Intelligent selection system for electrosurgical instrument

#Electrosurgical instruments are well known and widely used in the medical, dental, and veterinarian fields. They offer the capability of precision cutting and coagulation with electrosurgical currents preferably in the megacycle range using a handpiece with, for example, needle, ball, or loop electrodes in a unipolar operating mode or with a forceps in a bipolar operating mode. Ellman International, Inc. makes available an electrosurgical instrument for Radiosurgery which provides on its front panel connectors for receiving the plug of a cable-connected unipolar handpiece and a ground or indifferent plate, as well as connectors for receiving the plug of a cable-connected bipolar electrode. One form of such an instrument is described in U.S. Pat. No. 5,954,686, whose contents are incorporated herein by reference. Such instruments are characterized by different modes and sub-modes of operation. For example, the instrument described in the patent, which is typical of other similar instruments, has a cutting mode, separable into CUT and CUT/COAG sub-modes, and a coagulation mode, separable into HEMO, FULGURATE, and BIPOLAR sub-modes.

#In a typical surgical setting using such an instrument, a surgeon may first use a handpiece while the instrument is in its cutting mode to perform a desired cutting procedure and then desire to use the same handpiece for coagulation of blood vessels while the instrument is in its coagulation mode. To this end, the electrosurgical instrument has on its front panel push buttons or switches for activating internal circuitry for switching the electrosurgical instrument from its cutting to its coagulation mode or vice-versa. A current electrosurgical instrument contains a power-supply-controlled radio-frequency (RF) oscillator which generates RF currents typically in the megacycle range as high-frequency AC waves. For most cutting purposes, the AC waveform is fully filtered to produce an approximate DC waveform. For most coagulation purposes, the AC waveform is partially rectified (commonly half-wave rectification) to produce the characteristic half-wave rectified waveform. This is accomplished by switching in certain rectifier and filter components for the cutting mode, and switching in certain rectifier components for the coagulation mode. This is well known in the art and further description is unnecessary. Suffice to say, the switching action occurs inside the instrument when the front panel controls are activated by the surgeon.

#To simplify mode selection by the surgeon, it is known to place on the handpiece two finger-activated switches that can be connected by appropriate wiring to the electrosurgical instrument and wired in parallel with the front panel switches so that activation of either the finger switches on the handpiece or the front panel switches will allow mode selection. This is similar to the connection and operation of a foot switch that can be used by the surgeon to activate and deactivate the RF currents. More modern electrosurgical instruments, however, do not lend themselves to such a simple approach. The typical modern electrosurgical instrument is computer-controlled, typically by a microcontroller (μC); hence simple parallel-connected circuitry may not work satisfactorily. Another problem is that the standard handpiece has only three terminals, one of which is dedicated to carrying the high-frequency or RF electrosurgical currents; hence, mode selection must be carried out in a safe manner using only two of the three terminals.

#In the drawings:

#FIG. 1 is a schematic view of one form of electrosurgical instrument in accordance with the invention;

#FIG. 2 is a circuit block diagram of one form of system circuitry for the electrosurgical instrument of FIG. 1;

