Importance

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Abstract

A device is provided for use with a medical instrument including a tip which is designed to penetrate the wall of an internal cavity (e.g., the abdomen) of a patient, for detecting when that tip penetrates through the wall. The device includes a source of a medium frequency detection signal and circuitry for coupling the signal to the tip of the medical instrument. The circuitry includes a transformer forming a high Q resonant circuit having an initial value of Q when the medical instrument is not in use. A return path for the signal provides that, in use of the instrument, a circuit is completed through the resonant circuit such that when the tip contacts patient tissue the initial Q of the resonant circuit changes and when the tip penetrates through the patient tissue of the Q of the circuit is restored to the initial value thereon. A detector detects the change in Q of the resonant circuit and produces an output when changed Q is restored to the initial value thereof so as to indicate that the tip has penetrated through the patient tissue.

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First Claim