Patent Grant
11744631
The present disclosure generally relates to electrosurgical generators. More particularly, the present disclosure relates to systems and methods for providing, controlling, and applying electrosurgical energy for coagulation.
An electrosurgical generator is used in surgical procedures to provide electrical energy for treating the tissue of a patient. When bipolar forceps or another electrosurgical instrument is connected to the generator, the instrument can be used for cutting, coagulation, or sealing the tissue of a patient with high frequency electrical energy. During operation, electrical current from the generator flows between an active electrode and a return electrode of the instrument by passing through tissue and bodily fluids of a patient.
The electrical energy provided by the electrosurgical generator has different waveforms shaped to enhance its ability to cut, coagulate, or seal tissue. Different waveforms correspond to different modes of operating the generator, and each mode provides the surgeon various operating advantages. A surgeon can select and change various modes of operation as the surgical procedure progresses.
In the various modes, it is important to apply the appropriate amount of energy for the electrosurgical procedure. For example, applying too much energy may result in dissection or destruction of tissue. Applying too little energy may result in inhibiting the surgical procedure. Therefore, it is desirable to control the amount of energy provided by the electrosurgical generator for the surgical procedure being performed and for the operating conditions that are encountered. Accordingly, there is continued interest in developing and improving the control of electrical energy provided by an electrosurgical generator.
The electrosurgical systems and methods of the present disclosure relate to systems and methods for providing, controlling, and applying electrosurgical energy for coagulation. As will be described in more detail, when a generator operates in coagulation mode to provide electrosurgical energy to an instrument, an adjustable voltage ramp rate is set based on a load impedance of a load of the instrument reaching a predetermined threshold, and voltage of the electrosurgical energy is changed based on the adjustable voltage ramp rate.
In one aspect of the disclosed technology, the disclosed technology includes an electrosurgical generator for providing electrical treatment energy to an instrument having an active electrode and a return electrode. The generator includes a processor and a memory storing instructions which are executable by the processor. When the instructions are executed, they cause the generator to control a treatment energy to the instrument in a coagulation mode, where the treatment energy has an adjustable voltage ramp rate which can be set to a ramp rate in a range of voltage ramp rates that effectuate coagulation and do not cause dissection of tissue in coagulation mode. The generator receives signals from the instrument over time relating to a load impedance between the active electrode and the return electrode of the instrument. When the load impedance is above a threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and decreases, at the adjustable voltage ramp rate, a voltage of the treatment energy being provided to the instrument. When the load impedance is below the threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and increases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument.
In various embodiments, the threshold is between approximately five-hundred fifty ohms and five-hundred ohms. In various embodiments, when the load impedance is below the threshold, the adjustable voltage ramp rate is set to approximately one-hundred eighty volts per second, and when the load impedance is higher than the threshold, the adjustable voltage ramp rate is set to approximately two-hundred volts per second.
In various embodiments, the memory includes further instructions which, when executed by the processor, cause the generator to determine, based on the signals, that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue.
In various embodiments, in determining that the instrument is currently grasping tissue, the memory includes further instructions which, when executed by the processor, cause the generator to determine, based on the signals, that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue based on the load impedance decreasing from above a second threshold to below the second threshold. In various embodiments, the second threshold is approximately eight-thousand ohms.
In accordance with aspects of the present disclosure, the present disclosure includes a method for providing electrical treatment energy to an instrument having an active electrode and a return electrode, the method including controlling a treatment energy to provide to the instrument in a coagulation mode, where the treatment energy has an adjustable voltage ramp rate which can be set to a ramp rate in a range of voltage ramp rates that effectuate coagulation and do not cause dissection of tissue in the coagulation mode. The method includes receiving signals from the instrument over time relating to a load impedance between the active electrode and the return electrode of the instrument. When the load impedance is above a threshold, the method sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and decreases, at the adjustable voltage ramp rate, a voltage of the treatment energy being provided to the instrument. When the load impedance is below the threshold, the method sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and increases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument.
