US4572206A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring cardiac output
Assignee: Purdue Research Foundation
•
Filing: 1982-04-21
•
Granted: 1986-02-25
•
Expires: 2002-04-21
Abstract
Abstract Cardiac output is measured utilizing an indicator, such as saline, which alters blood resistivity, and an electrically calibrated conductivity cell positioned at the tip of a catheter. The catheter with the tetrapolar conductivity cell at the tip is inserted into a blood vessel for current injection to develop a potential which is proportional to blood resistivity for inscribing the dilution curve occurring due to injection of the indicator, which curve is utilized to determine blood flow or cardiac output.
Inventors
- 👤 Leslie A. Geddes
- 👤 David S. Grubbs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:05
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/14542; A61B5/02; A61B5/026; A61B5/0275; A61B5/1468; A61B5/1473; A61B5/68; A61B5/6846; A61B5/6847; A61B5/6852
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
97 words
An indicator-dilution method for measuring cardiac output, said method comprising: placing a conductivity cell in the flow path of blood; electrically calibrating said conductivity cell without withdrawing blood from said flow path, said calibrating being accomplished by utilizing said conductivity cell to generate an output indicative of baseline blood resistivity; injecting an indicator into said blood flow path and obtaining an output signal from said conductivity cell indicative of blood resistivity as altered by said indicator; and determining cardiac output from said output indicative of baseline blood resistivity and said output signal indicative of altered blood resistivity.
Claim 2
Dependent Claim
97 words
An indicator-dilution method for measuring cardiac output, said method comprising: placing a conductivity cell in the flow path of blood; electrically calibrating said conductivity cell without withdrawing blood from said flow path, said calibrating being accomplished by utilizing said conductivity cell to generate an output indicative of baseline blood resistivity; injecting an indicator into said blood flow path and obtaining an output signal from said conductivity cell indicative of blood resistivity as altered by said indicator; and determining cardiac output from said output indicative of baseline blood resistivity and said output signal indicative of altered blood resistivity.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein said conductivity cell is positioned at the end of a catheter.
Claim 4
Dependent Claim
29 words
The method of claim 2 wherein said catheter is inserted into a blood vessel so that said conductivity cell is in the flow path of blood in said vessel.
Claim 5
Dependent Claim
57 words
The method of claim 1 wherein said method includes generating an electrical signal and coupling the same to said conductivity cell, developing a potential at said conductivity cell responsive to said generated electrical signal, and utilizing said developed potential to generate said output indicative of baseline blood resistivity and said output signal indicative of altered blood resistivity.
Claim 6
Dependent Claim
39 words
The method of claim 1 wherein said method includes developing a dilution curve based upon said output signal indicative of altered blood resistivity, converting said dilution curve to mean concentration, and determining said cardiac output from said mean concentration.
Claim 7
Dependent Claim
13 words
The method of claim 5 wherein said injected indicator is a saline solution.
Claim 8
Dependent Claim
116 words
An indicator-dilution method for measuring cardiac output, said method comprising: positioning a detector on a catheter; inserting said catheter into a body such that said detector is in the flow path of blood in said body; electrically calibrating said detector without withdrawing blood from said body, said calibrating including electrically exciting said detector so that said detector provides an output indicative of baseline blood resistivity; injecting an indicator into said blood flow path and electrically exciting said detector so that said detector provides an output signal indicative of blood resistivity as altered by said indicator; and determining cardiac output from said output indicative of baseline blood resistivity and said output signal indicative of altered blood resistivity.
Claim 9
Dependent Claim
116 words
An indicator-dilution method for measuring cardiac output, said method comprising: positioning a detector on a catheter; inserting said catheter into a body such that said detector is in the flow path of blood in said body; electrically calibrating said detector without withdrawing blood from said body, said calibrating including electrically exciting said detector so that said detector provides an output indicative of baseline blood resistivity; injecting an indicator into said blood flow path and electrically exciting said detector so that said detector provides an output signal indicative of blood resistivity as altered by said indicator; and determining cardiac output from said output indicative of baseline blood resistivity and said output signal indicative of altered blood resistivity.
Claim 10
Dependent Claim
50 words
The method of claim 7 wherein said detector is a tetrapolar conductivity cell, and wherein said method includes electrically exciting a first pair of poles of said tetrapolar conductivity cell to develop a potential indicative of baseline blood resistivity on a second pair of poles of said tetrapolar conductivity cell.
Claim 11
Dependent Claim
15 words
The method of claim 8 wherein said electrical excitation is provided by a constant-current source.
Claim 12
Dependent Claim
32 words
The method of claim 8 wherein said output indicative of baseline blood resistivity is developed by dividing said potential indicative of baseline blood resistivity by the cell constant of said conductivity cell.
Claim 13
Dependent Claim
24 words
The method of claim 8 wherein said detector is excited by providing a current to said first pair of poles from a constant-current source.
Claim 14
Dependent Claim
43 words
The method of claim 7 wherein said method includes inscribing a dilution curve from said output signal indicative of altered blood resistivity, calibrating said dilution curve in ohms, converting said dilution curve to mean concentration, and determining cardiac output from said mean concentration.
Claim 15
Dependent Claim
18 words
The method of claim 12 wherein said injected indicator is an indicator having a higher conductivity than blood.
