Bipolar electrosurgical instrument with replaceable electrodes

ES 2 328 367 T3

DESCRIPTION

Bipolar electrosurgical instrument with replaceable electrodes.

Field of the invention

This invention relates to a bipolar electrosurgical instrument and, more particularly, to a bipolar electrosurgical instrument having replaceable electrodes for sealing blood vessels and vascular tissue.

Background to the description

A hemostat is commonly used in surgical procedures to grasp, dissect, and clamp tissue. Typically, it is a tool similar to simple pliers that uses a mechanical action between its jaws to constrict vessels without cutting them. Also, it is typical to have a locking pawl between the handles so that the device can be clamped and locked in place.

Many hemostats are typically used in open bipolar surgery. Once the vascular tissue has been secured with a hemostat, it is common for a surgeon to place a suture around the tissue to permanently close it before removing the hemostat. Multiple hemostats may remain in the surgical field until the surgeon has a chance to place a suture around each section of attached tissue.

Neurosurgeons have used bipolar instruments to coagulate vessels in the brain that are less than two millimeters in diameter. These bipolar instruments are typically tweezer-like devices with two arms that can be deflected towards each other to grasp tissue. However, it has been found that these instruments are not capable of sealing blood vessels with diameters greater than about two millimeters. There has been a long felt need for an easy way to seal larger vessels and bundles of vascular tissue without the need for sutures.

The procedure of coagulating small vessels is thought to be fundamentally different from sealing vessels. Coagulation is defined as a procedure for desiccating tissue in which tissue cells are disrupted and dried. Vessel sealing is defined as the process of liquefying collagen in tissue so that it crosslinks and becomes a fused mass. Therefore, the coagulation of small vessels is sufficient to permanently close them. Larger vessels need to be sealed to ensure permanent closure.

A number of bipolar electrosurgical compression forceps and forceps are known in the art. However, these instruments are not designed to apply the correct pressure to a blood vessel in order to achieve a lasting seal. Also, all these instruments suffer from the disadvantage that they do not combine the simplicity and familiarity of a hemostat with a bipolar electrosurgical circuit.

An example of a bipolar electrosurgical power curve for sealing vessels is described in US Patent 5,827,271, entitled "Vessel Sealing Power Delivery System".

US Patent 5,776,130, entitled "Vascular Tissue Seal Pressure Control," describes another surgical tool for sealing vessels.

US Patent 371,664 describes a pair of electric forceps with positive and negative electric poles located in the jaws.

US Patent 728,883 describes an electrothermal instrument in which electricity is used to heat one of the jaws of the instrument.

US Patent 1,586,645 describes a bipolar instrument for coagulating tissue.

US Patent 2,002,594 describes a bipolar laparoscopic instrument for treating tissue, whereby tissue coagulation and cutting can be performed with the same instrument.

US Patent 2,176,479 describes an instrument for finding and removing metal particles. The instrument jaws are designed to complete an electrical circuit when conductive material is placed between them. An insulated pivot and insulated ratchet are used to prevent a short circuit.

US Patent 3,651,811 describes a bipolar electrosurgical instrument for cutting and coagulating tissue.

US Patent 4,005,714 describes a bipolar coagulation forceps with jaws that are opened and closed by an actuating sleeve.

US Patents 4,370,980 and 5,116,332 describe an electrocautery hemostat in which the hemostatic clamping function and the electrocautery function can be performed with a single instrument.

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Monopolar electrosurgical designs are shown and described. The preamble of claim 1 is based on US Patent 4,370,980.

European patent 03 06 123 provides a forceps-type biopisia instrument, in which the blades can be removed. In one embodiment, the electrodes are attached to insulator sections that are removably attached to jaw members.

US Patent 4,552,143 describes a family of removable switchable electrocautery instruments, including an electrocautery hemostat. Monopolar electrosurgical designs are shown and described.

US Patent 5,026,370 describes an electrocautery forceps instrument including an electrical switching mechanism. Monopolar electrosurgical designs are shown and described.

US Patent 5,443,463 describes a coagulation forceps having a plurality of electrodes.

US Patent 5,484,436 describes bipolar electrosurgical instruments for simultaneously cutting and coagulating tissue.

The article "The mechanism of blood vessel closure by high-frequency electrocoagulation" describes experiments on blood vessels of dogs. The sentence beginning on the last line of page 823 describes "an electrode forceps, each of the blades being isolated from each other and connected to a terminal of the high frequency generator."

The article "Coagulation Studies and the Development of an Automated Computerized Bipolar Coagulator" describes on page 150 that, "It was not possible to safely coagulate arteries with a diameter greater than 2 to 2.5 mm." On page 151, line 5, it is noted that "Veins can be safely coagulated to a diameter of 3 to 4 mm."

Russian patent 401,367 describes a bipolar instrument with an articulated mechanism that joins the operating jaws in a parallel manner.