In various embodiments, the threshold is between approximately five-hundred fifty ohms and five-hundred ohms. In various embodiments, when the load impedance is below the threshold, the adjustable voltage ramp rate is set to approximately one-hundred eighty volts per second, and when the load impedance is higher than the threshold, the adjustable voltage ramp rate is set to approximately two-hundred volts per second.
In various embodiments, the method determines, based on the signals, that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue. In various embodiments, the method determines that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue based on the load impedance decreasing from above a second threshold to below the second threshold. In various embodiments, the second threshold is approximately eight-thousand ohms.
In accordance with an aspect of the present disclosure, the present disclosure includes an electrosurgical system for providing electrical treatment energy. The system includes an instrument having an active electrode and a return electrode, and an electrosurgical generator configured to provide a treatment energy to the instrument. The generator includes a processor and a memory having instructions stored thereon. When the instructions are executed by the processor, they cause the generator to control a treatment energy to provide to the instrument in a coagulation mode, where the treatment energy has an adjustable voltage ramp rate which can be set to a ramp rate in a range of voltage ramp rates that effectuate coagulation and do not cause dissection of tissue in the coagulation mode. The generator receives signals from the instrument over time relating to a load impedance between the active electrode and the return electrode of the instrument. When the load impedance is above a threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and decreases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument. When the load impedance is below the threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates, and increases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument.
Various embodiments of the present disclosure are described with reference to the accompanying drawings wherein:
The present disclosure relates to systems and methods for providing, controlling, and applying electrosurgical energy for coagulation. As will be described herein in more detail, in one aspect of the present disclosure, when a generator operates in coagulation mode to provide electrosurgical energy to an instrument, an adjustable voltage ramp rate is set based on a load impedance of a load of the instrument reaching a predetermined threshold, and voltage of the electrosurgical energy is changed based on the adjustable voltage ramp rate.
Where the term “approximately” is used herein in connection with a parameter having approximately a value, it is intended that the parameter can have exactly the value or can have another value which differs from the value due to environmental factors such as noise or due to hardware or software limitations such as, without limitation, number of bits or processor speed or interrupt priority.
Referring now to
With continuing reference to
In
Referring now to
In the illustrated embodiment, the controller 24 includes a microprocessor 25 and a memory 26. In various embodiments, the controller 24 or the microprocessor 25 may be another type of processor such as, without limitation, a digital signal processor, a field-programmable gate array (FPGA), or a central processing unit (CPU). In various embodiments, the memory 26 can be random access memory, read only memory, magnetic disk memory, solid state memory, optical disc memory, and/or another type of memory. In various embodiments, the memory 26 can be separate from the controller 24 and can communicate with the microprocessor 25 through communication buses of a circuit board and/or through communication cables such as serial ATA cables or other types of cables. The memory 26 includes machine instructions that are executable by the microprocessor 25 to operate the generator 20. Various operations of the generator 20 are described below. Such operations can be controlled by the machine instructions executed by the microprocessor 25.
