Obviousness

The analysis of US Patent 12324873 under 35 U.S.C. § 103 requires identifying combinations of prior art references that would render the claimed invention obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention. The PHOSITA in this field would be a biomedical engineer or a technician with experience in designing, operating, or maintaining blood apheresis systems, knowledgeable in fluid mechanics, blood physiology, sensor technology, control systems for medical devices, and relevant regulatory requirements such as FDA guidelines for plasma collection.

The core inventive step disclosed in US12324873 is the calculation of a "volume of pure plasma" (i.e., plasma without anticoagulant) by accounting for the volume of anticoagulant added and the donor's hematocrit, and then using this "pure plasma" volume as a target for collection. The patent explicitly states that "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)". This leads to variable amounts of pure plasma being collected depending on donor hematocrit, even when the total collected volume is within limits-. The motivation for the invention is to address this variability and comply with regulatory limits by collecting a standardized volume of pure plasma from each donor. This recognized problem and the desire for standardized product collection would have provided a clear motivation for a PHOSITA to combine existing technologies.

Obviousness Analysis for Independent Claims

Claim 1 (Method for collecting plasma)

Claim 1 requires:
(a) inserting a venous-access device;
(b) withdrawing whole blood;
(c) introducing anticoagulant;
(d) separating into plasma and at least a second blood component;
(e) collecting the plasma component; and
(f) calculating a volume of pure plasma collected within the plasma collection container based, at least in part, on a volume of plasma component collected within the plasma collection container, a ratio of anticoagulant added to the withdrawn whole blood, and a hematocrit of the donor.

Combination of Prior Art: US4086924A in view of US5470483A and general knowledge regarding hematocrit measurement.

• US4086924A (Plasmapheresis apparatus): This patent teaches a basic plasmapheresis apparatus and method, which would include steps (a) through (e) of Claim 1, i.e., inserting a venous-access device, withdrawing whole blood, introducing anticoagulant, separating blood components (plasma and other components) using a centrifugal separator, and collecting the plasma component. The patent's description notes that such systems are common prior art.
• US5470483A (Device and method for controlling the balance of fluids in an extracorporeal blood circuit): This reference teaches systems and methods for monitoring and controlling fluid volumes within extracorporeal blood circuits. This would inherently encompass mechanisms for determining the volume of the collected plasma component (e.g., using a weight sensor on the collection container, as described in US12324873 at,) and for monitoring the volume or ratio of anticoagulant introduced into the whole blood (e.g., by tracking anticoagulant pump rotations or measuring the weight change of the anticoagulant source, as described in US12324873 at,).
• General Knowledge/Other Prior Art for Hematocrit Determination: The determination of a donor's hematocrit is a standard medical procedure. In the context of blood processing, relevant prior art classifications such as A61M1/3609 ("Physical characteristics of the blood, e.g. haematocrit") and G01N2015/055 ("Investigating sedimentation of particle suspensions in blood for hematocrite determination") indicate that hematocrit measurement, both pre-procedure and in-line (e.g., via optical sensors as described in US12324873 at-), was known.

Motivation to Combine: A PHOSITA would be motivated to combine the established plasmapheresis methods of US4086924A with the fluid monitoring capabilities of US5470483A and known hematocrit determination techniques to address the recognized problem of variable pure plasma collection volumes. The background of US12324873 explicitly highlights this issue: "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.". Given regulatory limits (e.g., FDA limits on "pure plasma" volume), a PHOSITA would find it obvious to use the available data (total collected volume, anticoagulant volume added, and donor hematocrit) to perform a calculation to determine the "pure plasma" volume. The understanding that anticoagulant primarily mixes with the plasma component (due to osmolarity, as stated in US12324873 at) provides the physiological basis for such a calculation, which would be a routine step for a skilled practitioner seeking to standardize the collected product.

Claim 13 (System for collecting plasma)

Claim 13 requires:
A system comprising: a venous-access device; a blood component separation device; a blood draw line with a blood draw pump; an anticoagulant line fluidly coupled to an anticoagulant source; and a controller configured to control operations and calculate a volume of pure plasma collected based on a volume of plasma component collected, a ratio of anticoagulant added, and a hematocrit of the subject.

Combination of Prior Art: US4713176A in view of EP0654277A1, US5470483A, and general knowledge regarding hematocrit measurement.

