Dialysis probe

• US 5,191,900 A
• Filed: 04/10/1991
• Issued: 03/09/1993
• Est. Priority Date: 04/10/1991
• Status: Expired due to Term

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Mishra, Pravin K.
• Primary Examiner(s): ASCHENBRENNER, PETER
• Application Number:
  US07/683,080
• Time in Patent Office: 699 Days
• Field of Search: 604/43, 604/27, 604/28, 604/96, 128/768, 128/769
• US Class Current: 600/585
• CPC Class Codes: A61B 10/0045 Devices for taking samples of body liquids devices for taking blood samples A61B5/15
• CPC Class Codes: A61B 5/14528 invasively
• CPC Class Codes: B01D 61/28 Apparatus therefor
• CPC Class Codes: G01N 1/34 Purifying; Cleaning processes or apparatus for extracting or separating nucleic acids from biological samples C12N15/1003
• CPC Class Codes: G01N 2001/4016 being a selective membrane, e.g. dialysis or osmosis

Abstract

A microdialysis probe for living tissue having respective inlet and outlet, fluid impermeable tubes connected by a dialysis fiber membrane permeable only to small molecular weight compounds. A U-shaped, loop probe tip configuration of the fiber membrane contains a biologically inert wire insertion to prevent kinking and ensure continuous fluid flow through the tip. The length and/or inner diameter of the outlet tube is selected with respect to a given flow rate to create an optimum positive fluid pressure inside the probe membrane tip sufficient to self-support the membrane during insertion and dialysis sampling. Alternative side-by-side and concentric probe configurations are described.

Claims

1. In microdialysis probe apparatus for fluid sampling of biological substances in living tissue, including an inlet tube for continuously delivering a fluid flow under positive fluid pressure to said living tissue, an outlet tube for continuously removing a fluid flow and biological substances from said living tissue, and a semipermeable dialysis fiber membrane at one end of said inlet and outlet tubes for insertion into said living tissue and performing dialysis, the improvement comprising:

membrane support means, including said outlet tube inner diameter bring less than the inner diameter of said inlet tube, and said fluid flow being maintained at a rate with respect to the inner diameter of said outlet tube and the length of said outlet tube sufficient for enabling an effective optimum positive pressure to be maintained within said membrane provided by partial restriction of the continuous fluid flow sufficient to reliably self-support and maintain the shape of said membrane during insertion and dialysis sampling without requiring a physical support to maintain the membrane shape.

2. The improvement of claim 1, wherein said membrane support means enables a positive pressure of at least about 80 mm Hg to be maintained within said membrane.

3. The improvement of claim 2, wherein said membrane support means enables a positive pressure of less than about 610 mm Hg to be maintained within said membrane.

4. The improvement of claim 1, wherein said membrane support means includes said outlet tube having a diameter less than said inlet tube diameter.

5. The improvement of claim 1, wherein said membrane support means comprises a relationship between (a) the length of said outlet tube, (b) the diameter of said outlet tube, and (c) the fluid flow rate sufficient to obtain said effective optimum positive pressure, P, to self-support said membrane said relationship being,

6. The improvement of claim 5, wherein said membrane support means enables a positive pressure of at least about 80 mm Hg to be maintained within said membrane.

7. The improvement of claim 5, including said membrane being a cylindrical shaped member with open ends, and means for forming said membrane into a loop configuration with one loop end communicatively connected to said inlet tube end and the other loop end communicatively connected to said outlet tube end.

8. The improvement of claim 7, including a thin, rigid member within said loop configured membrane to prevent kinking of said membrane during insertion and dialysis sampling.

9. The improvement of claim 5, including said membrane being a cylindrical shaped member with an open end and an opposite closed end, a tubular sleeve surrounding and mounted to said inlet and outlet tubes adjacent said one end thereof, and means for mounting said membrane open end to said tubular sleeve with said inlet tube projecting beyond said one outlet tube end and terminating within said membrane.

10. The improvement of claim 5, including said outlet tube concentrically disposed within said inlet tube, said membrane being a cylindrical shaped member with an open end and an opposite closed end, and means for mounting said membrane open end to said one end of said inlet tube, said outlet tube projecting beyond said inlet tube one end and terminating within said membrane.

11. Microdialysis probe apparatus for fluid sampling of biological substances in living tissue comprising:

an inlet tube for continuously delivering a fluid flow under positive fluid pressure to said living tissue at an inlet tube end;

an outlet tube for continuously removing said fluid flow and biological substances from said living tissue at an outlet tube end;

a U-shaped dialysis fiber membrane having respective legs of the U connected to the inlet tube end and to the outlet tube end; and

membrane support means, including said outlet tube inner diameter being less than the inner diameter of said inlet tube, and said fluid flow being maintained at a rate with respect to the inner diameter of said outlet tube and the length of said outlet tube sufficient for enabling an effective optimum positive pressure to be maintained within said U-shaped membrane provided by partial restriction of the continuous fluid flow sufficient to reliably self-support and maintain the shape of said U-shaped membrane during insertion and dialysis sampling without requiring a physical support to maintain the membrane shape.

12. A microdialysis probe according to claim 11, including a thin, rigid U-shaped wire within said U-shaped membrane to prevent kinking of said U-shaped membrane during insertion and dialysis sampling.

13. A microdialysis probe according to claim 12, wherein said membrane support means enables a positive pressure of at least about 80 mm Hg to be maintained within said U-shaped membrane.

14. A microdialysis probe according to claim 13, wherein said membrane support means enables a positive pressure of less than about 610 mm Hg to be maintained within said U-shaped membrane.