Apparatus and method for measuring osmotic pressure in situ

• US 4,603,699 A
• Filed: 11/20/1984
• Issued: 08/05/1986
• Est. Priority Date: 11/20/1984
• Status: Expired due to Fees

• Current Assignee: Jacques M. Himpens
• Original Assignee: Jacques M. Himpens
• Inventors: Himpens, Jacques M.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Hanley, John C.
• Application Number:
  US06/673,290
• Time in Patent Office: 623 Days
• Field of Search: 128/673-675, 128/748, 128/637, 128/632, 128/635, 73/64.3
• US Class Current: 600/486
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61M 2025/0002 with a pressure sensor at the distal end

Abstract

A multiple-lumen Swanz-Ganz catheter is disclosed wherein said first and second lumens are connected to an osmotic pressure sensor and a third lumen is connected to a hydrostatic pressure sensor. First and second lumens are fluidly continuous, connected through six hollow fibrils. Pressure in the first and second lumens is added to the pressure of the third lumen to determine colloid osmotic pressure.

The fibrils are made of a cellulose acetate material permeable to substances having a molecular weight less than 30,000 and filled with nylon filaments. The fibrils are exposed to the bloodstream through a port in the catheter which also provides an external opening for the third lumen. Fluid in the fibrils is pulsed to remove debris from the surfaces of the fibrils 16. The surfaces of the fibrils are also flushed periodically with physiological saline solution from the third lumen to prevent obstruction. The catheter is held in place by a flotation balloon.

Claims

1. Apparatus for use in a system for measuring osmotic pressure in a bloodstream, said apparatus comprising:

catheter means for insertion in a subject'"'"'s bloodstream, said catheter means having first and second lumens therein and a port adapted to permit contact of the interior of said catheter with said bloodstream;

at least one tube of a material that is semi-permeable to a fluid of said bloodstream, said tube fluidly connecting said first lumen with said second lumen and extending across said port, the ends of said tube being connected to said first and second lumens, respectively, in airtight and watertight seals; and

a pressure sensor means for measuring the pressure in said first lumen.

4. Apparatus as claimed in claim 1, 2 or 3 wherein said apparatus further comprising value means for selectively connecting said third lumen to a source of fluid pressure for flushing fluid past said tube to remove debris.

5. Apparatus as claimed in claim 1, 2 or 3 wherein said tube is filled with fibers, said tube having a fluid volume which is reduced by said fibers, with said fibers providing support for said tube against external pressure.

2. Apparatus for measuring osmotic pressure, said apparatus comprising:

catheter means for insertion in a subject'"'"'s bloodstream, said catheter means having three lumens, and a port adapted to permit passage of fluid from said bloodstream into said catheter means;

at least one tube of a material that is semi-permeable to said fluid from said bloodstream, said tube fluidly connecting a first lumen with a second lumen and extending across said port, the ends of said tube being connected to said first and second lumens, respectively, in airtight and watertight seals;

the third lumen being in fluid communication with the exterior of said tube opposite said port;

a first pressure sensor means for measuring the pressure of fluid in said first lumen; and

a second pressure sensor means for measuring the pressure of fluid in the third lumen, said third lumen opening to the bloodstream at said port.

3. Apparatus for measuring osmotic pressure, said apparatus comprising:

catheter means for insertion in a subject'"'"'s bloodstream, said catheter means having three lumens and a port adapted to permit contact of the interior of said catheter with said bloodstream;

at least one tube of material that is semi-permeable to a fluid of said bloodstream fluidly connecting a first lumen with a second lumen and extending across said port, the ends of said tube being connected to said first and second lumens, respectively, in an airtight and watertight seal, said material being permeable to substances having a molecular weight not greater than 30,000;

the third lumen being in fluid communication with the exterior of said tube opposite said port;

a first pressure sensor means for measuring the pressure in said first lumen; and

a second pressure sensor means for measuring the pressure in the third lumen, said third lumen opening to said bloodstream at said port.

6. A method for measuring osmotic pressure in the bloodstream comprising the steps:

inserting a multiple-lumen catheter into the circulatory system of a subject, said catheter having first, second, and third lumens filled with a physiologically normal fluid and having said first and second lumens fluidly connected by at least one semi-permeable tube extending across a port in said catheter, and a third lumen in communication with the exterior of said tube opposite said port;

measuring the fluid pressure in said first lumen;

measuring the fluid pressure in said third lumen; and

adding the pressure of the fluid in the first lumen to the pressure of the fluid in the third lumen to determine the intravascular osmotic pressure.

7. A method as claimed in claim 6 further comprising the step of periodically flushing a physiologically normal fluid through said third lumen past said tube to prevent thrombic activity from interfering with the measurement of osmotic pressure.