Apparatus and method for withdrawing an optimum amount of blood per unit of time from a donor

• US 5,045,057 A
• Filed: 05/30/1989
• Issued: 09/03/1991
• Est. Priority Date: 06/01/1988
• Status: Expired due to Fees

• Current Assignee: Akzo N.V., Arnhem, The Netherlands
• Original Assignee: AKZO NV (Nouryon BV)
• Inventors: Dalmolen, Lambertus G. P., Van Driessche, Petrus J. D. M.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): TSO, LAURA K
• Application Number:
  US07/358,770
• Time in Patent Office: 826 Days
• Field of Search: 604/4, 604/6, 604/50, 604/67, 604/66, 128/670, 128/673, 364/413.02, 364/413.27, 340/537
• US Class Current: 604/540
• CPC Class Codes: A61M 1/02 Blood transfusion apparatus blood infusion by syringes A61M5/14
• CPC Class Codes: A61M 2205/3344 Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/3351 Controlling upstream pump pressure

Abstract

Apparatus for withdrawing blood from a donor by means of a blood pump. The apparatus incorporates an extracorporeal system which, on the basis of donor blood pressure measurement, controls the flow rate of the blood pump in such a way that during the withdrawal procedure the pump withdraws an optimum amount of blood per unit of time from the donor.

Claims

1. An apparatus for withdrawing an optimum amount of blood (Qo) per unit of time from a donor comprising:

a. a blood connection means for connecting the apparatus to the vascular system of the donor having an inlet open to said vascular system and an outlet;

b. blood flow conduit means for conducting blood withdrawn from the donor by way of said blood connection means, having an inlet connected to said outlet of said blood connection means and an outlet;

c. a blood pump connected to the outlet of said blood flow conduit means for withdrawing blood from the donor through said blood flow conduit means, said pump being connected to a power source so as to be energized by it;

d. blood flow rate (Q) measuring means cooperating with said blood pump to obtain an electric signal representing the flow rate of blood through said blood pump which is supplied to a flow rate output connection;

e. a pressure transducer for measuring the blood pressure (P_A), connected to said blood flow conduit means between said blood connection means and said blood pump, said pressure transducer converting P_A into an electric signal supplied to a transducer output connection;

f. a control device connected to said transducer output connection, said blood flow rate measuring means output connection, and said power source of said blood pump for controlling Q through said blood pump in response to P_A and Q, wherein said control device comprises means for adjusting Q through said blood pump to Qo at which the change in pressure (Δ

P_A) resulting from a particular change in the flow rate remains less than a maximum allowable value (Δ

P_A)_m.

2. The apparatus of claim 1 wherein said control device is adapted to be so programmed that at the start of the withdrawal of blood from the donor ("situation 1") the flow rate is increased until P_A ultimately falls below a preset initial value of donor pressure target (P_S)-Δ

₂ ("situation 3a"), where Δ

₂ is a suitable pressure margin constant, whereupon Q is reduced until P_A exceeds the value P_S -Δ

₂.

3. The apparatus of claim 2 wherein said control device is adapted to be so programmed that as long as P_A is in the range represented by

4. The apparatus of claim 3 wherein P_S is

a. (P_S)₁ if "situation 2" is attained without P_A having first reached a value represented by

P_A <

P_S -Δ

₃ ("situation 3b"), wherein Δ

₃ is a further suitable pressure margin constant,

b. (P_S)₂ if "situation 2" is attained after P_A having earlier reached a value represented by

space="preserve" listing-type="equation">P.sub.A <

P.sub.S -Δ

.sub.3 ("situation 3b")

and if,

space="preserve" listing-type="equation">aQ.sub.max ≦

Q≦

bQ.sub.max

wherein Q_max is the maximum blood flow rate.

c. (P_S)₃ if "situation 2" is attained after P_A having earlier reached a value represented by

space="preserve" listing-type="equation">P.sub.A <

P.sub.S -Δ

.sub.3 ("situation 3b")

and

space="preserve" listing-type="equation">Q<

aQ.sub.max or Q>

bQ.sub.max,

where (P_S)₁ >

(P_S)₂ >

(P_S)₃, a and b are constants and a <

b.

5. The apparatus of claim 4 wherein in "situation 3b" P_S is increased by Δ

P_S after "situation 1" has been attained, where Δ

P_S is a constant.

6. The apparatus of claim 1 further including a modulating means through which the blood flow passes between said blood connection means and said blood pump, said modulating means subjecting the blood flow to a periodic variation in flow rate and said control device comprising means for adjusting the blood flow rate to a value at which the amplitude of the pressure response to said periodic blood flow variation reaches a particular maximum and is maintained at or below said maximum.

7. The apparatus of claim 6 wherein said blood flow conduit means comprises a flexible blood line and that the modulating means comprises means for periodically compressing said blood line.

8. A method for withdrawing an optimum amount of blood per unit of time from a donor comprising:

a) passing blood from the vascular system of the donor through blood withdrawal means; and

b) adjusting the flow rate of blood Q through said blood withdrawal means to a value at which the change in pressure (Δ

P_A) of the blood being withdrawn from the donor resulting from a particular change in the flow rate remains just below a maximum allowable value.

9. The method of claim 8 wherein at the start of the withdrawal of blood from the donor ("situation 1") the flow rate is increased until the measured pressure (P_A) ultimately falls below a preset initial value of donor pressure target (P_S)-Δ

₂ ("situation 3a"), where Δ

₂ is a suitable pressure margin constant, whereupon Q is reduced until P_A exceeds the value P_S -Δ

₂.

10. The method of claim 9 wherein as long as P_A is in the range represented by

11. The method of claim 10 wherein P_S is

a. (P_S)₁ if "situation 2" is attained without P_A having first reached a value represented by

12. The method of claim 11 wherein in "situation 3b" P_S is increased by the constant Δ

P_S after "situation 1" has been attained.

13. The method of claim 8 wherein the blood flow rate is modulated to a periodic variation and the blood flow rate is adjusted to a value at which the amplitude of the pressure response to said periodic blood flow modification reaches a particular maximum and is maintained at or below said maximum.