Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to systems and methods for processing fluids and fluid components. More particularly, the present invention relates to an apheresis system for separating whole blood from a donor into at least two components.
2. Description of Related Art
Continuous flow fluid separation is useful in many chemical, medical, research, and industrial contexts. Many times, fluids mix with other fluids and it is desired to reverse that process and separate those fluids, sorting the fluid subcomponents according to density and/or molecular weight. In some cases, particles are present in solution and these particles need to be precipitated out of or removed from the solution.
Blood apheresis is one common medical use of continuous fluid separation. Apheresis has many clinical uses, including multiple therapies that involve removing blood from a patient's body, separating the blood into components, altering one of the components, and putting some mixture or selection from the removed and/or altered fluid back into the patient's body. Some exemplary therapeutic apheresis procedures include: therapeutic plasma exchange (TPE), a procedure by which cell-free plasma is removed and replaced with colloid/saline solution; cytoreduction, a process by which platelets and white blood cells are removed; photopheresis, a procedure by which mononuclear cells collected by therapeutic apheresis are exposed to ultraviolet-A light and psoralen, and reinfused into the patient; and selective adsorption, a process by which plasma is adsorbed on a column and returned to the patient.
Additionally, efficient apheresis can be used to provide a more efficient and less uncomfortable experience for those who wish to donate blood, in addition to helping make donated blood safer for clinical use. For example, if only a portion of the blood is in demand, that portion can be separated and the remaining portions can flow back in to the donor. Many other applications exist. For example, apheresis can be used to test athletes for doping violations without excess blood removal, and those who have had a drug overdose can be treated by detoxifying their blood with apheresis techniques.
In a basic apheresis procedure, blood is withdrawn from a donor through a needle inserted into the vein of a donor. The needle is attached to one end of a plastic tube which provides a flow path for the blood. The other end of the tube leads to a separator, such as a centrifuge, for separating the blood into its components. Flow-through centrifuges which allow for the continuous inflow and outflow of materials to and from the centrifuge are well known within the art. For example, U.S. Pat. No. 4,425,112, which is hereby incorporated by reference in its entirety, describes a sealless centrifuge that allows the continuous transfer of material to and from a centrifuge bowl via tubes which are directly connected to the bowl from the outside of the centrifuge without the use of rotating seals. This result is achieved by threading a multi-lumen tube through the top housing of a centrifuge drum, the multi-lumen tube enters the housing inline with the driveshaft of the centrifuge. The multi-lumen tube extends radially outward from the axis of rotation of the drive shaft to a hollow outer shaft located within a first circular plate. The multi-lumen tube extends downwardly through the hollow outer shaft, and then extends radially inward to a hollow center shaft within the first circular plate. The multi-lumen tube then extends upwardly though the hollow center shaft of the first plate and attaches in fluid communication to the centrifuge bowl located above the first circular plate. The first circular plate is driven by the drive shaft at a predetermined angular velocity ω. By utilizing pulleys and a 1:1 gear ratio, the centrifuge bowl rotates at an angular velocity of 2ω. Finally, the hollow outer shaft of the first plate is caused to rotate about its own axis at an angular velocity of −ω, thereby causing the multi-lumen tube to remain untwisted while also allowing fluid communication into and out of the centrifuge bowl without any rotating seals.
Automated apheresis systems are now routinely used which utilize disposable, pre-sterilized fluid circuits through which the blood flows. The fluid circuits are mounted on reusable machines that may have pumps, valves, sensors, and the like. These automated systems further include an internal computer and associated software programs which control many of the processing functions. The fluid circuits of these automated systems, however, typically have complex routing procedures that require skill and training by the apheresis operator in order to assemble the system. For example, U.S. Pat. No. 6,706,008 B2, which is herein incorporated by reference in its entirety, illustrates and describes an automated apheresis system. Although this system is simpler and easier to use than previous apheresis systems, it still includes complex routings of tubes through peristaltic pump rotors which can be difficult to properly assemble and/or can be assembled improperly.
Additionally, existing apheresis processes can have negative effects on patients. For example, many apheresis and similar processes draw blood in sudden, relatively large doses from the patient, causing trauma, nausea, or other harmful side effects. These large draws are often repeated in order to obtain enough blood for the desired medical test or therapy, but the effect of repeated heavy draws of blood from a patient can be harmful. Furthermore, existing methods can be inefficient and can cause inconvenient delays in the time it takes for blood to separate or travel through the apheresis machine. Moreover, many existing apheresis systems are expensive and difficult to assemble by the apheresis operator. Therefore, a need exists for improved systems and methods for separating fluids. In particular, a need exists for improved systems and methods for efficiently separating blood constituents in a continuous flow apheresis device, and for apheresis devices that are easier to assemble and operate.
