Method and apparatus for measuring cardiac output
First Claim
Patent Images
1. 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.
1 Assignment
0 Petitions
Reexamination
Accused Products
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.
103 Citations
26 Claims
-
1. 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. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. 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. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. 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. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
-
-
26. 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.
-
Specification