Electrosurgical processor and method of use

• US 5,370,645 A
• Filed: 04/19/1993
• Issued: 12/06/1994
• Est. Priority Date: 04/19/1993
• Status: Expired due to Term

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Valleylab Inc. (Medtronic Plc)
• Inventors: Patterson, William G., Klicek, Michael S.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/047,907
• Time in Patent Office: 596 Days
• Field of Search: 606/32-40
• 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 2018/00666 using a threshold value
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00708 switching the power on or off
• CPC Class Codes: A61B 2018/00875 Resistance or impedance

Abstract

A circuit, for monitoring and controlling parameters of an electrosurgical unit, ESU, relative to load and the RF energy, has a load responsive output sensing circuit that measures the ESU load. A signal modifier, attached to the sensing circuit enhances the signals measured and transmits them to a buffer. An analog to digital converter, A/D, digitize the signals and samples wave pulse train at about eight million samples per second. A data memory stores the digitized signals. A RF drive clock connects to the ESU output; a sample clock uses phase shifting to interrogate the input signals to a processor, DSP, at a greater sampling rate of frequency than without. The DSP receives the stored signals from the data memory and processes them while monitoring and calculating ESU parameters measured, i.e. voltage, current, power, load impedance, leakage current, peak to peak voltage, peak to peak current, spectral content and/or crest factor of the RF wave pulse train energy to use as controlling feedback to the either a high voltage power supply in the ESU, regulating the RF drive pulses or both. A method monitors and controls the ESU relative to load has the steps of collecting parameters with the ESU output sensing circuit responsive to loads; enhancing signals with the signal modifier; transmitting signals to the buffer; converting signals with the A/D converter; storing signals in the data memory; receiving signals in the DSP, and processing, monitoring and controlling signals by repeatedly measuring ESU output parameters.

Claims

1. A circuit for monitoring operating parameters of an electrosurgical unit with an output transformer having primary and secondary windings and for controlling in real time those parameters relative to a load placed upon the radio frequency energy supplied by the electrosurgical unit, comprising:

a sensing circuit means connected to receive radio frequency energy supplied by the output of the electrosurgical unit and responsive to loads applied across the radio frequency energy supplied, the sensing circuit means connected for providing instantaneous values of current and voltage from the secondary windings so the sensing circuit means collects parameters indicative of the operation of the electrosurgical unit under load;

a signal modifier connected to the sensing circuit means, the signal modifier including enhancement means to adjust or attenuate the amplitude of the parameters from the sensing circuit means in response to signal processing and feedback;

a buffer connected to the signal modifier for receiving the enhanced parameters collected to set the level thereof;

a flash type analog to digital converter connected to the buffer for receiving signals therefrom and converting the analog form of those signals into digital form multiple times during a cycle, the flash type analog to digital converter capable of sampling wave pulse train output periodically and several times during a cycle or some cycles;

a data memory connected to the analog to digital converter for storing the converted signals in their digitized form, and

a processor connected to the data memory so as receive the stored signals from the data memory, the processor connected to the electrosurgical unit and capable of processing the stored signals while continually monitoring the electrosurgical unit by measurement of the voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy and then controlling the electrosurgical unit to achieve a predefined voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy in accord with a mode setting and an algorithm in the processor.

2. The circuit for monitoring and for controlling of claim 1 wherein the flash type analog to digital converter is capable of sampling wave pulse train at about eight million samples per second.

3. The circuit of claim 2 wherein a sample clock means is in circuit with the flash type analog to converter so as to set the timing for storing converted signals into the data memory so the number of samples taken times the sample frequency is an integral number of RF cycle times and a RF drive clock means is in circuit with, connected to the electrosurgical unit output and the flash type analog to digital converter so as to synchronize the sample clock means of the flash type analog to digital converter with output of the electrosurgical unit.

4. The circuit of claim 3 wherein a feedback loop connecting the processor to the electrosurgical unit and the feedback loop regulates the electrosurgical unit by control of pulses of the RF drive clock means.