With continuing reference to
With continuing reference to
In various embodiments, the controller 24 and the sensor module 22 can determine whether the instrument is grasping tissue in other ways. As mentioned above, a user can set an energy setting at the generator 20, and the generator 20 can control the voltage and/or current provided by the power supply 27 and RF output stage 28 to provide the indicated energy. When the instrument is not grasping tissue, no meaningful current is drawn by the instrument. Thus, no treatment energy is actually provided by the generator 20 to the instrument, and the voltage at the output of the RF output stage 28 stays essentially the same. When the instrument grasps tissue, a current is then drawn by the instrument, which causes the generator 20 to vary the voltage to provide the indicated treatment energy setting. The variations in voltage can be characterized using a parameter known as crest factor, which persons skilled in the art will understand as a ratio of peak voltage to root-mean-squared (RMS) voltage. In various embodiments, the sensor module 22 can include one or more voltage sensors that measure voltages and can communicate the measurements to the controller 24 for the purpose of determining crest factor. In various embodiments, if the crest factor is greater than a predetermined threshold, the controller can determine that the instrument has grasped tissue. The illustrated embodiment of
The electrical connector 11 is attached to two arms 12, 14 that extend from the electrical connector 11. The two arms 12, 14 terminate in electrodes 18, 19 at the end opposite the electrical connector 11. One electrode 18 is referred to herein as an active electrode, and the other electrode 19 is referred to as a return electrode. The active electrode 18 conveys current received from the generator, and the return electrode 19 returns current back to the generator. The two arms 12, 14 include conductors (not shown) that connect the terminals 16, 17 of the electrical connector 11 with the electrodes 18, 19. Additionally, the two arms 12, 14 are mechanically biased away from each other so that the arms 12, 14 are apart in their resting state. A surgeon using the bipolar forceps 10 can squeeze the arms 12, 14 with varying amounts of force to press the arms 12, 14 and the electrodes 18, 19 closer together and to grasp tissue between the electrodes 18, 19.
In accordance with one aspect of the present disclosure, the instrument 10 can include one or more sensors 15 for determining whether the instrument 10 is grasping tissue. In connection with
The illustrated embodiment of
What have been described above are systems, methods, and devices for producing, controlling, and applying electrosurgical energy. The following will describe methods for controlling electrosurgical energy during a coagulation procedure.
As mentioned above, a user can set an electrical treatment power for the generator using a user interface. Because power is the product of voltage and current, the generator will generally attempt to provide the indicated electrical power by adjusting current and/or voltage. That is, if the indicated power is denoted as Ps=V·I, the generator attempts to vary V and/or I so that their product results in Ps.
Additionally, the current actually flowing through the instrument depends on the load impedance of the tissue being treated by the instrument. Tissue impedance can change for various reasons. In various situations, tissue impedance can increase when tissue temperature increases. Also, as tissue becomes desiccated, the tissue's moisture content drops, causing the tissue's impedance to rise. Additionally, in the case of forceps where a surgeon can exert varying degrees of pressure on tissue by applying varying degrees of force to the instrument, tissue impedance can increase with increasing pressure applied to the tissue. If the load impedance is denoted as ZL, then the current is I=V/ZL. Combining the power and impedance equations, it can be seen that Ps=V2/ZL. Based on this relationship, when the load impedance ZL increase, the generator attempts to maintain the indicated electrical power Ps by increasing the voltage V so that V2/ZL=Ps is maintained. Thus, when load impedance increases, the generator increases voltage in order to maintain a particular power setting.
When using electrosurgical energy for coagulation, it has been found that applying too much voltage to the tissue can cause unintended dissection, even when the generator operates in coagulation mode. Because generator voltage increases with tissue impedance, as discussed above, the voltage may reach a certain point where dissection occurs. In accordance with one aspect of the present disclosure, the generator can decrease voltage to prevent the voltage from rising so high that it causes dissection in the coagulation mode. Based on Ps=V2/ZL, decreasing voltage will also decrease the power provided by the generator. At a certain point, providing too little power will result in insufficient coagulation. Therefore, to sustain sufficient coagulation, the generator will need to increase the voltage and power at a certain point.
