INTRAOPERATIVE SCHMERZREIZE VERANDERN SOMATOSENSORISCH EVOZIERTE POTENTIALE, ABER NICHT AKUSTISCH EVOZIERTE POTENTIALE WAHREND ISOFLURAN/STICKOXYDUL-ANASTHESIE

Translated title of the contribution: Intraoperative pain stimuli change somatosensory evoked potentials but not auditory evoked potentials during isoflurane/nitrous oxide anaesthesia

I. Rundshagen, E. Kochs, P. Bischoff, J. Schulte Am Esch

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Purpose: Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. Methods: After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 ± 15 y, 73 ± 14 kg, 1.71 ± 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 μg/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group I) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N2O, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb), Recordings were performed during 30 min before the start of. surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, end-tidal pCO2 and isoflurane (P(et)Iso) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p < 0.05 significant. Results and discussion: During steady state isoflurane anaesthesia surgical stimulation (SURG2) resulted in significant increases of N2O P25 amplitudes compared with BL (BL: 1.4 ± 0.7 μV; SURG2: 2.0 ± 0.8 μV; p < 0.05). Latencies of SEPs and midlatency components of AEPs did not change over time. There were no differences in autonomic parameters between SEP and AEP groups. MAP increased from 76 ± 6 mmHg at BL to 93 ± 16 mmHg at SURG1 and 96 ± 17 mmHg at SURG2 (n = 36; p < 0.05). HR increased from BL (60 ± 8 beats/min) to SURG2 (76 ± 12 beats/min). Increases of amplitudes of midlatency SEP amplitudes indicate increased nociceptive signal transmission which is not blunted by isoflurane-nitrous oxide anaesthesia. In contrast, unchanged AEPs indicate adequate levels of the hypnotic components of anaesthesia.

Translated title of the contributionIntraoperative pain stimuli change somatosensory evoked potentials but not auditory evoked potentials during isoflurane/nitrous oxide anaesthesia
Original languageGerman
Pages (from-to)604-609
Number of pages6
JournalAnasthesiologie Intensivmedizin Notfallmedizin Schmerztherapie
Volume32
Issue number10
DOIs
StatePublished - Oct 1997
Externally publishedYes

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