• US4713176A (Plasmapheresis system and method): This patent discloses a system for plasmapheresis, providing the fundamental components such as a venous-access device, a blood component separation device (e.g., a centrifuge), a blood draw line with a pump, and an anticoagulant line.
• EP0654277A1 (Blood component collection system with optimizer): This reference teaches a blood component collection system featuring an "optimizer." An "optimizer" in this context implies a controller capable of managing collection parameters and performing calculations to achieve improved or specific collection outcomes. This provides the framework for a controller to perform more sophisticated calculations beyond simple volume measurement.
• US5470483A (Device and method for controlling the balance of fluids in an extracorporeal blood circuit): As with Claim 1, this reference teaches the necessary sensors and control mechanisms within an apheresis system for monitoring fluid volumes, including the volume of plasma collected (e.g., via a weight sensor) and the volume/ratio of anticoagulant added (e.g., by monitoring pump rotations or the weight of the anticoagulant source).
• General Knowledge/Other Prior Art for Hematocrit Determination: As discussed previously, the means and methods for determining donor hematocrit (e.g., pre-procedure testing or in-line optical sensors) were well-known in the art.

Motivation to Combine: A PHOSITA would be motivated to integrate a conventional plasmapheresis system (US4713176A) with an advanced control system or "optimizer" (EP0654277A1) that incorporates comprehensive fluid monitoring (US5470483A) and known hematocrit data. The problem of inconsistent pure plasma collection volumes due to anticoagulant dilution and varying donor hematocrit is a persistent challenge in the field, further exacerbated by regulatory requirements for specific pure plasma volumes. Therefore, it would be obvious to configure the "optimizer" or controller to perform the explicit calculation of pure plasma volume based on the available input data (collected plasma volume, anticoagulant ratio, and donor hematocrit). This combination would yield a system that addresses a known problem by implementing a straightforward computational solution using existing measurement capabilities.

Claim 24 (System for collecting plasma with prospective calculation)

Claim 24 requires:
A system comprising: a venous-access device; a blood component separation device; a blood draw line with a blood draw pump; an anticoagulant line fluidly coupled to an anticoagulant source; and a controller configured to control operations and calculate a volume of pure plasma to be collected based on a volume of plasma component to be collected, a ratio of anticoagulant to be added, and a hematocrit of the subject.

Combination of Prior Art: US4713176A in view of EP0654277A1, US5470483A, JPH0252665A, and general knowledge regarding hematocrit measurement.

• US4713176A (Plasmapheresis system and method): Provides the foundational plasmapheresis system components.
• EP0654277A1 (Blood component collection system with optimizer): An "optimizer" in a blood collection system would inherently involve setting targets and planning collection based on desired outcomes and initial parameters. To "optimize" collection, a controller would logically be configured to calculate how much pure plasma should be collected, effectively making a prospective calculation.
• US5470483A (Device and method for controlling the balance of fluids in an extracorporeal blood circuit): This reference provides the mechanisms for monitoring fluid volumes and ratios within the system, which are essential for informing both retrospective and prospective calculations by a controller.
• JPH0252665A (Blood plasma taking device and control method thereof): This patent explicitly refers to a "control method thereof" for a blood plasma taking device. Control methods in such systems often involve predictive or planning algorithms to optimize efficiency or meet specific targets.
• General Knowledge/Other Prior Art for Hematocrit Determination: As before, the determination of donor hematocrit is standard. US12324873 itself describes determining the donor's weight and hematocrit as initial steps (Steps 410 and 415 in FIG. 4) before commencing blood processing, indicating these parameters are known for planning purposes.

Motivation to Combine: The motivation to combine these references for Claim 24 builds upon the motivation for Claim 13, with an emphasis on predictive control and planning. A PHOSITA, recognizing the need to comply with pure plasma volume regulations and to standardize collection outcomes, would find it obvious to equip an apheresis system's controller (such as one with an "optimizer" from EP0654277A1) with the ability to prospectively calculate the target volume of pure plasma. This prospective calculation would utilize pre-determined donor parameters (like hematocrit, which is taken before the procedure starts) and the planned ratio of anticoagulant to be added. Given that the underlying physiological principles and measurement techniques for individual components (total volume, anticoagulant, hematocrit) are known, implementing a control algorithm that performs these calculations to predict and achieve a desired pure plasma yield would be a predictable and obvious improvement for a PHOSITA in the field.