Electrosurgical instrument and method of use
An electrosurgical medical device and method for creating thermal welds in engaged tissue. In one embodiment, at least one jaw of the instrument defines a tissue engagement plane carrying a variable resistive body of a positive temperature coefficient material that has a selected decreased electrical conductance at each selected increased temperature thereof over a targeted treatment range. The variable resistive body can be engineered to bracket a targeted thermal treatment range, for example about 60° C. to 80° C., at which tissue welding can be accomplished. In one mode of operation, the engagement plane will automatically modulate and spatially localize ohmic heating within the engaged tissue from Rf energy application across micron-scale portions of the engagement surface. In another mode of operation, a variable resistive body will focus conductive heating in a selected portion of the engagement surface.
1. A bi-polar electrosurgical jaw structure comprising:
first and second openable-closeable jaws with first and second tissue-engaging surfaces, respectively;
first and second opposing polarity bi-polar electrodes in the first and second tissue-engaging surfaces, respectively, the bi-polar electrodes configured to be coupled to a radiofrequency source; and
at least one jaw surface including a positive temperature coefficient of resistance body in contact with a bi-polar electrode for interacting with ohmically heated tissue and for modulating Rf current flow in engaged tissue.
2. The bi-polar electrosurgical jaw structure of claim 1 , wherein the first tissue-engaging surface includes a positive temperature coefficient of resistance body that at least partly surrounds a bi-polar electrode.
3. The bi-polar electrosurgical jaw structure of claim 1 , wherein the first tissue-engaging surface includes first and second opposing polarity bi-polar electrodes.
4. A bi-polar electrosurgical jaw structure, comprising:
first and second openable-closeable jaws with first and second tissue-engaging surfaces, respectively;
a first positive temperature coefficient of resistance body in the first tissue-engaging surface, the body configured to be operatively connected to a first pole of a radiofrequency source; and
a second positive temperature coefficient of resistance body in the second tissue-engaging surface configured to be operatively connected to a second opposing pole of the radiofrequency source wherein the opposing polarity positive temperature coefficient of resistance bodies modulate bi-polar current flow in tissue to cause ohmic heating therein and to prevent arcing.
5. The bi-polar electrosurgical jaw structure of claim 4 , wherein the positive temperature coefficient of resistance bodies modulate bipolar current flow in tissue to maintain a level of hydration within an engaged tissue volume.
6. The bi-polar electrosurgical jaw structure of claim 4 , wherein the jaws apply sufficient force to engaged tissue to prevent an arc producing gap.
7. The bi-polar electrosurgical jaw structure of claim 4 , wherein the jaws apply sufficient force to engaged tissue to cause uniform protein denaturation by the ohmic heating.
8. The bi-polar electrosurgical jaw structure of claim 4 , wherein the jaws apply sufficient force to engaged tissue to cause a tissue weld by uniform cross-linking upon thermal relaxation.