MXPA97009433A - Cable generator electroquirurg - Google Patents

Abstract

The present invention relates to an adapter cable for coupling a bipolar electro-surgical instrument having a pair of electrodes towards an electro-surgical generator having bipolar output terminals, the adapter cable comprises: first and second conductors adapted to couple the electrodes of the instrument electro-surgical to the bipolar output terminals of the electro-surgical generator, and at least one resistance wire coupled between the first and second conductors, wherein at least one resistance wire that limits the maximum voltages developed between the bipolar output terminals

Description

ELECTROOUROPATHIC GENERATOR CABLE FIELD OF THE INVENTION This invention relates to cables that are used with conventional electrosurgical generators (ESGs) to provide output voltage (voltage) waveforms that are effective in reducing clots and preventing adhesion in electrosurgical hemostatic instruments. More particularly, this invention relates to adapter cables that limit the voltage present between the electrodes of an electrosurgical instrument, when it is not in contact with the tissue.

BACKGROUND DB THE INVENTION Bipolar hemostatic electrosurgical techniques are known to reduce bleeding of the tissue to which an incision has been made, both before and during and after the incision is made. Generally, these techniques pass a high-frequency, high-voltage current through the patient's tissue, between two electrodes, to cut and coagulate the tissue. This current causes tissue heating by joule effect, as a function of current density and tissue impedance. The heat deposited in the tissue coagulates the blood of the blood vessels present in the tissue, in this way the blood flow of the severed blood vessels and capillary vessels is reduced. ESGs already known in the art typically provide monopolar and bipolar modes of operation, which supply high frequency AC voltages (AC) (above 100 kHz), within the limit of 150 to 500 volts peak to peak (or more) high) at power speeds less than 400 watts. Examples of these generators are provided in U.S. Pat. No. 4,590,934 to Matis et al., U.S. Pat. No. 4,092,986 to Schneider, U.S. Pat. No. 4,969,885 of Farin. See also, for example, the Operator's Manual for the Forcé 2 ® and Forcé 4 ® Valleylab generators. The bipolar output voltage of these generators increases as the load impedance increases and the peak to peak peak voltages occur under open circuit conditions, i.e. when the electrosurgical instrument is on before coming into contact with the tissue. This voltage increase is not important in the bipolar instruments known before, such as the clamps, since the insulation between the two "legs" of the clamps is more than adequate to handle the Vpp from 800 to 2500 that can be generated by bipolar units electrosurgical, when operating in the open circuit condition (ie, without being in contact with the tissue). However, as soon as the bipolar device grasps the tissue, the charge becomes much lower, within the limit of 50 to a few hundred ohms. The newer bipolar devices incorporating bipolar electrodes spaced narrower have been introduced to the market. For example, bipolar scissors are currently available where the members of the scissors are spaced by a distance of only 3 to 6 mils, using a layer of ceramic insulation. Also, these apparatuses can include other components such as pivot screws that have a relatively thin layer of insulation within the range of a few mils. Preferably, these devices employ an output voltage in a range that generally does not exceed 300 to 400 volts (peak to peak). It has been found that the use of voltages with large ridge to ridge distances in some instruments leads to the arc between the tissue and the instrument, when the instrument first comes in contact with the tissue. This arch can cause a deep necrosis of the tissue and in this way causes the tissue to adhere to the instrument. Actually, these effects can still occur in some of the known low voltage systems F519 above, for example, those disclosed in U.S. Pat. No. 4,232,676 to Herczog and in U.S. Pat. No. 4, 492,231 of Auth. To remedy this situation, ESGs and special low-voltage adapters have been developed that limit the peak voltages that are supplied to the electrosurgical instrument, as described in US Pat. co-pending Serial No. 08 / 275,598, entitled "Electrosurgical Generator Adapters", filed July 15, 1994 and U.S. Patent Application Ser. entitled "Electrosurgical Apparatus for Employing Constant Voltage and Methods of Use", filed March 17, 1994, which is a continuation in part of US Pat. Serial No. 07 / 877,533 filed on June 7, 1991. The foregoing applications describe special design methods and ESGs and adapters that use electronic circuitry to "limit" the peak-to-peak voltage when it exceeds a preselected value. For example, the apparatus described in the above claims references limits a bipolar output voltage, for example, when the surgeon operates the bipolar scissors before the scissors come into contact with the tissue (i.e., an open circuit condition). Once the scissors take up the fabric, the load resistance (i.e., the fabric) is sufficiently low so that the output voltage is below the preselected threshold limit (e.g., 400 Vpp). The adapters described in the previous applications employ electronic circuits with active electronic components mounted on a heat sink and are contained within a 1.5"x 1.5" x 6"long electrically insulating module.The adapters require an appropriate adapter plug for allow the connection to the bipolar output of the different available electrosurgical generators, while the special purpose ESGs described above provide excellent results for the new systems installations, they do not allow the modification or quick adaptation of the large installed base of more conventional generators. Also, while the previously described adapters present excellent performance when used to readjust the previously known electrosurgical generators, the use of active circuit components (eg, transformers and transistors) and heat sinks in those apa At times, it tends to increase the size, cost and manufacturing effort for these adapters. Therefore, it is desirable to provide a low-cost, easy-to-use adapter for use with commercially available ordinary ESGs that reduces the problems associated with excessively open circuit voltages. It would also be desirable to provide an adapter that could be connected between the bipolar output connectors of the commercially available ordinary ESGs and most electrosurgical instruments to limit the peak to peak voltage supplied to the instruments, to reduce the electric arc between the electrodes of the instrument, and between the electrodes and the tissue. Additionally, it would also be desirable to provide an adapter that is manufactured quickly, and that avoids the use of active circuit components and specific heat sinks.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of this invention to provide a user-friendly, low-cost adapter for use with commercially available conventional ESGs, which reduces the problems associated with excessive open-circuit voltages. amplitude crest to crest. It is another object of the present invention to provide adapters that can be connected between the monopolar and bipolar output connectors of commercially available conventional ESGs and most of the electrosurgical instruments to limit the peak to peak voltage supplied to the instruments, to in this way reduce the electric arc between the electrodes of the instrument and between the electrodes and the tissue. It is still another object of this invention to provide an adapter that is quick to manufacture and that avoids the use of open circuit components and specific heat sinks. These and other objects are achieved in accordance with the principles of the present invention by providing an adapter cable, for use with commercially available conventional sources of energy, which limit the maximum voltage applied to the bipolar apparatus, by never allowing the resistance of load is greater than a preselected value. For example, a 600 ohm load resistor connected to a bipolar output of most conventional electrosurgical generators limits the maximum output voltage from 350 to 500V peak to peak - a voltage limit sufficiently low to avoid severe arcing. and / or the damage of the bipolar instrument.