5. The circuit of claim 3 wherein the electrosurgical unit has a high voltage power supply associated with the electrosurgical unit and a feedback loop connecting the processor to the electrosurgical unit for manipulating and adjusting the electrosurgical unit RF output by control of the electrosurgical unit high voltage power supply and the feedback loop regulates the electrosurgical unit by control of pulses of the RF drive clock means.

6. The circuit of claim 5 wherein the processor and feedback loop are connected to control performance parameters of the electrosurgical unit including peak to peak voltage, peak to peak current, and leakage current and considers each as the control signal for the feedback loop of the electrosurgical unit.

7. The circuit of claim 3 wherein the sample clock means connected the flash type analog to digital converter and synchronized with the wave form of the electrosurgical unit output defines a square wave having rising edges and falling edges for thereby taking 16 output wave form amplitude measurements timed with each rising edge and across 16 cycles of the output wave form so 256 data points are in the data memory and in the next 16 substantially adjacent output cycles taking 16 output waveform amplitude measurements in each timed with each falling edge of each square wave pulse to merge with those in the data memory to double the number of amplitude reading of the monitored waveform for enhanced resolution.

8. The circuit of claim 1 wherein the electrosurgical unit has a high voltage power supply associated with the electrosurgical unit and a feedback loop connecting the processor to the electrosurgical unit for manipulating and adjusting the electrosurgical unit RF output by control of the electrosurgical unit high voltage power supply.

9. The circuit of claim 1 wherein an input of the processor monitors, calculates and regulates the electrosurgical unit output performance parameters received from the data memory including the constant current, constant voltage or power as a root mean square value.

10. The circuit of claim 1 wherein the processor connected to the data memory enhances the resolution of the converted signals and a phase shifting sample clock means permits signal handling at a frequency greater than the processor could handle converted signals without the sample clock means phase shifting so that the instantaneous values of current and voltage of the electrosurgical unit can be monitored and controlled to correct the transformer output thereof in real time in accord with measured load.

11. A circuit for monitoring operating parameters of an electrosurgical unit with an output transformer having primary and secondary windings and for controlling in real time those parameters relative to a load placed upon the radio frequency energy supplied by the electrosurgical unit, comprising:

a sensing circuit means connected to receive radio frequency energy supplied by the output of the electrosurgical unit and responsive to loads applied across the radio frequency energy supplied, the sensing circuit means connected for providing instantaneous values of current and voltage from the secondary windings so the sensing circuit means collects parameters indicative of the operation of the electrosurgical unit under load;

a signal modifier connected to the sensing circuit means the signal modifier including enhancement means to adjust or attenuate the amplitude of the parameters from the sensing circuit means in response to signal processing and feedback;

a buffer connected to the signal modifier for receiving the enhanced parameters collected to set the level thereof;

a flash type analog to digital converter connected to the buffer for receiving signals therefrom and converting the analog form of those signals into digital form multiple times during a cycle, the flash type analog to digital converter capable of sampling wave pulse train output periodically and several times during a cycle or some cycles at millions of samples per second;

a data memory connected to the analog to digital converter for storing the converted signals in their digitized form, and

a sample clock means is in circuit with the flash type analog to digital converter so as to set the timing for storing converted signals into the data memory so the number of samples taken times the sample frequency is an integral number of RF cycle times;

a RF drive clock means is in circuit with, connected to the electrosurgical unit output and the flash type analog to digital converter so as to synchronize the sample clock means of the flash type analog to digital converter with output of the electrosurgical unit;

a processor connected to the data memory so as receive the stored signals from the data memory, the processor connected to the electrosurgical unit and capable of processing the signals while continually monitoring the electrosurgical unit by measurement of the voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy and then controlling the electrosurgical unit to achieve a predefined voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy in accord with a mode setting and an algorithm in the processor so the output parameters of the electrosurgical unit may be calculated for controlling performance parameters including peak to peak voltage, peak to peak current, and leakage current for consideration of each as the control signal for feedback into the electrosurgical unit;

the sample clock means for permitting measurement handling at a frequency greater than the processor could without the sample clock means so that the instantaneous values of current and voltage of the electrosurgical unit can be monitored and controlled over its broad spectral input to correct in real time the output in accordance with measured load, and

a feedback loop connected to the electrosurgical unit so a high voltage power supply therein may be manipulated and so the radio frequency drive pulses of a main control circuit of the electrosurgical unit may be regulated and wherein the transformer output performance parameters including the constant current, constant voltage or power may be calculated as a root mean square value, monitored and/or regulated through an input of the processor.