Certain embodiments of the present invention include a fluid component separation system having a sealless rotating drum, a disposable centrifuge cartridge, a multi-lumen tube, and a control system. The sealless rotating drum includes a first independently rotatable disc as well as a second independently rotatable disc; the first disc being positioned above the second disc within the drum. The disposable centrifuge cartridge is capable of being temporarily attached to the first disc during the fluid separation process. The multi-lumen tube can attach to the centrifuge cartridge at one end and is capable of attaching at least to a fluid source located outside of the drum at the other end, thereby being able to transmit fluid to and from the centrifuge cartridge. The control system is capable of independently controlling the flow rate of liquid within each lumen of the multi-lumen tube.
Additionally, the disposable centrifuge cartridge may include stacked separation levels for separating fluid components by their density. The multi-lumen tube may include any number of lumens, but in one embodiment of the invention it is envisioned that the tube will have six lumens.
Furthermore, the control system may be a peristaltic block including rows of independently controllable caterpillar rollers. The number of roller rows may be made to correspond to the number of lumens within the multi-lumen tube. In particular, the multi-lumen tube may further include a ribbon section, wherein the lumens are aligned in a plane so that each lumen may be positioned in contact with an independently controlled caterpillar roller row within the peristaltic block. Although, the number of roller rows and lumens may correspond, it is also envisioned that a peristaltic block may have a greater number of rollers than is present in the multi-lumen tube used with the block.
Additionally, the ribbon section of the multi-lumen tube may be bounded on each side by fittings, wherein each fitting is shaped differently than the other. Optionally, at least one of these fittings may be asymmetric in form. The peristaltic block will be designed to include compatible recesses, which are capable of receiving the ribbon section fittings. By having dissimilar fittings on each end of the ribbon section, including at least one which may be asymmetric in form, improper operator installation of the multi-lumen tube in the peristaltic block is minimized, since the tube will only fit into the block in the intended direction.
Another embodiment of the present invention includes an apheresis system useful for separating whole blood from a patient into at least two components. The apheresis system includes a sealless rotating drum, a disposable centrifuge cartridge, a multi-lumen tube, and a control system. The sealless rotating drum includes a first independently rotatable disc as well as a second independently rotatable disc; the first disc being positioned above the second disc within the drum. The disposable centrifuge cartridge is capable of being temporarily attached to the first disc during the blood component separation process. The multi-lumen tube can attach to the centrifuge cartridge at one end and is capable of attaching at least to a blood source located outside of the drum at the other end, thereby being able to transmit blood and blood components to and from the centrifuge cartridge. The control system is capable of independently controlling the flow rate of liquid within each lumen of the multi-lumen tube.
The disposable centrifuge cartridge may include stacked separation levels for separating blood components by their density. In particular, the centrifuge cartridge may include three separation levels stacked on top of each other. When the centrifuge cartridge includes three separation levels, the upper separation level may separate out red blood cells from the remainder of the blood before routing the remaining blood components to the mid separation level. The mid separation level may then separate out component poor plasma before routing the remaining component rich plasma to the lower separation level. The lower separation level may then separate white blood cells from platelets.
Although the multi-lumen tube may contain as many lumens as is necessary for a given procedure, it is envisioned that in one embodiment the multi-lumen tube may include six lumens. In particular, one lumen may convey blood or blood components to and from the centrifuge cartridge and to and from a blood source. This blood source may be a donor giving blood during the apheresis process. The blood source also may be a supply of blood previously drawn from a donor prior to the apheresis process.
After separation, the blood components may be routed out of the centrifuge cartridge by dedicated lumens within the multi-lumen tube. These blood components may be routed through their individual lumens in numerous ways, including, but not limited to, routing them back to the patient, routing them to a collection bag for storage, or routing them to another system for further processing.
The control system of the apheresis unit may be a peristaltic block made up of rows of independently controllable caterpillar rollers. The number of roller rows may be made to correspond to the number of lumens within the multi-lumen tube. In addition, the multi-lumen tube may further include a ribbon section. In this ribbon section, the lumens are aligned in a plane so that each lumen may be positioned in contact with an independently controlled caterpillar roller row of the peristaltic block. Although, the number of roller rows and lumens may correspond, it is also envisioned that a peristaltic block may have a greater number of rollers than is present in the multi-lumen tube used with the block.
Additionally, the ribbon section of the multi-lumen tube may be bounded on each side by fittings, wherein each fitting is shaped differently than the other. Optionally, at least one of these fittings may be asymmetric in form. The peristaltic block will be designed to include compatible recesses, which are capable of receiving the ribbon section fittings. By having dissimilar fittings on each end of the ribbon section, including at least one which may be asymmetric in form, improper operator installation of the multi-lumen tube in the peristaltic block is minimized, since the tube will only fit into the block in the intended direction.
The apheresis system of the present invention may further include a camera unit mounted above the centrifuge cartridge. In this case, the top of the centrifuge cartridge may be transparent so that the contents of the centrifuge cartridge may be viewed by the camera unit. The camera unit thus may be able to differentiate a separation boundary within the centrifuge cartridge. This separation boundary may mark the line between separation of red blood cells, and the remaining blood components.