The above descriptions have not provided a design for a bipolar electrosurgical instrument with removable electrodes capable of conveniently applying a constant pressure, from a calibrated spring loaded source held by a ratchet, that is sufficient to seal vessels and vascular tissue.

Summary of the invention

The general object of this invention is to provide a bipolar electrosurgical instrument for sealing vessels and vascular tissue. The instrument is designed to grasp and clamp vessels or vascular tissue between its jaws. The jaws have removable electrodes that are electrically connected to an electrosurgical generator. Electrosurgical current flows through the tissue clamped between the electrodes. The instrument is bipolar because electrosurgical current flows from one electrode, through tissue, to another electrode, and both electrodes are located on the instrument. In contrast, a monopolar instrument requires a separate electrode (sometimes called the "neutral electrode") that is located away from the instrument.

One of the advantages of the instrument is that vessels and vascular tissue can be sealed without the use of sutures, staples or other material that is foreign to the tissue.

Another advantage of the instrument is that the removable electrodes provide safety against electrical shock and burns. Electrically insulating materials, such as plastics, can be damaged or compromised by repeated sterilization cycles. Also, the electrical insulator may be cut or nicked by sharp surgical tools. The removable electrodes provide a safety advantage as they can be replaced before each procedure. The electrodes can also be replaced at any time if the surgeon suspects an electrical insulation failure. This advantage is particularly important in vessel sealing instruments, as currents up to 4 amps can be used.

The present invention is a bipolar electrosurgical instrument as defined in claim 1, comprising first and second members having first and second jaws near a distal end, and having first and second handles near a proximal end. A pivot joint connects the first and second members to allow arcuate movement of the first and second jaws toward each other. First and second mechanical interfaces are located respectively on the first and second jaws. The first and second mechanical interfaces are preferably configured to removably mate with first and second electrodes. The mating portions of the electrodes are made of an insulating material to prevent electrical conduction to the members. Sealing surfaces on the opposing electrodes are preferably designed to grip vessels and vascular tissue and conduct electrosurgical current therethrough in a bipolar circuit. First and second locking pawls are located at the proximal end of the members to provide a constant closing force between the sealing surfaces.

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Brief description of the drawings

Figure 1 is a perspective view of a bipolar electrosurgical instrument, showing the electrodes mated to one another in parallel opposition.

Figure 2 is a perspective view of a bipolar electrosurgical instrument, showing an electrode removed with the receptacle in view and an electrode in place.

Figure 3 is a perspective view of a bipolar electrosurgical instrument, showing an electrode in place and an electrode removed.

Figure 4 is a bottom view of a replaceable electrode showing the electrically insulating substrate with an attached wire portion.

Figure 5 is a side view of Figure 4.

Figure 6 is a detailed view of a forked snap-fit ​​extension.

Figure 7 is a perspective view of a replaceable electrode.

Figure 8 is a side view of an electrode showing a forked snap-fit ​​extension.

Figure 9 is a partial side view of a portion of a receptacle designed to receive the snap-in extension.

Figure 10 is a partial side view of an electrode seated in a receptacle.

Figure 11 is an enlarged view of a portion of a snap-in extension seated in a socket.

Detailed description of the invention

Referring to Figure 1, a bipolar electrosurgical instrument 10 is shown with replaceable electrodes 11 and 12 for sealing vessels and vascular bundles. The instrument 10 comprises a first member 13 and a second member 14 that are connected at a pivot joint 15. Handles 16 and 17 are located generally at the proximal end 18. Jaws 19 and 20 are located generally at the distal end 21 . Sockets 22 and 23 are located on jaws 19 and 20. Each of sockets 22 and 23 preferably comprises various features, as shown in Figure 2 at the location where electrode 11 has been removed. In one embodiment , shown in Figure 1, the jaws 19 and 20 are straight. In alternative embodiments, the jaws 19 and 20 may be curved to accept the curved electrodes 11 and 12, as shown in Figure 4.

The first and second electrodes 11 and 12 are removably mounted in the respective first and second receptacles 22 and 23. Although the term receptacle is used herein, it will be understood that a male mechanical interface may be used on jaws 19 and 20. or female, with a mating mechanical interface on electrodes 11 and 12. In Figure 2, one of the receptacles 22 is shown with the electrode 11 removed. Figure 3 shows the receptacle 23 with an electrode 12 paired therewith.

Each of the first and second electrodes 11 and 12 has an electrically conductive sealing surface 24 and an electrically insulating substrate 25, as shown in Figures 5 and 7. Each substrate 25 is configured to mate with one of the first and second receptacles. second 22 or 23 with matching features that removably fit within receptacles 22 or 23. In the preferred embodiment, the sealing surfaces 24 are relatively flat to avoid current concentrations at sharp edges, and to avoid arcing between high points.

