Differential conductivity recirculation monitor
First Claim
1. A method for determining a difference in electrical conductivity of at least two fluids comprising:
- placing a first fluid into a first conductivity cell having a tubular ring configuration, said fluid forming a continuous electrical path;
placing a second fluid into a second conductivity cell having a tubular ring configuration, said fluid forming a continuous electrical path;
inducing a first electrical current in the first fluid in the first conductivity cell and a second electrical current in the second fluid in the second conductivity cell;
sensing the first electrical current in the first fluid in the first conductivity cell and the second electrical current in the second fluid in the second conductivity cell; and
subtracting the second electrical current from the first electrical current to produce a signal representative of the difference in the conductivity between the first and the second fluids.
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0 Petitions
Accused Products
Abstract
A differential conductivity recirculation monitor quantitatively determines the degree of recirculation in a fistula by comparing the conductivity of blood entering the fistula to the conductivity of blood being withdrawn from the fistula. A discrete quantity of a high conductivity marker fluid is injected into the blood entering the fistula, altering the conductivity of the blood entering the fistula. The altered conductivity blood enters the fistula and, if recirculation is present, co-mingles with blood in the fistula, altering the conductivity of the blood ion the fistula in proportion to the degree of recirculation. Blood withdrawn from the fistula has an altered conductivity related to the degree of recirculation. Quantitative values of the conductivity of the altered conductivity blood entering the fistula and the conductivity of the blood being withdrawn from the fistula are measured and a difference determined. The determined difference between the conductivities is used to determine a quantitative measurement of the degree of recirculation in the fistula.
92 Citations
12 Claims
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1. A method for determining a difference in electrical conductivity of at least two fluids comprising:
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placing a first fluid into a first conductivity cell having a tubular ring configuration, said fluid forming a continuous electrical path; placing a second fluid into a second conductivity cell having a tubular ring configuration, said fluid forming a continuous electrical path; inducing a first electrical current in the first fluid in the first conductivity cell and a second electrical current in the second fluid in the second conductivity cell; sensing the first electrical current in the first fluid in the first conductivity cell and the second electrical current in the second fluid in the second conductivity cell; and subtracting the second electrical current from the first electrical current to produce a signal representative of the difference in the conductivity between the first and the second fluids. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for determining a difference in electrical conductivity of at least two fluids comprising:
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a first conductivity cell adapted to contain a first fluid and having a tubular ring configuration forming a continuous fluid path; a second conductivity cell adapted to contain a second fluid and having a tubular ring configuration forming a continuous path; means for inducing a first electrical current in the first fluid in the first conductivity cell and a second electrical current in the second fluid in the second conductivity cell; means for sensing the first electrical current in the first fluid in the first conductivity cell and the second electrical current in the second fluid in the second conductivity cell and for subtracting the second electrical current from the first electrical current to,produce a signal representative of the difference in the conductivity between the first and the second fluids. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification