Systems and methods for estimating platelet counts using a spleen mobilization function

• US 6,197,202 B1
• Filed: 02/23/1998
• Issued: 03/06/2001
• Est. Priority Date: 06/07/1995
• Status: Expired due to Term

• Current Assignee: Fenwal Incorporated (Fresenius SE & Co. KGaA)
• Original Assignee: Baxter International Inc.
• Inventors: Brown, Richard I.
• Primary Examiner(s): KIM, SUN U
• Application Number:
  US09/027,638
• Time in Patent Office: 1,107 Days
• Field of Search: 210/85, 210/86, 210/87, 210/96.1, 210/143, 210/739, 210/767, 604/4, 604/5, 604/6, 604/65, 604/66, 604/67, 604/4.01, 604/5.01, 604/6.01, 604/6.04, 702/FOR.157
• US Class Current: 210/739
• CPC Class Codes: A61M 1/02 Blood transfusion apparatus blood infusion by syringes A61M5/14
• CPC Class Codes: A61M 1/0209 Multiple bag systems for separating or storing blood components
• CPC Class Codes: A61M 1/3672 Means preventing coagulation
• CPC Class Codes: A61M 1/3693 using separation based on different densities of components, e.g. centrifuging
• CPC Class Codes: A61M 1/3696 with means for adding or withdrawing liquid substances during the centrifugation, e.g. continuous centrifugation
• CPC Class Codes: A61M 1/385 taking into account of the patient characteristics
• CPC Class Codes: A61M 2202/0092 starting product created by centrifuging
• CPC Class Codes: A61M 2202/0415 Plasma
• CPC Class Codes: A61M 2202/0427 Platelets; Thrombocytes

Abstract

Systems and methods separate platelets from a selected donor. The systems and methods convey anticoagulated blood containing plasma and platelets from the selected donor into the separation device for separating into a plasma yield and a platelet yield. The systems and methods estimate, at least in part while separation occurs, a count of platelets (Plt_Circ) available for collection from the selected donor by measuring the selected donor'"'"'s platelet precount (Plt_pre), estimating a dilution factor caused by addition of anticoagulant (Dilution), and estimating a depletion factor (Depletion) caused by removal of available platelets during blood processing. In estimating Depletion, the systems and methods take into account a splenic mobilization function (Spleen), which is derived from a population of donors and not specific to the selected donor, where Spleen comprises a function of Plt_PRE.

Claims

1. A system for separating platelets from a selected donor comprising

a separation device for separating blood into plasma and platelets,

an inlet to the separation device communicating with the selected donor to convey anticoagulated blood containing plasma and platelets from the selected donor into the separation device for separating into a plasma yield and a platelet yield,

a processing element coupled to the separation device including a first element that estimates, at least in part while separation occurs in the separation device, a count of platelets (Plt_Circ) available for collection from the selected donor by a method comprising the steps of:

measuring the selected donor'"'"'s platelet precount (Plt_pre),

estimating a dilution factor caused by addition of anticoagulant (Dilution),

estimating a depletion factor (Depletion) caused by removal of available platelets during blood processing including applying a splenic mobilization function (Spleen) derived from a population of donors and not specific to the selected donor, where Spleen comprises a function of Plt_PRE, and

wherein;

2. A system according to claim 1 wherein Dilution is estimated as follows:

$\mathrm{Dilution}=1-\frac{\mathrm{Prime}+\mathrm{Kid}-\mathrm{PPP}}{\mathrm{DonVol}}$

where;

Prime is a priming fluid volume (ml) of the separation device,

PPP is a value reflecting volume of plasma yield that is not returned to the donor(ml),

Kid is an empirically determined constant reflecting kidney function, and

DonVol (ml) is the total volume of donor blood.

3. A system according to claim 2

wherein DonVol is derived as:

4. A system according to claim 1 wherein Depletion is estimated as follows:

$\mathrm{Depletion}=\frac{100,000<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Yld}}{\mathrm{Spleen}\times <br><br>\mathrm{DonVol}}$

where;

Yld is the derived yield of platelets (k/μ

l) at the time Depletion is estimated, and

DonVol is the total volume of donor blood (ml).

5. A system according to claim 1 wherein a curve estimates the function Spleen as follows:

6. A system according to claim 5 wherein Spleen is expressed as follows:

7. A method for separating platelets from a selected donor comprising the steps of

conveying blood from the selected donor to a separation device for separating into a plasma yield and a platelet yield,

estimating, at least in part while separation occurs in the separation device, a count of platelets (Plt_Circ) available for collection from the selected donor by

measuring a donor'"'"'s circulating platelet count (Plt_pre),

estimating a dilution factor caused by addition of anticoagulant (Dilution),

estimating a depletion factor (Depletion) caused by removal of available platelets during blood processing including applying a splenic mobilization function (Spleen) derived from a population of donors and not specific to the selected donor, where Spleen comprises a function of Plt_PRE, and,

wherein:

8. A method according to claim 7 wherein Dilution is estimated as follows:

$\mathrm{Dilution}=1-\frac{\mathrm{Prime}+\mathrm{Kid}-\mathrm{PPP}}{\mathrm{DonVol}}$

where;

Prime is a priming fluid volume (ml) of the separation device,

PPP is a value reflecting volume of plasma yield that is not returned to the donor(ml),

Kid is an empirically determined constant reflecting kidney function, and

DonVol (ml) is the total volume of donor blood.

9. A method according to claim 8 wherein DonVol is derived as:

10. A method according to claim 7 wherein Depletion is estimated as follows:

$\mathrm{Depletion}=\frac{100,000<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Yld}}{\mathrm{Spleen}\times <br><br>\mathrm{DonVol}}$

where;

Yld is the derived yield of platelets (k/μ

l) at the time Depletion is estimated, and

DonVol is the total volume of donor blood (ml).

11. A method according to claim 7 wherein a curve estimates the function Spleen as follows:

12. A method according to claim 11 wherein Spleen is expressed as follows: