Importance

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Abstract

A single needle system for withdrawing donated blood, processing the blood to harvest components such as platelets, and returning processed blood to the donor through the single needle. Processing is performed by a centrifuge which separates blood components into stratified layers with a buffy coat containing platelets and white blood cells stably interfacing a red blood cell layer. Blood is withdrawn during a draw cycle and returned to the donor during a return cycle. A recirculation system is provided so that blood flows at a reduced rate through the processing system during the return cycle in order to minimize return cycle time while maintaining the stable position of the interface between buffy coat and red blood cell layers. A storage bag receives processed blood during the draw cycle and blood is squeezed from the bag during the return cycle, a portion returned to the donor and another portion entering the recirculation path. A pressure sensor is located in the return path to indicate an empty storage bag upon a precipitous drop in pressure. In that manner an immediate switch to the draw cycle is made to further minimize return cycle time. To still further minimize the return cycle time, flow resistance in the return path is minimized with more than 80% of the flow resistance in the return path associated with the needle.

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First Claim