Feasibility of continuous sedation monitoring in critically ill intensive care unit patients using the NeuroSENSE WAVCNS index
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Sedation in the intensive care unit (ICU) is challenging, as both over- and under-sedation are detrimental. Current methods of assessment, such as the Richmond Agitation Sedation Scale (RASS), are measured intermittently and rely on patients’ behavioral response to stimulation, which may interrupt sleep/rest. A non-stimulating method for continuous sedation monitoring may be beneficial and allow more frequent assessment. Processed electroencephalography (EEG) monitors have not been routinely adopted in the ICU. The aim of this observational study was to assess the feasibility of using the NeuroSENSE™ monitor for EEG-based continuous sedation assessment. With ethical approval, ICU patients on continuous propofol sedation were recruited. Depth-of-hypnosis index (WAVCNS) values were obtained from the NeuroSENSE. Bedside nurses, blinded to the NeuroSENSE, performed regular RASS assessments and maintained the sedation regimen as per standard of care. Participants were monitored throughout the duration of their propofol infusion, up to 24 h. Fifteen patients, with median [interquartile range] age of 57 [52–62.5] years were each monitored for a duration of 9.0 [5.7–20.1] h. Valid WAVCNS values were obtained for 89% [66–99] of monitoring time and were widely distributed within and between individuals, with 6% [1–31] spent < 40 (very deep), and 3% [1–15] spent > 90 (awake). Significant EEG suppression was detected in 3/15 (20%) participants. Observed RASS matched RASS goals in 36/89 (40%) assessments. The WAVCNS variability, and incidence of EEG suppression, highlight the limitations of using RASS as a standalone sedation measure, and suggests potential benefit of adjunct continuous brain monitoring.
KeywordsSedation monitoring Critical care Electroencephalography Depth of hypnosis Richmond Agitation Sedation Scale
We thank Denise Foster and all of the nurses at the Vancouver General Hospital ICU for their help during data collection.
PBM, MG, SS, JMA, GAD and DEGG conducted the literature review and designed the study. PBM, JMA, GAD and DEGG obtained the ethical approval to conduct the research. SB, NW, MG and SS performed the data collection. PBM, SB, NW, KVH, MG, and JMA analyzed and interpreted the findings. NW, PBM, SB, MG, and JMA drafted the manuscript. All authors critically reviewed the manuscript and read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
Guy A Dumont is a co-inventor of the NeuroSENSE (NeuroWave Systems Inc., Cleveland, OH) and has consulted for NeuroWave Systems Inc. J Mark Ansermino has consulted for NeuroWave Systems Inc. All remaining authors have no disclosures.
Ethical approval was obtained for this study from the University of British Columbia (UBC) Clinical Research Ethics Board (H14-01358). All study procedures were performed in accordance with the ethical standards of this institutional research committee and with the 1964 Helsinki declaration and its later amendments.
Research involving human and animal participants and informed consent
Informed consent was obtained for all individual participants included in the study; with permission from the UBC Clinical Research Ethics Board, informed consent was deferred to a substitute decision maker, and obtained post-hoc from participants when possible.
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