The influence of depth of anesthesia and blood pressure on muscle recorded motor evoked potentials in spinal surgery. A prospective observational study protocol

Sebastiaan E Dulfer; M M Sahinovic; F Lange; F H Wapstra; D Postmus; A R E Potgieser; C Faber; R J M Groen; A R Absalom; G Drost

doi:10.1007/s10877-020-00645-1

The influence of depth of anesthesia and blood pressure on muscle recorded motor evoked potentials in spinal surgery. A prospective observational study protocol

J Clin Monit Comput. 2021 Oct;35(5):967-977. doi: 10.1007/s10877-020-00645-1. Epub 2021 Jan 28.

Authors

Sebastiaan E Dulfer¹, M M Sahinovic², F Lange³, F H Wapstra⁴, D Postmus⁵, A R E Potgieser⁶, C Faber⁴, R J M Groen⁶, A R Absalom², G Drost^{6

3}

Affiliations

¹ Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. s.e.dulfer@umcg.nl.
² Department of Anesthesiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
³ Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
⁴ Department of Orthopedics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
⁵ Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
⁶ Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Abstract

For high-risk spinal surgeries, intraoperative neurophysiological monitoring (IONM) is used to detect and prevent intraoperative neurological injury. The motor tracts are monitored by recording and analyzing muscle transcranial electrical stimulation motor evoked potentials (mTc-MEPs). A mTc-MEP amplitude decrease of 50-80% is the most common warning criterion for possible neurological injury. However, these warning criteria often result in false positive warnings. False positives may be caused by inadequate depth of anesthesia and blood pressure on mTc-MEP amplitudes. The aim of this paper is to validate the study protocol in which the goal is to investigate the effects of depth of anesthesia (part 1) and blood pressure (part 2) on mTc-MEPs. Per part, 25 patients will be included. In order to investigate the effects of depth of anesthesia, a processed electroencephalogram (pEEG) monitor will be used. At pEEG values of 30, 40 and 50, mTc-MEP measurements will be performed. To examine the effect of blood pressure on mTc-MEPs the mean arterial pressure will be elevated from 60 to 100 mmHg during which mTc-MEP measurements will be performed. We hypothesize that by understanding the effects of depth of anesthesia and blood pressure on mTc-MEPs, the mTc-MEP monitoring can be interpreted more reliably. This may contribute to fewer false positive warnings. By performing this study after induction and prior to incision, this protocol provides a unique opportunity to study the effects of depths of anesthesia and blood pressure on mTc-MEPs alone with as little confounders as possible. Trial registration number NL7772.

Keywords: Blood pressure; Depth of anesthesia; Intraoperative neurophysiological monitoring; Motor evoked potentials.

MeSH terms

Anesthesia*
Blood Pressure
Evoked Potentials, Motor*
Humans
Muscles
Neurosurgical Procedures
Observational Studies as Topic