P519 BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and advantages of the invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which the same reference numerals are consistently used "to indicate like parts. In the drawings: FIG 1 is a perspective view of an adapter cable constructed in accordance with the present invention, coupled between a conventional electrosurgical generator and an electrosurgical instrument, FIG 2 is an enlarged illustrative view of the adapter cable FIG.1 is a comparison of the electrical output characteristics of an illustrative electrosurgical generator, with and without the adapter cable of the present invention, and FIG.4 is a sectional view of an adapter cable manufactured in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIGS. 1 and 2, the adapter cable 20 of the present invention is shown coupled between the conventional electrosurgical generator 10 and the bipolar instrument 12. As described hereinafter, the adapter cable 20 reduces: the formation of clots, the arc and the adhesion of the electrosurgical instrument 12 by limiting the open circuit peak voltage (developed when the electrosurgical instrument 12 is actuated before making contact with the electrosurgical instrument 12). the tissue) supplied to the instrument electrodes (and tissue) at about 200 VpiCO (400 V peak to peak). Conventional ESG 10 is shown with bipolar output connectors 14 and may be, for example, a Forcé 4®, Forcé 2® from Valleylab, or another ESG similar to those commercially available from Valleylab, Aspen, Clinical Technology or Neomed, while instrument 12 may consist of bipolar scissors such as those described in U.S. Pat. No. 5,324,289. Preferably, the generator 10 is capable of performing within the limit of at least 50 watts of power in the bipolar mode and has maximum peak-to-peak open-circuit voltages less than about 1500 V in the bipolar mode. The adapter cable 20 is preferably connected to the bipolar output connectors 14 of the conventional ESG 10 by means of the pins 22, which may be banana-type plugs or other suitable connection mechanism, disposed at the ends of the inlets 24. The adapter cable 20 similarly includes connectors 26 located in the inlets 28, which allow the adapter cable 20 to be coupled to the electrosurgical instrument 12. The entrances 24 and 28 leave the main section of the cable 20 at the junctions 29A and 29B. The adapter cable 20 accepts a high frequency and high frequency output waveform (eg, approximately 1500 V peak to peak) from the generator 10 through the bipolar output connectors 14 and supplies a waveform to the electrosurgical instrument 12 which has a voltage that does not exceed approximately 350-400 V peak to peak. The adapter cable 20 according to the principles of the present invention suppresses any open circuit high tension voltage, appearing, for example, when the electrosurgical instrument 12 is actuated before contacting the tissue of the patient. The adapter cable 20 limits the maximum voltage applied to the bipolar apparatus so that the load resistance does not exceed a preselected value. For example, if a 600 ohm load resistor is connected to the bipolar output of most conventional electrosurgical generators, the maximum output voltage is limited between 350 to 500 V peak to peak. This reduced voltage limit is low enough to avoid severe arcing and / or damage to the bipolar instrument 12. In the applied voltages of typical electrosurgical generators, which operate at a maximum set point, a load of 600 ohms will result in the dissipation of 15 to 20 watts. However, this power dissipation only occurs during those periods in which the surgeon is operating the bipolar instrument but is not in contact with the tissue. Therefore, the operating cycle for this heating rate will not be greater than 25% y. therefore, the average or continuous heating rate will be less than about 4 to 5 watts. For a 0.2 inch (5mm) diameter adapter cable, this average heating rate will lead to a maximum elevation of the cable surface temperature of 4.5 to 6.0 ° C. During normal use of the bipolar instrument 12 (ie, while in contact with the tissue), the output voltage of the generator 10 will be much lower than that described above, in this way the energy dissipated in a 600 ohm resistor will be much lower. For example, at a tissue load of 60 ohms, the total energy dissipated in a parallel load of 600 ohms will be 10.4 watts instead of 16 watts in an open-circuit condition (ie, the bipolar instrument 12 is not in contact with the tissue). In a cycle of operation of PS19 25% this translates into approximately 2.6 watts or at a