Apparatus and method for direct measurement of blood parameters

• US 5,242,382 A
• Filed: 08/20/1990
• Issued: 09/07/1993
• Est. Priority Date: 08/05/1988
• Status: Expired due to Fees

• Current Assignee: HFG Healthco-4 LLC (Apollo Global Management, Inc.)
• Original Assignee: Healthdyne, Inc. (Abbott Laboratories Incorporated)
• Inventors: Cooper, Tommy G., Gorsuch, Reynolds G. F., Atkin, John
• Primary Examiner(s): Green, Randall L.
• Assistant Examiner(s): CLARKE, ROBERT A
• Application Number:
  US07/570,002
• Time in Patent Office: 1,114 Days
• Field of Search: 604/4-6, 604/48, 422/44, 422/101
• US Class Current: 604/6.09
• CPC Class Codes: A61B 5/14528 invasively
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits
• CPC Class Codes: A61M 1/1643 with weighing of fresh and used dialysis fluid
• CPC Class Codes: A61M 1/1678 intracorporal peritoneal dialysis A61M1/28
• CPC Class Codes: A61M 1/1696 with dialysate regeneration
• CPC Class Codes: A61M 1/34 Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
• CPC Class Codes: A61M 1/3479 by dialysing the filtrate
• CPC Class Codes: A61M 1/3486 Biological, chemical treatment, e.g. chemical precipitation; treatment by absorbents
• CPC Class Codes: A61M 1/36 Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
• CPC Class Codes: A61M 2202/0042 filtrate, i.e. the fluid passing through the filter
• CPC Class Codes: A61M 2202/046 Low-density lipoprotein
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3553 remote, e.g. between patient's home and doctor's office
• CPC Class Codes: A61M 2205/3584 using modem, internet or bluetooth

Abstract

Continuous or periodic measurement of blood gas parameters and blood pressure by separating plasma from blood and then using that plasma to measure the blood parameters. Plasma is separated from blood in vivo with a filter implanted within a blood vessel, and the separated plasma is removed to extracorporeal apparatus for analyzing blood gas parameters or measuring blood pressure. The use of plasma is equivalent to the use of whole blood for measuring blood gas parameters as the gas parameters reside in the plasma, not in the separated blood cells which remain in the blood vessel. This arrangement permits the continuous measurement of blood gases without removal of blood from the body.

Claims

1. An apparatus for measuring at least one parameter of blood flowing in an organism, comprising:

at least one elongated microporous fiber having a hollow interior, said fiber being dimensioned to be received within a blood vessel of the organism without significantly obstructing fluid flow through the blood vessel;

the pore size of the fiber being sufficient to allow plasma to diffuse through the pores into the hollow interior of the fiber but not sufficient to allow cellular components larger than plasma to diffuse therethrough, so as to accomplish in vivo separation of plasma from blood;

the hollow interior of said elongated fiber being in fluid communication with a means for conducting plasma comprising a first hollow tube which connects to the hollow interior of the fiber and permits passage of plasma from the fiber, and a second hollow tube which returns plasma to said blood vessel;

extracorporeal means responsive to a predetermined parameter of the plasma passing through the first tube for producing a signal indicative of the parameter; and

means conducting the plasma from the extracorporeal means to the second hollow tube for return to the blood vessel.

2. Apparatus as in claim 1, wherein the last-mentioned means comprises a pump for moving the plasma from the extracorporeal means to the second hollow tube.

3. Apparatus as in claim 1, wherein the fiber is composed of a polymeric material having a pore size of from about 0.1 to 1.0 μ

m.

4. Apparatus as in claim 1, wherein the fiber is composed of a polymeric material having a pore size of about 0.2 to 0.8 μ

m.

5. Apparatus as in claim 1, wherein the fiber is composed of a polymeric material having a pore size of about 0.4 to 0.6 μ

m.

