Abstract: An electrosurgical generator having a source of electrosurgical energy connected to a patient and including control circuitry for decreasing the output power from the source with increasing patient impedance, the rate of power decrease being substantially greater than that which would result if the output voltage from the source were maintained constant over the range of increasing patient impedance. The control circuitry may, in particular, decrease the output power over the range of increasing patient impedance in accordance with the square of the impedance.

Abstract: An IV filter and pump assembly having first and second bodies secured into a unitary assembly. The first and second bodies provide a chamber. One of the bodies has an opening therein in communication with said chamber and an inlet port therein. The other of the bodies has an outport therein. The inlet and outlet ports are in communication with the chamber. An inlet valve controls the flow of liquid through the inlet port and an outlet valve controls the flow of liquid through the outlet port. A hydrophobic filter is carried by the unitary assembly and is in communication with the upper portion of said chamber for venting to ambient small quantities of air in said chamber. An actuator supplies a pumping action to the liquid in the chamber so that liquid is caused to be moved out of the chamber through the outlet valve and into the chamber through the inlet valve.

Abstract: An electrosurgical generating system including an electrosurgical generator; a handpiece including an active electrode connected to the generator for applying electrosurgical current from the generator to a patient; and an initializing device or circuit for making an initial determination as to whether the handpiece includes power changing switches for changing the level of the output power delivered from the generator to the patient. Assuming the handpiece does include such switches, circuitry is also disclosed for limiting the amount the power can be increased or decreased from the handpiece. Also circuitry is disclosed for effecting the power increase or decrease in incremental steps.

Abstract: A flow monitor including an optical sensing chamber and an electronic controller which allows determination of exact drop volumes and flow rates. In one embodiment, the flow monitor forms part of a gravity fed volumetric controller in an IV system. In another embodiment, the flow monitor takes the form of a urinary output monitor in a urine collection system. Basically, the flow monitor comprises a microcontroller which responds to parametric information fed into the system through a keyboard and variable information detected by a novel drop diameter detector. The electronic controller, in response to the parametric and variable information being fed into it, is able to determine the precise volume of IV solution or urine passing through the respective systems. In the volumetric controller, the microcontroller causes a linear actuator to control the diameter of a flexible pinch tube found in the IV system. Under one mode of operation, the diameter of the pinch tube is regulated to control drop size.

Abstract: A return electrode monitoring system for use with a split patient return electrode having two, electrically isolated electrode elements adapted for contacting a patient, the system comprising means responsive to the impedance between the two electrode elements for producing a signal which is a function of the impedance; means for establishing a desired range having an upper limit and a lower limit for the impedance when the patient is in contact with the electrode elements; determining means responsive to the signal for determining whether the impedance is within the desired range; and adjusting means for adjusting the upper limit to adapt the system to the particular impedance of the patient in response to the particular impedance occurring within the desired range.

Abstract: A return electrode monitoring system for use with a patient return electrode adapted for contacting a patient, the return electrode having two, spaced apart conductors attached thereto for connecting the electrode to a generator of electrosurgical current which passes through the electrode, the system comprising means for applying a monitoring current through the conductors to the electrode; detecting means responsive to the monitoring current for producing a signal which is a function of the impedance between the two conductors, the detecting means including means for substantially eliminating any effect the electrosurgical current might have on the production of the signal when the generator is operational and the patient is in contact with the electrode; means for establishing a desired range having at least an upper limit for the impedance; and determining means responsive to the signal for determining whether the impedance is within the desired range.

Abstract: Cryosurgical apparatus for necrosing human tissue or the like, the apparatus comprising a coolant supply where coolant comprising nitrous oxide, carbon dioxide, Freon 13 or Freon 23 is disposed within a container as a liquid under its own vapor pressure; pressure elevating means for increasing the vapor pressure so that it is greater than what it would be at room temperature and for maintaining the elevated vapor pressure substantially constant; a cryosurgical instrument having a hollow tissue contacting portion and a coolant expansion means disposed at the distal end of a feed passageway and a discharge path disposed outside of the passageway; and means for supplying the coolant to the feed passageway of the cryosurgical instrument so that the temperature of the coolant discharged through the expansion means is lowered.

Abstract: An improved liquid pumping system wherein gas within the pump may be detected to indicate an error in desired flow rate or displaced volume. The system may be shut down if excessive gas is detected in the pump. Further, the flow rate may be corrected to the desired rate.

Abstract: A radio-frequency electrosurgical device which includes an active electrode, a passive electrode, and means for generating a radio-frequency potential. The generating means induces the radio-frequency potential on a primary winding of an isolation transformer. The secondary winding of the isolation transformer powers the active electrode. One end of the secondary winding of the isolation transformer is coupled to a return lead connected to the passive electrode and also is coupled to ground through a primary winding of a second transformer. If the passive electrode is disconnected from the return line, there can be an alternate radio-frequency current return path to ground, and a potential is developed across the primary winding of the second transformer. This potential is used to energize a relay to actuate an alarm and to disable the radio-frequency generator if the passive electrode becomes disconnected.

Abstract: A safety monitoring circuit for use in an electrosurgical unit is disclosed. The circuit is useful to indicate a fault in the return path between an RF source and a patient electrode in contact with a patient to prevent electrical burns to the patient that can occur due to improper patient contact with the patient electrode or a break in the return path. The circuit includes a current sensor connected in series in the return path to the RF source, which sensor provides an output indicative of the sensed current that is coupled through a DC amplifier to a comparator, the comparator providing an output only if a predetermined threshold is exceeded. When a comparator output is provided, a timer is triggered to energize, for a predetermined period of time, an alarm to indicate a sensed fault and/or actuate disabling circuitry to terminate application of electrical energy to the active electrode utilized in electrosurgery for cutting or coagulation.

