CONTINUITY CIRCUITS FOR DETECTING ACCESS DISCONNECTION

• US 20090088613A1
• Filed: 09/27/2007
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• 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: Marttila, Alan W., Chan, William W., Bhagtani, Reema A.
• Granted Patent: US 8,360,977 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61M 1/3653 Interfaces between patient blood circulation and extra-corporal blood circuit
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/3659 Cannulae pertaining to extracorporeal circulation
• CPC Class Codes: A61M 2005/1588 having means for monitoring, controlling or visual inspection, e.g. for patency check, avoiding extravasation
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 5/158 Needles for infusions; Accessories therefor, e.g. for inserting infusion needles, or for holding them on the body
• CPC Class Codes: A61M 5/16836 by sensing tissue properties at the infusion site, e.g. for detecting infiltration detecting tissue temperature for diagnostic purposes A61M39/0247
• CPC Class Codes: A61M 5/5086 for indicating if defective, used, tampered with or unsterile

Abstract

A monitor for an extracorporeal therapy access site is disclosed. The monitor includes a bandage atop or adjacent the access site and a sensor for monitoring the bandage. The bandage includes a layer of polymer that expands when wetted with blood. The expansion causes a break in continuity of the sensor, or in an alternate embodiment, causes a sensor to cease detecting a target. When the break occurs, the control circuit monitoring the bandage sends a signal that a break has occurred, and a remote monitor then takes appropriate action, such as ceasing therapy, sending an alert, or sounding an alarm. In another embodiment, connecting wires in a continuity circuit are held apart by a polymer that dissolves when contacted by blood. If a leak occurs and a small portion of the polymer dissolves, the wires make contact, thus detecting a blood leak.

Claims

1. A method for detecting blood leakage, the method comprising:

furnishing a pad with an expandable polymer layer and a sensor;

placing the pad near an access site for an extracorporeal blood therapy;

taking an initial reading of the sensor;

monitoring the access site by taking additional readings of the sensor during an extracorporeal blood processing therapy; and

sending a signal if a reading of the sensor is consistent with expansion of the expandable polymer layer and a break of continuity of the sensor.

2. The method of claim 1, wherein the sensor comprises a metallic object or a detection circuit that is broken by the expandable layer.

3. The method of claim 1, further comprising sending an alert or sounding an alarm with a local output device.

4. The method of claim 1, wherein the detection circuit comprises a continuity circuit or a circuit for detection of targets by proximity sensors.

5. The method of claim 4, wherein the proximity sensors are selected from the group consisting of hall-effect sensors, capacitance sensors, and inductance sensors.

6. The method of claim 1, further comprising wicking blood from the access site using a fluid conveyor with a hydrophilic layer.

7. A method of detecting a fluid, the method comprising:

providing a fluid conveyor comprising at least one outer layer and a hydrophilic inner layer, the hydrophilic inner layer configured to wick blood;

placing the fluid conveyor near an extracorporeal therapy access site;

monitoring a sensor to detect a presence of blood in the fluid conveyor; and

sending a signal to a monitoring circuit if blood is detected.

8. The method according to claim 8, wherein the hydrophilic inner layer is configured for absorbing and wicking blood

9. An access disconnect detector, comprising:

a pad having an expandable layer; and

a detection circuit mounted near or atop the pad, wherein the pad is configured for placement adjacent an extracorporeal therapy access site, the expandable layer is configured for expanding upon contact with blood, and the detection circuit is configured for wireless communication with an extracorporeal therapy machine or a controller in communication with the extracorporeal therapy machine.

10. The detector according to claim 9, wherein the detection circuit comprises a continuity circuit, a controller, and a wire communications module.

11. The detector according to claim 9, wherein the detection circuit comprises a thin metallic object.

12. The detector according to claim 9, wherein the detection circuit comprises at least one metallic or magnetic target and at least one hall-effect or proximity sensor for detecting the target.

13. The detector according to claim 9, further comprising a local output device for raising an alert or sounding an alarm.

14. The access disconnect detector according to claim 9, further comprising an access needle attached to an access mount, and at least one target on the mount, the target suitable for detection by the detection circuit.

15. The access disconnect detector according to claim 9, wherein the polymeric expandable layer is made from polyvinyl alcohol, a polyvinyl alcohol derivative, acrylic acid, an acrylic acid derivative, or a combination thereof.

16. The access disconnect detector according to claim 9, wherein the extracorporeal therapy machine is a hemodialysis machine and further comprising the hemodialysis machine.

17. The access disconnect detector according to claim 9, further comprising a fluid conveyor with a hydrophilic layer placed between the access site and the pad.

18. The access disconnect detector according to claim 9, wherein the expandable layer is asymmetric.

19. An access disconnect detector, comprising:

a fluid conveyor comprising at least one outer layer and a hydrophilic inner layer, the hydrophilic inner layer configured to wick blood away from an extracorporeal therapy access site;

a detector for detecting the blood within the fluid conveyor; and

a control circuit in operable communication with the detector, wherein the detector is configured to detect blood in the fluid conveyor and the control circuit is configured to send a signal to alert a user or a caregiver of a presence of blood.

20. The access disconnect detector of claim 19, wherein the outer layer is a hydrophilic layer.

21. The access disconnect detector of claim 19, wherein the detector is a conductivity or capacitance detector.

22. The access disconnect detector of claim 19, further comprising a therapeutic amount of anticoagulant on an inside of the fluid conveyor.

23. An access disconnect detector, comprising:

a first layer comprising a dissolving polymer and a first plurality of wires;

a second layer comprising a second plurality of wires; and

a cover over the second layer of wires, wherein the detector is configured for placement near or atop an access site of a patient for an extracorporeal therapy, wherein when the dissolving polymer is contacted by blood, the polymer dissolves sufficiently for at least one wire in the first plurality to make electrical contact with at least one wire in the second plurality.

24. The access disconnect detector of claim 23, further comprising a control circuit in operable communication with the detector, wherein the control circuit is configured to send a signal to alert a user or a caregiver of a presence of blood.

25. The access disconnect detector claim 23, wherein the detector is configured for wireless communication with an extracorporeal therapy machine or a controller in communication with the extracorporeal therapy machine.