Blood gas catheter

• US 4,016,864 A
• Filed: 09/08/1975
• Issued: 04/12/1977
• Est. Priority Date: 08/01/1974
• Status: Expired due to Term

• Current Assignee: Airco, Inc. (Linde Plc)
• Original Assignee: Airco, Inc. (Linde Plc)
• Inventors: Peickert, Wilfried R., Sielaff, Ulrich
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/611,473
• Time in Patent Office: 582 Days
• Field of Search: 128/2 L, 128/2 E, 128/2 G, 128/2 F, 128/2 R, 128/348, 128/214.4, 23/230 B, 23/232 C, 23/254 R, 73/421.5 R, 73/23 R, 73/23.1
• US Class Current: 600/364
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61M 2025/004 characterized by lumina being arranged circumferentially
• CPC Class Codes: A61M 25/0045 multi-layered, e.g. coated coating materials A61L29/08
• CPC Class Codes: A61M 25/005 with embedded materials for reinforcement, e.g. wires, coils, braids

Abstract

An instrument for withdrawing equilibrated blood gases in vivo, which comprises a tubular gas permeable membrane inserted through a cannular into the blood stream. In preferred form, the tubular membrane comprises a continuous conduit in contact with the blood. An inlet supply gas terminal is constructed for connection to a carrier gas source, and an outlet gas terminal, for connection to an appropriate analyzer. In preferred forms of the invention, a heater maintains the equilibrated gases at above normal body temperature as they pass to the analyzer; and a port is provided for drawing blood samples from the area being analyzed without dislodging the catheter.

Claims

1. A device for sampling gases dissolved in the blood of a living subject, comprising in combination:

a catheter having distal and proximal ends,

means disposed at the distal end of said catheter comprising a tubular gas permeable membrane primarily of material highly permeable to gas but substantially impermeable to blood, constructed for insertion through a cannula percutaneously into the blood vessel in a direction extending along the principal axis thereof, said tubular membrane including a continuous gas permeable conduit, at least a portion of the lateral walls of said conduit being constructed and arranged during percutaneous deposition of said tubular membrane to make contact with the blood of said subject,

means comprising a housing at the proximal end of said catheter including input and output gas receptacles respectively constructed and arranged for connection in circuit relation to a source of carrier gas at said input receptacle and to gas receiving means at said output receptacle,

said conduit having input and output terminals respectively connected through separate connecting means to said input and output gas receptacles.

2. The combination in accordance with claim 1 wherein R, the permeability of said gas permeable membrane, is at least of the same order of magnitude as the permeability for oxygen through dimethyl silicone.

3. The combination in accordance with claim 1 wherein said gas permeable membrane consists essentially of a polysiloxane polymer.

4. A catheter in accordance with claim 1 wherein said gas permeable conduit has a substantially uniform cross-section and permeability along its length between said terminals.

5. The combination in accordance with claim 1 wherein said tubular gas permeable membrane comprises a plurality of lumens interconnected to form said continuous gas permeable conduit of substantially uniform cross section and permeability between said input and output terminals which is constructed and arranged to have a length in contact with the blood during said percutaneous disposition which substantially exceeds the length of the said tubular membrane.

6. The combination in accordance with claim 5 wherein said tubular gas permeable membrane comprises at least two substantially parallel lumens of substantially uniform cross section and permeability forming said gas permeable conduit substantially double the length of said membrane and joined together near the distal end of said catheter to provide a reversal of the direction of gas flow from one to the other, the opposite ends of said lumens respectively comprising said input and output terminals.

7. The combination in accordance with claim 6 wherein said tubular gas permeable membrane has an overall cross-sectional dimension not exceeding about 0.028 inch, and each of said lumens has an internal diameter not exceeding about 0.011 inch.

8. The combination in accordance with claim 5 comprising a stiffening wire interposed into an additional lumen in said tubular gas permeable membrane in substantially fixed position and extending substantially parallel to the length of said membrane.

9. The combination in accordance with claim 1 wherein said separate connecting means comprise a pair of tubes substantially impermeable to gas connected in mating relation between the input and output terminals of said tubular gas permeable conduit and the housing at the proximal end of said catheter.

10. The combination in accordance with claim 9 wherein said tubes substantially impermeable to gas consist essentially of stainless steel.

