MXPA98001151A - Energy supply system to close va - Google Patents

Abstract

Electro-surgical energy is used in combination with a surgical tool to close the vessels and vascular tissue of a patient, one of the important advances of the present system is that it can effectively close a patient's vessels without leaving any foreign material in them. the body of the patient, the present system is also able to close vessels as large as ten millimeters in diameter, another advantage of the present system is that the surgeon can visually inspect the integrity of the closure, the invention works with a combination of pressure and application Controlled electrosurgical energy to achieve the desired result, a surgical tool is used to catch and apply an appropriate amount of closing force to the patient's tissue, the useful is able to conduct electro-surgical energy to the tissue in a manner coincident with the application of force closure, a method to close the vessels and the vascular tissue of a patient includes the steps of applying pressure to the vessels and other tissues of the patient, applying a first level of electro-surgical energy to the vessels and to other tissue sufficient to fuse the proteins of the tissue, apply a second level of electro-surgical energy to the vessels and other tissue sufficient to cause desiccation without singeing, reduce the electro-surgical energy substantially to zero for a sufficient period of time to allow the vessels and other tissues to cool with a new compressed form, and eliminate tissue pressure

Description

POWER SUPPLY SYSTEM FOR CLOSING VESSELS 1. FIELD OF THE INVENTION This invention relates to a medical system for closing vessels and other vascular tissue, and more particularly to a system for applying pressure in combination with electro-surgical energy to a patient's tissue to permanently close the flow through the vessels and vascular tissue. 2- BACKGROUND OF THE DESCRIPTION The ligation or occlusion of ducts, veins, arteries, vascular fascicles or blood vessels is common in many surgical procedures. Larger structures are typically closed using sutures. Sometimes ligation clips are used in a procedure in which it is difficult or time is reversed to suture the vessel. The placement and integrity of the clamp must be checked carefully by the surgeon. If the staple or clamp were released, the result could be an undesirable bleeding. Surgeons often use different clamps or staples to ensure the integrity of the closure. Some devices for clamping vessels include the use of electro-surgical energy to help secure the clamp. U.S. Pat. No. 5,207,691 discloses an electro-surgical clip applier in which the electro-surgical energy is applied through the clip to the tissue. The electro-surgical energy causes the clamp and the adjacent tissue to fuse with each other, resulting in a safer placement. U.S. Pat. UU No. 5,201,900 discloses a bipolar surgical clamp having two separate conductive portions. One end of the staple has been connected to the active electrode, and the other end of the electrode has been connected to the return electrode. All the systems mentioned above have the disadvantage that they leave foreign material in the patient. Other methods for closing structures have been described, although none has been widely accepted due to reliability aspects. For example, U.S. Pat. UU US 5,151,102 discloses a blood vessel coagulation / retention device that works with bipolar electro-surgical energy. The device acts with a pair of tweezers to grasp the vessel and apply electro-surgical energy. During this process, the walls of the vessel contract and the tissue becomes rigid. This method has proved infallible and inadequate to close structures that are larger than approximately two millimeters in diameter. Several journalistic articles have described methods to close small blood vessels using electro-surgery. An article entitled Studies on Coagulation and the Development of an Automatic Computerized Bipolar Coagulator (Coagulation and Development Studies of an Automatic Computerized Bipolar Coagulator), J. Neuro-surg., Volume 75, July 1991, describes a bipolar coagulator that is used to close small blood vessels. The article states that it was not possible to safely coagulate arteries with a diameter greater than 2 to 2.5 mm. A second article is entitled "Automatically Controlled Bipolar Electrocoagulation -" C0A-C0MP " (Automatically Controlled Bipolar Electrocoagulation - "C0A-COMP"), Neurosurg. Rev. (1984), pp. 187-190. The article describes a method for cutting the electro-surgical energy towards the vessel so that scorching of the vessel walls can be avoided. The electro-surgical energy is cut off when the impedance of the generator load has reached a local minimum. This article is directed to applications of precision neuro-surgery in which the diameters of the vessels are small. A related patent application entitled "Vascular Tissue Closure Method and Control", file number of agent PC 9200, has been filed in coincidence with this application.

