Abstract: A gas delivery apparatus used in gas-assisted electrocoagulation temporarily reduces a gas flow rate in a flowpath to an application which applies the flow of gas and electrical energy to the tissue during an arc initiation sequence. The reduced gas flow rate enhances the arc initiation capabilities and reduces the possibilities of embolism. After the arc initiation sequence is complete, the gas flow rate returns to a greater rate used during electrocoagulation. The back pressure in the flowpath and a user requested flow rate are control variables used to reduce the flow rate upon the occurrence of back pressure-related conditions and to increase the flow rate after the dissipation of those back pressure conditions.

Abstract: Apparatus for monitoring the resistance of the return part of the patient circuit of either a dual foil or single foil return electrode according to a user's selection is disclosed. The apparatus measures the quality of the contact between the return electrode and the patient. A DC or AC converter provides a substantially DC voltage at its input that varies in relation to the resistance of the return part of the patient circuit at its AC output. Preferably, a constant current fed sinusoidal oscillator with a low pass filter at its DC output provides a substantially DC voltage related to the resistance at its AC input. An analog to digital converter converts the substantially DC voltage to a corresponding binary digital signal that is input to a programmed microprocessor. A manually operable set point switch coupled to the microprocessor is acatuated by the user which actuation establishes a resistance level with the pad (return electrode) in place on the patient.

Abstract: A drill includes a plurality of lips with enlarged portions at one end defining heads therefore. The heads form frusto-conical surfaces and cutting edges extend from the frusto-conical surfaces to remove chips. The cutting edges are limited in size with respect to the frusto-conical surfaces to control the removal of chips and a pocket behind each head readily receives the shavings to convey the latter away from the one end.

Abstract: This invention relates to a new control valve intended to be used to control the supply and exhaust of fluids to a dual tourniquet system. The tubes supplying and exhausting the tourniquets are of a flexible nature, and as such may be squeezed to stop the flow of fluids therethrough. The inventive valve includes cam members with camming projections formed thereon at various predetermined positions on the circumferences thereof. Simultaneous rotation of the cam members by a control knob results in sequential filling and emptying of the tourniquets in a predetermined sequence. The valve is especially useful in the practice of the Bier block procedure.

Abstract: This invention relates to an improved tourniquet cuff. The cuff is of the type which includes an inflatable member for wrapping about a body part, such that the inflatable member is secured to the body part, and at least one tube is provided to facilitate inflation of the inflatable member, with the inflatable member having a length dimension, and a width dimension. The inflatable member is formed in a substantially arcuate shape, with the radius of the arc passing along the width dimension. In the preferred embodiment, the inflatable member includes a bladder and a polyester reinforced backing, both of which have the arcuate shape. The invention also provides a set of tourniquet cuffs having the arcuate shape and in which the cuffs of the set nest one within the other. In the preferred embodiment, the inside radius of one cuff is equal to the outside radius of the next smaller size cuff.

Abstract: An electrosurgical unit having a power source, and an amplifier which includes a bipolar transistor and a FET in series with the amplifier load. In cut and blend modes, the power output of the unit is controlled by a variable voltage applied to the base terminal of the bipolar transistor. In coagulation, fulgration, and bipolar modes the power output is controlled by a variable duty cycle voltage applied to the gate terminal of the FET.

Abstract: An electrosurgical unit having feedforward power regulation. In one embodiment there is an amplifier which produces a pulse modulated electrosurgical output signal. A microprocessor calculates an adjusted pulse width (duty cycle) just sufficient to account for the power changes due to voltage fluctuations. The microprocessor controls the pulse width of the gate voltage of a power transistor in the amplifier to regulate the amplifier output. In another embodiment the supply voltage is fed into the base drive circuitry of an amplifier power transistor through the photo-resistor side of an optoisolator. The lamp brightness of the optoisolator and thus the gain of the base drive circuitry is adjusted by the amplifier power level control. The nonlinearity of the optoisolator complements the nonlinearity of the amplifier so that the net gain in the amplifier drive at any power setting is just sufficient to account for the voltage fluctuation.