The apheresis system of the present invention may further include a microcontroller. This microcontroller may communicate with the camera unit in order to receive separation boundary information from the camera unit. The microcontroller may then adjust the angular velocity of the centrifuge cartridge accordingly based on the separation boundary information. In particular, if the separation boundary is below a desired limit, the microcontroller may increase the angular velocity of the centrifuge cartridge in order to increase the level of separation.
Another embodiment of the present invention includes a method for separating whole blood obtained from a donor into at least two components. In order to effectuate this method, one supplies a source of whole blood to a sealless rotating drum. The blood enters the drum via a dedicated lumen within a multi-lumen tube. The whole blood is then separated into at least two components based on the density of the various components. This separation is achieved via centrifugal forces placed on the components within a rotating centrifuge cartridge located within the rotating drum. Finally, the blood components are directed out of the rotating drum via separate dedicated lumens with the multi-lumen tube.
In this method, the flow rate of blood and blood components within each lumen of the multi-lumen tube may be controlled independently. Also, improved separation of blood components may be achieved in this method in numerous varied ways. For example, separation may be improved by increasing the angular velocity of the rotating centrifuge cartridge. Separation of blood components may also be improved by increasing the flow rate of an individual blood component leaving the centrifuge cartridge. Another manner for improving blood component separation is by decreasing the flow rate of an individual blood component. Additionally, one may combine the above improvements. For example, blood component separation can be improved by increasing the flow rate of one blood component while simultaneously decreasing the flow rate of a different blood component.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:
As can best be seen in
The central disc 14 is attached by a sidewall 26 to a lower disc 28, which is likewise attached to a drive unit 30. The drive unit 30 causes the lower disc 28, and consequently the central disc 14, to rotate at a predetermined angular velocity ω. By virtue of the sidewall 26 attaching the central disc 14 to the lower disc 28, the central disc 14 may be rotated at angular velocity ω by the drive unit 30 without the need for a center shaft support system. The rotation of the central disc 14 causes the peripheral hollow channel 20, as well as the multi-lumen tube 12 when inserted therein, to move in an orbital path around the interior periphery of the drum 10. By conventional methods well known within the art, the peripheral hollow channel 20, and consequently the multi-lumen tube 12 inserted therein, is caused to rotate itself at an angular velocity of −ω thereby preventing twisting of the tube 12 between the entry point of the tube 12 within the drum 10 from the exterior and the peripheral hollow channel 20. By these same conventional methods, the upper disc 16, and consequently the disposable cartridge 18 attached to the upper disc 16, is caused to rotate at an angular velocity 2ω. This rotation of twice the speed prevents twisting of the tube 12 between the peripheral hollow channel 20 and the connection point of the tube 12 at the disposable cartridge 18. Exemplary methods for creating angular velocities as described above is discussed in U.S. Pat. No. 4,425,112, the entire contents of which are incorporated herein by reference.
Although the multi-lumen tube 12 is shown in
The peristaltic block 34 may be controlled by a computer program which regulates the speed of each independent roller as is necessary. By adjusting the speed of each roller, flow into and out of the system may likewise be adjusted. Furthermore, as will be discussed in greater detail below, adjusting the flow rate of certain components may allow for changes in separation of the components.
The disposable cartridge 18 illustrated in
Since the flow rates through each lumen within the tube 12 may be independently controlled via the peristaltic block 34, it is additionally envisioned that separation of the components may be fine tuned by changing particular flow rates in response to the achieved separation. For example, the components exiting the drum 10 may be analyzed for concentration and particular flow rates may be accordingly adjusted in order to achieve a more desired separation of components. By increasing the exit flow rate of a component within a particular level, more of the blood will be drawn through that particular exit resulting in a more dilute separation. Thus, for example, if the concentration of RBCs leaving through the RBC lumen is lower than would be expected, the flow rate of the RBC lumen can be increased in order to draw more of the fluid through that lumen, thereby increasing the RBC content. In contrast, if the RBC lumen is being “tainted” with non-RBC components, the RBC lumen flow rate can be decreased in order to allow for greater separation of the components before exiting the upper level. Although this was explained using RBCs, it is envisioned that any flow rate could be adjusted in this manner leading to improved separation of any component.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including various ways of designing and operating the sealless rotating drum. In particular, it is contemplated that the apheresis system of the present invention may be controlled by a microcomputer, wherein the operator inputs the desired apheresis conditions and the microcomputer controls the operating conditions of the system, including but not limited to the rotation speed of the drums, the flow rates of each individual lumen in the multi-lumen tube, and the degree of separation contrast in the upper level. Additionally, the configuration of the disposable cartridge may be altered in numerous ways, for example, any number of stacked levels may be present in the cartridge depending on the desired separation requirements. Also, the multi-lumen tube may contain any number of lumens as may be needed for particular applications. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.