11. The combination in accordance with claim 1 wherein said tubular gas permeable membrane is in the form of a sleeve surrounding a return gas tube substantially impermeable to gas, said tubes and said sleeve being internally interconnected near the distal end of said catheter, said sleeve connected at its proximal end to said input terminal, and said substantially impermeable return gas tube connected at its proximal end to said output terminal.

12. The combination in accordance with claim 11 wherein supporting means comprising a coil of wire is interposed into said sleeve extending along the length of said sleeve and surrounding said substantially impermeable return gas tube.

13. A device for sampling gases dissolved in the blood of a living subject comprising in combination:

a catheter having distal and proximal ends,

means disposed at the distal end of said catheter comprising a tubular membrane primarily of gas permeable material constructed for insertion through a cannula percutaneously into the blood vessel in a direction extending along the principal axis thereof, said tubular membrane including a continuous gas permeable conduit, at least a portion of the lateral walls of said conduit being constructed and arranged in percutaneous disposition of said tubular membrane to make contact with the blood of said subject,

means comprising a housing at the proximal end of said catheter including input and output gas receptacles respectively constructed and arranged for connection in circuit relation to a source of carrier gas at said input receptacle and to gas receiving means at said output receptacle,

said conduit having input and output terminals respectively connected through separate connecting means to said input and output gas receptacles,

said separate connecting means comprising a pair of tubes substantially impermeable to gas connected in mating relation between said input and output terminals and said corresponding input and output gas receptacles of said housing, and

heating means in the form of at least one high-resistance wire loop extending substantially the length of the tubes of said pair and connected to a source of power, for maintaining the gases in said tubes at a temperature at least exceeding body temperature.

14. A device for sampling gases dissolved in the blood of a living subject comprising in combination:

a catheter having distal and proximal ends,

means disposed at the distal end of said catheter comprising a tubular membrane primarily of gas permeable material constructed for insertion through a cannula percutaneously into the blood vessel in a direction extending along the principal axis thereof, said tubular membrane including a continuous gas permeable conduit, at least a portion of the lateral walls of said conduit being constructed and arranged during percutaneous disposition of said tubular membrane to make contact with the blood of said subject,

means comprising a housing at the proximal end of said catheter including input and output gas receptacles respectively constructed and arranged for connection in circuit relation to a source of carrier gas at said input receptacle and to gas receiving means at said output receptacle,

said conduit having input and output terminals respectively connected through separate connecting means to said input and output gas receptacles,

said separate connecting means comprising a pair of tubes substantially impermeable to gas, and

an adapter hub having a male taper constructed to fit concentrically into the mouth of said cannula when the same is interposed into the blood vessel of the said subject, said male taper including a first passage constructed to surround and secure connections to the proximal end of said gas permeable membrane adjacent the junction with said substantially gas-impermeable tubes, and said male taper including a second passage substantially parallel to said first passage constructed to lead directly through the open end of said cannula at its distal end and terminating in a female taper at its proximal end, whereby said second passage is adapted to tap directly into the bloodstream of the said subject for drawing a blood sample without disturbing the position of the said catheter when interposed in a blood vessel.

15. A device for contacting the blood of a subject to remove gases from the blood, comprising in combination:

a catheter having distal and proximal ends,

said catheter comprising an inlet flow path means for introducing a carrier gas to the distal end of said catheter and an outlet flow path means for removing said carrier gas from the distal end of said catheter,

a portion of at least one of said flow path means comprising a membrane material highly permeable to gas but impermeable to blood, said portion constructed and arranged when in contact with the blood of said subject for allowing equilibration through the lateral wall thereof between said gases in the blood and the carrier gas passing along said at least one flow path means whereby gases in the blood enter said at least one flow path means and are mixed with the carrier gas, and the mixed gases are removed in said outlet flow path means.

16. A catheter as set forth in claim 15 wherein said portion of at least one of said flow path means comprises a portion of both said inlet flow path means and said outlet flow path means.

17. A catheter as set forth in claim 15 wherein said inlet flow path means and said outlet flow path means are elongated, capillary paths extending substantially along the length of the catheter.

18. A catheter as set forth in claim 15 wherein said membrane material is silicone polymer having a thickness of between 0.002 and 0.0025 inches.