Electrosurgical tissue sealer and cutter

A surgical instrument comprises an end effector including a pair of jaw members configured to move with respect to one another between an open configuration and a closed configuration for clamping tissue. At least one jaw member includes an elongate cam slot extending in a longitudinal direction over a substantial a length a tissue clamping surface of the at least one jaw member. A plurality of electrically isolated, and longitudinally spaced electrodes is supported by the tissue clamping surface and is configured to deliver electrosurgical energy to tissue. A reciprocating member engages the elongate cam slot and is extendable to a sealing position with respect to each of the electrodes to define a predetermined gap distance between a particular electrode and an opposing tissue clamping surface.

BACKGROUND

1. Technical Field

The present disclosure relates to an apparatus and related method for electrosurgically sealing tissue. In particular, the disclosure relates to sealing tissue with a series of discrete electrode segments spaced over a targeted region of the tissue.

2. Background of Related Art

Instruments such as electrosurgical forceps are commonly used in open and endoscopic surgical procedures to coagulate, cauterize and seal tissue. Such forceps typically include a pair of jaws that can be controlled by a surgeon to grasp targeted tissue, such as, e.g., a blood vessel. The jaws may be approximated to apply a mechanical clamping force to the tissue, and are associated with at least one electrode to permit the delivery of electrosurgical energy to the tissue. The combination of the mechanical clamping force and the electrosurgical energy has been demonstrated to join adjacent layers of tissue captured between the jaws. When the adjacent layers of tissue include the walls of a blood vessel, sealing the tissue may result in hemostasis, which may facilitate the transection of the sealed tissue. A detailed discussion of the use of an electrosurgical forceps may be found in U.S. Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodes disposed on clamping surfaces of the jaws. The electrodes are charged to opposite electrical potentials such that an electrosurgical current may be selectively transferred through tissue grasped between the electrodes. To effect a proper seal, particularly in relatively large vessels, two predominant mechanical parameters should be accurately controlled; the pressure applied to the vessel, and the gap distance established between the electrodes.

Both the pressure and gap distance influence the effectiveness of the resultant tissue seal. If an adequate gap distance is not maintained, there is a possibility that the opposed electrodes will contact one another, which may cause a short circuit and prevent energy from being transferred through the tissue. Also, if too low a force is applied the tissue may have a tendency to move before an adequate seal can be generated. The thickness of a typical effective tissue seal is optimally between about 0.001 and about 0.006 inches. Below this range, the seal may shred or tear and above this range the vessel walls may not be effectively joined.

Certain surgical procedures may be performed more quickly and accurately with an electrosurgical forceps having relatively longer electrodes than one having shorter electrodes. To this end, electrosurgical forceps have become available with electrodes 60 mm in length or more. Longer electrodes, however, may tend to present difficulties in maintaining a uniform pressure and gap distance, and thus, creating an effective seal along the entire length of the jaws may prove difficult. For example, where a pair of jaws is pivotally coupled by a pivot pin at a proximal region of the jaws, the effects of manufacturing tolerances may be amplified according to a longitudinal distance from the pivot pin. Tissue captured at a distal region of the jaws may thus encounter greater gap distances and lower clamping forces than tissue captured at a proximal region near the pivot pin. This non-uniformity may make it difficult to adequately control the necessary mechanical parameters to generate an effective seal along the entire length of the electrodes.

Also, longer electrodes may tend to have greater power requirements than shorter electrodes. Current up to 5 amps may be drawn by longer electrodes, which is near a limit set for some commercially available electrosurgical generators.

SUMMARY

The present disclosure describes a surgical instrument for sealing tissue. The instrument comprises an end effector including a pair of jaw members having a opposing tissue clamping surfaces, wherein at least one of the jaw members configured to move with respect to the other jaw member to move the end effector between an open configuration for receiving tissue and a closed configuration for clamping tissue between the opposing clamping surfaces. The at least one jaw member includes an elongate cam slot extending longitudinally along the at least one jaw member over a substantial a length of the tissue clamping surfaces. A plurality of electrically isolated electrodes is supported by at least one of the tissue clamping surfaces of the jaw members, and each of the plurality of electrodes is longitudinally spaced along the at least one tissue clamping surface and is configured to deliver electrosurgical energy to the tissue. A reciprocating member is extendable through the elongate cam slot to a longitudinal sealing position with respect to each of the electrodes, wherein when the reciprocating member is in the sealing position with respect to a particular electrode the reciprocating member defines a predetermined gap distance between the particular electrode and the opposing clamping surface.

