Electrosurgical generator and method for cross-checking output power

• US 20040097915A1
• Filed: 11/19/2002
• Published: 05/20/2004
• Est. Priority Date: 11/19/2002
• Status: Active Grant

• Current Assignee: Conmed Corporation (Jefferies Financial Group, Inc.)
• Original Assignee: Conmed Corporation (Jefferies Financial Group, Inc.)
• Inventors: Pantera, Jim, Refior, Tim
• Granted Patent: US 6,948,503 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00892 Voltage

Abstract

The functionality and the output power delivered are evaluated in an electrosurgical generator by calculating first and second values related to the output power delivered by using separate first and second computations. The two calculated values are compared, and an error condition is indicated when the two values differ by a predetermined amount. The separate computations, coupled with the other separate activities of measuring, averaging and sampling the output current and voltage measurements, serve as an effective basis for detecting errors caused by malfunctions or equipment failure. The error condition may be used to as a basis to terminate the output power delivery or indicate the error.

Claims

1. A method of evaluating functionality of an electrosurgical generator which delivers electrosurgical output power, comprising:

calculating with a first computation a first value related to the output power delivered;

calculating with a second computation separate from the first computation a second value related to the output power delivered;

comparing the first and second values; and

indicating an error condition when the first and second values differ by a predetermined amount.

2. A method as defined in claim 1, wherein the electrosurgical output power is established by the output current and the output voltage, and further comprising:

calculating the first and second values using the output current and the output voltage in each of the first and second computations;

sensing the output voltage and the output current separately for the first and second computations.

3. A method as defined in claim 2, wherein the electrosurgical generator includes a control processor which controls the delivery of the electrosurgical output power and also includes a monitor processor which monitors performance of the electrosurgical generator, and further comprising:

performing the first calculation using the control processor; and

performing the second calculation using the monitor processor.

4. A method as defined in claim 3, further comprising:

calculating the first and second values as the average power delivered from the electrosurgical generator over a predetermined period of time.

5. A method as defined in claim 4, further comprising:

calculating the first value over a first predetermined period of time;

calculating the second value over a second predetermined period of time; and

establishing different first and second predetermined periods of time.

6. A method as defined in claim 4, further comprising:

sensing the output current and the output voltage at a first sampling frequency for calculating the first value with the first computation;

sensing the output current and the output voltage at a second sampling frequency for calculating the second value with the second computation; and

establishing different first and second sampling frequencies.

7. A method as defined in claim 4, further comprising:

activating the electrosurgical generator to deliver the output power during an activation time period; and

using the activation time period as the predetermined period of time over which the average power delivered is calculated as the first and second values.

8. A method as defined in claim 3, further comprising:

communicating the first value to the monitor processor; and

comparing the first and second values using the monitor processor.

9. A method as defined in claim 8, further comprising:

indicating the error condition from the monitor processor.

10. A method as defined in claim 3, wherein the electrosurgical generator further includes a system processor which oversees functionality of the control and monitor processors, and further comprising:

communicating the first and second values to the system processor; and

comparing the first and second values using the system processor.

11. A method as defined in claim 10, further comprising:

indicating the error condition from the system processor.

12. A method as defined in claim 3, further comprising:

sensing the output current in a plurality of current values for each of the first and second computations;

sensing the output voltage in a plurality of voltage values for each of the first and second computations;

collecting a plurality of the current values and a plurality of the voltage values for each of the first and second computations;

performing a root mean square computation on each of the collected pluralities of current values and on each of the collected pluralities of voltage values; and

using the root mean square current value and the root mean square voltage value in the first and second computations to calculate the first and second values.

13. A method as defined in claim 1, wherein the electrosurgical generator includes a control processor which controls the delivery of the electrosurgical output power and also includes a monitor processor which monitors functions of the electrosurgical generator, and further comprising:

performing the first calculation using the control processor; and

performing the second calculation using the monitor processor.

14. A method as defined in claim 1, further comprising:

terminating delivery of the electrosurgical output power upon indicating an error condition.

15. A method as defined in claim 1, further comprising:

incrementing a count number with each instance where the first and second values differ by more than the predetermined amount; and

indicating the error condition upon the count number reaching a predetermined threshold.

16. A method as defined in claim 15, further comprising:

resetting the count number to a predetermined count value upon the first and second values not differing by the predetermined amount.

17. A method as defined in claim 15, further comprising:

incrementing the count number only with each instance where the first and second values differ by the predetermined amount within a predetermined number of most recent comparisons.

