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 that carries a recessed central portion. In another embodiment, the controller coupled to the Rf source is adapted to switch from a power control operational mode to a voltage controlled operational mode at a selected transition impedance level.
1. An electrosurgical jaw structure for delivering energy to engaged tissue, the structure comprising: first and second openable-closeable jaw members, at least one jaw member defining a first peripheral portion and a second central portion wherein the second portion is recessed relative to the first portion; at least one jaw carrying a conductive material comprising a positive temperature coefficient material, the a positive temperature coefficient material capable of conducting current to engaged tissue; and an Rf source operatively coupled to the conductive material.
2. The electrosurgical jaw structure of claim 1 , wherein the second portion is recessed relative to the first portion by at least about 0.0005 inch.
3. The electrosurgical jaw structure of claim 1 , wherein the second portion is recessed relative to the first portion by between about 0.0005 inch and 0.020 inch.
4. The electrosurgical jaw structure of claim 1 , wherein the second portion is recessed relative to the first portion by between about 0.001 inch and 0.010 inch.
5. The electrosurgical jaw structure of claim 1 , wherein the second portion is recessed relative to the first portion by between about 0.003 inch and 0.007 inch.
6. The electrosurgical jaw structure of claim 1 , wherein the conductive material is carried in the second portion.
7. The electrosurgical jaw structure of claim 1 , wherein the conductive material comprises at least in part a positive temperature coefficient material, wherein the a positive temperature coefficient material is disposed beneath a jaw surface.
8. An electrosurgical jaw structure for delivering energy to engaged tissue, the structure comprising: first and second paired jaw members each defining a respective surface engagement plane for contacting tissue, the paired jaw members moveable between an open and closed position; the paired jaw members defining a peripheral portion and a central portion; wherein the paired jaw members in the closed position define an engagement gap between respective engagement planes that has a first dimension in the peripheral portion and a second dimension in the central portion, and wherein said second dimension is greater than said first dimension, wherein a portion of at least of one the jaw members comprises a positive temperature coefficient material, the a positive temperature coefficient material capable of conducting current to engaged tissue.
9. The electrosurgical jaw structure of claim 8 , wherein the difference between said first and second dimensions is at least about 0.0005 inch.
10. The electrosurgical jaw structure of claim 8 , wherein the difference between said first and second dimensions is at least about 0.001 inch.
11. The electrosurgical jaw structure of claim 8 , wherein the difference between said first and second dimensions is at least about 0.003 inch.
12. The electrosurgical jaw structure of claim 8 , wherein said second dimensions is at least about 110% of said first dimension.
13. The electrosurgical jaw structure of claim 2 , wherein the recessed portion is configured to form a seal against engaged tissue to trap vapor and liquids to denature protein within tissue proximate the recessed portion.
14. The electrosurgical jaw structure of claim 8 , wherein the central portion is configured to form a seal against engaged tissue to trap vapor and liquids to denature protein within tissue proximate the recessed portion.
15. The electrosurgical jaw structure of claim 8 , wherein the engagement gap is sufficient to trap vapor and liquids to denature protein within tissue proximate the central portion.