SUMMARY OF THE INVENTION One of the important advantages of the present system is that it can effectively close the major vessels of a patient without leaving any foreign material in the patient's body. The present system is capable of closing vessels as large as ten millimeters in diameter. Another advantage of the present system is that the surgeon can visually inspect the integrity of the closure. This invention works with a combination of pressure and controlled application of electro-surgical energy to achieve the desired result. Thus, the system requires a tool to catch or apply an appropriate amount of pressure to the patient's tissue. The term "pressure" refers to the force of closure on the vessels or other tissue to which it is applied by means of the applicators of the tool. The tool must also be able to conduct electro-surgical energy up to the tissue normally with the application of pressure. An electro-surgical generator is used to generate electro-surgical energy. The electro-surgical energy is preferably applied in a specific way using an automatic control system. The control system regulates the output current and the output voltage of the electro-surgical generator so as to provide an optimum closure of the vessel. One of the advances of the present invention is that a high current is applied to the tissue in order to melt the proteins. The high current is important for its effect on the tissue. Similarly, the output voltage is regulated to reduce spark and localized tissue heating. The voltage is preferably maintained below one hundred sixty volts RMS, and in the preferred embodiment is maintained below one hundred twenty volts RMS. The first attempts to close vessels with electro-surgery were not successful due in part to the relatively low current that was applied. The present invention can extract a maximum current above two amperes RMS through the tissue. This level of output current is higher than the design capabilities of many of the electro-surgical generators currently available. The singeing of tissue can be avoided by cutting the flow of electro-surgical energy to the tissue at an appropriate time. There are several techniques to determine when to cut electro-surgical energy. One technique is to control the impedance of the output load of the electro-surgical generator. When the impedance reaches a certain level, preferably above one thousand ohms, the electro-surgical energy must be cut off. Another technique is to control the phase angle between the output voltage and the output current. The transmission of energy to the surgical tool will be determined preferably when the output current is forward to the output voltage at an angle of about fifty degrees. A third technique to determine when to cut electro-surgical energy is to control the output current. As the tissue is dried, the amount of electrical current flowing through the tissue decreases. The generator can cut the power transmission to the surgical tool when the output current falls below approximately RMS 200 milliamps. It is preferable to maintain pressure on the patient's vessels or tissue for a short time after the electro-surgical energy has been substantially cut off. This allows the fabric to cool in its closed state again. An audible tone indicator is preferably available on the generator to indicate to the surgeon when it is appropriate to release the pressure on the tissue. The time delay can be up to five seconds after the completion of the transmission of energy to the surgical tool. In the preferred embodiment there are four main stages for the use of the tissue closure system. The first stage may include the application and maintenance of the pressure on the tissue. The second step may include rapidly heating the tissue with electro-surgical energy. The third step may include lowering the energy delivered to the tissue so that the tissue can be resected without being scorched. The final step may include terminating the transmission of electro-surgical energy to the tissue so that the tissue is allowed to cool while still under pressure. An automatic control system is preferably located inside the electro-surgical generator and has, as one of its functions, the ability to automatically pass through the various levels of electro-surgical energy delivery. In an alternative embodiment, the transmission of energy to the surgical tool may not have discrete, staggered levels. In contrast, energy transmission can be a continuous function that initially delivers a high current, and then switches to a lower energy level to resect the tissue, followed by the termination of energy transmission when the impedance of the tissue exceeds approximately one thousand ohms. The following is a summary of the various embodiments of the invention. The preferred embodiment of the electro-surgical power supply system is used to close vessels and other tissues of a patient. The system comprises a generator, a surgical tool, and means for controlling the level of electro-surgical energy that is transmitted to the tissue. The generator is preferably capacitated to transmit a controlled level of high frequency electro-surgical energy. The output of the generator can be characterized by having an output voltage and an output current that are each regulated in the preferred embodiment of the generator. The generator of the present system could limit the output voltage to a value below one hundred sixty volts RMS. One of the reasons for limiting the output voltage is to avoid sparks and arcs that cause areas of high local temperature in the fabric, and which can also result in tissue sticking to the electrodes. Another disadvantage of the arc formation is that it can result in the cross section of the vessel. The surgical tool is connected, more preferably, to the generator outlet to receive the electro-surgical energy. The surgical tool can take the form of clamps, clamps, or any other instrument with articulated members for grasping the tissue. In a bipolar configuration, one member of the surgical tool will be electrically connected to be an active electrode, and another member of the surgical tool will be electrically connected to be a return electrode. Alternatively, in an onopolar arrangement, the surgical tool may be electrically connected to only one electrical pole of the generator, while the patient is electrically connected to the other electrical pole. While the members are gathering tissue, electro-surgical energy will flow from the generator closing circuit with the tissue.

