Systems and methods for achieving target post-procedure fraction of cells remaining, hematocrit, and blood volume during a therapeutic red blood cell exchange procedure with optional isovolemic hemodilution

Patent metadata

Field	Value
Publication number	US-9393359-B2
Application number	US-201313840113-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Apr 10, 2012
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

Systems and methods for performing a therapeutic red blood cell exchange procedure are disclosed. In one aspect, a system includes a first flow path for flowing whole blood from a patient. A separator communicates with the first flow path for separating at least red blood cells from plasma. Second and third flow paths communicate with the separator for respectively flowing the separated plasma and red blood cells from the separator. A flow controller is associated with the flow paths to control fluid communication between the flow paths. The controller is configured to perform the procedure to achieve a target fraction of patient cells remaining, target hematocrit, and a target patient fluid volume change at the completion of the procedure based on data input by the operator.

First claim

What is claimed is:

1. A method for controlling a red blood cell exchange procedure for a patient by means of a blood processing system with a programmable controller having an operator interface so as to achieve isovolemic hemodilution prior to infusion of replacement red blood cells to the patient, the method comprising:
entering into the operator interface of the controller a target dilution hematocrit and a target end hematocrit for the patient;
entering into the operator interface an identification of a cell-free replacement fluid;
calculating with the programmable controller an amount of whole blood to be processed to achieve the target dilution hematocrit;
processing whole blood from the patient to remove patient red blood cells and returning said replacement fluid to the patient with the blood processing system;
monitoring with the programmable controller the amount of whole blood processed to achieve the target dilution hematocrit; and
continuing the processing of whole blood and returning infusing the replacement red blood cells to the patient to achieve the target end hematocrit.

2. The method of claim 1 in which the replacement fluid is selected from one of saline, albumin and an albumin solution.

3. A method of performing isovolemic hemodilution in a red blood cell exchange procedure for a patient by means of a blood processing system with a programmable controller having an operator interface in which whole blood is processed to remove patient red blood cells and replacement red blood cells are infused to the patient, comprising:
entering a target dilution hematocrit and a target end hematocrit for the patient into the programmable controller by means of the operator interface;
calculating with the programmable controller a volume of replacement fluid necessary to be infused to the patient to achieve the targeted dilution hematocrit;
selecting a first replacement fluid;
processing whole blood with the blood processing system to separate patient red blood cells from plasma and infusing at least a portion of the separated plasma and said first replacement fluid to the patient;
determining with the programmable controller an amount of said first replacement fluid that has been infused to the patient;
infusing a second replacement fluid to the patient when the amount of said first replacement fluid that has been infused to the patient is equal to the calculated volume of replacement fluid required to attain the target hemodilution; and
continuing to infuse the second replacement fluid to the patient until the target end hematocrit is achieved.

4. The method of claim 3 wherein said second replacement fluid includes red blood cells.

5. The method of claim 4 in which the target end hematocrit is achieved by linearly increasing the hematocrit of the replacement red blood cells introduced into the patient over the course of the red blood cell exchange procedure.

6. The method of claim 4 in which the target end hematocrit is achieved by exponentially increasing the hematocrit of the replacement red blood cells introduced into the patient over the course of the red blood cell exchange procedure.

7. The method of claim 3 further comprising ceasing returning said first replacement fluid prior to introducing said second replacement fluid.

8. The method of claim 3 wherein the patient has a whole blood volume V and a whole blood hematocrit value H T , further comprising:
a) inputting into a programmable controller values relating to patient condition and clinical objectives;
b) deriving operating values for the for a prescribed flow rate for whole blood, Q WB , a prescribed flow rate for plasma, Q P , and a prescribed flow rate for replacement red blood cells, Q RF , such that the clinical objectives are achieved simultaneously at the end of the procedure; wherein the values for Q WB , Q P and Q RF are maintained and or adjusted in accordance with changing procedural conditions;
c) conveying whole blood at the prescribed rate Q WB from the patient into the blood processing system where the whole blood is separated into a red blood cell component and a plasma component;
d) conveying separated plasma at the prescribed flow rate Q P from the blood processing system to the patient;
e) conveying separated red blood cells from the blood processing system to a waste container; and
f) conveying replacement red blood cells having a hematocrit H T1 at the prescribed flow rate Q RF to the patient.

9. The method of claim 8 wherein at least the following values relating to the patient condition and clinical objectives are inputted into or derived by the controller: the target post-procedure fraction of patient cells remaining (FCR), hematocrit (H TF ), and patient fluid volume change (ΔV); the initial patient fluid volume (V 0 ); the initial patient hematocrit (H T0 ), the hematocrit of the replacement fluid (H T8 ); and the maximum blood draw rate (Q WB, MAX ).

10. The method of claim 8 further comprising determining parameters M and F as follows:

M
=

1
-

ln
⁡

(
FCR
)

ln
⁡

(

1
+

Δ
⁢

⁢

V
/

V
0

)

⁢

⁢
Δ
⁢

⁢
V

≠
0

and

F
=

H

T
⁢

⁢
8

H

T
⁢

⁢
0

⁡

Assignees

• Fenwal Inc

Inventors

• Boggs Daniel R
• Min Kyungyoon
• Nguyen Lan T
• Foley John T
• Case Brian

Classifications

• A61M2205/3334

  Measuring or controlling the flow rate · CPC title

• A61M1/342

  Adding solutions to the blood, e.g. substitution solutions (for preventing coagulation A61M1/3672) · CPC title

• A61M1/3458

  having electrolytes not present in the dialysate · CPC title

• A61M1/3437

  downstream of the filter, e.g. post-dilution with filtrate · CPC title

• A61M2230/005

  Parameter used as control input for the apparatus · CPC title