Variability of somatosensory cortical evoked potentials during spinal surgery. Effects of anesthetic technique and high-pass digital filtering |
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Authors: | C J Kalkman S A ten Brink H D Been J G Bovill |
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Affiliation: | Department of Anesthesiology, University of Amsterdam, The Netherlands. |
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Abstract: | The effects of anesthetic technique (nitrous oxide or propofol) and high-pass digital filtering on within-patient variability of posterior tibial nerve somatosensory cortical evoked potentials (PTN-SCEP) were compared prospectively in two groups of 20 patients undergoing spinal surgery. Average P1N1 amplitude was significantly higher and P1N1 amplitude variability lower during propofol/alfentanil anesthesia than during nitrous oxide/alfentanil anesthesia. Off-line 30-Hz high-pass digital filtering significantly reduced P1N1 amplitude variability without decreasing P1N1 amplitude. In 93 patients studied retrospectively, a significant negative logarithmic correlation (r = -0.77) was observed between P1N1 amplitude and P1N1 amplitude variability. This study shows the importance of maintaining the highest possible PTN-SCEP amplitudes during spinal surgery. Propofol/opioid anesthesia may be an alternative anesthetic technique to nitrous oxide/opioid anesthesia during spinal cord function monitoring. |
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