temperature rise of 2.9 ° C. As shown in FIG. 3, the output voltage of a typical ESG increases with the load impedance increasing. When the electrodes of an electrosurgical instrument are not in contact with the tissue, the load impedance that occurs at the output of the ESG 10 is essentially an infinite impedance, or an open circuit. In open circuit conditions, the output of the ESG 10 can approach several thousand volts. FIG. 3 also shows the limiting effect that the present invention has on the peak-to-peak voltage of the ESG 10, which limits the peak to peak voltage to approximately 400 volts, for example. With reference to FIG. 4, a preferred embodiment of the present invention is described. The adapter cable 20 consists of conductors 32 and 34 coupled, respectively, between the pins 22 and the connectors 26. As shown in FIG. 4, a high-strength electrical wire loop consisting of the strands 36A and 36B runs along the length of the adapter cable 20. The conductors 32 and 34 and the resistive wires 36A and 36B, each are electrically isolated from one another, for example, by means of Teflon or silicone coatings (not shown). The outer cover 38 P519 also consists of an electrically insulating material that serves to protect and insulate the conductors 32 and 34 and the resistor wires 36A and 36B, for example, a silicone rubber material. According to the present invention, in order to keep the temperature rise as low as possible, the loop 36A and 36B of high electrical resistance wire can consist, for example, of a 36 gauge 316 of stainless steel wire (for example, as the one manufactured by Cooner Wire Co.) which has a strength of approximately 18.4 ohs / ft at 25 ° C. According to the cable length of 5 meters (preferred for international markets), the total resistance of a loop extending back and forth 'of the 5 meter cable length is: 5 meters = 16.4 feet Rr = 2 x 16.4 feet x 18.4 ohms / ft = 604 ohms With the use of a 38 gauge wire of 316 stainless steel, the total resistance would be approximately 1000 ohms. The resistance of the loop 36A and 36B can be selected depending on the characteristics of the particular output of the electrosurgical generator with which the bipolar instrument 12 is to be used. The applicant expects loop 36A and 36B of resistance wire that P519 has a resistance of 600 ohms is appropriate for most electrosurgical generators. However, if a particular generator is operated at a high output voltage with a 600 ohm load (e.g., greater than 500 V peak to peak) then a lower resistance would be desirable. In the same way, some generators may allow the use of a higher load resistance. Therefore, the adapter cable of the present invention provides an effective load on the electrosurgical generator 10 by adding a loop of high strength wire (wires 36A and 36B) to any other conventional medical grade wire for use with bipolar instruments and generators. conventional electrosurgical As can be seen in FIG. 4, the high strength wire is connected in parallel with the bipolar instrument so that the load resistance applied to the electrosurgical generator is not greater than the resistance of the wire loop inside the wire (e.g., 400 to 1000 ohms). By extending the resistance wire along the majority of the length of the adapter wire 20, the heat generated in the adapter wire is dissipated over a large volume and, therefore, the temperature increase is kept low in an adequate manner . The adapter cable 20 can be easily P519 manufactured by removing a portion of the outer cover 38; then the electrical insulation is left without insulation of the conductors 32 and 34 and of the resistance wires 36A and 36B. Then, the conductors 32 and 34 are coupled to the pins 22 and connectors 26, while the resistance wires 36A and 36B are coupled to the conductors 32 and 34 as shown in FIG. 4. The uninsulated ends of the wires 36A and 36B are coupled to one another. The connections between the resistance wires 36A, 36B and the conductors 32 and 34 can be sealed, for example, by a lock on the connections 29A and 29B (shown in FIG.2), to protect the wires and connections. This present invention provides valuable benefits for controlling the arc and reducing the risk of tissue damage / damage to the instrument, while providing the simplicity of ordinary medical grade cables for use with bipolar electrosurgical instruments. A person skilled in the art will appreciate that the present invention can be practiced by other means than those described herein, which are presented for purposes of illustration and not limitation, and that the present invention is limited only by the following claims.

