Mechanisms underlying brain monitoring during anesthesia: limitations, possible improvements, and perspectives

Abstract

Currently, anesthesiologists use clinical parameters to directly measure the depth of anesthesia (DoA). This clinical standard of monitoring is often combined with brain monitoring for better assessment of the hypnotic component of anesthesia. Brain monitoring devices provide indices allowing for an immediate assessment of the impact of anesthetics on consciousness. However, questions remain regarding the mechanisms underpinning these indices of hypnosis. By briefly describing current knowledge of the brain's electrical activity during general anesthesia, as well as the operating principles of DoA monitors, the aim of this work is to simplify our understanding of the mathematical processes that allow for translation of complex patterns of brain electrical activity into dimensionless indices. This is a challenging task because mathematical concepts appear remote from clinical practice. Moreover, most DoA algorithms are proprietary algorithms and the difficulty of exploring the inner workings of mathematical models represents an obstacle to accurate simplification. The limitations of current DoA monitors — and the possibility for improvement — as well as perspectives on brain monitoring derived from recent research on corticocortical connectivity and communication are also discussed.

Osthole Enhances the Therapeutic Efficiency of Stem Cell Transplantation in Neuroendoscopy Caused Traumatic Brain Injury

“…In present endoscopic surgery instruments must avoid vital vessels and avert damage to tissue around the wound. 58,59) Here we choose the 0.7 mm needle, which is close to the mainstream diameter endoscope adopt by clinical surgery 60) and we did not observe any side-effect conditions, such as haemorrhage and death. Previous studies suggested that all kinds of trauma could influence neural function in a certain extent.…”

Physiological Closed-Loop Control (PCLC) Systems: Review of a Modern Frontier in Automation

“…neuromuscular blocking agents), and brain ischaemia, have a significant effect on raw EEG data. Additionally, DoA monitors are limited by their calibration range and inter patient variability in dose response curves..." [186]. These limitations and interactions can degrade the performance of manual infusion systems and will nodoubt impose challenges to high-quality closed-loop control of anesthesia.…”

“…These limitations and interactions can degrade the performance of manual infusion systems and will nodoubt impose challenges to high-quality closed-loop control of anesthesia. Recently, patient state index (PSI) algorithm-based devices have been considered as alternatives to BIS monitors for their high sensitivity to variations in sedation/hypnosis and uniform response to various anesthetic agents [186], [187]. Although the PSI devices have some advantages to classical EEG monitors, including reduced sensitivity to noise, the PSI index is more sensitive to interpatient variability than BIS [188] and may be affected by EMG signals [186], [189].…”

“…In general, there remains a need for studies investigating the effects of drug combinations and EMG signals on sedation indices. For more detailed information on current challenges and limitations of monitoring during anesthesia, readers are referred to the extensive coverage in the literature (e.g., [186]).…”

Gamma Coherences in the Default Mode Resting State as a Measure of Consciousness Level

“…It has been shown that GA is associated with decrease in the coherences in several frequency bands (John et al, 2001). The medial prefrontal cortex and posterior cingulate/precuneus region have been found to be two of the brain areas most sensitive to anaesthetics (Vogt & Laureys, 2005;Boveroux et al, 2010;Cascella, 2016). The observed changes in DMN connectivity during loss of consciousness and alteration of external awareness mean that DMN integrity may represent the level of consciousness.…”