System and method for collecting plasma

What is this patent about?

’916 is related to the field of blood apheresis, specifically systems and methods for collecting plasma from a donor. In traditional plasma collection, regulatory limits are often based on the total volume of the collected product, which is a mixture of pure plasma and anticoagulant. Because the amount of anticoagulant that ends up in the collection bag varies depending on a donor’s specific physiology, prior systems often fail to maximize the amount of pure plasma collected or inadvertently collect inconsistent amounts of the actual biological product.

The underlying idea behind ’916 is that the volume of pure plasma collected can be precisely controlled by accounting for the donor's hematocrit and the specific amount of anticoagulant metered into the system. The inventor recognized that anticoagulant does not mix with red blood cells due to their osmolarity, meaning nearly all added anticoagulant is diverted into the plasma component. By mathematically factoring in the donor’s hematocrit and the volume of anticoagulant used, the system can distinguish between the diluted mixture and the volume of pure plasma, allowing the collection to continue until a specific biological target is reached.

The claims of ’916 focus on a plasma collection system that utilizes a controller to dynamically determine and adjust target volumes for plasma product or raw plasma based on donor-specific parameters. The system includes a blood separator, pumps for blood and anticoagulant, and a controller programmed to receive the donor's weight and hematocrit. Crucially, the independent claims describe a controller that establishes a current value of the hematocrit and calculates a new target volume during the procedure, ensuring that the collection process adapts to the donor's changing blood composition across multiple draw and return cycles.

In practice, the system functions by integrating data from various sensors to maintain an accurate mass balance of the fluids. The controller monitors the anticoagulant pump rotations or the weight of the anticoagulant source to determine exactly how much chemical additive has been introduced. Simultaneously, an optical sensor on the separation bowl can monitor the red blood cell layer to calculate the donor's hematocrit in real-time. This allows the system to subtract the calculated anticoagulant volume from the total weight of the collection container, yielding a real-time measurement of pure plasma.

This approach differs from prior solutions by moving away from static, one-size-fits-all collection limits that rely on the total weight of the bag. Instead of stopping when the mixture of plasma and anticoagulant hits a generic threshold, this system uses a dynamic feedback loop to account for the fact that a donor's hematocrit may shift during the procedure. By adjusting the target volume on the fly, the invention ensures that the maximum allowable amount of pure plasma is collected safely, regardless of how much the donor's blood was diluted by anticoagulant or compensation fluids.