Simultaneous comparison of depth of sedation performance between SedLine and BIS during general anesthesia using custom passive interface hardware: study protocol for a prospective, non-blinded, non-randomized trial

Abstract

Background: Intraoperative brain function monitoring with processed electroencephalogram (EEG) indices, such as the bispectral index (BIS) and patient state index (PSI), may improve characterization of the depth of sedation or anesthesia when compared to conventional physiologic monitors, such as heart rate and blood pressure. However, the clinical assessment of anesthetic depth may not always agree with available processed EEG indices. To concurrently compare the performance of BIS and SedLine monitors, we present a data collection system using shared individual generic sensors connected to a custom-built passive interface box.

Methods: This prospective, non-blinded, non-randomized study will enroll 100 adult American Society of Anesthesiologists (ASA) class I-III patients presenting for elective procedures requiring general anesthesia. BIS and SedLine electrodes will be placed preoperatively according to manufacturer recommendations and their respective indices tracked throughout anesthesia induction, maintenance and emergence. The concordance between processed EEG indices and clinical assessments of anesthesia depth will be analyzed with chi-square and kappa statistic.

Discussion: Prior studies comparing brain function monitoring devices have applied both sensors on the forehead of study subjects simultaneously. With limited space and common sensor locations between devices, it is not possible to place both commercial sensor arrays according to the manufacturer's recommendations, thus compromising the validity of these comparisons. This trial utilizes a custom interface allowing signals from sensors to be shared between BIS and SedLine monitors to provide an accurate comparison. Our results will also characterize the degree of agreement between processed EEG indices and clinical assessments of anesthetic depth as determined by the anesthesiologists' interpretations of acute changes in blood pressure and heart rate as well as the administration, or change to the continuous delivery, of medications at these timepoints. Patient factors (such as burst suppression state or low power EEG conditions from aging brain), surgical conditions (such as use of electrocautery), artifacts (such as electromyography), and anesthesia medications and doses (such as end-tidal concentration of volatile anesthetic or hypnotic infusion dose) that lead to lack of agreement will be explored as well.

Trial registration: Clinical Trials ( ClinicalTrials.gov ), NCT03865316 . Registered on 4 February 2019 - retrospectively registered.

Sponsor: Masimo Corporation.

Keywords: Bispectral index (BIS); Brain function monitoring; Burst suppression state; Depth of anesthesia; Depth of sedation; Electromyography (EMG); Patient state index (PSI); Processed electroencephalogram (EEG); SedLine.

Conflict of interest statement

Two authors (NF and RLA) have served as Principal Investigators sponsored by Masimo and one (RLA) has served as a Scientific Advisory Committee Consultant for Masimo. The remaining authors declare no competing interests.

Figures

Fig. 1

Proper placement of 11 EEG electrodes to allow for simultaneous recording of BIS and PSI indices

Fig. 2

Custom interface adapter to allow for concurrent connection of EEG sensors to both BIS and SedLine modules

Fig. 3

Mobile data collection station showing laptop computer with data collection software; custom interface adapter with ports for connection to sensory electrodes and cables to BIS and SedLine monitors; BIS monitor; and SedLine Root monitor

Fig. 4

Timeline of Events and Experimental Recordings

Fig. 5

Changes in BIS and PSI indices during general anesthesia induction for 5 different patients