Multi-purpose multi-parameter cardiac catheter

• US 5,634,720 A
• Filed: 09/02/1994
• Issued: 06/03/1997
• Est. Priority Date: 07/16/1992
• Status: Expired due to Term

• Current Assignee: Hospira Incorporated (Pfizer Inc.)
• Original Assignee: Abbott Laboratories
• Inventors: Hughes, Timothy J., Gallup, David A.
• Primary Examiner(s): BENNETT, GEORGE B
• Application Number:
  US08/300,272
• Time in Patent Office: 1,005 Days
• Field of Search: 374/163, 374/164, 374/170, 374/171, 374/183, 374/141, 128/736, 128/668, 128/670
• US Class Current: 374/183
• CPC Class Codes: A61B 5/028 by thermo-dilution
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence

Abstract

A multi-lumen, multi-purpose cardiac catheter which incorporates optical filaments and an optical coupler for use with external apparatus for determining the oxygen concentration in the blood of a patient under critical care conditions, as well as incorporating therein a thermal element useable with a second external apparatus for measurement of continuous cardiac output. A thermal plug provides an interface between a temperature control apparatus and the thermal element to simply and accurately monitor and control the temperature of the thermal element. A temperature monitoring circuit in the thermal plug facilitates temperature measurement at the thermal element. The catheter also includes a thermistor and at least one injectate port for enabling the user to also conduct thermal dilution readings and obtain intermittent measurements of cardiac output. The combination of a thermal dilution catheter with a SV0₂ catheter and a continuous cardiac output catheter gives the multi-purpose catheter above described substantial versatility as well as providing the user with a versatile cardiac catheter device which enables him to conduct multiple evaluations of disparate blood-related parameters which require the use of separate apparatus. Simply by switching from one external apparatus to the other, the user can obtain readings for different blood-related parameters useful in the treatment of the cardiac patient.

Claims

1. A temperature monitoring circuit comprising:

a thermal element comprising an electrical resistance heater having first and second terminals;

a calibration resistance element having first and second terminals, said first terminal of said thermal element and said first terminal of said calibration resistance element electrically connected to a common terminal;

a voltage sensing means electrically connected between said second terminal of said thermal element and said second terminal of said calibration resistance element;

a current source;

a first electrical path selectively connecting said current source between said second terminal of said thermal element and said common terminal; and

a second electrical path selectively connecting said current source between said second terminal of said calibration resistance element and said common terminal.

2. A temperature monitoring circuit as claimed in claim 1 wherein the calibration resistance element comprises at least one resistor having at least one adjusting resistor connected in parallel therewith.