18. A method of evaluating functionality of an electrosurgical generator which delivers electrosurgical output power and which includes a control processor for controlling the delivery of the output power, a monitor processor for monitoring performance of the electrosurgical generator, and sensors for sensing current and voltage of the output power delivered, comprising:

activating the electrosurgical generator to deliver the output power;

sensing the current and the voltage at first periodic intervals to obtain a first set of measurements of the current and voltage of the output power delivered;

sensing the current and the voltage at second periodic intervals to obtain a second set of measurements of the current and voltage of the output power delivered;

recording the first and second sets of measurements;

deactivating the electrosurgical generator to terminate the delivery of the output power;

calculating a first value related to the output power delivered from the first set of recorded measurements by executing a first computation with the control processor;

calculating a second value related to the output power delivered from the second set of recorded measurements by executing a second computation with the monitor processor;

comparing the calculated first and second values to determine whether the calculated first and second values differ by a predetermined amount; and

executing an error response upon determining that the calculated first and second values differ by the predetermined amount.

19. A method as defined in claim 18, wherein the electrosurgical generator also includes a system processor which oversees functionality of the control and monitor processors, further comprising:

communicating the calculated first value from the control processor to the system processor;

communicating the calculated second value from the monitor processor to the system processor;

comparing the calculated first and second values by a computation executed by the system processor; and

executing the error response by the system processor.

20. A method as defined in claim 18, further comprising:

determining a time period between activating and deactivating the electrosurgical generator; and

performing the comparing step only when the time period between activating and deactivating falls between a predetermined minimum time and a predetermined maximum time.

21. A method as defined in claim 18, further comprising:

including within the error response executed at least one of logging an error occurrence, issuing an alert, and terminating the output power delivery.

22. An electrosurgical generator which delivers electrosurgical output power and which regulates the amount of output power delivered from feedback information, comprising:

a plurality of sensors connected to sense current and voltage of the output power delivered and operative to supply current and voltage measurement signals related to the amount of current and voltage sensed;

a control processor receptive of the current and voltage measurement signals and which performs a first computation based on the current and voltage measurement signals to derive the feedback information and to derive a first value related to the output power delivered;

a monitor processor receptive of the current and voltage measurement signals and which performs a second computation separate from the first computation to derive a second value related to the output power delivered;

a communication path connecting the control and monitor processors over which the control and monitor processors communicate information including the first and second values, one of the control or monitor processors receiving the first and second values being a comparison processor;

the comparison processor executing a comparison procedure for comparing the first and second values and delivering an error condition signal when the first and second values differ by a predetermined amount; and

the electrosurgical generator responding to the assertion of the error condition signal by one of either issuing an error indication or terminating the delivery of output power.

23. An electrosurgical generator as defined in claim 22, wherein the plurality of sensors includes:

a first current sensor for supplying a first current sense measurement signal used in performing the first computation;

a second current sensor for supplying a second current sense measurement signal used in performing the second computation;

a first voltage sensor for supplying a first voltage sense measurement signal used in performing the first computation; and

a second voltage sensor for supplying a second voltage sense measurement signal used in performing the second computation.

24. An electrosurgical generator as defined in claim 23, wherein the control and monitor processors are digital processors.

25. An electrosurgical generator as defined in claim 24, further comprising:

a first analog to digital converter (ADC) connected to the first current and voltage sensors and operative to convert the first current and voltage sense measurement signals, respectively, into digital form;

a first direct memory access (DMA) controller;

a first buffer connected to the first ADC and to the first DMA controller, the first DMA controller placing the digital form of the first current and voltage sense measurement signals into the first buffer;

the control processor connected to the first buffer to read the digital form of the first current and voltage sense measurement signals from the first buffer to perform the first computation;

a second analog to digital converter (ADC) connected to the second current and voltage sensors and operative to convert the second current and voltage sense measurement signals, respectively, into digital form;

a second direct memory access (DMA) controller;

a second buffer connected to the second ADC and to the second DMA controller, the second DMA controller placing the digital form of the second current and voltage sense measurement signals into the second buffer; and

the monitor processor connected to the second buffer to read the digital form of the second current and voltage sense measurement signals from the second buffer to perform the second computation.

26. An electrosurgical generator as defined in claim 22, further comprising:

a system processor which oversees functionality of the control and monitor processors, the system processor connected to the communication path to communicate with the control and monitor processors, the system processor being the comparison processor which issues the error indication.

27. An electrosurgical generator as defined in claim 26, wherein:

the control processor executes the first calculation;

the monitor processor executes the second calculation; and

the control and monitor processors send the first and second values to the system processor over the communication path.

28. An electrosurgical generator as defined in claim 26, further comprising:

an alarm connected to the system processor and responsive to the error condition signal to deliver an alarm.

29. An electrosurgical generator as defined in claim 26, wherein:

the system controller responding to the assertion of the error condition signal by logging an error occurrence.