Method and apparatus for determining cross-sectional area of a blood conduit and volumetric flow therethrough

• US 3,896,373 A
• Filed: 11/30/1972
• Issued: 07/22/1975
• Est. Priority Date: 11/30/1972
• Status: Expired due to Term

• Current Assignee: Leon W. Zelby
• Original Assignee: Leon W. Zelby
• Inventors: Zelby, Leon W.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/310,872
• Time in Patent Office: 964 Days
• Field of Search: 324/64,65R,3R,57R,71R 128/2.5F,2.5V
• US Class Current: 600/505
• CPC Class Codes: A61B 5/027 using catheters
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: G01F 1/64 by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects G01F1/58 takes precedence

Abstract

An improved method and apparatus for determining the crosssectional area of a blood conduit or the like, as defined herein, and, in one form, the instantaneous and continuous volumetric flow therethrough by means of pair of electrodes disposed within the blood conduit (located on a cardiac catheter, in one form). The electrodes are spaced a predetermined distance apart and connected to an electrical power supply, and the voltage drop between the pair of electrodes is measured, the measured voltage drop providing an instantaneous and continuous electrical parameter indicative of the internal cross-sectional area of the blood conduit. In one form, the apparatus includes a flow transducer providing an output velocity signal indicative of the velocity of the fluid flowing through the blood conduit, the product of the determined cross-sectional area and the velocity providing an output indication indicative of the volumetric flow of fluid through the blood conduit and, in one other form, conductivity sensing electrodes are utilized to provide an in vivo determination of the fluid conductivity.

Claims

1. Apparatus for determining parameters of a fluid flowing through a conduit or the like comprising:

means for insertion within the conduit;

a pair of electrodes, each electrode secured to the means for insertion within the conduit and the pair of electroDes spaced apart a predetermined distance;

electrical power source means connected to the pair of electrodes impressing a predetermined electrical energy therebetween;

circuit means electrically connected to the electrodes of the pair of electrodes measuring and determining the voltage drop between the electrodes of the pair of electrodes impressed with the predetermined electrical energy and providing an output indication indicative of the measured and determined voltage drops, the measured and determined voltage drop being indicative of the internal cross-sectional area of the conduit generally between the electrodes;

output indicator means, having programmed therein the distance between the electrodes, receiving the measured and determined voltage drop between the electrodes, receiving a provided input signal indicative of the fluid conductivity, receiving the impressed predetermined electrical energy between the electrodes, and providing an output indication indicative of the internal cross-sectional area of the conduit.

2. Apparatus for determining parameters of a fluid flowing through a conduit or the like comprising:

means for insertion within the conduit;

a pair of electrodes, each electrode secured to the means for insertion within the conduit and the pair of electrodes spaced apart a predetermined distance;

electrical power source means connected to the pair of electrodes impressing a predetermined electrical energy there-between;

circuit means electrically connected to the electrodes of the pair of electrodes measuring and determining a voltage drop between the electrodes of the pair of electrodes impressed with the predetermined electrical energy and providing an output indication indicative of the measured and determined voltage drop, the measured and determined voltage drop being indicative of the internal cross-sectional area of the conduit generally between the electrodes; and

compensating network means connected to the means measuring the voltage drop and linearizing the relationship between the measured and determined voltage drop and internal cross-sectional area of the conduit providing a compensated output linearly indicative of the internal cross-sectional area of the conduit generally between the pair of electrodes.

3. Apparatus for determining parameters of a fluid flowing through a conduit or the like comprising:

means for insertion within the conduit;

a pair of electrodes, each electrode secured to the means for insertion within the conduit and the pair of electrodes spaced apart a predetermined distance;

electrical power source means connected to the pair of electrodes impressing a predetermined electrical energy therebetween;

a pair of condutivity sensing electrodes secured to the means for insertion within the conduit, the conductivity sensing electrodes being disposed generally near and between the electrodes of the pair of electrodes;

means connected to conductivity sensing electrodes prividing a conductivity signal indicative of the conductivity of the fluid flowing within the conduit; and

circuit means electrically connected to the electrodes of the pair of electrodes measuring and determining an electrical parameter between the electrodes of the pair of electrodes impressed with the predetermined electrical energy and providing an output indication indicative of the measured and determined electrical parameter, the measured and determined electrical parameter being indicative of the internal cross-sectional area of the conduit generally between the electrodes.

4. Apparatus for determining parameters of a fluid flowing through a conduit or the like comprising:

means for insertion within the conduit;

a pair of electrodes, each electrode secured to the means for insertion within the conduit and the pair of electrodes spaced apart a predetermined distance;

electrical power source means connected to the pair of electrodes impressing a predetermined eleCtrical energy therebetween;

a pair of conductivity sensing electrodes secured to the means for insertion within the conduit, the conductivity sensing electrodes being disposed generally near and between the electrodes of the pair of electrodes;

means connected to conductivity sensing electrodes providing a conductivity signal indicative of the conductivity of the fluid flowing within the conduit;

circuit means electrically connected to the electrodes of the pair of electrodes measuring and determining the voltage drop between the electrodes of the pair of electrodes impressed with the predetermined electrical energy and providing an output indication indicative of the measured and determined voltage drop, the measured and determned voltage drop being related to the electrical resistance generally between the pair of electrodes and indicative of the cross-sectional area of the conduit; and

output indicator means, having programmed therein the determined values of current and distance between the electrodes of the pair of electrodes, receiving the conductivity signal, the measured and determined voltage drop between the electrodes of the pair of electrodes and proving an output indication indicative of the internal cross-sectional area of the conduit.

5. Method for determining the internal cross-sectional area of a blood conduit or the like having blood or the like flowing therethrough, the method comprising the steps of:

disposing a first pair of electrodes within the blood conduit spaced apart a predetermined distance;

impressing a predetermined, known electrical energy between the electrodes of the first pair of electrodes;

measuring the voltage drop of the blood flowing through the blood conduit between the electrodes of the first pair of electrodes impressed with the known electrical energy, the measured voltage drop being indicative of the electrical resistance generally between the first pair of electrodes impressed with the known electrical energy defined as the current impressed generally between the electrodes of the first pair of electrodes;

disposing a second pair of electrodes within the blood conduit spaced apart a predetermined distance generally near and between the electrodes of the first pair of electrodes;

measuring the conductivity of the blood flowing within the blood conduit utilizing the second pair of electrodes to provide determination of the blood conductivity; and

determining the internal cross-sectional area of the blood conduit as determined via the relationship;

6. Method for determining the internal cross-sectional area of a blood conduit or the like having blood or the like flowing therethrough, the method comprising the steps of:

disposing a first pair of electrodes within the blood conduit spaced apart a predetermined distance;

impressing a predetermined, known electrical energy between the electrodes of the first pair of electrodes;

determining the electrical capacitance of the blood flowing through the blood conduit between the electrodes of the first pair of electrodes impressed with the known electrical energy;

measuring the permittivity ( epsilon ) of the blood flowing through the blood conduit; and

determining the internal cross-sectional area of the blood conduit via the relationship;

7. Method for determining the internal cross-sectional area of a blood conduit or the like having blood or the like flowing therethrough, the method comprising the steps of:

disposing a first pair of electrodes within a blood conduit spaced apart a predetermined distance;

impressing a predetermined, known electrical energy between the electrodes of the first pair of electrodes; and

determining the electrical inductance of the blood flowing through the blood conduit between the electrodes of the first pair of electrodes impressed with the known electrical energy;

measuring the permeability ( Mu ) of the blood flowing through the blood conduit; and

determining the internal cross-sectional area of the blood conduit via the relationship;