The surgical instrument may also include an interruption mechanism to interrupt advancement of the reciprocating member at each of the longitudinal sealing positions. The interruption mechanism may includes a handle movable with respect to a grip member, wherein the reciprocating member is operatively coupled to the movable handle such that the reciprocating member is advanced upon approximation of the movable handle with the grip member and advancement of the reciprocating member is interrupted upon separation of the movable handle from the grip member. Alternatively, the interruption mechanism may include a motor and a controller, wherein the motor is operatively associated with the reciprocating member to advance the reciprocating member upon activation of the motor and interrupt advancement upon deactivation of the motor, and wherein the controller is operatively associated with the motor to activate and deactivate the motor. A sensor array in electrical communication with the controller may be adapted to detect the position of the reciprocating member with respect to at least one sealing position.

The surgical instrument may further comprise a controller for providing electrical energy to a particular electrode while maintaining other electrodes in an electrically inactive state. A sensor array in electrical communication with the controller may be adapted to detect a characteristic of the tissue indicative of a completed electrosurgical treatment. The sensor array may include at least one of a temperature sensor, an impedance sensor and an optical sensor.

The reciprocating member may include a blade for transecting tissue. The reciprocating member may include a cam driver configured to engage the elongate cam slot and the blade may be disposed proximally with respect to a cam driver. The blade may be disposed sufficiently proximally with respect to the cam driver such that when the reciprocating member is in a sealing position associated with a particular electrode, the blade is disposed proximally of the particular electrode.

The reciprocating member may generally exhibit an I-beam geometry including a pair of opposed flanges connected by an intermediate web. One of the pair of opposed flanges may engage the elongate cam slot defined in one of the jaw members and the other of the pair of opposed flanged may engage a second cam slot defined in the other of the jaw members. The elongate cam slot may include a proximal portion curved such that advancement of the reciprocating member therethrough urges the end effector to the closed configuration.

The plurality of electrodes may include a plurality of electrode sets. Each electrode set may include at least two electrodes of opposite polarity supported by respective clamping surfaces such that the electrodes of opposite polarity may cooperate to induce an electrosurgical current to flow through tissue positioned between the clamping surfaces.

According to another aspect of the disclosure, a surgical instrument comprises an end effector including a pair of jaw members. At least one of the jaw members is configured to move with respect to the other jaw member to move the end effector between an open configuration for receiving tissue and a closed configuration for clamping tissue between a pair of opposed clamping surfaces supported by the jaw members. A plurality of electrically isolated electrodes is supported by at least one of the clamping surfaces of the jaw members. Each of the plurality of electrodes is longitudinally spaced along the at least one clamping surface and is configured to deliver electrosurgical energy to the tissue. A reciprocating member includes a blade, the reciprocating member extendable to a longitudinal sealing position with respect to each of the electrodes, wherein when the reciprocating member is in the sealing position with respect to a particular electrode the blade is disposed immediately proximally of the particular electrode. An interruption mechanism is provided to interrupt advancement of the reciprocating member at each of the sealing positions.

