Erbe Elektromedizin Gmbh

Peter Putz

Gunter Farin

Reiner Haag

A high frequency surgical apparatus for the thermal coagulation of biologic tissues is described, in which for monitoring the fluctuations in amplitude of the high frequency current during each coagulation process a current monitor (25) is provided, which by means of a current-to-voltage coverter generates an electrical voltage proportional to the amplitude fluctuations of the high frequency current, from which voltage, by means of a first detector, a first direct voltage proportional to the amplitude fluctuations is formed and, by means of a second detector acting as a peak value detector, a second direct voltage is formed that rises in proportion to the amplitude of the high frequency current. The first direct voltage (U.sub.a) and the second direct voltage (kU.sub.b), which is divided downward by an adjustable factor by means of a voltage divider, are supplied to a voltage comparator, the output signal of which sets a bistable circuit as soon as the first direct voltage (U.sub.a) becomes lower than the downwardly divided second direct voltage (kU.sub.b). The output signal of the bistable circuit switches the high frequency current off until the high frequency current is switched back on again by actuation of a manual switch and/or by means of an automatic switch. Instead of or in addition to this current monitor (25), and electric arc monitor (26) for monitoring the generation of anharmonic frequencies of the base frequency of the frequency generator can be connected to the output of the surgical apparatus, the arc monitor including a filter which passes at least one of the anharmonic frequencies, generated by the electric arc, of the base frequency of the high frequency generator. The output signal of the filter is supplied to a voltage comparator, the output signal of which resets a bistable circuit such that its output signal switches off the high frequency current.

High frequency electrosurgical apparatus for thermal coagulation of

Described is a safety circuit for a high-frequency surgical instrument for the monopolar cutting and coagulating of biological tissue, where the neutral electrode is high-frequency-grounded through a capacitor. The safety circuit monitors the low-frequency leakage current which flows through the capacitor against the ground potential and interrupts the electric connection between this capacitor and ground potential immediately when the low-frequency leakage current exceeds an adjustable limiting value. Simultaneously, an optical signal and an acoustical signal are activated.

High-frequency surgical instrument

A supplementary acoustic warning signal is provided for a high-frequency electrosurgical unit which sounds only after the lapse of an interval set by a first delay circuit shows that one of the high-frequency generators in the unit remains active longer than what, on the average, is normal. A second delay circuit is provided to assure shut-off of the high-frequency generators if at least one of the high-frequency generators remains active without interruption longer by an interval set by a second delay circuit beyond the lapse of an interval of the interval set by the first delay circuit. The supplementary acoustic signal thus sounds before the second delay circuit shuts off the high-frequency generators. The intervals determined by each of the delay circuits are adjustable. The output signal of the second delay circuit which activates the shut-off relays is maintained until a switch is operated to reset the system, so that the malfunction which has led to shut-down will be dealt with before the unit is used again.

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Tubingen, Germany

Peter Putz