In the preferred embodiment, there are means for controlling the level of electro-surgical energy transmitted to the surgical tool. The level of electro-surgical energy is controlled in such a way that the vessels and other tissues close as they are picked up by the members of the surgical tool. The electro-surgical energy level can be referred to the RMS energy output of the generator, which can be a function of the output voltage, output current, frequency, and work factor. The surgical tool may also have means to apply pressure to the vessels and other tissues between the members in accordance with the application of the electro-surgical energy. The pressure applying means may take the form of a latch or tooth that holds a known spring force against the members of the tool. There may be various selectable levels of pressure available in the surgical tool. For example, it may be desirable to apply a high level of pressure to the arteries and vascular tissue, and a lower level of pressure to the veins. During an operation, the surgeon can take a vessel with the surgical tool and activate the mechanisms of the tool. to apply the desired pressure level to the glass. Once the pressure has been applied to the vessel, the surgeon can activate the electro-surgical energy. The generator applies the appropriate amount of electro-surgical energy according to a specific power curve.

There are several methods for feedback control to the generator. The feedback control is important because the transition points of the power curve have been projected to occur according to the state of the fabric. Furthermore, it would not be desirable to apply too much energy to the fabric and thereby cause a scorch and its sticking. Various parameters must be controlled for feedback control purposes. These parameters include the impedance of the tissue, the phase angle between the output voltage and the output current, the level of output current flowing through the tissue, and the temperature of the tissue. It is preferable that the generator has means to at least approximate the impedance of the vessels and other tissues of the patient as they are grasped by the members of the surgical tool. For example, one way to approximate the impedance of the tissues is to assume that the impedance is mainly resistive and thus make the approximation by dividing the output voltage by the output current. Other numerical techniques are available for the approximation of the impedance, so that a long division is not necessary. Such an approach technique consists of classifying the output voltage and the output current appropriately, so that a range of impedances can be estimated by mere comparison and a small change in a digital circuit.

