RF return pad current detection system

• US 7,736,359 B2
• Filed: 01/12/2006
• Issued: 06/15/2010
• Est. Priority Date: 01/12/2006
• Status: Expired due to Fees

• Current Assignee: Sherwood Services AG
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: McPherson, James W.
• Primary Examiner(s): Cohen; Lee S
• Application Number:
  US11/331,303
• Publication Number:
  US 20070161979A1
• Time in Patent Office: 1,615 Days
• Field of Search: 606/33, 606/34, 606/35, 606/42
• US Class Current: 606/35
• CPC Class Codes: A61B 18/1206 Generators therefor
• 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 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/1253 monopolar

Abstract

The present disclosure provides an electrosurgical return pad current detection system for use in monopolar surgery as well as a method of using the same. The detection system comprises a plurality of conductive pads which include a plurality of conductive elements. The detection system further includes a sensor which senses the current returning to each conductive pad as well as a comparator which determines the difference in current among a plurality of conductive pads. If the current differential is above or below a prescribed limit, the system will alert the user of potential hazards and/or alter the amount of energy delivered to a surgical device.

Claims

1. A return pad current detection system for use in monopolar surgery, comprising:

a plurality of conductive pads, wherein each conductive pad includes a plurality of conductive elements;

a plurality of sensors operatively connected to the plurality of conductive pads which sense current returning to each pad; and

a comparator which determines the difference in current among the plurality of conductive pads, said comparator operatively connected to a warning device which warns a user if the current differential among pads is above or below a certain predetermined limit,

wherein the comparator receives an output of at least two distinct AC to DC converters that are in operative electrical communication with the plurality of sensors.

2. The return pad current detection system according to claim 1, further comprising an ablation generator, wherein the ablation generator regulates the amount of power delivered to a surgical device based upon the current sensed from each pad.

3. The return pad current detection system according to claim 2, wherein the ablation generator utilizes information provided by at least one comparator to substantially correct a current differential among pads.

4. The return pad current detection system according to claim 3, wherein the information provided to the ablation generator is processed by neural networks or fuzzy logic algorithms.

5. The return pad current detection system according to claim 1, wherein the sensor is a current sense transformer.

6. The return pad current detection system according to claim 1, wherein the sensor is a non-inductive sense resistor.

7. The return pad current detection system according to claim 1, wherein the comparator is a differential or instrumentation amplifier.

8. The return pad current detection system according to claim 1, wherein the sensor is a Hall-Effect device.

9. The return pad current detection system according to claim 1, further comprising a full-wave rectifier connected to the plurality all of sensors, wherein the full-wave rectifier substantially converts a signal from AC to DC.

10. A method for performing monopolar surgery, the method comprising the steps of:

providing a return pad current detection system comprising;

a plurality of conductive pads, wherein each conductive pad includes a plurality of conductive elements, the conductive pad defining a perimeter;

a plurality of sensors operatively connected to the plurality of conductive pads which sense current returning to each pad; and

a comparator which determines the difference in current among the plurality of conductive pads, wherein the comparator receives an output of at least two distinct AC to DC converters that are in operative electrical communication with the plurality of sensors;

placing the return pad current detection system in contact with a patient;

generating electrosurgical energy via an electrosurgical generator;

supplying the electrosurgical energy to the patient via an active electrode;

measuring, with the plurality of sensors, the current returning to each conductive pad;

detecting with the comparator, imbalances in current by comparing the current returning to one conductive pad with the current returning to each of the remaining pads;

warning the user of possible hazardous conditions; and

regulating the imbalances among pads.

11. The method for performing monopolar surgery according to claim 10, wherein the current returning to each conductive pad undergoes full-wave rectification resulting in direct current.

12. The method for performing monopolar surgery according to claim 10, further comprising the step of curing the imbalances using one or more safety control algorithms.

13. The method for performing monopolar surgery according to claim 12, wherein the safety control algorithms are operatively associated with an ablation generator.

14. The method for performing monopolar surgery according to claim 10, wherein the current returning to each conductive pad is measured using at least one of a current-sense transformer and a non-inductive sense resistor.

15. The method for performing monopolar surgery according to claim 10, wherein the imbalances in current are detected using a series of differential or instrumentation amplifiers.

16. A return pad current detection system for use in monopolar surgery, comprising;

an electrosurgical generator capable of generating electrical current;

a plurality of conductive pads, wherein each conductive pad includes a plurality of conductive elements, the conductive pad defining a perimeter;

a plurality of sensors operatively connected to the plurality of conductive pads which sense current returning to each pad;

a plurality of ac to dc converters producing an output, wherein each converter is connected to a respective sensor of each pad; and

a plurality of differential sensing devices, wherein each sensing device receives the output of at least two distinct ac to de converters and each sensing device'"'"'s output corresponds to a signal representative of the current differential among at least two pads.

17. A return pad current detection system according to claim 16, wherein the electrosurgical generator provides a warning if the current differential among pads is above or below a certain limit.

18. The return pad current detection system according to claim 16, wherein the electrosurgical generator modulates the amount of power delivered if the current differential among pads is above or below a certain limit.

19. The return pad current detection system according to claim 16, wherein the sensor is at least one of a current-sense transformer and non-inductive sense resistor.

20. The return pad current detection system according to claim 16, wherein the differential sensing device is at least one of a differential amplifier and an instrumentation amplifier.

21. The return pad current detection system according to claim 16, wherein the ac to dc converter is a full-wave rectifier.