According to another aspect of the disclosure, a method for electrosurgically treating tissue comprises providing an instrument including a plurality of electrically isolated electrodes spaced longitudinally along at least one tissue clamping surface of one of a pair of jaw members. The instrument also includes a reciprocating member longitudinally movable to a sealing position with respect to each of the plurality of electrodes. The reciprocating member defines a predetermined gap distance between a particular electrode an opposing tissue clamping surface jaw member when in the sealing position with respect to the particular electrode. The method also comprises positioning tissue between the opposing tissue clamping surfaces such that at least a first proximal electrode and a second distal electrode of the plurality of electrodes contacts the tissue, and advancing the reciprocating member to the sealing position with respect to the first proximal electrode to clamp the tissue between the first proximal electrode and the opposing tissue clamping surface at the predetermined gap distance. Advancement of the reciprocating member is interrupted to maintain the reciprocating member at the sealing position with respect to the first proximal electrode while providing electrosurgical energy to the first proximal electrode and maintaining the second distal electrode in an electrically inactive state. The reciprocating member is further advanced to the sealing position with respect to the second distal electrode to clamp the tissue between the second distal electrode and the opposing tissue clamping surface at the predetermined gap distance, and advancement of the reciprocating member is again interrupted to maintain the reciprocating member at the sealing position with respect to the second distal electrode while providing electrosurgical energy to the second distal electrode and maintaining the first proximal electrode in an electrically inactive state.

DETAILED DESCRIPTION

Referring initially toFIG. 1, an embodiment of an electrosurgical instrument is depicted generally as10. The instrument10includes a handle assembly12for remotely controlling an end effector14through an elongate shaft16. Although this configuration is typically associated with instruments for use in laparoscopic or endoscopic surgical procedures, various aspects of the present disclosure may be practiced in connection with traditional open procedures as well as endoluminal procedures.

Handle assembly12is coupled to an electrosurgical cable20, which may be used to connect the instrument10to a source of electrosurgical energy. The cable20extends to connector22including prong members22aand22b, which are dimensioned to mechanically and electrically connect the instrument10to an electrosurgical generator (not shown). Each of the two prong members22aand22bmay be associated with an opposite electrical potential (supplied by the generator) such that bipolar energy may be conducted through the cable20, and to the end effector14.

To control the end effector14, the handle assembly12includes a stationary handle24and movable handle26. The movable handle26may be separated and approximated relative to the stationary handle24to respectively open and close the end effector14. A trigger30is also disposed on the handle assembly12, and is operable to initiate and terminate the delivery of electrosurgical energy through the end effector14.

Referring now toFIG. 2, end effector14is depicted in an open configuration. Upper and lower jaw members32and34are separated from one another such that tissue may be received therebetween. The jaw members32,34are each pivotally coupled to the elongate shaft16by a respective pivot pin36. The lower jaw member34includes a proximal flange38extending into a bifurcated distal end of the elongate shaft16and engaging the pivot pin36. The upper jaw member32is similarly coupled to the elongate shaft16such that the two jaw members32,34are pivotally movable relative to one another. End effector14is thus movable between the open configuration depicted inFIG. 2and a closed configuration depicted inFIG. 6wherein the jaw members32,34are closer together. Other constructions are also envisioned including constructions in which only one jaw member moves.

The upper and lower jaw members32,34define clamping surfaces42and44. Tissue positioned between the clamping surfaces42and44will encounter a clamping force applied by the jaw members32,34when the end effector14is moved to the closed configuration. Each of the clamping surfaces42,44carries a plurality of discrete electrode segments thereon collectively identified as50. The electrode segments50are arranged in pairs longitudinally spaced along the clamping surfaces42,44. For example, a first pair of electrodes50a(+) occupies a first a proximal region of the clamping surface44of the lower jaw member34. Four additional pairs of electrodes50b(+),50c(+),50d(+) and50e(+) are spaced longitudinally in successively distal regions of the clamping surface44. Electrode pairs50a(−),50b(−),50c(−),50d(−) and50e(−) (FIG. 3) occupy corresponding regions of the clamping surface42of the upper jaw member32. The corresponding electrode pairs,50a(+) and50a(−), for example, may be charged to opposite polarities such that they cooperate to induce an electrosurgical current to flow through tissue positioned between the clamping surfaces42and44. Although the clamping surfaces42,44are each depicted as including five electrode pairs, any number of longitudinally spaced electrodes is contemplated.

A knife channel52extends longitudinally through each of the jaw members32and34. The knife channel52permits a reciprocating member54(FIG. 3) to traverse the clamping surfaces42,44to sever tissue positioned therebetween. Since each electrode of the electrode pairs,50a(+) for example, includes one electrode50disposed on each lateral side of the knife channel52, an accurate cut may be generated between regions of sealed tissue.