First and second wires 26 and 27 are connected to first and second electrodes 11 and 12, respectively, as shown in Figures 1, 4, 5 and 7. In the preferred embodiment, wires 26 and 27 are bundled together at along one of members 13 or 14 from proximal end 18 to pivot 15. Near pivot 15, wires 26 and 27 are spaced apart and each is connected to its respective electrode 11 or 12. This arrangement of wires 26 and 27 is designed to be comfortable for the surgeon so that there is little interference with manipulation of the instrument 10. Wires 26 and 27 are preferably terminated in a connector 28 near the proximal end 18, although in another In embodiment wires 26 and 27 can be fully extended to an electrosurgical generator. In an alternative embodiment, each of the wires 26 and 27 extend along a separate handle 16 or 17.

First and second pawls 29 and 30 are located on members 13 and 14 near handles 16 and 17, as shown in Figures 1, 2 and 3. Pawls 29 and 30 are locked in at least one position, shown

ES 2 328 367 T3 in Figure 1 at 31. In the preferred embodiment, there are various immobilization positions. The ratchet position 31 maintains the stress energy in the first and second members 13 and 14 to force the electrodes 11 and 12 against each other in an opposite position.

Each member 13 and 14 is preferably designed to deflect in a shank portion, defined as the section between the pivot 15 and the location of the pawl. The jaws 19 and 20 are preferably stiffer than the shank portions. A lateral deflection of the shank portion causes a stress due to a bow that behaves like a spring. The stress energy that is stored in the shank provides a constant closing force between the electrodes 11 and 12. A non-ratcheting design requires the surgeon to hold the electrodes together by applying a constant squeeze to the handles. It has been found through experimentation that a constant force throughout the sealing procedure will produce a more predictable surgical result. It is difficult to maintain a constant force with the hand and therefore a ratchet in combination with a deflectable shank will provide a better surgical result.

The electrically insulating substrate 25 of each of the electrodes 11 and 12 is preferably made of an injection moldable plastic. Substrate 25 is preferably overmolded to capture electrically conductive sealing surface 24, as shown in Figure 8. Wires 26 and 27 are electrically connected to sealing surface 24 of each electrode 11 or 12. There is preferably a stress relief feature 33 on electrodes 11 and 12, as shown in Figures 4 and 7.

The substrate 25 preferably comprises a forked snap-fit ​​extension 32 as shown in detail in Figure 6. Each jaw 19 and 20 has a receptacle 22 and 23 comprising a recess 34, shown in Figure 9, configured to capture the extension. forked snap-fit ​​32. One of the advantages of this design is that manufacturing tolerances can be absorbed by the snap-fit ​​as shown in figure 11. The preferred embodiment also comprises a pair of alignment pins 34 and 35 that fit within sockets 22 and 23.

In the preferred embodiment, instrument 10 is designed so that electrodes 11 and 12 meet each other in parallel opposition. In this way, the opposing sealing surfaces 24 meet one another in the same plane, as shown in Figure 1. In an alternative embodiment, the sealing surfaces may be slightly urged to meet each other at the distal end, and an additional closing force on the handles will cause the sealing surfaces 24 of each electrode 11 and 12 to deflect together in the same plane. In certain embodiments, there may be a stopper to create a fixed clearance, preferably about 0.3 millimeters, to prevent shorting of the electrodes. Other embodiments have an insulating element in each jaw that opposes conductive sealing surface 24 on the opposite jaw, such that instrument 10 is not shorted when jaws 19 and 20 close against each other.

It has been experimentally determined that the closing force between the sealing surfaces 24 is preferably sufficient to overcome a tendency of the tissue to expand during heating. The thickness of the sealed tissue must be less than the thickness of the initial tissue, under pressure, in order to create a fused vessel wall. The degree of pressure required depends on the type of tissue, the dimensions of the sealing surfaces 24, and the size of the tissue that is gripped with the instrument 10. Pressure is expressed herein as a formula that depends on the width of the the sealing surface and the closing force between the sealing surfaces.

For an instrument designed for abdominal vascular vessels and packages, each sealing surface 24 has a width that is preferably in the range of 2 to 5 millimeters, and a length in the range of 10 to 30 millimeters. For abdominal vessels and vascular bundles, experimental results indicate that good vessel sealing performance can be achieved when instrument 10 is calibrated to have at least one ratcheting position 31 set such that the closing force (in grams) divided by the width of the sealing surface (in millimeters) is in the range of 400 to 650 and most preferably 525. For example, an instrument with a sealing surface width of 4 millimeters would preferably have a closing force of 2100 grams.

For an instrument designed for connective tissues and ligaments, particularly a hysterectomy-style Heaney device, the closing force (in grams) divided by the width of the sealing surface (in millimeters) is in the range of 1000 to 2000. Such an instrument would also preferably have scored or knurled sealing surfaces 24 to improve gripping ability, but the height of the roughness features should be minimized to avoid arcing.

Although a particular preferred embodiment has been illustrated and described, the scope of protection sought is found in the claims that follow.