The impedance of the tissues is a good indicator of the state of tissue desiccation. One reason for having an estimate of the impedance is to control the electro-surgical energy level so that it is substantially cut off when the impedance of the vessels and other tissues rises above about one thousand ohms. In certain embodiments of the invention, it may be convenient to cut off the power supply to the surgical tool when the impedance estimate rises above 2048 ohms. The preferred means for controlling the level of electro-surgical energy comprises several steps. The first stage is a rapid energy supply function to rapidly increase the supply of energy to the vessels and other tissues until a first point of impedance interruption is reached. The second stage is a constant energy transmission function to maintain a constant supply of energy to the vessels and other tissues until the proteins in the vessels and other tissue have melted. The third stage consists of a low energy delivery function to maintain a low supply of energy to the vessels and other tissues until a second impedance breakpoint is reached. In the preferred embodiment, the passes between stages are performed automatically in the generator without the surgeon needing to introduce more energy. The impedance breakpoints are preferably 16 ohms for the first interruption point and 2048 for the second interruption point. A method for closing vessels and other tissues of a patient is also claimed. The method comprises the steps of: applying pressure to the vessels and other tissues of the patient; apply a first level of electro-surgical energy to the vessels and other tissues sufficient to fuse the proteins of the tissue; apply a second level of electro-surgical energy to the vessels and other tissues sufficient to cause drying without singeing; reduce the electro-surgical energy for a sufficient amount of time to allow the vessels and other tissues to cool in a new compressed form, and eliminate tissue pressure. The step of removing tissue pressure can be performed after a delay of less than five seconds. Additionally, there could be a step of generating an audible indication once the delay has ended. An additional step of the method may be to approximate the impedance of the vessels and other tissues. If this step is carried out, there could be another step of terminating the second level of electro-surgical energy after the impedance of the vessels and other tissues rises above about one thousand ohms.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of an electro-surgical closure system of a vessel. Figure 2 is a set of power curves representing the electro-surgical energy transmitted to the tissue as a function of tissue impedance.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a system 10 for supplying electro-surgical energy. The system 10 is used to close vessels and other tissues of a patient 13, including the ducts, veins, arteries, and vascular tissue. The system 10 comprises an electro-surgical generator 11, useful for surgery, and means for controlling the output of the electro-surgical generator 11 so as to work in cooperation with the surgical tool 12 to effectively close vessels and other tissues of a patient. 13. The electro-surgical generator 11 must be capable of supplying a controlled level of electro-surgical output energy. The output power can be controlled by adjusting the output current and the output voltage. The surgical tool is electrically connected to the generator 11 to receive the electro-surgical energy. The surgical tool 12 has members 14, or end applicators, capable of grasping the vessels and other tissues of the patient 13. The member 14 may also be capable of applying and maintaining a relatively constant level of pressure on the vessel. The electro-surgical generator 11 must have means for automatically controlling the level of electro-surgical energy delivered to the surgical tool 12. This can be done in the form of a feedback control system. In the preferred embodiment, there are also circuits to limit the output current and the output voltage. In one embodiment, an adjustable source of high voltage power is used to adjust an RF output stage to control the electro-surgical output. The energy output of the generator 11 is described in terms of the power curve, and a preferred embodiment is shown in Figure 2. The power curve can be described in terms of various stages. The stages may be discrete, or they may be approximated by a smooth continuous function. In the first stage of the power curve, the electro-surgical generator 11 transmits output energy even with impedances below about sixteen ohms, and maintains a high power level until the tissue proteins have sufficiently melted. During this first stage, the output current is allowed to increase to a maximum amplitude that is typically greater than two RSM amps. It has been found that a high current is important to close a vessel efficiently. After the first stage, the elect ro-qui surgical energy is lowered to a level sufficient to resect the vessels and other tissues. The lower energy allows drying to occur without the fabric singeing. A final stage includes allowing the tissue to cool with its new closed form. During this final stage, the application of electro-surgical tissue energy is substantially terminated. After the fabric has cooled, the closing force is removed. The amount of time for cooling is typically less than five seconds. In the preferred embodiment, an audible tone could indicate to the surgeon that the closure process has been completed. The surgeon will therefore release the vessel from the surgical tool 12. It is believed that the high initial current causes the tissue proteins to melt. The subsequent delivery of lower energy to the tissue allows the proteins to form a lattice. As the fabric cools, the new reticulated tissue will form a permanent closure of the vessel. The surgical tool 12 may further comprise an index for selectively applying multiple levels of closing force between the members 14. For example, the arteries will require a greater closing force than the veins. It has been found that a closing force greater than 1,500 grams is effective for closing the arteries. A closing force of less than 500 grams is effective for closing the veins. In the preferred embodiment, the surgical tool 12 will have a support that is compressed to maintain a closing force on the members 14. The index is mechanically attached to the spring such that each successive stop of the index maintains a higher compression of the spring. The spring will not begin to compress until the members 14 encounter resistance to closure. In the preferred embodiment, the generator 11 further comprises means for approximating the impedance of the vessels and other tissues of the patient 13 as they are grasped by the members 14 of the surgical tool 12. The calculation of the impedance may require a long division and other prolonged mathematical manipulations. There is a variety of techniques for making a rapid approximation of impedance that would be sufficient for the purpose of controlling the output energy of the electro-surgical generator. For example, comparing the output voltage with the output current can produce an estimate of the impedance without resorting to long division. The impedance of the tissue gives an indication of the state of tissue desiccation. By controlling the impedance, the generator 11 can provide the appropriate amount of electro-surgical energy without scorching the tissue. For example, the power control circuit includes a power-breaker function to substantially cut off the power supply to the surgical tool 12 when the impedance of the vessels and other tissues rises above about one thousand ohms.

