Method of separating the constituents of the blood
First Claim
1. A method for separating constituents of whole blood which is withdrawn from a donor, mixed with anticoagulant, and supplied to a speed-adjustable blood centrifuge from which blood constituents are withdrawn and thereafter partially collected and partially returned to the donor, which method comprises:
- measuring flow rates of the whole blood, anticoagulant and of the blood fractions; and
adjusting a speed of rotation of the centrifuge upon a variation of the flow rate of whole blood according to transition function, which transition function is chosen such that a ratio of volume parts of the blood fractions separated in the centrifuge per unit time to a volume of the whole blood and anticoagulant supplied to the centrifuge in a unit time is approximately the same before an after the variation in the flow rate of whole blood.
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Accused Products
Abstract
The invention relates to the control of a system in a blood centrifuge for separating the constituents (fractions) of the whole blood taken from a donor "in vivo" and provided with anticoagulants. A control is provided which as input quantity includes a signal on the flow rate of the full blood and on the output side is connected to the speed setting means for the blood centrifuge. The transfer function of the control is so defined that on a change of the full blood flow the speed of rotation is set so that the volume ratios of the blood fractions to the full blood remain constant. Preferably, the output signal of the control is proportional to the square root of the full blood flow. The control is preferably formed by a microprocessor.
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Citations
16 Claims
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1. A method for separating constituents of whole blood which is withdrawn from a donor, mixed with anticoagulant, and supplied to a speed-adjustable blood centrifuge from which blood constituents are withdrawn and thereafter partially collected and partially returned to the donor, which method comprises:
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measuring flow rates of the whole blood, anticoagulant and of the blood fractions; and adjusting a speed of rotation of the centrifuge upon a variation of the flow rate of whole blood according to transition function, which transition function is chosen such that a ratio of volume parts of the blood fractions separated in the centrifuge per unit time to a volume of the whole blood and anticoagulant supplied to the centrifuge in a unit time is approximately the same before an after the variation in the flow rate of whole blood. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for separating constituents of whole blood withdrawn from a donor, said apparatus comprising:
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a blood centrifuge with means associated for blood withdrawal, delivery of anticoagulant, delivery of withdrawn blood to the blood centrifuge, and for separating constituents which are partially collected and partially returned to the donor; means for adjusting flow rates of the anticoagulant, the whole blood and the blood fractions and a speed of rotation of rotation of the centrifuge; and a sensor means for detecting the flow rate of the whole blood, a signal from said sensor being switched to a control stage which has a transition function and whose output is connected to the adjusting means, wherein the transition function of the control stage is chosen such that on a variation in a flow of whole blood an associated input signal at an input of the control stage and an output signal for setting a speed of rotation of the centrifuge changes such that a ratio of volume parts of blood fractions separated in the centrifuge per unit time to volume of whole blood conveyed in the unit time into the centrifuge is approximately the same ratio before and after the variation in the flow of whole blood. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification