Method for optimizing spin time in a centrifuge apparatus for biologic fluid

1. A method of separating blood into at least a first component and a second component, comprising

providing a centrifuge blood separation apparatus with a quantity of whole blood;

calculating a predicted processing time for said quantity of whole blood;

centrifuging a separation bag containing said whole blood so as to cause the sedimentation of at least a first component and a second component;

transferring some of the first component to a first transfer bag;

detecting time of passage of a red blood cell interface at a pre-selected location in the separation bag;

adjusting said predicted processing time based on the time of passage of the red blood cell interface.

2. The method of claim 1 further comprising the steps of

selecting a nominal hematocrit value for said whole blood such that an actual hematocrit value is expected to be less than said nominal hematocrit; and

calculating said predicted processing time, at least in part, from said nominal hematocrit value.

3. The method of claim 2 further comprising calculating a packing factor from said nominal hematocrit value.

4. The method of claim 3 wherein said packing factor, Fp, is calculated as:

Fp= 5 Ho/ (11(1− H ) 2 )− Ho/ (3(1− H ))−16 Ho 2 +8 Ho+ 1.1

Where

Ho is equal to a starting hematocrit; and

H is equal to a packed red blood cell hematocrit.

5. The method of claim 4 wherein said packing factor is modified during a centrifugation process from an initial nominal value to a calculated value based on a determination of a donor's hematocrit.

6. The method of claim 5 wherein said red blood cell interface is detected by a photo sensor.

7. The method of claim 6 wherein the photo sensor is located in a separation chamber for receiving said separation bag and is placed at a location such that the hematocrit when the red blood cell interface reaches the photo sensor would be expected to be 80 or greater.

8. The method of claim 7 wherein an expected time for said red blood cell interface to reach said photo sensor after a beginning of centrifugation is about one half an expected total sedimentation time.

9. The method of claim 1 wherein calculating said predicted processing time comprises calculating said predicted processing time in part from a predicted sedimentation time.

10. The method of claim 9 wherein said predicted sedimentation time, Ts, is computed by said controller according to the following formula:

Ts=CK ( Ds/Rs ) Fp /( VsN 2 )

Wherein

Ts is spin time,

Fp is a packing factor,

N is centrifuge speed,

K is (30/π) 2 g, which is 8.95×10 4 rpm 2 -cm

C is a calibration factor,

Ds is a characteristic sedimentation distance,

Rs is an average spin radius of sample volume, and

Vs is an average RBC sedimentation velocity at one g.