System and method for return electrode monitoring

• US 8,100,898 B2
• Filed: 08/01/2007
• Issued: 01/24/2012
• Est. Priority Date: 08/01/2007
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Tyco Healthcare Group LP (Medtronic Plc)
• Inventors: Gregg, William N.
• Primary Examiner(s): Dvorak, Linda
• Assistant Examiner(s): SCOTT, AMANDA L
• Application Number:
  US11/888,585
• Publication Number:
  US 20090036885A1
• Time in Patent Office: 1,637 Days
• Field of Search: 606 32- 35, 606 37- 38
• 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 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2018/1467 using more than two electrodes on a single probe

Abstract

A system for determining probability of tissue damage is disclosed. The system includes an electrosurgical generator adapted to generate an electrosurgical current and a plurality of return electrodes adhered to a patient and adapted to couple to the electrosurgical generator. Each of the return electrodes includes an impedance sensor attached thereto. The system also includes a current monitor connected in series with each of the plurality of the return electrodes to measure the electrosurgical current passing therethrough and a processor coupled to each of the current monitors. The processor is configured to calculate a cooling factor and a heating factor for each of the plurality of the return electrodes. The processor further configured to determine probability of tissue damage for each of the plurality of the return electrodes as a function of the cooling factor and the heating factor.

Claims

1. A system for determining probability of tissue damage, the system comprising:

an electrosurgical generator adapted to generate an electrosurgical current;

a plurality of return electrodes adhered to a patient and adapted to couple to the electrosurgical generator;

a plurality of current monitor monitors, each current monitor coupled to a corresponding return electrode of the plurality of return electrodes, each current monitor configured to measure the electrosurgical current passing through the corresponding return electrode to obtain a return electrode current value;

a processor coupled to the plurality of current monitors, the processor configured to calculate a cooling factor and a heating factor with respect to each return electrode of the plurality of return electrodes, the processor further configured to determine probability of tissue damage for each return electrode of the plurality of the return electrodes as a function of at least one of the cooling factor and the heating factor, the processor further configured to compare the return electrode current values with each other to determine a highest return electrode current value; and

a comparator coupled to the processor, the comparator configured to compare the highest return electrode current value with a current threshold value.

2. A system according to claim 1, wherein the processor is further configured to calculate the heating factor as a function of the corresponding return electrode current value.

3. A system according to claim 2, further comprising a plurality of impedance sensors, each impedance sensor coupled to a corresponding return electrode of the plurality of return electrodes, each impedance sensor configured to measure the impedance of the corresponding return electrode, wherein the processor is further configured to calculate the heating factor as a function of the measured impedance of the corresponding return electrode.

4. A system according to claim 3, wherein the processor is further configured to calculate the heating factor as a function of an adherence constant representative of the adherence of the corresponding return electrode.

5. A system according to claim 4, wherein the processor is further configured to calculate the heating factor as a function of on time of the corresponding return electrode, wherein the on time is a time period during which the corresponding return electrode is in electrical communication with the electrosurgical generator.

6. A system according to claim 1, wherein the processor is further configured to calculate the cooling factor as a function of off time of the corresponding return electrode, wherein the off time is a time period during which limited or no electrosurgical current flows through the corresponding return electrode.

7. A system, according to claim 1, wherein the processor is further configured to calculate the cooling factor as a function of a constant indicative of the body'"'"'s ability to remove heat.

8. A system according to claim 1, wherein the processor is further configured to determine the probability of tissue damage by comparing a difference between the cooling factor and the heating factor with a predetermined threshold.

9. A system according to claim 8, wherein, if the difference between the cooling factor and the heating factor exceeds the predetermined threshold, the processor is further configured to perform an action selected from the group consisting of generating an alarm, signaling the electrosurgical generator to adjust output of the electrosurgical current, and signaling the electrosurgical generator to terminate output of the electrosurgical current.