In accordance with one aspect of the present disclosure, it has been found that decreasing the power provided by the generator causes the tissue impedance to decrease. Because increased tissue impedance corresponds with increasing generator voltage, and decreasing generator voltage and power corresponds with decreased tissue impedance, tissue impedance can, in accordance with an aspect of the present disclosure, be used to control voltage and power in the coagulation mode to maintain coagulation and mitigate unintentional dissection. As discussed in connection with
As will be explained in more detail in connection with
Additionally, the voltage ramp rates are appropriately selected. If voltage ramp rates are too high, the voltage would return to a high voltage too quickly and expose the tissue to high voltages, possibly causing tissue dissection in the coagulation mode. And if voltage ramp rates are too low, the operating time of the procedure may extend too long. In various embodiments, voltage ramp rates can be between approximately sixty volts per second and approximately four-hundred thirty volts per second. In various embodiments, when the load impedance is greater than the threshold, the voltage may be reduced at, for example, a ramp rate of approximately two-hundred volts per second. In various embodiments, when the load impedance is below the threshold, the voltage may be increased at, for example, a ramp rate of approximately one-hundred eighty volts per second. These parameters can be stored in the memory. (
Referring now to
At step 404, the generator receives signals from the instrument over time relating to a load impedance between the active and return electrodes of the instrument. As discussed in connection with
At step 406, the generator determines, based on the signals, that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue. As described in connection with
In response to the determination that the instrument is currently grasping tissue and that, prior to the grasp, the instrument was not grasping tissue, the generator, at step 408, sets the adjustable voltage ramp rate to an initial voltage ramp rate. In various embodiments, the voltage of the treatment energy is changed at the initial voltage ramp rate until the load impedance reaches the impedance threshold. As discussed above, the threshold can be between approximately five-hundred and five-hundred fifty ohms, inclusive. For example, the load impedance threshold can be approximately five-hundred ohms, or the load impedance threshold can be approximately five-hundred fifty ohms. In various embodiments, the initial voltage ramp rate can be a ramp rate that causes the voltage to quickly reach high voltages that may cause dissection in the coagulation mode, and can be approximately nine-hundred volts per second.
At step 410, when the load impedance is above the threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates that effectuate coagulation without causing tissue dissection, and decreases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument. As mentioned above, the range of voltage ramp rates that effectuate coagulation without causing tissue dissection can be between approximately sixty volts per second and approximately four-hundred thirty volts per second. For example, when the load impedance is greater than the threshold, the voltage may be reduced at a ramp rate of approximately two-hundred volts per second.
At step 412, when the load impedance is below the threshold, the generator sets the adjustable voltage ramp rate to a ramp rate in the range of voltage ramp rates that effectuate coagulation without causing tissue dissection, and increases, at the adjustable voltage ramp rate, the voltage of the treatment energy being provided to the instrument. For example, when the load impedance is below the threshold, the voltage may be increased at a ramp rate of approximately one-hundred eighty volts per second.
At step 414, the generator determines whether the instrument is still grasping tissue. If the instrument is still grasping tissue, the illustrated operation returns to step 410. Otherwise, the illustrated operation ends.
Referring also to
In various embodiments, when the controller 24 controls the treatment energy to increase the voltage of the treatment energy, the voltage is increased up to the voltage limit. In various embodiments, the sensor module 22 can sense the voltage provided by the RF output stage. When the sensed voltage reaches the voltage limit, the controller 24 can stop increasing the voltage of the treatment energy. In various embodiments, if the sensed voltage exceeds the voltage limit, the controller 24 can decrease the voltage of the treatment energy so that it decreases to the voltage limit or to below the voltage limit. In various embodiments, changes to the current of the treatment energy are subject to the current limit and the current ramp rate. In various embodiments, changes to treatment energy are subject to the power limit and the power ramp rate.
Accordingly, what have been described are systems, methods, and devices for providing, controlling, and applying electrosurgical energy. Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modification may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure.
The present application claims priority to U.S. Provisional Application No. 62/562,012, filed on Sep. 22, 2017, U.S. Provisional Application No. 62/562,078, filed on Sep. 22, 2017, and U.S. Provisional Application No. 62/562,110, filed on Sep. 22, 2017. The entire contents of each of the foregoing applications are hereby incorporated by reference.
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| Number | Date | Country | |
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| 20190090932 A1 | Mar 2019 | US |
| Number | Date | Country | |
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| 62562110 | Sep 2017 | US | |
| 62562012 | Sep 2017 | US | |
| 62562078 | Sep 2017 | US |
