Device for monitoring a neutral electrode during HF surgery
First Claim
1. A device for monitoring the application of a unipolar neutral electrode with two separated neutral electrode partial surfaces during unipolar HF surgery, whereby the two separated neutral electrode partial surfaces are respectively connected via a HF input capacitor to source terminal, said device comprising:
- an impedance sensor comprising an excitation source that excites a resonant circuit by variable frequencies in a range which includes a resonant frequency, the resonant circuit being provided by the HF capacitors to source terminal and a secondary coil of a transformer, the secondary coil being connected between the two separated neutral electrode partial surfaces and serving as excitation input, and the resonant circuit being attenuated by transition impedances of the two separated neutral electrode partial surfaces connected in series to a patients tissues;
a peak value detector which detects an alternating voltage peak value at the resonant frequency via the secondary coil of the transformer;
a voltage controlled oscillator for providing the excitation source, said voltage controlled oscillator being controlled by a ramp generator;
a current asymmetry sensor comprising a compensating transformer, said current asymmetry sensor detecting a mean value of a periodic quantity of a difference in currents flowing through the two separated neutral electrode partial surfaces during the deactivation of a HF output signal; and
an electronic control and analysis means, said electronic control and analysis means deriving a signal for the quality of the application of the unipolar neutral electrode from signals of the impedance sensor and of the current asymmetry sensor.
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Accused Products
Abstract
The invention refers to a device for monitoring the application of a neutral electrode in unipolar HF surgery, having an impedance sensor with a resonant circuit comprising a secondary coil of a transformer and HF input capacitors of preferably two partial electrode surfaces. The impedance sensor detects the transient impedances of two partial electrode surfaces connected in series with the patient'"'"'s tissues by application of a patient auxiliary current and is moderated by the transition impedances.
The invention is characterized in that the resonant circuit is excited by alternating voltages of variable frequencies in the range of a resonant frequency, and in that a peak value detector is provided which detects an alternating voltage peak value at the resonant frequency.
The disclosed device excites the resonant circuit in such a manner that a faultless measurement of the transition impedance at the level of the patient'"'"'s tissues is made possible.
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Citations
16 Claims
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1. A device for monitoring the application of a unipolar neutral electrode with two separated neutral electrode partial surfaces during unipolar HF surgery, whereby the two separated neutral electrode partial surfaces are respectively connected via a HF input capacitor to source terminal, said device comprising:
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an impedance sensor comprising an excitation source that excites a resonant circuit by variable frequencies in a range which includes a resonant frequency, the resonant circuit being provided by the HF capacitors to source terminal and a secondary coil of a transformer, the secondary coil being connected between the two separated neutral electrode partial surfaces and serving as excitation input, and the resonant circuit being attenuated by transition impedances of the two separated neutral electrode partial surfaces connected in series to a patients tissues;
a peak value detector which detects an alternating voltage peak value at the resonant frequency via the secondary coil of the transformer;
a voltage controlled oscillator for providing the excitation source, said voltage controlled oscillator being controlled by a ramp generator;
a current asymmetry sensor comprising a compensating transformer, said current asymmetry sensor detecting a mean value of a periodic quantity of a difference in currents flowing through the two separated neutral electrode partial surfaces during the deactivation of a HF output signal; and
an electronic control and analysis means, said electronic control and analysis means deriving a signal for the quality of the application of the unipolar neutral electrode from signals of the impedance sensor and of the current asymmetry sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification