ADAPTIVE ALGORITHM FOR ACCESS DISCONNECT DETECTION

• US 20090088683A1
• Filed: 10/01/2007
• Published: 04/02/2009
• Est. Priority Date: 10/01/2007
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Hogard, Michael E., Roger, Rodolfo G., Tejedor, Joel
• Granted Patent: US 7,938,792 B2
• Time in Patent Office: Days
• US Class Current: 604/65
• 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 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 2039/1005 Detection of disconnection
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066

Abstract

An extracorporeal therapy machine removes blood from a patient in order to treat the blood and then return the blood to the patient. If the removal needle or the return needle is dislodged and blood is not returned, the patient may suffer a great blood loss. A new technique for detecting dislodgement uses the normal, initial values of a plurality of parameters of the patient and the therapy machine to set criteria or limits for an alarm, and then adjusts those criteria based on the later values of those parameters as they change during one therapy or over several therapies experienced by the patient.

Claims

1. A method for detecting an access disconnection, the method comprising:

inputting or accessing information about a patient for an extracorporeal blood therapy;

inputting or accessing at least one value for an alert criterion for an access disconnection;

beginning the extracorporeal blood therapy;

taking a first reading of a plurality of properties concerning the therapy and blood of the patient;

proceeding with the extracorporeal blood therapy;

taking a second reading of the plurality of properties concerning the therapy and the blood of the patient;

calculating a change in the at least one value for the alert criterion based on the second reading of the plurality of properties; and

adjusting the at least one value for an alert for the access disconnect criterion.

2. The method of claim 1, wherein the plurality of properties is selected from the group consisting of:

an electrical property of the blood of the patient;

a distance between access needles for the extracorporeal therapy;

a temperature of a portion of an extracorporeal blood therapy machine;

a speed of a pump of the extracorporeal blood therapy machine;

an administration of a bolus to the extracorporeal blood circuit;

a value of a blood chemistry component of the patient; and

a dialysate temperature.

3. The method of claim 1, further comprising taking a reading of the property corresponding to the access disconnect criterion and sending a signal if the reading exceeds the value of the access disconnect criterion after the step of adjusting.

4. The method of claim 1, wherein the extracorporeal blood therapy comprises hemodialysis.

5. A method for detecting an access disconnection, the method comprising:

inputting or accessing information about a patient for an extracorporeal blood therapy;

selecting or accessing at least one electrical property value of an electrical circuit selected from the group consisting of the patient and an extracorporeal blood therapy machine as an alert criterion for an access disconnection;

beginning the extracorporeal blood therapy;

taking a first reading of a plurality of properties concerning the therapy and blood of the patient;

proceeding with the extracorporeal blood therapy;

taking a second reading of the plurality of properties concerning the therapy and the blood of the patient;

calculating a change in the electrical property value of the alert criterion based on at least one change in the plurality of properties; and

adjusting the alert criterion value.

6. The method of claim 5, wherein the plurality of parameters is selected from the group consisting of:

a distance between access needles for the extracorporeal therapy;

an elapsed time of the therapy;

a temperature of at least a portion of the extracorporeal blood therapy machine;

a speed of a pump of the extracorporeal blood therapy machine;

administration of a bolus to the extracorporeal blood circuit;

a value of a blood chemistry component of the blood of the patient; and

a dialysate temperature.

7. The method of claim 5, further comprising sending an alert or sounding an alarm if the second reading of the electrical property value exceeds the alert criterion value after the step of adjusting.

8. The method of claim 5, further comprising applying a voltage or a current to the electrical circuit in order to take the first and second readings.

9. An access disconnect detection system, comprising:

arterial and venous contacts configured for use with an extracorporeal blood therapy machine for administering a therapy;

an electrical circuit connected to the contacts, the electrical circuit configured for sensing at least one electrical property sensed by the contacts;

at least one sensor configured for sensing a property concerning the patient or a component of the extracorporeal blood therapy machine;

a computer having a memory, the computer configured for receiving and storing values for a plurality of properties concerning the patient and the extracorporeal blood therapy machine; and

a computer program on a computer readable medium configured for accepting first values of the plurality of properties, and for using or setting an initial criterion for determining an access disconnection, and for accepting second values of the plurality of properties and for adjusting the criterion based on the second values.

10. The system according to claim 9, further comprising a lookup table in the computer or in the memory, the lookup table including a table of minimum and maximum impedance values for the plurality of properties concerning the patient and the extracorporeal blood therapy machine.

11. The system according to claim 9 wherein the contacts comprise connectors configured for connecting to arterial and venous access needles.

12. The system according to claim 9, wherein the extracorporeal therapy machine comprises a hemodialysis machine, and further comprising the hemodialysis machine.

13. The system according to claim 9, wherein the plurality of properties concerning the patient and the extracorporeal blood therapy machine are selected from the group consisting of a pressure, a speed, an infusion rate, a value of a component of blood chemistry, an impedance, a capacitance, a resistance, a presence or absence of a bolus, a presence or absence of a medication, a duration of time, and a temperature.

14. The system according to claim 9, further comprising at least one input device and at least one output device operably connected to the computer.

15. The system according to claim 9, further comprising a current or voltage source connected to the contacts, the current or voltage source configured for sending an electrical current or voltage into the electrical circuit.

16. The system according to claim 9, wherein the at least one electrical property is selected from the group consisting of an impedance, a resistance, a conductivity, and a capacitance.

17. An extracorporeal therapy machine, comprising:

a machine for administering a dialysis therapy;

arterial and venous contacts configured for use with the machine;

an electrical circuit connected to the contacts, the electrical circuit configured for sensing an electrical property concerning the patient or a component of the machine;

a computer having a memory, the computer configured for receiving and storing values for a plurality of properties concerning the patient, the therapy, and the machine;

a computer program on a computer readable medium configured for accepting first values of the plurality of properties, and for setting an initial criterion for determining an access disconnection, and for accepting second values of the plurality of properties and for adjusting the criterion based on the second values; and

at least one input device and one output device operably connected to the computer.

18. The extracorporeal therapy machine according to claim 17, further comprising at least one sensor configured for sensing a property concerning the patient, the therapy, or a component of the machine, the at least one sensor selected from the group consisting of a clock, a pressure sensor, a temperature sensor, and a speed sensor.

19. The extracorporeal therapy machine of claim 17, wherein the electrical circuit is selected from the group consisting of a current source and a voltage source.

20. A hemodialysis machine for administering a hemodialysis therapy, the machine comprising:

a housing containing components of the machine;

a monitor for monitoring the machine;

a dialyzer;

at least one blood pump for moving blood of the patient to and from the patient and through the dialyzer;

arterial and venous contacts configured for use with the machine;

an electrical circuit connected to the contacts, the electrical circuit configured for sensing an electrical property concerning the patient or a component of the machine;

a computer having a memory, the computer configured controlling the machine and for receiving and storing values of a plurality of properties concerning the patient, the therapy, and the machine;

a computer program on a computer readable medium configured for accepting first values of the plurality of properties, and for setting an initial value for a criterion for determining an access disconnection, and for accepting second values of the plurality of properties and adjusting the criterion value based on the second values; and

at least one input device and one output device operably connected to the computer.

21. The machine of claim 20, wherein the contacts comprise arterial and venous access needles.

22. The machine of claim 20, wherein the criterion is a maximum value of an impedance or a resistance, or a minimum value of a conductivity or a capacitance.

23. The machine of claim 20, wherein the computer program includes instructions for narrowing a range of minimum and maximum values of the criterion.