Impact of EEG-guided Sevofluorane on Opioid Consumption and Quality of Awakening

Overview

This prospective, randomized, single-blind, two-arm parallel-group clinical trial evaluates whether EEG-guided sevoflurane titration affects intraoperative opioid consumption and emergence quality in children undergoing painful elective surgery without regional anesthesia. Children aged 2-8 years (ASA I-II) scheduled for elective tonsillectomy (±adenoidectomy) are randomized 1:1 to a Control Group (standard 1 age-adjusted MAC; EEG screen concealed) or a Study Group (sevoflurane titrated to a stable slow-delta/alpha EEG pattern, SEF 17-20 Hz, starting at \~0.7 MAC). In both arms, fentanyl (0.5-1 mcg/kg IV) is added when nociception signs occur. The primary outcome is intraoperative fentanyl consumption (mean mcg/kg rate). Secondary outcomes include sevoflurane exposure (EtSevo, MAC-hours), EEG burst suppression, emergence time, emergence delirium (PAED scale), postoperative pain and opioid use, and hemodynamic events. Sample size: 50 participants (25/arm; 90% power, α=0.05, expected difference 2 mcg/kg, SD=2). EEG spectral analysis is performed in MATLAB using multitaper frequency-domain bootstrap. The study has institutional ethics approval; parental consent and patient assent (≥7 years) are obtained prior to enrollment.

Electroencephalography (EEG)-guided anesthetic titration has demonstrated significant clinical benefits in both pediatric and adult patients. However, proprietary EEG-based indices widely used for monitoring anesthetic depth are affected by patient age and the specific anesthetic agent used, limiting their validity and generalizability. More recently, titrating anesthetics based on a specific interpretation of EEG waveforms and their oscillatory patterns observed on the spectrogram has gained popularity. Previous studies indicate that sevoflurane titration based on specific EEG waveforms and oscillatory patterns yields more substantial reductions in sevoflurane exposure than previously reported with proprietary EEG indices. Furthermore, reducing sevoflurane exposure decreases the incidence of EEG burst suppression, results in faster emergence times, and reduces emergence delirium. However, most of these benefits have been reported in the context of surgeries where intraoperative antinociception was provided via central or peripheral nerve blocks, in the absence of increased intraoperative analgesic and opioid requirements. It remains unclear whether the benefits associated with reduced sevoflurane exposure are also observed in surgeries where intraoperative antinociception cannot be provided through regional blocks. In such cases, antinociception depends primarily on the co-administration of inhaled anesthetics and opioids. Therefore, the clinical benefits of decreasing sevoflurane exposure via electroencephalographic guidance must be weighed against the side effects of higher perioperative opioid requirements. What will be the impact of strict titration of the hypnotic component using electroencephalography in a painful surgery, in terms of intraoperative opioid consumption and the quality of anesthetic emergence? It is hypothesized that to adjust the sevoflurane dose according to EEG targets in children undergoing surgeries where intraoperative antinociception cannot be provided via regional blocks will result in a reduction of sevoflurane requirements. However, a compensatory increase in intraoperative opioid consumption is expected to be observed, which could subsequently affect the quality and duration of the anesthetic recovery period.