Electrosurgical apparatus with retractable blade

1. An electrosurgical apparatus comprising:

a housing having a passage extending therethrough, the housing having a proximal end and a distal end;

an electrically conducting tube having a proximal end and a distal end, the electrically conducting tube being disposed in the passage of the housing;

an insulating outer tube having a proximal end and a distal end, the outer tube disposed around the electrically conducting tube with the proximal end of the outer tube coupled to the distal end of the housing, the electrically conducting tube being movable along a longitudinal axis of the housing and outer tube; and

an electrically conducting blade coupled to the distal end of the electrically conducting tube, wherein in a first position of the electrically conducting tube, the blade extends beyond the distal end of the outer tube for mechanical cutting and, in a second position of the electrically conducting tube, the blade is retracted within the outer tube and is energized via the electrically conducting tube to form plasma when an inert gas flows through the electrically conducting tube,

wherein the electrically conducting tube includes:

a first, inner flow tube having a proximal end and a distal end;

a second, outer flow tube having a proximal end and a distal end; and

a cylindrical insulator disposed around the distal end of the first, inner flow tube for coupling the first, inner flow tube to an inner portion of the proximal end of the second, outer flow tube,

wherein an overlapping portion of the first, inner flow tube, the cylindrical insulator and the second, outer flow tube forms a structural current limiting capacitor to limit current applied to an operative site when the electrically conducting tube is energized and at least one of the first, inner flow tube and second, outer flow tube is movable relative to each other to varying a capacitance value of the structural Cu ent limiting capacitor.

2. The electrosurgical apparatus of claim 1 , further comprising a first slider member coupled to the first, inner flow tube for variably setting a current limit of the capacitor, the first slider member being accessible on the housing.

3. The electrosurgical apparatus of claim 2 , further comprising a second slider member coupled to the second, outer flow tube for extending and retracting the blade, the second slider member being accessible on the housing.

4. The electrosurgical apparatus of claim 3 , wherein the second slider member includes a ratchet mechanism for incrementally moving the blade.

5. The electrosurgical apparatus of claim 1 , further comprising a transformer disposed on the proximal end of the housing, the transformer coupled to the electrically conducting tube for providing electrosurgical energy thereto.

6. The electrosurgical apparatus of claim 5 , further comprising a button disposed on the housing and coupled to an output of the transformer for activating and deactivating the electrosurgical energy to the electrically conducting tube.

7. The electrosurgical apparatus of claim 1 , wherein the electrically conducting blade is generally planar and is coupled to an inner circumference of the electrically conducting tube.

8. The electrosurgical apparatus of claim 1 , wherein the electrically conducting tube and the insulating outer tube are configured to articulate at their respective distal ends.

9. The electrosurgical apparatus of claim 8 , wherein the electrically conducting tube is configured from a conductive mesh.

10. The electrosurgical apparatus of claim 8 , wherein the electrically conducting blade is configured from a flexible material to articulate with the electrically conducting tube and the insulating outer tube.

11. The electrosurgical apparatus of claim 8 , wherein the electrically conducting blade is configured from at least two linked members to articulate with the electrically conducting tube and the insulating outer tube.