6. Apparatus as in claim 1, wherein the extracorporeal means comprises a cuvette connected to receive the extracorporeal flow of plasma;

and

sensor means responsive to the plasma flowing through the cuvette to measure the parameter.

7. Apparatus as in claim 6, wherein the sensor means comprises a plurality of sensors responsive to a corresponding plurality of blood gas parameters in the plasma flowing through the cuvette.

8. An apparatus for measuring at least one parameter of blood flowing in an organism, comprising:

a filter comprising at least one elongated microporous fiber having a hollow interior and dimensioned to fit within a blood vessel;

the pore size of the fiber being sufficient to allow plasma to diffuse through the pores into the hollow interior but not sufficient to allow cellular components larger than plasma to diffuse therethrough, so as to accomplish in vivo separation of plasma from blood;

means comprising a first hollow tube connected to the filter to conduct the plasma from the interior of the fiber to an extracorporeal location;

a sensor at the extracorporeal location and operatively associated with the plasma to measure a predetermined blood parameter of the plasma; and

means comprising a second hollow tube connected to return the plasma from the extracorporeal location to a blood vessel of the body from which the plasma was removed.

9. The apparatus as in claim 8, wherein:

the primary filter includes a header dimensioned to fit within the first-mentioned blood vessel without substantially obstructing fluid flow through the blood vessel;

the fiber extends outwardly from the header within the blood vessel;

the first hollow tube is in fluid flow communication with the header to remove the plasma from the blood vessel; and

the second hollow tube is in fluid flow communication with the header to return the plasma from the extracorporeal location to said blood vessel.

10. The apparatus as in claim 8, wherein:

the sensor comprises a cuvette connected to receive the extracorporeal flow of plasma; and

a plurality of optical sensor means exposed to the plasma flowing through the cuvette and operative to determine certain blood gas parameters of the plasma.

11. The apparatus as in claim 8, wherein the fiber has a pore size of about 0.1 to 1.0 μ

m.

12. An apparawtus for measuring at least one value of blood gas in blood flowing in an organism, comprising:

a primary filter comprising a microporous membrane dimensioned to be received within a blood vessel without significantly obstructing fluid flow through said blood vessel;

the pore size of the membrane being sufficient to allow plasma to diffuse through the pores but not sufficient to allow cellular components larger than plasma to diffuse therethrough, so as to accomplish in vivo separation of plasma from blood;

plasma collection means in fluid communication with the membrane and having a hollow tube which conducts plasma from the primary filter;

extracorporeal analytical means connected to receive the plasma passing through the tube and operative to measure a blood gas parameter of the plasma; and

means conducting the plasma from the extracorporeal analytical means for return to a blood vessel.

13. A method for measuring at least one parameter of blood flowing in an organism, comprising the steps of:

implanting in a blood vessel at least one elongated microporous fiber having a hollow interior and dimensioned to be received within a blood vessel without significantly obstructing fluid flow through the blood vessel, the pore size of the elongated microporous fiber being sufficient to allow plasma to diffuse through the pores into the hollow interior of the fiber but not sufficient to allow cellular components larger than plasma to diffuse therethrough, so as to accomplish in vivo separation of plasma from blood;

placing the hollow interior of said elongated fiber in fluid communication with a means for conducting plasma comprising a first hollow tube which connects to the hollow interior of the fiber and permits passage of plasma from the fiber, and a second discrete tube which returns plasma to said blood vessel;

removing plasma from the blood vessel to an extracorporeal location;

analyzing the removed plasma at the extracorporeal location to determine at least one blood parameter from the plasma; and

then

re-infusing the plasma into the blood vessel.

14. A method for measuring at least one parameter of blood using plasma in lieu of blood, comprising the steps of:

separating plasma from blood in vivo in a blood vessel;

removing the separated plasma from the blood vessel to an extracorporeal location;

analyzing the removed plasma at the extracorporeal location to determine at least one blood parameter from the plasma; and

then

re-infusing the plasma into the blood vessel.