The power control curves shown in Figure 2 represent the electro-surgical output of the generator 11 as a function of tissue impedance. At low impedances, the electro-surgical energy rapidly increases the output current, as shown by the segment marked with A. The increase in electro-surgical energy is terminated after reaching a first point of impedance interruption. The first impedance breakpoint is shown as Point 1 in Figure 2. In the preferred embodiment, this point is typically below 20 ohms. Next, the electro-surgical energy remains approximately constant until the proteins of the vessels and other tissues have been melted. The impedance at which this segment ends will vary according to the magnitude of the RMS power. Thus, when the maximum RMS power is approximately 125 watts, the segment will end at approximately 128 ohms. This is shown as a segment marked B in Figure 2. When using a lower power, such as 75 watts, the segment may end at 256 ohms. This is shown as a segment marked with C in figure 2. The output energy is then reduced to less than half of its maximum value. The low-energy transmission ends when a second impedance breakpoint is reached. In the preferred embodiment, the second breakpoint is at approximately 2048 ohms. As an alternative to using the impedance to determine the second breakpoint, the phase angle between current and voltage can be used. In this alternative embodiment, the generator 11 includes means for substantially cutting the transmission of energy to the surgical tool 12 when the output current advances the output voltage by an angle greater than about fifty degrees. In still another alternative embodiment, the generator 11 will terminate the transmission of energy to the surgical tool 12 when the output current falls below about 200 milliamperes RMS. It is desirable that the generator 11 limit its output voltage at all times to less than one hundred sixty volts RMS. The reason for keeping the output voltage low is to prevent the formation of an electric arc and to result in burnt spots of the localized tissue that could cause tissue closure failure. A method for closing the vessels and other tissues of a patient 13 comprises the following steps. First, apply a closing force to the vessels and other tissues of the patient 13, sufficient to substantially close the interior passages of the vessels or tissue. Second, apply a first level of electro-surgical energy to the vessels and other tissues, in which the peak of the output current is greater than two amps and the peak of the output voltage is less than one hundred and sixty volts RMS. Third, reduce the electro-surgical energy to a second level that is less than half the first level. Fourth, apply the second level of electro-surgical energy to the vessels and other tissue of patient 13 for a sufficient amount of time to cause drying without singeing. Fifth, reduce the electro-surgical energy substantially for a sufficient amount of time to allow the vessels and other tissues to cool with a new compressed form. Sixth, eliminate the closing force of the fabric. The fifth step of reducing the electro-surgical energy can be performed either by cutting off the energy towards the surgical tool 12, or either by reducing the energy towards the surgical tool 12 to a very low level. In realization, the electro-surgical energy will be completely cut off so that the tissue 13 is cooled in the fastest possible time. In an alternative embodiment, the generator 11 could continue to provide at the output approximately one watt of power in order to maintain a closed circuit with the fabric 13 until the fabric has cooled with its compressed form. In the preferred embodiment, the method for closing vessels and other tissues will have the additional step of periodically approximating the impedance of the vessels and other tissues. This step will allow a control system in the generator 11 to adjust the output power according to the tissue impedance. For example, the step of applying a second level of electro-surgical energy could end after the impedance of the vessels and other tissues rises above about one thousand ohms. Alternatively, the step of substantially cutting the delivery of energy to the surgical tool 12 may occur when the output current advances to the output voltage at an angle greater than about fifty degrees. An alternative is to cut off the delivery of energy to the surgical tool 12 when the output current falls below approximately RMS 200 milliamperes. In the preferred embodiment, there are the additional steps of limiting the output voltage to a value below about one hundred sixty volts RMS, and of audibly indicating when the closing force on the vessels and other tissues must be removed. The audible indication occurs after substantially reducing the level of electro-surgical energy, and after an additional delay of less than five seconds. It will be understood that the arrangements described in the foregoing are only illustrative of the application of the principles of the present invention. Those skilled in the art can make numerous modifications and alternative arrangements without thereby abandoning the spirit and scope of the present invention. The appended claims are intended to cover such modifications and provisions. Having described the invention in the foregoing, property contained in the following is declared as property

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - A system (10) for supplying electro-surgical energy to close vessels and other tissues of a patient 13, the system comprising: a generator 11 capable of delivering a controlled level of electro-surgical energy by producing an output voltage and of an output current; a surgical tool 12 electrically connected to the generator 11 to receive the electro-surgical energy, the surgical tool 12 having electrically conductive members 14 arranged to grip the vessels and other tissues of the patient 13 and to transmit the electro-surgical energy to the members, the surgical tool 12 having means for maintaining a known closing force between the members 14, and an energy control circuit in the generator 11 for sequentially ordering the level of electro-surgical energy transmitted to the surgical tool 12, in the that the sequence includes the raising of the output current to a maximum amplitude greater than about two amperes RMS while the surgical tool 12 applies the closing force, then lowering the electro-surgical energy to a level sufficient to dry the vessels and the other tissues without scorching, and then cutting off the energy transmission electro-surgical to the surgical tool 1

2. 2. The electro-surgical power supply system of claim 1, wherein the means for maintaining the closing force in the surgical tool 12 further comprises means for selectively applying multiple levels of closing force between the members 14.

