turn drives a chuck 230. The controller 226 may be operably coupled to and in communication with the user interface 190.

In operation, the disposable collection devices 200 (e.g., the inlet disposable device 200A and the outlet disposable device 200B) may be loaded onto/into the blood processing system 100 prior to blood processing. In particular, blood/inlet line 218 is routed through blood pump/first pump 232 and anticoagulant line 225 from anticoagulant container 210 is routed through anticoagulant pump/second pump 234. The centrifuge drum 214 may then be securely loaded into the chuck 230. Once the drum 214 is secured in place, the technician may install the exit disposable 200B. For example, a technician may connect the drum connector 300 to the outlet 224 of the drum 214, install the plasma container 216 into the weight sensor 195, pass the saline line 223 through the valve 135, and pass the plasma/outlet line 222 through the valve 130 and line sensor 185. Once the disposable set 200 is installed and the anticoagulant container 210 and the saline container 217 are connected, the blood processing system 100 is ready to begin blood processing.

Fig. 4 is a flow diagram illustrating an exemplary method of collecting plasma according to various embodiments of the invention. Before connecting the donor to the blood processing apparatus 100, it is beneficial (and in some cases may be desirable) to obtain/determine some information about the donor, i.e., the weight of the donor (step 410) and the hematocrit (step 415). This information not only helps determine whether an individual is a viable donor and the volume of blood components that can be drawn/collected (e.g., according to the U.S. food and drug administration guidelines), but also the hematocrit can be used to help collect a target volume of plasma during processing. The technician may obtain/determine the donor's weight by weighing the donor (e.g., on a scale). To obtain/determine the hematocrit of a donor, a technician may draw a blood sample from the donor and test the blood sample. Additionally or alternatively, as discussed in more detail below, the system may determine 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 blood processing system 100 may determine the hematocrit based on the volume of red blood cells collected within the drum 214.

Once line 222/223 is 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 withdrawn from the donor (step 425), anticoagulant from container 210 is introduced into the withdrawn whole blood (step 430), and now anticoagulated whole blood is passed to inlet port 220 of drum 214.

It should be noted that anticoagulant line 225 may also include a bacterial filter (not shown) that prevents any bacteria in anticoagulant source 210, anticoagulant, or anticoagulant line 225 from entering blood processing 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 lines of the blood processing system 100 may cause problems with the operation of the blood processing system 100 and may also be harmful to the subject in the event that air bubbles enter the bloodstream. Accordingly, the air detector may be connected to an interlock that stops flow within anticoagulant line 225 if an air bubble is detected (e.g., by stopping anticoagulant pump 234), thereby preventing the air bubble from entering the subject.

When anticoagulated whole blood is drawn 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 whole blood into first, second, third, and possibly fourth blood components. More specifically, the blood component separation device 214 (and the centrifugal force created by the rotation of the blood component separation device 214) may separate the whole blood into plasma, platelets, red blood cells ("RBCs"), and possibly white blood cells ("WBCs"). The higher density components (i.e., RBCs) are pushed to the outer wall of drum 214 while the lower density plasma is closer to the center portion. A buffy coat is formed between the plasma and the red blood cells. The buffy coat consists of platelets in the inner layer, platelets and white blood cells in the transition layer, and white blood cells in the outer layer. Plasma is the component closest to the outlet port and is the first fluid component that is discharged from the drum 214 via the outlet port 224 as additional anticoagulated whole blood enters the drum 214 through the inlet port 220.

As shown in fig. 3, blood processing system 100 may also include an optical sensor 213, which may be applied to a shoulder portion of drum 214. The optical sensor monitors each layer of blood components as they progress progressively and coaxially from the outer wall toward the central portion of the drum 214. Optical sensor 213 may be mounted in a location (e.g., within aperture 180) where it can detect buffy coat and/or red blood cells reaching a particular radius, and may alter and/or terminate the steps of drawing whole blood from the subject/donor and introducing whole blood into drum 214 in response to the detection.

Additionally, in certain embodiments, the optical sensor 213 may be used to determine the donor's hematocrit during processing. For example, when the drum 214 is filled with red blood cells and the optical sensor 213 detects a red blood cell layer, the blood processing system 100 (e.g., a controller) can determine the volume of red blood cells within the drum 214 based on the location of the red blood cell layer and the fixed/known drum volume. The blood processing system 100 may then calculate the donor's 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.

