Effects of propofol, propofol-nitrous oxide and midazolam on cortical somatosensory evoked potentials during sufentanil anaesthesia for major spinal surgery

Abstract

Recording of cortical somatosensory evoked potentials (CSEP) enables monitoring of spinal cord function. We studied the effects of propofol, propofol-nitrous oxide or midazolam during sufentanil anaesthesia on CSEP monitoring during major spinal surgery. Thirty patients with normal preoperative CSEP were allocated randomly to one of the following anaesthesia regimens: propofol (2.5 mg kg-1 followed by 10-6 mg kg-1 h-1) with or without nitrous oxide, or midazolam (0.3 mg kg-1 followed by 0.15 mg kg-1 h-1) combined with sufentanil 0.5 microgram kg-1 h-1 in the propofol and midazolam groups, or 0.25 microgram kg-1 h-1 in the propofol-nitrous oxide group. CSEP were elicited by alternate right and left tibial posterior nerve stimulation and recorded before and after induction (15 min, 1, 2 and 3 h), and during skin closure. CSEP latencies were not significantly modified in the three groups. CSEP amplitude decreased significantly in the propofol-nitrous oxide group (from mean 2.0 (SEM 0.3) to 0.6 (0.1) microV; P < 0.05) but not in the propofol (from 1.8 (0.6) to 2.2 (0.3) microV) or midazolam (1.7 (0.5) to 1.6 (0.5) microV) groups. The time to the first postoperative voluntary motor response (recovery) delay was significantly greater in the midazolam group (115 (19) min) compared with the propofol and propofol-nitrous oxide groups (43 (8) and 41 (3) min, respectively). Consequently, the use of propofol without nitrous oxide can be recommended during spinal surgery when CSEP monitoring is required.

Brain activity changes in a macaque model of oxaliplatin-induced neuropathic cold hypersensitivity

“…In another fMRI study that utilized rats under propofol anesthesia, reliable changes were detected in signal intensity in the somatosensory cortex during median nerve stimulation 22 . Furthermore, propofol sedation has little effect on cortical somatosensory evoked potentials in humans 23, 24 . Together with the fact that the analgesic effect of propofol is extremely weak 25, 26 , propofol sedation is appropriate for detecting pain-related activation patterns in the brain.…”

Predictive value of somatosensory evoked potentials for awakening from coma*

“…tients. Although sedation usually does not have a marked effect on SEP responses in people with normal brain function, it could have greater unknown effects in those with very damaged brains (54,55).…”

Reliability of perioperative SSEP recordings in spine surgery

“…The depressant effect of volatile anesthetics on evoked potentials is well known. [11][12][13] While low-dose volatile anesthetics in combination with an opioid is considered as appropriate anesthesia for monitoring purpose, recent studies evaluated the performance of total intravenous anesthesia (TIVA) for intraoperative neuromonitoring with the combination of propofol and fentanyl. 3,[12][13][14][15][16][17][18] TIVA in combination with a target-controlled infusion (TCI) device allows the determination of the amount of applicated propofol and the estimation of the plasma propofol concentration.…”