3. The electro-surgical power supply system of claim 1, wherein the generator 11 further comprises means for approximating the impedance of the vessels and other tissues of the patient 13 as they are picked up by the limbs. of the surgical tool 12.

4. The electro-surgical power supply system of claim 3, wherein the control circuit includes a power cut function for substantially cutting off the power supply to the surgical tool 12 when the impedance of the vessels and of the other tissues rises above about one thousand ohms.

5. The electro-surgical power supply system of claim 3, wherein the energy control circuit further comprises: an output current delivery capability for rapidly increasing the output current supply to the vessels and to the other tissues until a first impedance interruption point is reached; a constant energy delivery capacity to maintain a constant delivery of energy to the vessels and other tissues until the proteins of the vessels and other tissues have melted, and a low energy delivery capacity to maintain a supply of Low energy to vessels and other tissues until a second impedance breakpoint has been reached.

6. The electro-surgical power supply system 10 of claim 5, wherein the first impedance breakpoint is located at approximately 16 ohms and the second impedance breakpoint is located at approximately 2048 ohms. .

7. The electro-surgical power supply system 10 of claim 1, wherein the generator 11 includes means for substantially cutting the delivery of energy to the surgical tool 12 when the output current advances the output voltage in a angle greater than about fifty degrees, or wherein the generator 11 has a means of limiting the output voltage to limit the level of the output voltage to below about one hundred sixty volts RMS.

8. The electro-surgical power supply system 10 of claim 1, wherein the generator 11 includes means for substantially cutting the delivery of energy to the surgical tool 12 when the output current falls below approximately RMS 200 milliamps. .

9. The electro-surgical energy supply system 10 of claim 1, wherein the generator 11 further comprises means for substantially cutting off the delivery of energy to the surgical tool 12, and an indicator for alerting the surgeon after the delivery of energy to the surgical tool 12 has been substantially completed, eliminating the closing force of the surgical tool 12. tissue.

10. A method for managing an electro-surgical delivery system using electro-surgical energy, the electro-surgical energy having an output voltage and an output current that is applied through the end applicators of a surgical tool 12, the method comprising the steps of: applying the end applicators sufficiently for substantial closure; increase the level of electro-surgical energy towards the extreme applicators until the output current has a maximum value that is sufficient to melt the proteins between the extreme applicators; decrease the supply of electro-surgical energy to the extreme applicators; reduce the electro-surgical energy substantially to zero for a sufficient period to cool the end applicators, and eliminate the closing force on the end applicators. SUMMARY OF THE INVENTION Electro-surgical energy is used in combination with a surgical tool to close the vessels and vascular tissue of a patient; One of the important advances of the present system is that it can effectively close a patient's vessels without leaving any foreign material in the patient's body; the present system is also capable of closing vessels as large as ten millimeters in diameter; Another advantage of the present system is that the surgeon can visually inspect the integrity of the closure; the invention works with a combination of pressure and controlled application of electro-surgical energy to achieve the desired result; a surgical tool is used to grasp and apply an appropriate amount of closure force to the patient's tissue; the tool is capable of conducting electro-surgical energy up to the tissue coincident with the application of the closing force; a method for closing vessels and vascular tissue of a patient includes the steps of applying pressure to the vessels and other tissues of the patient; apply a first level of electro-surgical energy to the vessels and to other tissue sufficient to fuse the proteins of the tissue; apply a second level of electro-surgical energy to the vessels and to the other sufficient tissue to cause the desiccation without singeing; reducing the electro-surgical energy substantially to zero for a sufficient period of time to allow the vessels and other tissues to cool with a new compressed form, and to eliminate tissue pressure. PF / JJ / apm * P98 / 85F