Apparatus and method for regulating tissue welder jaws

Abstract

A surgical apparatus and methods for severing and welding tissue, in particular blood vessels. The apparatus includes an elongated shaft having a pair of relatively movable jaws at a distal end thereof. A first heating element on one of the jaws is adapted to heat up to a first temperature and form a welded region within the tissue, while a second heating element on one of the jaws is adapted to heat up to a second temperature and sever the tissue within the welded region. The first and second heating elements may be provided on the same or opposite jaws. A control handle provided on the proximal end of the elongated shaft includes controls for opening and closing the jaws, and may include an actuator for sending current through the first and second heating elements. The first and second heating elements may be electrically connected in series, and the first heating element may be bifurcated such that it conducts about one half of the current as the second heating element. A force-limiting mechanism provided either within the control handle, in the elongated shaft, or at the jaws limits the pressure applied to the tissue by the jaws to ensure that the tissue is severed and the ends effectively welded within a short amount of time.

1 . A surgical apparatus for welding and severing tissue, comprising:
 first and second relatively movable elongated jaws having facing surfaces;   an elongated shaft having the first and second relatively movable jaws attached to a distal end thereof;   at least one heating element provided on the facing surface of one of the first or second jaws;   a control handle connected to the elongated shaft; a control actuator for alternately separating and bringing together the facing surfaces of the elongated jaws; and   a force-limiting mechanism interposed between the control actuator and the jaws adapted to regulate the magnitude of closing force of the jaws to between about 1-3 lbs (0.45-1.36 kg) to ensure the heating element effectively welds and severs tissue held within the facing surfaces of the closed elongated jaws.   
     
     
         2 . The apparatus of  claim 1 , further including a second heating element provided on the facing surface of one of the first or second jaws, wherein the first heating element is adapted to weld tissue and the second heating element is adapted to sever tissue. 
     
     
         3 . The apparatus of  claim 1 , further including a control rod extending from the control handle to the distal end of the elongated shaft and connected to translate movement of the control actuator into movement of the jaws, the force-limiting mechanism comprising a spring mounted coaxially on the control rod. 
     
     
         4 . The apparatus of  claim 3 , wherein the spring is located within the elongated shaft. 
     
     
         5 . The apparatus of  claim 4 , wherein the spring comprises a portion of the control rod. 
     
     
         6 . The apparatus of  claim 4 , wherein the control rod is a hollow tube and the spring portion of the hollow tube is formed into a helix. 
     
     
         7 . The apparatus of  claim 3 , further including a second spring mounted coaxially on the control rod and being arranged such that deformation of the first and second springs does not occur simultaneously upon closing of the jaws. 
     
     
         8 . The apparatus of  claim 1 , wherein the force-limiting mechanism comprises a spring located within the control handle. 
     
     
         9 . The apparatus of  claim 8 , further including a control rod extending from the control handle to the distal end of the elongated shaft and connected to translate movement of the control actuator into movement of the jaws, wherein the control actuator comprises a toggle journalled to pivot in two directions and accordingly displace the control rod in opposite directions, and wherein the spring is arranged to affect relative movement of the toggle and the control rod in one direction of pivot of the toggle. 
     
     
         10 . The apparatus of  claim 8 , further including a control rod extending from the control handle to the distal end of the elongated shaft and connected to translate movement of the control actuator into movement of the jaws, wherein the control actuator comprises a toggle journalled to pivot in two directions and connected to displace the control rod in opposite directions, and wherein the force-limiting mechanism comprises a ball-detent structure arranged to decouple relative movement of the toggle and the control rod in one direction of pivot of the toggle at a predetermined reaction force transmitted through the control rod from closing of the jaws. 
     
     
         11 . The apparatus of  claim 1 , wherein the force-limiting mechanism comprises an elastic member incorporated within the jaws. 
     
     
         12 . The apparatus of  claim 11 , wherein the elastic member is adapted to change shape at elevated temperatures. 
     
     
         13 . The apparatus of  claim 11 , wherein the elastic member comprises a compliant layer on at least one of the jaws. 
     
     
         14 . The apparatus of  claim 11 , wherein proximal ends of the jaws are mounted for pivoting movement on the end of the elongated shaft, and wherein the elastic member comprises a spring positioned between the proximal ends of two jaws which permits the proximal ends to separate at a predetermined force impeding further closing movement of the jaws. 
     
     
         15 . (canceled) 
     
     
         16 . A surgical apparatus for welding and severing tissue, comprising:
 first and second relatively movable elongated jaws having facing surfaces;   an elongated shaft having the first and second relatively movable jaws attached to a distal end thereof;   at least one heating element provided on the facing surface of one of the first or second jaws;   a control handle connected to the elongated shaft;   a control actuator for alternately separating and bringing together the facing surfaces of the elongated jaws; and   a force-limiting mechanism interposed between the control actuator and the jaws adapted to regulate the magnitude of closing force of the jaws so that the heating element effectively welds and severs tissue held within the facing surfaces of the closed elongated jaws within a time flame of 5 seconds or less.   
     
     
         17 . A surgical method of severing a target tissue while welding the severed ends, comprising:
 providing a surgical apparatus for severing and welding tissue including a pair of jaws having facing surfaces adapted to open and close upon the target tissue, at least one of the jaws including an electrically-resistive heating element on its facing surface;   closing the jaws upon a target tissue;   limiting the magnitude of closing force of the jaws to a value calibrated to ensure the heating element effectively severs and welds tissue held within the facing surfaces of the jaws within a time frame of about 5 seconds or less; and   electrically energizing the first heating element to form a welded region in the target tissue and sever the target tissue within the welded region.   
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . A surgical apparatus for welding tissue, comprising:
 an elongated shaft having a means for cauterizing tissue attached to a distal end thereof, the shaft having an internal channel along its length for passage of gas;   a control handle connected to the elongated shaft; and   a passive filter mounted within the control handle and positioned to intercept gas passing in a proximal direction through the channel of the elongated shaft so as to filter the gas before it is released to the interior of the control handle or the environment.   
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . The apparatus of  claim 23 , wherein the elongated shaft has at least one port formed therein within the control handle open to the internal channel, and wherein the passive filter comprises a hollow permeable member arranged around the elongated shaft at the port. 
     
     
         27 . The apparatus of  claim 26 , wherein the passive filter comprises a tubular member sealed at both ends around the elongated shaft and having an enlarged hollow cavity therein adjacent to which the port vents. 
     
     
         28 . The apparatus of  claim 23 , further including means for insufflating a body cavity such that a positive pressure within the body cavity forces gas in a proximal direction through the internal channel of the elongated shaft.