Once the blood component separation device 214 has separated the blood into various components, one or more components may be removed from the blood component separation device 214. For example, plasma may be removed via line 222 to plasma container 216 (e.g., a plasma bottle) (step 440). As described above, certain embodiments of the blood processing 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 is collected within the plasma collection container 216 (discussed in more detail below). Although not shown, if the blood processing system 100 and/or the disposable set 200 contains platelet bags, red blood cell bags, and/or white blood cell bags, each bag/container may contain a similar weight sensor (e.g., a load cell).

In certain embodiments, the blood processing system 100 may also include a line sensor 185 (mentioned above) that may determine the type of fluid (e.g., plasma, platelets, red blood cells, etc.) exiting the blood component separation device 214. In particular, line sensor 185 is comprised of a Light Emitting Diode (LED) that emits light through the blood components exiting drum 214 and a photodetector that receives light after it has passed through the blood components. The amount of light received by the photodetector is related to the density of the fluid passing through the pipeline. For example, if plasma is exiting the drum 214, the line sensor 185 will be able to detect when the plasma exiting the drum 214 becomes cloudy due to platelets (e.g., the fluid exiting the drum 214 changes from plasma to platelets). The blood processing system 100 may then use this information to stop removing blood components from the drum 214, stop drawing whole blood from the subject, or redirect flow by, for example, closing one valve and opening another valve.

It is important to note that during processing, the osmotic pressure of the red blood cells prevents the anticoagulant introduced into the whole blood from entering/remaining with the red blood cells (e.g., within drum 214). Instead, the anticoagulant is mixed with the plasma constituent. Thus, the anticoagulant exits the drum 214 with the plasma and is collected with the plasma in the collection container 216. In other words, the weight of the product measured by the weight sensor 195 is the weight of the plasma and any anticoagulant mixed with the plasma, and the weight provided by the weight sensor 195 is not the weight of pure plasma.

In addition, whole blood contains a variable amount of plasma as determined by the donor's hematocrit. The hematocrit of a typical donor may vary between 38% and 54%, meaning that the volume of plasma may vary between 36ml and 62ml for 100ml of whole blood. Furthermore, the amount of anticoagulant added to the drawn whole blood is fixed (e.g., it is not dependent on the donor's hematocrit), which means that for donor hematocrits between 38% and 54%, the percentage of anticoagulant in the collected plasma may vary between 9.7% and 12.7% respectively. Thus, not only does the volume measured by the weight sensor 195 contain the volume of anticoagulant, but that volume of anticoagulant can vary between donors based on hematocrit.

As described above, certain embodiments of the present invention continue the blood processing/separation procedure until a target volume of pure plasma (e.g., a volume of only plasma without any anticoagulant mixed with the plasma contained in the target volume) is collected within the plasma collection container 216. To this end, certain embodiments of the present invention may calculate the volume of pure plasma within the plasma collection container 216. For example, the technician or the blood processing system 100 (e.g., a controller) may calculate the percentage of anticoagulant within the collected plasma (e.g., the plasma contained within the plasma collection container 216) based on the amount of anticoagulant added/metered to the whole blood and the donor's hematocrit (step 455). The technician and/or the system may calculate the percentage of anticoagulant according to the following equation, where AC is the amount of anticoagulant added to the blood processing system 100. As the osmotic pressure of the red blood cells prevents the anticoagulant from mixing with it, substantially all of the anticoagulant exits the drum 214 and is collected with the plasma in the plasma collection container 216, as described above.

The amount of anticoagulant added to the blood processing system 100 may be determined in a number of ways. For example, the blood processing system 100 may base the amount of anticoagulant (e.g., the value of "AC" in the equation above) on a predetermined ratio of anticoagulant per unit of anticoagulated whole blood. In certain embodiments, the value of "AC" may be the inverse of the predetermined ratio (e.g., if the ratio of anticoagulant to anticoagulated whole blood is 1: 16, then "AC" would be 16). Additionally or alternatively, the technician/blood processing system 100 may monitor the volume of anticoagulant added to the system. In such embodiments, the technician/system may monitor the volume of anticoagulant added to the blood processing system 100 based on the number of revolutions of the anticoagulant pump (e.g., each revolution of the anticoagulant pump introduces a set volume of anticoagulant into the blood processing system 100) and/or based on a change in weight of the anticoagulant container 210 as measured by a weight sensor (discussed in more detail below).

