Variability of somatosensory cortical evoked potentials during spinal surgery. Effects of anesthetic technique and high-pass digital filtering.
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.
Kalkman
C J
CJ
Department of Anesthesiology, University of Amsterdam, The Netherlands.
ten Brink
S A
SA
Been
H D
HD
Bovill
J G
JG
D000328:Adult; D015760:Alfentanil; D000768:Anesthesia, General / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D009609:Nitrous Oxide; D015742:Propofol; D012815:Signal Processing, Computer-Assisted; D013131:Spine / Q000601:surgery*; D013979:Tibial Nerve / Q000502:physiology
D015760:Alfentanil; D009609:Nitrous Oxide; D015742:Propofol