System and method for return electrode monitoring

• US 8,790,337 B2
• Filed: 05/25/2012
• Issued: 07/29/2014
• Est. Priority Date: 02/04/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Behnke, Robert J. II, Wham, Robert H.
• Primary Examiner(s): MENDEZ, MANUEL A
• Application Number:
  US13/480,644
• Publication Number:
  US 20120232548A1
• Time in Patent Office: 795 Days
• Field of Search: 604 32- 39, 604/22, 606 32- 39
• US Class Current: 606/35
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/16 Indifferent or passive electrodes for grounding
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00779 Power or energy
• CPC Class Codes: A61B 2018/00869 Phase
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure

Abstract

A return electrode monitoring (“REM”) system is disclosed. The REM system includes a return electrode pad having a pair of split electrode pads and a detection circuit coupled to the pair of split electrode pads. The detection circuit and the pair of split electrode pads are adapted to resonate across a predetermined resonance range. The REM system also includes a controller coupled to the detection circuit and configured to provide a sweeping drive signal to the detection circuit across the resonance range. The detection circuit generates a drive signal in response to the sweeping drive signal and the controller determines a complex impedance across the at least one pair of split electrode pads as a function of the drive signal.

Claims

1. A return electrode monitoring system comprising:

at least one return electrode pad including at least one pair of split electrode pads;

a detection circuit operatively coupled to the at least one pair of split electrode pads; and

a controller coupled to the detection circuit and configured to provide a drive signal to the detection circuit, wherein the detection circuit is adapted to measure a response signal in response to the drive signal and convert the response signal to a frequency response, the controller being further configured to determine a phase of the drive signal with respect to a frequency of the response signal, a complex impedance across the at least one pair of split electrode pads as a function of the frequency response, and a frequency shift as a function of the phase of the drive signal.

2. The return electrode monitoring system according to claim 1, wherein the detection circuit is configured to measure a voltage, a current and a phase difference therebetween of the drive signal.

3. The return electrode monitoring system according to claim 1, wherein the controller is configured to determine a reactance across the at least one pair of split electrode pads.

4. The return electrode monitoring system according to claim 3, wherein the controller is configured to determine a resistance across the at least one pair of split electrode pads as a function of a change in amplitude of the voltage of the drive signal.

5. The return electrode monitoring system according to claim 4, wherein the controller is configured to determine a complex impedance across the at least one pair of split electrode pads as a function of the resistance and the reactance.

6. The return electrode monitoring system according to claim 1, wherein the drive signal is at least one of a step or an impulse signal.

7. A method for monitoring a return electrode comprising:

providing a drive signal to a return electrode monitoring system including at least one return electrode pad having at least one pair of split electrode pads, the return electrode monitoring system being adapted to resonate across a predetermined resonance;

sweeping the drive signal across a resonance range of the predetermined resonance;

generating a response signal in response to the sweeping of the drive signal;

converting the response signal to a frequency response;

determining a complex impedance across the at least one pair of split electrode pads as a function of the frequency response; and

determining a resistance across the at least one pair of split electrode pads as a function of a change in amplitude of the drive signal.

8. The method for monitoring a return electrode according to claim 7, further comprising:

measuring a voltage and a current of the drive signal.

9. The method for monitoring a return electrode according to claim 8, further comprising:

measuring a phase of the drive signal; and

determining complex impedance across the at least one pair of split electrode pads as a function of the phase of the drive signal.

10. The method for monitoring a return electrode according to claim 7, further comprising:

determining a phase of the drive signal with respect to a frequency of the response signal.

11. The method for monitoring a return electrode according to claim 10, further comprising:

determining a frequency shift as a function of the phase of the drive signal.

12. The method for monitoring a return electrode according to claim 7, further comprising:

determining a complex impedance across the at least one pair of split electrode pads as a function of the resistance and the reactance.

13. The method for monitoring a return electrode according to claim 7, further comprising:

determining a reactance across the at least one pair of split electrode pads.

14. The method for monitoring a return electrode according to claim 13, further comprising:

mapping the reactance across the at least one pair of split electrode pads with adherence of the at least one return electrode pad.

15. The method for monitoring a return electrode according to claim 7, wherein the drive signal is at least one of a step or an impulse signal.