Differential conductivity hemodynamic monitor

• US 6,075,367 A
• Filed: 12/23/1998
• Issued: 06/13/2000
• Est. Priority Date: 09/30/1992
• Status: Expired due to Fees

• Current Assignee: Gambro Renal Products, Inc. (Baxter International Inc.)
• Original Assignee: Gambro, Inc. (DaVita Incorporated)
• Inventors: Brugger, James M
• Primary Examiner(s): Do, Diep N.
• Application Number:
  US09/220,139
• Time in Patent Office: 538 Days
• Field of Search: 324/439, 324/444, 324/445, 324/450, 324/722, 324/71.1, 73/861.04, 73/861.07, 73/861.08, 73/861.11, 73/861.16
• US Class Current: 324/439
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/361 before treatment
• CPC Class Codes: A61M 1/3612 after treatment
• CPC Class Codes: A61M 1/3653 Interfaces between patient blood circulation and extra-corporal blood circuit
• CPC Class Codes: A61M 1/3655 Arterio-venous shunts or fistulae
• CPC Class Codes: A61M 1/3658 Indicating the amount of purified blood recirculating in the fistula or shunt
• CPC Class Codes: A61M 1/3659 Cannulae pertaining to extracorporeal circulation
• CPC Class Codes: A61M 1/3661 for haemodialysis
• CPC Class Codes: A61M 1/3669 Electrical impedance measurement of body fluids; transducers specially adapted therefor
• CPC Class Codes: G01F 1/7046 using electrical loaded particles as tracer, e.g. ions or electrons
• CPC Class Codes: G01F 1/708 Measuring the time taken to traverse a fixed distance
• CPC Class Codes: G01F 1/7088 using electrically charged particles as tracers

Abstract

A flow rate of a fluid flowing in a tube is quantitatively determined by altering the electrical conductivity of the fluid by injection of a bolus of saline. The electrical conductivity of the altered conductivity is measured over the time it takes the altered conductivity fluid to pass a conductivity measuring location. The measured conductivity is integrated over the time it take to pass the conductivity measuring location. The integral is interpreted to determine the flow rate.

Claims

1. A method for quantitatively determining a flow rate of blood in an extracorporeal tube of a fluid having an electrical conductivity and a corresponding concentration of conductivity producing ions, said method comprising the steps of:

altering the electrical conductivity of the fluid;

measuring the electrical conductivity at a measuring location of the fluid after the conductivity is altered;

determining the period of time over which the altered conductivity fluid passes the measuring location;

integrating the measured conductivity over the period of time; and

interpreting the time integrated value of conductivity to determine flow rate.

2. A method for quantitatively determining a flow rate of blood in an extracorporeal tube of a first fluid having a first electrical conductivity and a corresponding first concentration of conductivity producing ions, said method comprising the steps of:

altering the electrical conductivity of the first fluid;

measuring the electrical conductivity at a measuring location of the first fluid after the conductivity is altered;

determining the period of time over which the altered conductivity fluid passes the measuring location;

integrating the measured conductivity over the period of time;

interpreting the time integrated value of conductivity to determine flow rate; and

displaying on a monitor the status or results of at least one of said steps of said method for quantitatively determining a flow rate.

3. A method for quantitatively determining a flow rate according to claim 2 which further includes a second extracorporeal tube of a second fluid having a second electrical conductivity and a corresponding second concentration of conductivity producing ions, said method further comprising the steps of:

measuring the electrical conductivity at a measuring location of the second fluid;

determining the period of time over which the second fluid passes the measuring location;

integrating the measured conductivity over the period of time;

interpreting the time integrated value of conductivity to determine flow rate; and

displaying on a monitor the status or results of at least one of said steps of said method for quantitatively determining a flow rate.

4. A method according to claim 3 further comprising the step of:

comparing the respective flow rates of the first and second fluids.

5. An apparatus for quantitatively determining a flow rate of blood in an extracorporeal tube of a first fluid having a first electrical conductivity and a corresponding first concentration of conductivity producing ions, said apparatus comprising:

means for altering the electrical conductivity of the first fluid;

means for measuring the electrical conductivity at a measuring location of the first fluid after the conductivity is altered;

means for determining the period of time over which the altered conductivity fluid passes the measuring location;

means for integrating the measured conductivity over the period of time;

means for interpreting the time integrated value of conductivity to determine flow rate; and

means for displaying on a monitor the status or results of at least one of said steps of said method for quantitatively determining a flow rate.

6. An apparatus for quantitatively determining a flow rate according to claim 5 which further includes a second extracorporeal tube of a second fluid having a second electrical conductivity and a corresponding second concentration of conductivity producing ions, said apparatus further comprising:

means for measuring the electrical conductivity at a measuring location of the second fluid;

means for determining the period of time over which the second fluid passes the measuring location;

means for integrating the measured conductivity over the period of time;

means for interpreting the time integrated value of conductivity to determine flow rate; and

means for displaying on a monitor the status or results of at least one of said means used in quantitatively determining a flow rate.

7. An apparatus according to claim 6 further comprising:

means for comparing the respective flow rates of the first and second fluids.