Abstract: This invention relates to an improved fluid pump. The pump is of the type, wherein a reciprocating motor acts in concert with supply and exhaust valves to pump fluid from a source to its destination. In the preferred embodiment, the motor comprises a reciprocating diaphragm and the supply and exhaust valves comprise a single resilient plate with individual valve members formed as cutouts therein. The valve plate is sandwiched between two plates which form the associated porting. The interaction between the various ports on the valve plates results in improved sealing effect for the valves.

Abstract: An electrosurgical unit including voltage control circuitry which operates to limit the voltage at the electrosurgical electrodes when the unit is not in coagulation mode. The electrosurgical unit includes sensing circuitry for providing a signal representative of the voltage at the electrosurgical electrodes, a mode setting switch or dial for changing between a cut mode setting and a coagulation mode setting, a circuit for producing a mode signal, and an RF power generator responsive to the mode setting switch for providing a cut mode waveform at the electrode outputs when the mode setting switch is in cut mode and a coagulation mode waveform when the mode setting switch is in the coagulation mode setting. A voltage limiting circuit is responsive to the signal from the sensing circuitry and limits the voltage at the outputs when the electrosurgical unit in cut mode. Suppression circuitry responsive to the mode signal prevents the voltage limiting circuitry from operating in coagulation mode.

Abstract: A pneumatic tourniquet which automatically adjusts the pressure in the tourniquet cuff and in which the pressure adjustment is variable and depends on the sign and magnitude of the pressure error. There is an inflatable cuff, a motor and pump for inflating the cuff, a valve for deflating the cuff, a transducer for sensing the pressure in the cuff, and a switch for setting a desired cuff pressure. A microprocessor is responsive to signals from the transducer and switches to calculate a duty cycle related to the pressure error. The microprocessor periodically applies a signal to the motor or valve during the calculated duty cycle to provide an adjustment to cuff pressure related to pressure error. The microprocessor also is responsive to motor speed and accumulated error history to provide further adjustments to the pressure.

Abstract: An electrosurgical instrument which includes an inner, insulated, elongated switching core integrally molded about an elongated main contact wire which extends continually throughout the core and extends from both the proximal and distal ends of the core. An electrode blade is connected to the distally extending portion of the main contact wire. Two selectively operable electrical contact switches are easily mounted on the core in a longitudinally spaced apart relation. Two windows are provided in the core, each exposing a portion of the main contact wire. Each window is respectively positioned beneath a portion of each of the contact switches so that one or the other of the switches may be selectively moved into engagement with the main contact wire. One of the switches provides a suitable electrical cutting signal to the electrode blade when in contact with the main contact wire, while the other switch provides a suitable electrical coagulation signal to the blade when in contact with the main contact wire.

Abstract: An automatic tourniquet with an improved occlusion detector. A pump and valve for inflating and deflating a tourniquet cuff are connected to a first port. A pressure transducer for sensing the pressure in the cuff is connected to a second port. A pair of pressure differential switches, which activate an alarm when a pressure difference developes across them, are connected anti-parallelly between the pump/valve and the transducer. The differential switches also deactivate the pump/valve upon detection of an occlusion.

Abstract: An automatic tourniquet including a mechanism for inflating and deflating a cuff, a pressure sensing mechanism, and a mechanism for displaying the pressure. The pressure sensing mechanism includes a pressure transducer producing a pair of digital signals, and a mechanism for adjusting the signals so that the pressures at which the transitions between the digital quanta occur for one signal are different from the pressures at which the transitions occur for the other signal. The mechanism for adjusting includes a mechanism for setting the signals to be equal at a selected pressure, and a mechanism for offsetting the signals from each other by a voltage corresponding to one-half a digital quantum. The offset signals are summed by a microprocessor to produce a display with twice the resolution of the individual signals.