Polyspikes and Rhythmic Polyspikes During Volatile Induction of General Anesthesia With Sevoflurane Result in Bispectral Index Variations

Abstract

Background Although electroencephalography (EEG)-based indices may show artifactual values, raw EEG signal is seldom used to monitor the depth of volatile induction of general anesthesia (VIGA). The current analysis aimed to identify whether bispectral index (BIS) variations reliably reflect the actual depth of general anesthesia during presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anesthesia. Methods Sixty patients receiving either VIGA with sevoflurane using increasing concentrations (group VIMA) or vital capacity (group VCRII) technique or intravenous single dose of propofol (group PROP) were included. Monitoring included facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, BIS, standard EEG, and hemodynamic parameters. Results In the PROP group no EPs were observed. During different stages of VIGA with sevoflurane in the VIMA and VCRII groups, presence of polyspikes and rhythmic polyspikes in patients’ EEGs resulted in artifactual BIS values indicating a false awareness/wakefulness from anesthesia, despite no concomitant change of FiAA, FeAA, and MAC of sevoflurane. Periodic epileptiform discharges did not result in aberrant BIS values. Conclusion Our results suggest that raw EEG correlate it with values of BIS, FiAA, FeAA, and MAC of sevoflurane during VIGA. It seems that because artifactual BIS values indicating false awareness/wakefulness as a result of presence of polyspikes and rhythmic polyspikes in patients’ EEGs may be misleading to an anesthesiologist, leading to unintentional administration of toxic concentration of sevoflurane in ventilation gas.

Adequacy of Anesthesia Guidance for Colonoscopy Procedures

“…Intraprocedural titration of propofol during CPs is a widely accepted anesthetic technique providing satisfactory sedation [ 11 ], superior to midazolam alone [ 12 ]. Numerous anesthesia techniques, such as intraprocedural opioid titration [ 13 ], intravenous lidocaine infusion [ 14 ], an addition of a low dose of intravenous ketamine [ 15 ], and inhalation of an anesthetic mixture of oxygen with nitrous oxide [ 16 ], are employed to alleviate the visceral pain associated with the performance of CPs. In order to optimize the depth of anesthesia, monitoring has been introduced into anesthesiology practices.…”

The Effect of Sex on the Remimazolam Dosage Required for Successful i-gel Supraglottic Airway Insertion with Remifentanil in Non-Paralyzed Patients: An Up-and-Down Sequential Allocation Trial

“…Third, although the sequential method is indeed an efficient and convenient approach for swift determination of the effective dose in a small sample, the limited sample size constitutes a weakness of this study. Fourth, in instances where the BIS exceeded 60 but was not correlated with raw electroencephalogram data, we acknowledge the potential for misleading interpretations regarding patient consciousness [38]. Considering other studies, there seems to be a ten-dency for higher BIS values when using remimazolam without any incidences of awareness with recall, highlighting the necessity for a cautious interpretation of BIS values when using remimazolam [39].…”

Phase Lag Entropy as a Surrogate Measurement of Hypnotic Depth during Sevoflurane Anesthesia

“…Variations of EEG depending on increasing concentration of sevoflurane were studied with state and response entropy as well as with BIS [18,19]. Therefore, knowledge about the effect of gradual increase in sevoflurane concentration on phase lag entropy was required.…”