Surgery – Instruments – Electrical application
Reexamination Certificate
2000-03-13
2003-12-16
Mulcahy, John (Department: 3739)
Surgery
Instruments
Electrical application
C606S037000, C606S042000
Reexamination Certificate
active
06663623
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric surgical operation apparatus and more specifically to an electric surgical operation apparatus which lets a high-frequency current flow through organic tissue to make treatments such as cutting, coagulation, and the like of organic tissue by heat generated by the high-frequency current.
An electric surgical operation apparatus is used generally in surgical operations to make treatments such as cutting, coagulation or the like on organic tissue by letting a high-frequency current flow through organic tissue. This kind of electric surgical operation apparatus comprises an electric surgical operation apparatus body, a treatment tool having an active electrode, and a feedback electrode which is let contact the body surface of a patient.
Further, a high-frequency power is generated from the electric surgical operation apparatus body, and the active electrode is brought into contact with a treating portion to let a high-frequency current concentrically through organic tissue. The high-frequency current is collected diffusely by the feedback electrode, and treatments such as cutting, coagulation, and the like of organic tissue can thereby be achieved.
In this kind of electric surgical operation apparatus, the time from turning-on of an output switch to appearance of a cutting or coagulation effect (which will be hereinafter called a rising time) is shortened to improve sharpness of cutting, shortening of the treating time, and the safety. That is, in a conventional apparatus as shown in
FIG. 1
, to shorten the rising time, a larger power (e.g., P
0
) than a setting value (e.g., 30 W) is supplied for a predetermined time period by a time point t
0
when a fixed delay time has elapsed after a time point when an output switch was turned on, and the setting power is supplied after the time point t
0
.
Meanwhile, in an electric surgical operation apparatus, various kinds of active electrodes to be provided at the top ends of the treatment tools are prepared in compliance with applications.
FIGS. 2A
,
2
B and
2
C show examples of active electrodes, more precisely a loop electrode a band electrode and a grooved roller electrode.
These electrodes have different volumes depending on their shapes. Therefore, even if an equal high-frequency current is supplied from an electric surgical operation apparatus body, the current density differs between electrodes, at the treating portion. That is, if an equal high-frequency current is used, a loop electrode
2
having a small volume attains the highest current density (which means that heat is easily generated), and a band electrode
4
and a grooved roller electrode
6
respectively attain the second and third highest current densities.
Then, as shown in
FIG. 3
, if an equal high-frequency power is used, the resistance of tissue rises in different ways among the loop electrode shown at a in the figure, the band electrode at b, and the grooved roller electrode at c, thereby causing differences. As a result of this, as described previously, for example, the loop electrode
2
may generate heat sufficient to achieve performance (e.g., denaturation of organic tissue) while the grooved roller electrode
6
cannot generate enough heat to attain sufficient performance, if a larger power than a present value is supplied for a predetermined time period after the output switch is turned on in order to hasten the rising.
Also, Japanese Patent Application KOKAI Publication No. 9-56725 discloses a high-frequency electronic knife apparatus which comprises an operation panel, a control circuit for controlling the entire apparatus based on the contents of an operation through the operation panel, a waveform generator circuit for generating a waveform corresponding to an output mode by receiving a waveform selection signal corresponding to the output mode from the control circuit, a switching circuit which is driven and turned on/off according to the waveform from the waveform control circuit, a variable power source circuit which generates a DC (direct current) power set under control by the control circuit, and a resonance circuit which causes the DC power of the variable power source circuit to resonate by driving the switching circuit thereby to generate a high-frequency power, wherein the control circuit controls the output timing of the high-frequency waveform from the waveform generator circuit.
In the high-frequency electric knife apparatus described in the above publication No. 9-56725, various outputs can be obtained by changing the drive waveform for the switching circuit. Also, the control signal for a switching element of the resonance circuit is switched merely according to the output mode but does not depend on the status of loads.
Meanwhile, the waveforms generated by the waveform generator circuit, e.g., the waveforms in a cutting mode, mixed mode, and coagulation mode use signals having fixed duties. In view of construction of the resonance circuit, for example, if switching is sequentially carried out as in the cutting mode and if the duty is fixed, the voltage supplied to the resonance circuit must be increased to increase the output.
However, if the control signal for switching has a small duty as in the high-frequency electric knife apparatus described in the above publication No. 9-56725, the power source supplied to the resonance circuit requires a power source of a considerably high voltage. A problem hence appears in that the power source must have a large size so that the apparatus itself also must have a large size or an expensive power source is required. In addition, if the supplied voltage is high, there is a problem that a high-frequency leakage current is caused.
Further, Japanese Patent Application KOKAI Publication No. 7-79996 discloses a tissue cutting apparatus comprising a source which supplies cutting energy, an electrode means which is connected to the supply source and discharges energy at a cutting voltage, a current monitor means which measures a current transferred to the electrode means and generates a measured current signal, a voltage monitor means which measures a voltage in the electrode means and generates a measured voltage signal, and a control means which performs predetermined functions based on measured tissue impedance.
This tissue cutting apparatus measures a current transferred to the electrode part and generates a measured current signal. This apparatus also measures a voltage at the electrode part and generates a measured voltage signal. Further, the measured voltage signal is divided by the measured current signal, to obtain a measured tissue impedance signal.
The tissue cutting apparatus described in the above publication No. 7-79996 includes a current sensor and a voltage sensor and further requires an calculation circuit for dividing a measured voltage signal by a measured current signal. Also, in this kind of tissue cutting apparatus or an electric surgical operation apparatus, a treatment on tissue is completed normally in a short time period of several tens to several hundreds sec., and therefore, a high-speed calculation circuit is required.
Meanwhile, necessities for a sensor and a calculation circuit as described above result in a complicated structure of the apparatus and increase of costs.
BRIEF SUMMARY OF THE INVENTION
Hence, the present invention has an object of providing an electric surgical operation apparatus capable of easily and securely shortening the rising time required till a cutting effect and a coagulation effect appear so that the cutting sharpness is improve, the operation time is shortened, and the safety is improved, without complicating the structure of the apparatus or increasing costs, even if electrodes having different volumes or different surface areas are used for an operation tool.
That is, a first object of the present invention is to provide an electric surgical operation apparatus comprising: treatment means for contacting an organism to make a treatment thereon; detection means for detect
Harano Kenji
Hijii Kazuya
Oyama Masahide
Takahashi Hiroyuki
Mulcahy John
Olympus Optical Co,. Ltd.
Ruddy David M.
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