Referring now toFIG. 3, reciprocating member54is slidably disposed within the elongate shaft16. The reciprocating member54may be advanced distally into the knife channel52of the jaw members32,34. Since each jaw member32and34is coupled to the elongate shaft16by a separate pivot pin36, the reciprocating member54may pass between the pivot pins36as the reciprocating member54is advanced distally. The reciprocating member54includes a sharpened blade56at a forward edge that permits the reciprocating member54to transect tissue as the reciprocating member54is advanced through the knife channel52.

The knife channel52includes a pair of elongate cam slots60extending longitudinally through each of the jaw members32,34. The elongate cam slots60each include a proximal region60afor engaging the reciprocating member54to move the end effector14between the open and closed configurations. The proximal regions60aare curved such that advancement of the reciprocating member54therethrough in a distal direction causes the jaw members32,34to pivot toward one another about the pivot pins36. Further advancement of the reciprocating member54causes the reciprocating member54to engage distal regions60bof the cam slots60. The distal regions60bare generally flat and allow the reciprocating member54to define a gap distance “G” between the electrodes50as described below with reference toFIG. 5.

Referring now toFIGS. 4 and 5, the geometry of a distal portion of the reciprocating member54generally resembles an I-beam having a pair of opposed flanges62connected by an intermediate web64. The flanges62each include a forward cam driver66at a distal end, and a cam engagement surface68extending laterally from the web64. The cam engagement surfaces68have a longitudinal length “L” approximating a length of the cam slots60, permitting the reciprocating member54to engage the jaw members32,34substantially over a length of the clamping surfaces42,44. A forward edge of the web64forming the sharpened blade56is recessed a distance “R” from the forward cam drivers66. This recess permits the reciprocating member54to engage the cam slots60at a distal location with respect to blade56.

The cam engagement surfaces68oppose one another and are separated by a predetermined distance “H.” When the reciprocating member54is advanced into the jaw members32,34, the engagement surfaces68engage the distal regions60bof the cam slots60to define a gap distance “G” between electrodes50. The gap distance “G” is typically between about 0.001 and about 0.006 inches for sealing many tissue types, although greater gap distances “G” may be suitable for some tissue types of for other electrosurgical processes.

Referring now toFIGS. 6 through 8C, a process for sealing and dividing tissue such as vessel “v” includes the steps of introducing the end effector14into a body cavity and clamping the vessel “V.” The end effector14may be introduced into the body cavity through a cannula “C” as depicted inFIG. 7, and the jaw members32,34may be approximated to contact the vessel “V.” The jaw members32,34may be approximated by advancing the forward cam drivers66of the reciprocating member54over the proximal regions60aof the cam slots60as discussed above.

Next the reciprocating member54is advanced to a first sealing position as indicated inFIG. 8A. With the reciprocating member54in the first sealing position, the forward cam drivers66extend sufficiently distally to define an appropriate gap distance “G” between a first set of electrodes50a(+) and50a(−). A separation distance greater than the gap distance “G” may be develop between electrodes50disposed distally with respect to the first set of electrodes50a(+) and50a(−). Such larger separation distances may occur in part due to relatively high reactionary forces applied by the vessel “V” and any inherent flexibility in the jaw members32,34. The flexibility of the jaw members32,34as illustrated inFIGS. 8A through 8Cis exaggerated for clarity.

The first sealing position depicted inFIG. 8Ais also characterized by the immediately proximal location of the forward blade56with respect to the vessel “V” and the first set of electrodes50a(+) and50a(−). This arrangement helps to ensure that no unsealed tissue is cut. Advancement of the reciprocating member54is interrupted to maintain the reciprocating member54at the first sealing position.

Next, electrosurgical energy is applied to the first set of electrodes50a(+) and50a( ) for an appropriate amount of time to effect tissue sealing. The remainder of the electrodes50may remain electrically inactive while an electrosurgical current is induced through the vessel “V” in the vicinity of the first set of electrodes50a(+) and50a(−). Thus, tissue in the immediate vicinity of the reciprocating member54may be sealed while tissue positioned between more distal electrodes50remains untreated. Once tissue sealing has been effected between the first set of electrodes50a(+) and50a(−), the application of electrosurgical energy is interrupted.