12. The circuit of claim 11 wherein the stored signals from the data memory received by the processor are split into two sets of 256 each with the sample clock means by phase shifting for receiving the converted signals in the form of square wave pulse train from the analog to digital converter and the processor reads the square wave pulse train at 8 megahertz at a rising edge and a falling edge of each square wave pulse of the sample clock means in adjacent cycles.

13. The circuit of claim 11 wherein for each 16 pulses of the electrosurgical unit radio frequency drive the processor is connected to the electrosurgical unit and samples the output of the electrosurgical unit 16 times thereby generating 256 data points read at a rising edge and then subsequently another 256 at a falling edge of each square wave pulse of the sample clock means in substantially adjacent cycles.

14. A method for monitoring operating parameters of an electrosurgical unit and for controlling those parameters relative to a load placed upon the radio frequency energy supplied by the electrosurgical unit, having the steps comprising:

collecting parameters indicative of the operation of the electrosurgical unit under load with a sensing circuit means connected to receive radio frequency energy supplied by the output of the electrosurgical unit and responsive to loads applied thereacross;

enhancing parameters of the signals collected with a signal modifier connected to the sensing circuit means;

converting the analog form of the signals into digital form with an analog to digital converter connected for receiving signals from the signal modifier;

storing the signals in digitized form in a data memory for transmission therefrom to a processor;

receiving the stored signals from the data memory in the processor, and

processing the signals while continually monitoring and controlling the electrosurgical unit by measurement of the voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy with the processor.

15. The method for monitoring operating parameters of claim 14 wherein the step of processing the signals while continually monitoring and controlling the electrosurgical unit includes shifting the timing for obtaining signals for adjacent cycles.

16. A circuit for monitoring operating parameters of an electrosurgical unit with an output transformer having primary and secondary windings and for controlling in real time those parameters relative to a load placed upon the radio frequency energy supplied by the electrosurgical unit, comprising:

a sensing circuit means connected to receive radio frequency energy supplied by the output of the electrosurgical unit and responsive to loads applied across the radio frequency energy supplied, the sensing circuit means connected for providing instantaneous values of current and voltage from the secondary windings so the sensing circuit means collects parameters indicative of the operation of the electrosurgical unit under load;

a signal modifier connected to the sensing circuit means, the signal modifier including enhancement means to adjust or attenuate the amplitude of the parameters from the sensing circuit means in response to signal processing and feedback;

a buffer connected to the signal modifier for receiving the enhanced parameters collected to set the level thereof;

a flash type analog to digital converter connected to the buffer for receiving signals therefrom and converting the analog form of those signals into digital form multiple times during a cycle, the flash type analog to digital converter capable of sampling wave pulse train output periodically and several times during a cycle or some cycles;

a data memory connected to the analog to digital converter for storing the converted signals in their digitized form;

a processor connected to the data memory so as to receive the stored signals from the data memory, the processor connected to the electrosurgical unit and capable of processing the stored signals while continually monitoring the electrosurgical unit by measurement of the voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy and then controlling the electrosurgical unit to achieve a predefined voltage, current, power, load impedance, leakage current, spectral content and/or crest factor of the wave pulse train of the radio frequency energy, the processor for controlling the electrosurgical unit in accord with the measurements, and.

a sample clock means is in circuit with the flash type analog to digital converter so as to set the timing for storing converted signals into the data memory so the number of samples taken times the sample frequency is an integral number of RF cycle times, and

a RF drive clock means is in circuit with, connected to the electrosurgical unit output and the flash type analog to digital converter so as to synchronize the sample clock means of the flash type analog to digital converter with output of the electrosurgical unit.