In an electrosurgical generator for generating radio frequency power, the generator includes a radio frequency output stage having two or more output connections, and a power supply coupled to the output stage for supplying power to the output stage. A controller is operable to cause the generator to supply a blended output signal alternating constantly between a first output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to at least a first predetermined threshold value for cutting or vaporisation of tissue, and a second output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to a second threshold value for coagulation. There is also provided adjustment means, operable by a user of the electrosurgical generator, for changing between various preset settings for the blended signal, the preset settings each having a predetermined duty cycle of the blended signal that is limited to the first threshold value for cutting or vaporisation, and a predetermined duty cycle of the blended signal that is limited to the second threshold value for coagulation.

Electrosurgical generator and system

An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes fully desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

Electrosurgical generator with adaptive power control

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 conductive-resistive matrix of a conductively-doped non-conductive elastomer. The engagement surface portions thus can be described as a positive temperature coefficient material that has a unique selected decreased electrical conductance at each selected increased temperature thereof over a targeted treatment range. The conductive-resistive matrix 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 conductive-resistive matrix can induce a “wave” of Rf energy density to sweep across the tissue to thereby weld tissue.

Electrosurgical instrument and method of use

An electrosurgical working end for automatic modulation of active Rf density in a targeted tissue volume. The working end of the probe of the present invention defines a tissue-engagement surface of an elastomeric material with conductive elements that extend therethrough. In one embodiment, the expansion of the elastomeric material can de-couple the conductive elements from an interior electrode based temperature to modulate current flow. In another embodiment, the elastomeric material can couple and de-couple the conductive elements from an interior electrode based engagement pressure to modulate current flow.

Electrosurgical working end for controlled energy delivery

A working end of a surgical instrument that carries first and second jaws for delivering energy to tissue. In a preferred embodiment, at least one jaw of the working end defines a tissue-engagement plane that contacts the targeted tissue. The cross-section of the engagement plane reveals that it defines a surface conductive portion that overlies a variably resistive matrix of a temperature-sensitive resistive material or a pressure-sensitive resistive material. An interior of the jaw carries a conductive material or electrode that is coupled to an Rf source and controller. In an exemplary embodiment, the variably resistive matrix can comprise a positive temperature coefficient (PTC) material, such as a ceramic, that is engineered to exhibit a dramatically increasing resistance (i.e., several orders of magnitude) above a specific temperature of the material. In use, the engagement plane will apply active Rf energy to captured tissue until the point in time that the variably resistive matrix is heated to its selected switching range. Thereafter, current flow from the conductive electrode through the engagement surface will be terminated due to the exponential increase in the resistance of variably resistive matrix to provide instant and automatic reduction of Rf energy application. Further, the variably resistive matrix can effectively function as a resistive electrode to thereafter conduct thermal energy to the engaged tissue volume. Thus, the jaw structure can automatically modulate the application of energy to tissue between active Rf heating and passive conductive heating of captured tissue to maintain a target temperature level.

Electrosurgical jaw structure for controlled energy delivery

A high frequency AC electro-surgery apparatus is equipped with an automatic regulation loop for controlling the output voltage (Ua) rather than the output power. An electrically isolating coupling in the form of an isolation transformer (5) is followed by a voltage converter (6) to provide DC voltage signal (a) proportional to a measure of the high frequency AC output voltage (Ua). The DC voltage signal (a) is supplied to a regulating amplifier (7) to which a reference voltage signal (b) is supplied by a reference voltage source (8), to produce an output signal (c) that is furnished to the control input of an electronically controlled power supply (16). The latter controls the operating voltage (Ub) for the amplifier (2) of the high frequency AC generator in such a manner that the output AC voltage (Ua) at the output terminals (10, 11) corresponds to a desired value set by the reference voltage signal (b).

Farin Guenter

Papers

High frequency surgery device for cutting and/or coagulating biologic tissue

High frequence surgical device to cut and/or coagulate biological tissues.