Once the technician/blood processing system 100 has calculated the percentage of anticoagulant within the plasma collection container 216, the technician/blood processing 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/blood processing system 100 may determine the volume of anticoagulant within the container (based on the percentage of anticoagulant within the container 216) and subtract that volume from the total volume of fluid within the container 216 as measured by the weight sensor 195. The blood processing system 100 may continue to monitor the volume of pure plasma collected in the container 216 and continue to process whole blood (e.g., continue to perform steps 425, 430, 435, 440, 455, 460, and 465) until a target volume of pure plasma is collected in the plasma collection container 216 (step 470) (e.g., 800mL for an adult donor weighing more than 175 pounds or other limit specified by the U.S. food and drug administration or similar regulatory body).

Once the blood processing system 100 has collected the target volume of pure plasma within the plasma collection container 216, the blood processing system 100 may return the remaining components (e.g., the components remaining within the drum 214) to the subject (step 475). For example, when all of the plasma has been removed and drum 214 is full of red blood cells (and any other blood components that are not collected), controller 226 stops drawing whole blood from the subject and reverses the direction of the blood/first pump 232 to draw red blood cells (and other components) directly from drum 214 back to the subject. Alternatively, if the blood processing system 100 is not so equipped, the system may return the components to the subject via a dedicated return line.

In addition to the uncollected blood components (e.g., components remaining in drum 214), blood processing system 100 may also return saline to the patient/subject. Saline may be used as a compensation fluid to replenish the volume of blood components (e.g., plasma) that are removed and collected and not returned to the patient. To this end, during a 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 drum 214 (via outlet 224), where it may be returned to the patient/donor along with or after the remaining blood components.

It should be noted that certain embodiments may perform certain additional and optional steps to help determine the volume of pure plasma within the plasma collection container 216. For example, as described above, certain embodiments may monitor changes in the 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 blood processing system 100 and may be used to help determine the percentage of anticoagulant within the plasma collection container 216. Additionally or alternatively, certain embodiments may similarly monitor changes in the weight and/or volume of the collected plasma and anticoagulant within the plasma collection container 216 (e.g., via the weight sensor 195) (step 450). This measurement may be used to calculate the total volume of pure plasma collected within the plasma collection container 216 (e.g., to obtain a total weight from which the calculated volume of anticoagulant was subtracted).

Certain embodiments may also (optionally) monitor the volume of anticoagulant remaining in drum 214 (e.g., anticoagulant that is not mixed with plasma and/or otherwise remains in the drum) (step 460). For example, the blood processing system 100 may utilize an optical sensor on the drum 214 to determine whether any anticoagulant remains within the drum 214. If so, the method 400/blood processing system 100 may modify the calculation of the amount of pure plasma collected within the plasma collection container (e.g., increase the calculated amount or decrease the calculated amount) based on the volume of anticoagulant remaining within the drum 214.

Various embodiments of the present invention provide a number of benefits over prior art plasma collection systems. In particular, as described above, prior art plasmapheresis devices end plasma collection based on the total volume of anticoagulated plasma (e.g., pure plasma plus added anticoagulant). Although this is the simplest method, as it only requires weighing the product collection container, the amount of the actual product, i.e., pure plasma, depends on the donor's hematocrit. In other words, due to the variation in the percentage of anticoagulant in the product, the prior art system will collect more plasma from low hematocrit donors than from high hematocrit donors. Various embodiments of the present invention solve the problems of prior art systems by collecting a standard volume (e.g., target volume) of pure plasma from each donor. As described 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 revolutions and/or using a gauge/weight sensor, etc.) to determine the percentage of anticoagulant in the product. In addition, by stopping the plasma collection process based on the volume of pure plasma collected, embodiments of the present invention are able to collect a larger volume of plasma than such stopping of prior art systems based on a plasma/anticoagulant mixture.

It is also important to note that while the various embodiments discussed above relate 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 a blood processing system that collects and/or processes red blood cells, platelets, and/or white blood cells.

The embodiments of the invention described above are intended to be exemplary only; many variations and modifications will be apparent to those of ordinary skill in the art. All such variations and modifications are within the scope of the present invention as defined in any appended claims.