Systems and Methods for Detecting Vascular Access Disconnection
First Claim
1. A system for detecting dislodgment of a catheter or needle in a vascular access comprising a first and second catheter or needle 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 connecter via a conductive path through the blood vessel, fistula or graft;
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;
sample and filter or smooth the signal using a first time constant, yielding a first filtered signal;
sample and filter or smooth the signal using a second longer time constant, yielding a second filtered signal;
provisionally set a disconnection flag and initiate a counter if at a point in time the difference between the first filtered signal and the second filtered signal is greater than a first threshold value;
clear the disconnection flag if the difference between the first filtered signal and the second filtered signal decreases to less than a second lower threshold value before the counter has reached a pre-determined count; and
declare a vascular disconnection if the disconnection flag is not cleared before the counter has reached the pre-determined count;
said declaration causing 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 possible vascular disconnection.
2 Assignments
0 Petitions
Accused Products
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.
56 Citations
35 Claims
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1. A system for detecting dislodgment of a catheter or needle in a vascular access comprising a first and second catheter or needle in a blood vessel, fistula or graft, the system comprising:
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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 connecter via a conductive path through the blood vessel, fistula or graft; 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;sample and filter or smooth the signal using a first time constant, yielding a first filtered signal; sample and filter or smooth the signal using a second longer time constant, yielding a second filtered signal; provisionally set a disconnection flag and initiate a counter if at a point in time the difference between the first filtered signal and the second filtered signal is greater than a first threshold value; clear the disconnection flag if the difference between the first filtered signal and the second filtered signal decreases to less than a second lower threshold value before the counter has reached a pre-determined count; and declare a vascular disconnection if the disconnection flag is not cleared before the counter has reached the pre-determined count; said declaration causing 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 possible vascular disconnection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for detecting dislodgment of a catheter or needle in a vascular access comprising a first and second catheter or needle in a blood vessel, fistula or graft, the system comprising:
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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 connecter via a conductive path through the blood vessel, fistula or graft; 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 a vascular disconnection if the disconnection flag is not cleared before the counter has reached the pre-determined count. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A system for detecting dislodgment of a catheter or needle in a vascular access comprising a first and second catheter or needle in a blood vessel, fistula or graft, the system comprising:
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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 connecter via a conductive path through the blood vessel, fistula or graft; 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;sample and filter or smooth the signal using a first time constant, yielding a first filtered signal; sample and filter or smooth the signal using a second longer time constant, yielding a second filtered signal; set a disconnection flag if at a point in time the difference between the first filtered signal and the second filtered signal is greater than a first threshold value; and declare a vascular disconnection causing 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 possible vascular disconnection. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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34. A system for detecting dislodgment of a catheter or needle in a vascular access comprising a first and second catheter or needle in a blood vessel, fistula or graft, the system comprising:
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a first line fluidly connecting the first catheter or needle to an inlet of a reciprocating positive displacement 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 connecter via a conductive path through the blood vessel, fistula or graft; 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;sample and filter or smooth the signal using a first time constant, yielding a first filtered signal; sample and filter or smooth the signal using a second longer time constant, yielding a second filtered signal; initiate a counter and set a provisional disconnection flag if a difference between the first filtered signal and the second filtered signal exceeds a first threshold value; temporarily clear the provisional disconnection flag if the difference between the first filtered signal and the second filtered signal drops below a second lower threshold value before the counter reaches a preset count; command an actuator of the pump to apply a force to a pumping chamber of the pump to complete a fluid delivery stroke to the first or second catheter or needle; command the actuator to apply a reduced force to the pumping chamber; and declare an access disconnection if the difference between the first filtered signal and the second filtered signal exceeds a third threshold value that is equal to or greater than the first threshold value.
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35. A system for detecting replacement of blood by dialysate solution in a blood tubing set of a hemodialysis apparatus in which dialysate is pumped from a dialysate side to a blood side of a dialyzer, the system comprising:
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a first fluid line fluidly connecting a first catheter or needle in a blood vessel, fistula or graft to an inlet of a blood pump; a second fluid line fluidly connecting a second catheter or needle in the blood vessel, fistula or graft to an outlet of the blood pump; a first connector connecting the first fluid line to the first catheter or needle, and a second connector connecting the second fluid line to the second catheter or needle, the first connector having a first electrode in fluid communication with a fluid carrying lumen of said first connector, and the second connector having a second electrode in fluid communication with a fluid carrying lumen of said second connector; an electronic circuit having a first terminal electrically connected to the first electrode and a second terminal electrically connected to the second electrode, and configured to measure electrical impedance of fluid between the first connector and the second connecter via a conductive path through the blood vessel, fistula or graft; 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; measure the signal or a filtered form of the signal as dialysate is pumped through the dialyzer to the blood tubing set; determine whether the signal or a filtered form of the signal has a first value approximately equal to an expected value of the signal for blood in the first and second fluid lines, or has a second value approximately equal to an expected value of the signal for dialysate solution in the first and second fluid lines; determine a point in time when the signal or a filtered form of the signal changes from the first value to the second value; and provide a first notification to a user if the controller detects a change from the first value to the second value, or provide a second notification to the user if the controller detects a change from the first value that is less than approximately the second value within a pre-determined period of time.
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Specification