Claim 16
Dependent Claim
12 words
The method of claim 13 wherein said indicator is a saline solution.
Claim 17
Dependent Claim
18 words
The method of claim 12 wherein said injected indicator is an indicator having a lower conductivity than blood.
Claim 18
Dependent Claim
13 words
The method of claim 15 wherein said indicator is 5% dextrose in water.
Claim 19
Independent Claim
99 words
An apparatus for enabling measurement of cardiac output by determination of blood resistivity, said apparatus comprising: detector means for detecting resistivity; positioning means for adapting said detector means to be positioned in the flow path of blood; electrical means connected with said detector means for generating an output that is proportional to the resistivity of the blood in said flow path, said electrical means including means for generating an output indicative of baseline blood resistivity, and calibration means for electrically calibrating said apparatus, said calibration means including baseline calibration means for calibrating said output indicative of baseline blood resistivity.
Claim 20
Independent Claim
99 words
An apparatus for enabling measurement of cardiac output by determination of blood resistivity, said apparatus comprising: detector means for detecting resistivity; positioning means for adapting said detector means to be positioned in the flow path of blood; electrical means connected with said detector means for generating an output that is proportional to the resistivity of the blood in said flow path, said electrical means including means for generating an output indicative of baseline blood resistivity, and calibration means for electrically calibrating said apparatus, said calibration means including baseline calibration means for calibrating said output indicative of baseline blood resistivity.
Claim 21
Dependent Claim
24 words
The apparatus of claim 17 wherein said apparatus includes indicating means for receiving said output from said electrical means and indicating said blood resistivity.
Claim 22
Dependent Claim
14 words
The apparatus of claim 18 wherein said indicating means includes a digital readout device.
Claim 23
Dependent Claim
18 words
The apparatus of claim 18 wherein said indicating means includes means for enabling inscribing of a dilution curve.
Claim 24
Dependent Claim
51 words
The apparatus of claim 17 wherein said detector means is a conductivity cell having a plurality of electrodes, and wherein said positioning means includes a catheter having said conductivity cell positioned at the tip thereof and means for preventing said electrodes from contacting a wall defining the flow path of blood.
Claim 25
Dependent Claim
14 words
The apparatus of claim 21 wherein said conductivity cell is a tetrapolar conductivity cell.
Claim 26
Dependent Claim
36 words
The apparatus of claim 22 wherein said tetrapolar conductivity cell includes a pair of exciting electrodes and a pair of output electrodes, and wherein said electrical means includes a constant-current source connected with said exciting electrodes.
Claim 27
Dependent Claim
30 words
The apparatus of claim 21 wherein said conductivity cell has four electrodes arranged along said tip of said catheter in a plane perpendicular to the longitudinal axis of said catheter.
Claim 28
Dependent Claim
39 words
The apparatus of claim 21 wherein said catheter is adapted for insertion in a blood vessel, has an inflatable balloon therein, and at least a first lumen for inflation of said balloon and a second lumen for injecting indicator.
Claim 29
Independent Claim
196 words
An apparatus for enabling measurement of cardiac output by determination of blood resistivity, said apparatus comprising: a tetrapolar conductivity cell having four electrodes; a catheter having said conductivity cell positioned on the tip thereof, said catheter being adapted for insertion into a body so that said conductivity cell is in the flow path of blood in said body; a constant-current source connected with two of said electrodes of said conductivity cell; first amplifying means connected with the other two of said electrodes of said conductivity cell for amplifying a potential appearing on said electrodes; indicating means connected with said first amplifying means for indicating resistivity; isolation means connected with said first amplifying means for providing signal isolation; and second amplifying means connected with said isolation means and providing an isolated analog output of blood resistivity for enabling inscribing of the dilution curve of blood resistivity, wherein said four electrodes are spaced with respect to one another in a line along the end of the tip of said catheter, and wherein the outer two of said electrodes are connected with said constant-current source and the inner two of said electrodes are connected with said first amplifying means.
Claim 30
Independent Claim
196 words
An apparatus for enabling measurement of cardiac output by determination of blood resistivity, said apparatus comprising: a tetrapolar conductivity cell having four electrodes; a catheter having said conductivity cell positioned on the tip thereof, said catheter being adapted for insertion into a body so that said conductivity cell is in the flow path of blood in said body; a constant-current source connected with two of said electrodes of said conductivity cell; first amplifying means connected with the other two of said electrodes of said conductivity cell for amplifying a potential appearing on said electrodes; indicating means connected with said first amplifying means for indicating resistivity; isolation means connected with said first amplifying means for providing signal isolation; and second amplifying means connected with said isolation means and providing an isolated analog output of blood resistivity for enabling inscribing of the dilution curve of blood resistivity, wherein said four electrodes are spaced with respect to one another in a line along the end of the tip of said catheter, and wherein the outer two of said electrodes are connected with said constant-current source and the inner two of said electrodes are connected with said first amplifying means.
References Cited (Backward Citations)
US3823706A
Cited
US3930493A
Cited
US4015593A
Cited
US3985123A
Cited
US4175566A
Cited
WO1980000530A1
Cited
US4380237A
Cited
WO1982001056A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-24 | 1989-08-26 | 1990-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-24 | 1993-08-26 | 1994-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-24 | 1997-08-26 | 1998-02-25 | $7700.00 | Window Closed / Lapsed |