Bispectral Index and Spectral Entropy in Neuroanesthesia

Abstract

Spectral Entropy (SpEn) is an alternative tool to the bispectral index (BIS) for monitoring depth of hypnosis. SpEn measures response entropy (RE) and state entropy (SE). This open-label prospective study was designed to evaluate SpEn and BIS in 20 patients undergoing elective supratentorial neurosurgery with craniotomy and resection of brain tumors. SpEn and BIS were obtained continuously by Datex Ohmeda M-entropy module S/5 (Helsinki, Finland) and Aspect Medical System BIS (Newton), respectively. Total intravenous anesthesia was performed in all patients by Fresenius Vial infusion system (Brezins, France) to maintain a plasma concentration of propofol of 2.5 to 5 microg mL(-1) and sufentanil of 0.2 to 0.4 etag mL(-1). SpEn, BIS, the estimated propofol effect-site concentrations (Ce), the mean arterial pressure (MAP), and the heart rate (HR) were recorded during 12 specific events: induction of anesthesia, patient stop counting, loss of blinking reflex, intubation, mayfield pinning, craniotomy, termination of propofol infusion, recovery of blinking reflex, coughing, limb movement, order execution, and extubation. Stated that prediction probability or P(K) represents an indicator probability to predict correctly the rank order of an arbitrary pair of distinct observed indices of depth of hypnosis (ie, clinical settings and SpEn indices, or BIS, Ce, MAP, HR), PK of BIS, SE, RE, and Ce provided a better depth of hypnosis than MAP and HR; RE being the best for rapidity, SE for sensitivity, and BIS for specificity. There is good correlation between the 3 hypnosis indices and Ce. This study demonstrates that SpEn provides a reproducible hypnosis index for patients undergoing supratentorial neurosurgical procedures.

Effect of preoperative anxiety on spectral entropy during induction with propofol

“…However, our study revealed that the use of propofol alone at an effect site concentration between 2.0-5.1 µg/ml was not an influential factor on the RE and SE values (Table 5 and 6). A prior model did not exclude the effects of opioid, muscle relaxants and intraoperative stimulations on spectral entropy values at a propofol plasma concentration between 2.5 and 5 µg/ml, which was similar to the propofol concentration of our study [22]. Thus, we presume that a reason of why the result of our study was different from the one of previous study [22] is likely the presence or absence of the effects of perioperative medications on RE and SE.…”

“…A prior model did not exclude the effects of opioid, muscle relaxants and intraoperative stimulations on spectral entropy values at a propofol plasma concentration between 2.5 and 5 µg/ml, which was similar to the propofol concentration of our study [22]. Thus, we presume that a reason of why the result of our study was different from the one of previous study [22] is likely the presence or absence of the effects of perioperative medications on RE and SE. Using propofol alone for anesthetic induction, based on the results of our study, we figured out that the spectral entropy values were not interfered by a propofol Ce between 2.0-5.1 µg/ml.…”

“…Also, spectral entropy values have been positively correlated to a plasma concentration of propofol above 2.5 µg/ml [22] although the values of RE and SE have not been correlated with the levels of effect site concentration of propofol below 2.0 µg/ml [23]. However, our study revealed that the use of propofol alone at an effect site concentration between 2.0-5.1 µg/ml was not an influential factor on the RE and SE values (Table 5 and 6).…”

Automated Analysis of EEG: Opportunities and Pitfalls

“…Clinicians can be frustrated by uneven performance or overly complicated algorithms and appear to be more accepting of a simple algorithm than a complicated one, and a widely accepted simple algorithm is shown in Figure 3 (Bell et al, 1991;Paolo Martorano et al, 2006). When an algorithm makes an inaccurate classification, the level of complexity of the algorithm seems to be proportional with the level of acceptance of that mistake.…”

Increases in Response Entropy to Skull Pin Insertion During Neurosurgery

“…1 In addition, entropy monitoring is useful to differentiate between inadequate analgesia from anesthesia. 1 In addition, entropy monitoring is useful to differentiate between inadequate analgesia from anesthesia.…”