Patent ID: 7022115

Claim:
A cannula assembly for anesthesia comprising: a flexible catheter inside; an electrically conductive rigid hollow tube ( 10 ) the hollow tube formed by a steel tube including a proximal end and a distal end, the distal end including a sharp tip ( 14 ) and an exit opening in the area of the sharp tip ( 14 ) dimensioned for passage of the catheter, a body part ( 18 ) provided at the proximal end of the hollow tube ( 10 ), the body part ( 18 ) including an inlet opening ( 32 , 34 ) axially aligned with the hollow tube ( 10 ) adapted for guiding the catheter for introduction into the proximal end of the hollow tube ( 10 ), and a connector ( 22 , 24 , 26 ) electrically connected to the hollow tube ( 10 ) in the area of the cannula body part ( 18 ) for transmission of electro-stimulation, wherein said hollow tube ( 10 ) has an electrically insulated outer covering extending from the body part ( 18 ) out to the sharp tip ( 14 ) and which leaves the sharp tip ( 14 ) exposed at least in its distal end area ( 16 ), and wherein said electrical connector ( 24 , 26 ) extends through the body part ( 18 ) to the outer surface of the hollow tube ( 10 ) wherein the cannula is assembly unipolar.