Abstract: Patient contact area measurement method and apparatus including a first electroconductive contact element adapted for contact with the patient; a second electroconductive contact element separated from the first contact element and also adapted for contact with the patient; and measuring circuitry disposed between the first and second electroconductive contact elements for measuring the area of contact of the patient with respect to the contact elements. The electroconductive contact elements may comprise (a) each electrode of a split electrosurgical patient electrode, (b) the active and patient electrodes employed in electrosurgery or (c) a cryosurgical probe together with a monitor electrode adapted for contact with the patient.

Abstract: A combined electrosurgery/cautery system wherein a common heater/electrode element is employed to effect electrosurgical and cautery procedures.

Abstract: A multiple source electrosurgical generator wherein one of the sources may be optimized for desiccation of the patient's tissue, another source may be optimized for fulguration thereof and a third source may be optimized for cutting. All sources operate into a common output circuit and may be actuated either individually or in combination. The sources may also be operated in desiccate only, fulgurate only and cut only modes of operation. The different modes of operation may be selected from a hand-held electrosurgical instrument. An insulated, split patient electrode may be used with the generator where the operating frequency of the desiccate source may be higher than that of the fulgurate or cut sources. A spark detection circuit may also be employed (a) to ensure fulguration when the active electrode is a needle, (b) to prevent neuromuscular stimulation and (c) to ensure continuity of the patient circuit when fulgurating with low levels of current.

Abstract: An improved electrosurgical safety circuit where the currents in the active and patient leads are monitored, the monitored currents being respectively rectified and then subtracted from one another. Whenever the active current exceeds the patient or return current by an amount corresponding to a dynamically variable threshold, an appropriate measure is taken such as the sounding of an alarm and/or the de-energization of the electrosurgical generator. The dynamic threshold varies in accordance with the level of the signal applied to the patient and compensates for leakage current through stray capacitance from the active lead to ground.The patient lead is substantially grounded at radio frequencies through a frequency sensitive network. The frequency sensitive network may include a capacitor, the value of which is such as to provide the foregoing frequency response.

Abstract: An electrosurgical instrument comprising a support member; at least one electrode mounted on the support, the electrode consisting essentially of a material having a figure of merit of at least 0.15 at room temperature where the figure of merit is the product of the thermal conductivity, the heat capacity and the density of the material in the metric system; and a heat sink in thermal contact with the electrode for removal of heat therefrom. A carbon coating for the electrode is also disclosed where the coating may be formed by different techniques including thermal decomposition of certain carbohydrate containing materials, the latter method providing a porous carbon coating particularly suited for expediting the starting of the instrument. Also disclosed are a number of heat sinks for effecting removal of heat from the electrode. Further disclosed is a monolithic blade made from carbon.

Abstract: An electrosurgical method and apparatus for coagulating by fulguration where the electrical discharge is established through a formation of flowing inert gas where the formation may either be a diffuse blanket of the flowing gas or a well defined column thereof.

Abstract: A method and apparatus for initiating an electrical discharge in a formation of flowing inert gas disposed adjacent the end of an electrode by generating charged particles in the vicinity of said inert gas formation. The charged particles may be generated by various means such as an electron emissive filament, a radioactive material or an auxiliary electrical discharge located adjacent to the electrode but removed from the end thereof. The auxiliary electrical discharge may be in electrical series with the electrode and it may be located inside or outside the flow of inert gas needed to establish the gas formation at the end of the electrode.RELATED APPLICATIONSThis application is related to a first U.S. patent application Ser. No. 649,725 filed on Jan. 16, 1976 by Charles F. Morrison, Jr., Frank W. Harris, and Michael C. Patzer, entitled "Electrosurgical Method and Apparatus for Establishing an Electrical Discharge in an Inert Gas Flow" and a second U.S. patent application Ser. No. 649,682 filed on Jan.

Abstract: An electrosurgical device adapted for connection to an electrical generator having active and return output terminals, the device being used to cut, coagulate, or otherwise treat organic tissue or the like, the device comprising: an insulative support connectors; an active electrode responsive to the active output terminal and a return electrode responsive to the return output terminal, the electrodes being supported by the electrode support connectors, the return electrode being symmetrically disposed completely about the active electrode, the active electrode extending as far as or beyond the distal end of the return electrode, both the electrodes being adapted for electrical connection to the tissue, the ratio of the return electrode area adapted to electrically connect to the tissue to the active electrode area adapted to electrically connect to the tissue being in the range of approximately 2 to 200; and connectors for connecting the active electrode to the active output terminal and the return electrode

Abstract: An electrosurgical forceps including a switching member disposed on only one tine thereof where the switching member may be disposed on the outside of the tine to permit operation thereof independent of the closing of the forceps or where the switching member is disposed on the inside of the tine such that the electrical contacts thereof are provided with an electrically insulative covering. There are also provided unique circuit paths on the tines whereby the forceps may be operated in either a monopolar mode with or without switching or a bipolar mode with or without switching. Also disclosed is a spacer for separating the tines and a removable sleeve which snaps over the spacer to hold the tines in place. Further, there is disclosed a double molding method for constructing an electrosurgical forceps or the like.