Thermodilution catheter and method

• US 4,153,048 A
• Filed: 09/14/1977
• Issued: 05/08/1979
• Est. Priority Date: 09/14/1977
• Status: Expired due to Term

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Magrini, Fabio
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US05/833,163
• Time in Patent Office: 601 Days
• Field of Search: 128/2.05 F, 128/2.05 R, 128/2.05 V, 128/2 H, 73/204
• US Class Current: 600/505
• CPC Class Codes: A61B 5/028 by thermo-dilution
• CPC Class Codes: A61B 5/6857 with a distal pigtail shape

Abstract

A new and improved pigtail type catheter and method particularly suited for the local thermodilution technique for determination of venous blood flow. The fluid injection aperture is disposed in the pigtail portion adjacent the most forward extending area thereof. A thermister is operably associated with the pigtail portion adjacent the distal end thereof intermediate the spaced apart side edges. A separate aperture may be conveniently included at the distal end of the pigtail portion to facilitate pressure readings of the venous flow. The new structural arrangement and method facilitate absolute thermal insulation between the fluid injected into the venous flow and the thermister, avoidance of contact between the thermister and vessel walls and a generally constant spacial relationship between the injection aperture and thermister.

Claims

1. A pigtail type of catheter for practicing the thermodilution technique of measuring venous blood flow, said catheter comprising:

an elongated hollow catheter body having spaced apart first and distal ends, said body merging into a pigtail portion including said distal end and forming a reversing loop-like area extending back over said body toward said first end with at least said distal end extending generally back toward said body adjacent the area of merger thereof with said pigtail portion;

a supply lumen at said first end for introduction of a fluid injectate into said hollow catheter body and a first aperture in said pigtail portion communicating with the hollow interior of said catheter body to allow fluid injectate flow outwardly of said catheter into said venous flow; and

, temperature sensing means operably associated with said pigtail portion spaced therealong toward said distal end from said first aperture for sensing a temperature change in said venous flow after said fluid injectate has been injected thereinto through said first aperture.

2. The catheter as defined in claim 1 further including a second aperture at the body distal end communicating with the hollow interior of said catheter body.

3. The catheter as defined in claim 1 wherein said body includes a generally straight section at least adjacent the area of merger between said body and pigtail portion, said first aperture being disposed in said reversing loop-like area at an angle of no more than approximately 45°

from said straight section whereby said fluid injectate will be directed outwardly from said first aperture into said venous flow.

4. The catheter as defined in claim 3 wherein said angle is in the range of approximately 30°

-40°

.

5. The catheter as defined in claim 1 wherein said reversing loop-like area has a generally arcuate configuration at least at the area thereof which reversely bends back toward said body.

6. The catheter as defined in claim 1 wherein said reversing loop-like area defines a pigtail portion plane with said distal end being in said plane and at least that portion of said pigtail portion having said temperature sensing means associated therewith being disposed generally normal to said body.

7. The catheter as defined in claim 6 wherein said reversing loop-like area is substantially closed with said distal end closely spaced to said body.

8. In a pigtail type catheter of the type employed to measure venous flow wherein said catheter includes a hollow elongated body having first and distal ends and which body merges into a pigtail portion adjacent said distal end which is inserted into communication with said venous flow, said pigtail portion generally forming a reversing loop-like area which extends back around said body and wherein a fluid injectate is introduced into said catheter from said first end and thence into said venous flow from at least one injection aperture spaced along said catheter from said first end in fluid communication with the hollow interior of said body in order that a temperature change in said venous flow may thereafter be monitored downstream thereof, the improvement comprising:

a portion of the pigtail portion including said distal end extending back toward said body adjacent the area of merger between said body and pigtail portion; and

, temperature sensing means operably mounted on said portion of said pigtail portion toward said distal end from said at least one injection aperture for sensing a temperature change in said venous flow following injection of said fluid injectate thereinto through said at least one injection aperture.

9. The improvement as defined in claim 8 wherein said at least one injection aperture is disposed in said pigtail portion to facilitate fluid injectate flow outwardly thereof generally axially of said venous flow, said at least one injection aperture being disposed in said pigtail portion at an angle of no more than 45°

as measured from a generally straight section of said body adjacent the area of merger between said body and pigtail portion.

10. The improvement as defined in claim 9 wherein the angle is in the range of between approximately 30°

-40°

.

11. The improvement as defined in claim 10 wherein said distal end is closely spaced to said body portion and includes a second aperture communicating with the hollow interior of said body.

12. A thermodilution method for monitoring venous blood flow through use of a pigtail type catheter wherein the pigtail portion thereof comprises a reversing loop-like area at one end of an elongated hollow catheter body and which pigtail portion terminates in a distal end with at least a portion of said loop-like area extending back toward said catheter body, said method comprising the steps of:

positioning the catheter in said venous flow with said pigtail portion disposed furthest upstream of said flow and generally centrally thereof;

injecting a fluid injectate having a temperature different from that of said venous flow into said hollow catheter body at the other end thereof from said pigtail portion;

allowing said fluid injectate to pass from said catheter pigtail portion into said venous flow generally upstream thereof through an injection aperture communicating with the hollow interior of said catheter body between the area of merger of said pigtail portion and body and the midpoint of said reversing loop-like area;

locating at least a temperature sensing means on said body spaced from said injection aperture toward the distal end thereof in said pigtail portion and between the side edges of said pigtail portion in a predetermined generally fixed spaced relationship from said injection aperture; and

,

sensing a change in temperature of said venous flow at the temperature sensing means downstream of the point of the injection of said fluid injectate thereinto.

13. The method as defined in claim 12 further including the steps of providing a pressure sensing aperture at said distal end in said pigtail portion communicating with the hollow interior of said catheter body and sensing pressure of said venous flow at said pressure sensing aperture.