Abstract: A hybrid cannula having first and second passages extending along its length, the first passage to transport liquid to be injected into a patient and the second passage to hold an electric wire. The cannula is formed by at least two concentric metal tubes. The liquid passage extends through the inner tube, while the wire passage extends through either the outer surface of the inner tube or through a middle tube, such that the outer periphery of the wire passage is always covered by the metal wall of the outer tube. Thus, the wire can be inserted without difficulty through the second passage and does not contact the insulation layer. This allows formation of the insulation layer with a smooth outer surface.

Abstract: A cannula having a hollow metal tube for injection of liquids such as an anesthetic, or RF energy, into a patient. A thermocouple or other temperature sensor is located at the bare tip of the cannula, and a wire for the temperature sensor extends along the length of the cannula, preferably in a groove formed in the tube, or through a passageway formed in the tube. An outer insulation layer covers the tube and wire. Thus, a single device serves as both a cannula and an electrode.