#One form of an electrosurgical instrument 10 according to the invention is illustrated in FIG. 1. It comprises a system unit 12 having a box-like housing comprising at the front a control panel 14 for the instrument. The control panel includes touch switches 90 for selecting cutting or coagulation modes and touch switches 18 for controlling the power output by increasing or decreasing in steps the power, as indicated by upper and lower digital displays showing all 8's. At the bottom are output female connectors 20, 22, 24 for plugging in, respectively, at the left, a fingerswitch-controlled unipolar handpiece 26; at the center, a bipolar handpiece or forceps 28; and at the right a single or split neutral plate 30. An on-off power switch 32 is at the far right. The circuitry used to provide a fingerswitch-controlled unipolar handpiece may be of the type described in connection with the control unit 50 of U.S. Pat. No. 4,463,759, whose contents are herein incorporated by reference, which circuitry is in this case incorporated in the console unit 12. A connector (not shown) is provided at the side for receiving a conventional footswitch 34. Both the unipolar and bipolar handpieces can be simultaneously connected to the system unit 12 and operated in any order without touching the system unit or the control panel when the control panel has been preset or activated at the desired powers by each of the handpieces. For example, if the surgeon determines that s/he is going to perform a cutting procedure with a particular electrode, then s/he can set the cutting mode power on the upper digital display to, say, 80 watts by the up/down buttons 18. (Typically, these units are designed to supply up to 100 watts of RF power to either handpiece.) For coagulation with the bipolar handpiece, s/he may desire to use, say, 50 watts, which can also be set on the lower digital display by the up/down buttons 18. In this first embodiment, the internal circuitry is controlled in a known manner so that, when the fingerswitch unipolar handpiece is used, then RF power can be supplied to the electrode in the unipolar handpiece when a fingerswitch 36 on the handpiece 26 is depressed. However, when it is desired to use the bipolar handpiece 28, then the footswitch 34 is depressed, which then supplies RF power to the forceps of the bipolar handpiece. This result is a consequence of software control such that, while the machine mode is selected such that the fingerswitches on the unipolar handpiece can be used to apply power to the electrode (footswitch mode non-selected), only the footswitch can be used to apply power to the bipolar handpiece. This prevents power selected for the unipolar handpiece to be applied to the bipolar handpiece, and vice-versa. On the other hand, when it is not intended to use the bipolar handpiece and the footswitch mode is selected, then the footswitch can be used to operate the unipolar handpiece.

#One form of the RF circuitry to achieve the foregoing operation is illustrated in the block diagram of FIG. 2. The block 40 in the upper left contains two independent conventional RF oscillators generating, preferably, RF oscillations at 8.0 and 3.42 MHz respectively. As will be explained in greater detail below, the arrow 42 labelled CPU represents a selection signal generated by a conventional microcontroller under software control and inputted into the block 40 to select for operation either the 8.0 MHz oscillator or the 3.42 MHz oscillator. Both oscillators are constantly on when the power switch is activated, and the CPU selection 42 determines which of the third or fourth frequencies are outputted to the divide-by-2 block 44, resulting in an RF carrier 46 at either the first (4.0 MHz) or the second (1.71 MHz) frequency. That carrier is then pre-amplified in block 48 and inputted to a conventional modulator stage 50. Also input to the modulator stage is a modulating signal 52 derived from a CPU selection signal 54 and a D/A converter 56. The modulations referred to are the different output waveforms used for the known CUT, CUT/COAG, HEMO, and FULGURATE modes. These typically are: CUT-CW (full-wave rectified and filtered) output with maximum average power; CUT/COAG-full-wave rectified but unfiltered, deeply modulated, at 37.5 or 75 Hz rate, envelope with approximately 70% average to peak power ratio; HEMO-half-wave rectified and unfiltered, deeply modulated, at 37.5 or 75 Hz rate, envelope with approximately 35% average to peak power ratio; FULGURATE (or Spark-Gap Wave)-deeply modulated, 3.6 KPPS random rate with approximately 20% average to peak power ratio. Selection of the bipolar mode will automatically select the HEMO mode.

#The RF power generating circuitry may be of the well known tube-type described in U.S. Pat. No. 3,730,188, whose contents are herein incorporated by reference, which is capable of generating a fully-rectified, filtered RF current for cutting, a full-wave rectified current for combining cutting and coagulation, and a half-wave rectified current for coagulation. Alternatively, the RF power generating circuitry can be of the well-known solid-state type capable of generating the same kinds of waveforms. The RF circuitry, as such, is not part of the present invention, as such circuits are well-known in the prior art. In this case, the RF circuitry provides two different frequencies of operation, a first high frequency in the range of 3.84.0 MHz, and a second high frequency in the range of 1.7-2.0 MHz, which is easily obtained by providing a known RF generator that provides a first and second outputs at the first and second higher frequencies and providing a simple known divide-by-two circuit for obtaining a second output at one half of the first or second frequency. Both outputs can be separately amplified and processed and made available at the console's output connectors depending on the switches activated. The present invention is not limited to the dual-frequency output operation.