P519

Claims (10)

1. CLAIMS I 1. An adapter cable for coupling an electrosurgical bipolar instrument that has a pair of electrodes towards an electrosurgical generator that has bipolar output terminals, the adapter cable consists of: first and second conductors adapted to couple the electrodes of the electrosurgical instrument to the bipolar output terminals of the electrosurgical generator; and at least one resistance wire coupled between the first and second conductors.
2. 2. The adapter cable according to the claim 1, wherein the adapter cable has a length and the at least one resistance wire consists of a loop extending along the length.
3. 3. The adapter cable according to the claim 2, wherein the loop consists of first and second resistance wires coupled in series between the first and second conductors.
4. 4. The adapter cable according to the claim 1, wherein at least one resistance wire consists of first and second resistance wires in parallel between the first and second conductors.
5. 5. The adapter cable to attach the bipolar electrosurgical instrument that has a pair of P519 electrodes directed towards an electrosurgical generator having bipolar output terminals, the adapter cable has a length and consists of: first and second conductors adapted to couple the electrodes of the bipolar electrosurgical instrument to the bipolar output terminals; at least one resistance wire coupled between the first and second conductors, wherein at least one resistance wire is distributed along the length portion of the adapter cable.
6. The adapter cable of claim 5, wherein at least one resistance wire consists of a calibrated wire loop of 316 stainless steel.
7. 7. The adapter cable of claim 6, wherein the 316 stainless steel wire has a gauge of between about 36 and about 38.
8. The adapter cable of claim 7, wherein the at least one resistance wire consists of additional conductors running along the length of the adapter cable.
9. 9. A method to limit the peak voltages between the electrodes of a bipolar electrosurgical instrument coupled to the output terminals of an ordinary electrosurgical generator, the method consists of the steps of: P519 providing a first and second conductors adapted to couple the electrodes to the output terminals; and providing at least one resistance wire coupled between the first and second conductors. The method of claim 9, wherein at least one resistance wire consists of a 316 stainless steel wire loop.