Next, the reciprocating member54is advanced to a subsequent sealing position as indicated inFIG. 8B. As the reciprocating member54is advanced, the forward blade56transects the tissue positioned between the first set of electrodes50a(+) and50a(−) while the forward cam drivers66establish the appropriate gap distance “G” between a the subsequent set of electrodes50b(+) and50b(−). Advancement of the reciprocating member54is again interrupted such that the reciprocating member54is maintained in the subsequent sealing position. The application of electrosurgical energy may be repeated for the subsequent set of electrodes50b(+) and50b(−) while the remainder of the electrodes50remain electrically inactive.

The steps of advancing the reciprocating member54, interrupting the advancement of the reciprocating member54, and applying electrosurgical energy to a selected set of electrodes50may be repeated until the reciprocating member reaches a final or distal most set of electrodes50e(+) and50e(−) as depicted inFIG. 8C. In this position, all of the tissue has been sealed and transected by the forward blade56. Thus, the reciprocating member54may be retracted, releasing the vessel “V” from the end effector14. Alternatively, and particularly in instances where tissue spills out beyond the end effector14, an electrosurgical current may be applied to the final set of electrodes50e(+) and50e(−) to effect sealing therebetween. Retracting the reciprocating member54at this point allows a portion of sealed tissue to remain unsevered by the forward blade56. The sealed and unsevered tissue may facilitate further surgical action on the tissue.

Several features may be incorporated into a surgical instrument to facilitate various aspects of the procedure. For example, indicators may be provided to alert an operator of an instrument status, or that a particular step of the procedure is complete and that the subsequent steps may be performed.

As depicted inFIG. 9, an indicator may be associated with an array of temperature sensors70. Each temperature sensor70is positioned appropriately to detect a temperature of tissue positioned adjacent one of the electrode pairs,50a(−) for example. The sensors70are electrically coupled to controller72through the elongate shaft16. The controller may be positioned within the handle assembly12(FIG. 1), or alternatively within the electrosurgical generator, which provides the electrosurgical energy to the electrodes50. The controller72provides an indication to an operator that a particular tissue temperature has been achieved. For example, as electrosurgical energy is applied to the first set of electrodes50a(+) and50a(−), tissue positioned therebetween may tend to heat up to a particular temperature associated with properly sealed tissue. When this temperature is achieved, the controller may emit an audible tone, provide a flashing light or otherwise alert the operator that sealing has been completed. The operator may interrupt the application of electrosurgical energy be releasing the trigger30(FIG. 1), or alternatively the controller70may be configured to provide a signal to the electrosurgical generator to automatically discontinue the delivery of electrosurgical energy. Sensors70may also include an impedance sensor and/or an optical sensor to detect a characteristic of effectively sealed tissue.

As depicted inFIG. 10, an array of position sensors76may be alternatively or additionally provided. Each position sensor76is configured and positioned to detect a position of the reciprocating member54within the elongate cam slots60. The sensors76are also electrically coupled to the controller72. Thus, the controller72may provide an indicator to the operator that the reciprocating member54has been advanced to a sealing position.

Each of the electrodes50may also be electrically coupled to the controller72to detect the presence of tissue positioned between a set of electrodes50. For example, when a vessel such as “V2” (FIG. 10) is positioned between the clamping surfaces42,44some of the electrodes50may contact tissue, and others may not. The controller72may be configured to send an electrical signal to a test electrode50a(+), for example, and monitor an opposite electrode50a(−) to determine whether tissue is positioned between the electrodes50a(+),50a(−). A signal detected at a tissue contacting electrode50b(−), for example, will be distinguishable from a signal detected at an electrode50a(−) that does not contact tissue. For the vessel “V2,” the controller72may provide an indicator to the operator that electrosurgical energy does not need to be applied to the first set of electrodes50a(+),50a(−), and that the reciprocating member54may be advanced directly to the subsequent set of electrodes50b(+),50b(−).

