The Cleveland Clinic Foundation

Joseph A Bova

Richard L Prass

The add-on circuit arrangement permits selective muting of noise signals which are caused by electrosurgery and by a stimulus source during neurophysiological monitoring of a surgical patient. Switches (39, 7 and 24) are provided to select: electrosurgery noise muting; stimulus artifact muting; and to select fixed or variable recorder recovery time. An inductive pickup (12) is coupled to a conductor (11) which carries radiofrequency signals during active periods of electrosurgery. The pickup (12) and associated circuitry (14-17) generate output signals (ES detect signals) which correspond in time to the active periods of electrosurgery. An active output signal of the '1' output of the flip-flop (38) operates the disable switches 44 which are interposed between the monitoring electrodes (41) and the recorder (46). The flip-flop is set by the ES detect signal and reset by selected recovery time signals. Stimulus artifacts are selectively muted by the stimulus disable switch (7), the pulse generator (4) which responds to synchronizing signals from the stimulus source (1) and the AND gate (9).

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Eastlake, OH, United States of America

Joseph A Bova