Systems and methods for detecting vascular access disconnection

Patent metadata

Field	Value
Publication number	US-12397097-B2
Application number	US-202117346959-A
Country	US
Kind code	B2
Filing date	Jun 14, 2021
Priority date	May 24, 2011
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A system for detecting whether a vascular access has been interrupted in an arrangement in which two catheters or needles are present in a blood vessel, fistula or graft. A fluid line leading to a pump is connected via a first connector to a first indwelling catheter, and a fluid line leading from a pump is connected via a second connector to a second indwelling catheter. Each connector is equipped with an electrode in contact with the lumen of the connector, the electrodes electrically connected to an electronic circuit that measures the impedance or conductivity of fluid between the first connector and second connectors via a fluid path through the blood vessel, fistula or graft. An electronic controller receives the impedance or conductivity data and processes the data to determine whether a vascular access disconnection has occurred. The processing may involve filtering the signal received by the controller, and/or setting provisional flags for a disconnection event that may be cleared if the signal changes before the expiration of a counter.

First claim

The invention claimed is:

1. A system for detecting dislodgment of a catheter or needle in a vascular access, the vascular access comprising a first and second catheter or needle configured for placement in a blood vessel, fistula or graft, the system comprising:
a first line fluidly connecting the first catheter or needle to an inlet of a pump;
a second line fluidly connecting the second catheter or needle to an outlet of the pump;
a first connector connecting the first line to the first catheter or needle, and a second connector connecting the second line to the second catheter or needle, each connector having an electrode in fluid communication with a fluid-carrying lumen of said connector;
an electronic circuit electrically connected to the electrodes of the first and second connectors, and configured to measure electrical impedance of fluid between the first connector and the second connector via a conductive path;
a controller configured to receive a series of sampled electrical impedance values from the electronic circuit, and to process the electrical impedance values as a signal;
wherein the controller is configured to:
provisionally set a disconnection flag and initiate a counter if at a point in time the signal is greater than a first threshold value;
clear the disconnection flag if the signal decreases to less than a second lower threshold value before the counter has reached a pre-determined count; and
declare an alert if the disconnection flag is not cleared before the counter has reached the pre-determined count.

2. The system of claim 1 , wherein the counter counts units of time, and the predetermined count is a pre-determined time interval.

3. The system of claim 1 , wherein the counter counts units of blood volume pumped to the vascular access and the pre-determined count is a pre-determined volume of blood.

4. The system of claim 1 , wherein the counter counts strokes of the pump and the pre-determined count is a pre-determined number of strokes.

5. The system of claim 1 , wherein the signal is a time derivative of the electrical impedance values.

6. The system of claim 1 , wherein the controller stops processing the electrical impedance values if the pump stops.

7. The system of claim 1 , wherein said alert declaration causes the controller to activate one or more mechanical line occluders to stop a flow of fluid in the first and second lines, stop the pump, or notify a user of the occurrence of a vascular disconnection.

8. The system of claim 7 , wherein notifying the user comprises requesting that the user verify a position of the first and second catheters or needles at the vascular access.

9. The system of claim 8 , wherein the controller is configured to receive from the user a command to resume operation of the pump or to discontinue further operation of the pump.

10. The system of claim 7 , wherein the controller continues to process the electrical impedance values if an alert declaration is made and the mechanical line occluders are activated, and wherein the controller is configured to confirm a vascular disconnection if the signal exceeds a third threshold value that is greater than the first threshold value.

11. The system of claim 10 , wherein the controller updates the notification of the user to a needle dislodgement.

12. The system of claim 7 , wherein the notification to the user is an occlusion alert.

13. The system of claim 1 , wherein operation of the pump comprises extracorporeal circulation of a portion of the user's blood.

14. The system of claim 1 , wherein the first threshold value and the second threshold value are compared to a filtered value of the electrical impedance values.

15. The system of claim 1 , wherein the signal is a difference between a first filtered value of the impedance values using a first time constant and a second filtered value of the impedance values using a second longer time constant.

16. The system of claim 15 , wherein the controller is configured to set the second filtered value to the first filtered value, if a plurality of declarations of a vascular disconnection are each followed by a user command to resume operation of the pump.

17. The system of claim 1 , wherein the second threshold value is a fixed fraction of the first threshold value.

18. The system of claim 1 , wherein the second threshold value is a fixed value less than the first threshold value.

19. The system of claim 1 , wherein the first and second thresholds are determined based on the electrical impedance values.

20. The system of claim 1 , wherein the first and second thresholds are adjusted proportionally to changes in the electrical impedance values.

21. The system of claim 1 , wherein the conductive path comprises liquid fluidly connecting the first connector and the second connector.

22. The system of claim 21 , wherein the conductive path comprises blood in the needles, and blood vessel, fistula or graft.

23. The system of claim 1 , wherein the conductive path comprises blood in the first line, second line and pump.

Assignees

• Deka Products Lp

Inventors

• Van Der Merwe Dirk A
• Norris Michael G
• Baker Michael A
• Ballantyne Todd A
• Wilt Michael J

Classifications

• A61M1/36225

  with blood pumping means or components thereof · CPC title

• A61M1/362266

  Means for adding solutions or substances to the blood · CPC title

• A61M1/362265

  Details of valves · CPC title

• A61M1/362263

  Details of incorporated filters · CPC title

• A61M1/36224

  with sensing means or components thereof · CPC title