Single needle recirculation system for harvesting blood components

A method of separating and collecting blood components during both a draw cycle and a return cycle of a run phase, said method for drawing and returning blood to a donor through a single lumen needle, said method comprising the steps of:

• providing a single lumen needle for insertion into the vein of a donor;
• providing a connector having at least three branches, a first branch connected to said needle;
• providing an inlet pump with an inlet and an outlet;
• providing an inlet line connected to a second branch of said connector and to said inlet pump for supplying blood to the inlet side of said pump;
• providing a centrifuge apparatus with a separation vessel connected to the outlet side of said pump, said vessel for separating blood components into stratified layers;
• providing a collection bag connected to said separation vessel for receiving and holding a collected component of the donated blood;
• providing a flexible storage bag with an inlet connected to said separation vessel for receiving and holding the processed donated blood other than the collected components, said storage bag having an outlet;
• providing a return system including said storage bag and a return line connected to a third branch of said connector and to said outlet of said storage bag;
• providing a pressure application member in communication with said return bag for applying pressure on the external sides of said return bag during said return cycle to force the fluids in said bag into said return line;
• providing a sensing device in communication with said return system;
• providing a return valve in fluid communication with said return line;
• providing a control device for operating said return valve to close said valve during said draw cycle so that blood enters said inlet pump from said donor, is processed by said centrifuge to harvest blood components, and to send the processed blood to said storage bag, said control device operating said return valve to open said valve during a return cycle so that blood in said storage bag is squeezed into said return line, a first portion of blood in said return line passing through the first branch of said connector to said needle for return to the donor, a second portion of blood in said return line passing through the second branch of said connector to the inlet side of said pump for maintaining circulation of blood through said centrifuge apparatus to said storage bag and return line thereby providing a recirculation flow for reprocessing that portion of the blood not returned to the donor during the return cycle, said control device for minimizing return cycle time by reclosing said return valve thereby ending said return cycle and reinstituting said draw cycle when said sensing device indicates that said storage bag is empty, and
• further minimizing return cycle time by providing return line flow resistance at a low level that produces return flow through said needle at a rate that is essentially independent of said recirculation flow.

A method of separating and collecting harvested blood components utilizing a centrifuge apparatus for separating blood components and one single lumen needle for insertion into a circulatory system of a donor, comprising:

• beginning a draw cycle of a predetermined duration;
• withdrawing whole blood from the circulatory system of the donor through the single lumen needle during the draw cycle;
• delivering the whole blood to the centrifuge apparatus at a first substantially constant predetermined flow rate during said draw cycle;
• centrifuging the whole blood in the centrifuge apparatus during the draw cycle to separate the whole blood into stratified layers stably positioned within said centrifuge apparatus, the stratified blood providing at least one harvested blood component and a remaining blood component;
• storing the remaining blood component in a storage reservoir during the draw cycle;
• ending the draw cycle at the end of the predetermined duration;
• beginning a return cycle;
• returning a first portion of the remaining blood component stored in the storage reservoir to the circulatory system of the donor during a return cycle;
• recirculating a second portion of the remaining blood component from the return storage reservoir to the centrifuge apparatus at a second predetermined flow rate during the return cycle, said second rate substantially lower than said first rate while maintaining the stability of the interface position of the stratified layers;
• centrifuging the second portion of the remaining blood component during the return cycle;
• sensing when the storage reservoir is substantially empty;
• and
• ending the return cycle when the storage reservoir is substantially empty.