Referring now toFIGS. 11A,11B and11C, a mechanism for appropriately advancing and interrupting the reciprocating member54is housed within handle assembly12. The reciprocating member54is coupled to a drive shaft78such that the longitudinal motion of the drive shaft78is transferred to the reciprocating member54. The drive shaft78includes a flange80at a proximal end, and a driving rack82and a locking rack84extending longitudinally along the shaft78. The drive shaft78is biased in a proximal direction by compression spring86captured between a fixed housing member88and the flange80.

A driving pawl92is pivotally mounted to movable handle26about a pivot pin94. The driving pawl92is pivotally biased toward the driving rack82by a biasing member such as a torsion spring (not shown). Similarly, a locking pawl96is pivotally mounted to a stationary housing member98about a pivot pin102. The locking pawl96is pivotally biased toward the locking rack84by a biasing member such as a torsion spring (not show).

In use, the movable handle26may be approximated with the stationary grip member28to drive the driving pawl92in a distal direction. The driving pawl92bears on a drive tooth82aof the driving rack82to drive the drive shaft78in a distal direction, which drives the reciprocating member54in a distal direction. Thus, the movable handle26may initially be approximated with the stationary grip member28to move the end effector14from an open configuration to a closed configuration as discussed above with reference toFIG. 3.

As the drive shaft78moves distally (see arrow “D” inFIG. 11B), a tooth84aof the locking rack84presses on the locking pawl96. The locking pawl96pivots in the direction of arrow “R” against the bias of the biasing member until the tooth84ahas moved sufficiently to disengage the locking pawl96. The biasing member then causes the locking pawl96to pivot back toward the locking rack84such that the locking pawl96engages a locking face104of the tooth84a. Engagement of the locking pawl96with the locking face104maintains a longitudinal position of the drive shaft78, and thus the reciprocating member54.

With the longitudinal position of the drive shaft78maintained, separation of the movable handle26from the stationary grip member28causes a motion of the driving pawl92in the direction of arrow “H” (FIG. 11B) relative to the driving rack82. The driving pawl92pivots against the bias of the biasing member in the direction of arrow “P” as it moves proximally past a second drive tooth82b. Once the driving pawl92is moved proximally beyond the second drive tooth82b, the biasing member causes the driving pawl92to pivot back toward the drive rack82such that the driving pawl92engages a driving face106of the second drive tooth82b. Once the driving face106is engaged, the movable handle26may again be approximated with the stationary grip member28to advance further advance the reciprocating member the drive shaft78and the reciprocating member54.

The mechanism depicted inFIG. 11Amay thus be used to advance the reciprocating member54to each subsequent sealing position by repeatedly approximating and separating the movable handle26relative to the stationary grip28. Advancement of the reciprocating member54is automatically interrupted at each sealing position as the movable handle26must be separated from the grip28to effect further advancement. When the reciprocating member54is fully advanced, a release (not shown) may be activated to pivot the driving pawl92and the locking pawl96away from the drive shaft78. This will permit retraction of the reciprocating member54under the bias of the compression spring86.

Referring now toFIG. 12, an instrument120includes an actuation mechanism for partially automating the advancement of the reciprocating member54. Instrument120includes a movable handle26, which is movable relative to a stationary grip member28similar to the instrument10discussed above with reference toFIG. 11A. A driving pawl92is mounted to the movable handle26and engages a drive wedge122protruding from a drive shaft124. The drive shaft124is coupled to the reciprocating member54such that longitudinal motion of the drive shaft124is transferred to the reciprocating member54. Thus, the movable handle26may initially be approximated with the stationary grip member28to move the end effector14from an open configuration to a closed configuration as discussed above with reference toFIG. 3.

Thereafter, a motor130may be activated to drive the reciprocating member54. The motor130is coupled to a clutch132, which drives a pinion gear134. The pinion gear134, in turn drives a toothed rack136of the drive shaft124.

The motor130is coupled to the controller72such that the motor130may receive instructions therefrom. The controller72may be configured to receive instructions from an operator as when to advance or interrupt motion of the reciprocating member54. Alternatively, the controller72may include an algorithm to receive information from the electrodes50and sensors70,76(FIGS. 9 and 10) to determine an appropriate time to advance and interrupt motion of the reciprocating member54.

Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.