Comparison Of Remimazolam And Propofol On Prefrontal EEG Characteristics In Elderly Patients Undergoing Hip Surgery

Background and Aim Remimazolam is a novel ultra-short-acting benzodiazepine with high affinity for the benzodiazepine binding site of the GABAA receptor in the brain and similarities in pharmacological mechanisms with propofol.A study of EEG characteristics with infusion of Remimazolam in healthy volunteers found that volunteers experienced an increase in beta power followed by an increase in delta power.However,no study has yet characterized the EEG features of the forehead associated with Remimazolam in detail in elderly patients.This study intends to investigate the prefrontal EEG characteristics of Remimazolam in elderly general anesthesia surgery using propofol as a control.Methods Elderly patients scheduled for elective hip surgery were randomly divided into remimazolam group(R group)and propofol group(P group).Patients in both groups were placed with Sed Line EEG electrodes preoperatively and subsequently connected to a Sed Line brain function monitor to collect EEG data in the awake,eye-closed state preoperatively.In group R,0.2 mg/kg remimazolam was injected intravenously for induction and maintained at 0.8 – 2 mg/kg/h pump rate.In P group,1.5 – 2 mg/kg propofol was injected intravenously for induction and maintained at 3 – 6 mg/kg/h pump rate.Patients in both groups were referred to PSI to adjust the depth of anesthesia.In this study,the primary outcome measures were spectral analysis and coherence analysis before induction of anesthesia and during stable maintenance of anesthesia,and the secondary indicators included relative/absolute power,α peak power,and α peak frequency in each band,and the differences in intraoperative indicators,hemodynamic parameters,sedative drug dosage,opioid dosage,and sedation-related adverse events were also compared between the two groups.Results Ninety patients were recruited in this study,11 were excluded cumulatively,and finally 79 were included in the analysis(R = 38,P = 41)。Remimazolam produced highly coherent α oscillations(9 ~ 12 Hz)and higher power slow wave oscillations(0.1~ 1 Hz)similar to propofol.Absolute θ power(R 0.08 ± 2.24 d B vs P 1.46 ± 2.93 d B)(P=0.022),relative θ power(R 7.44 ± 2.12 d B vs P 10.12 ± 3.13 d B)(P<0.001),and relative α power(R 16.72 ± 7.64 d B vs P 21.69 ± 13.35 d B)(P=0.045)were lower with remimazolam compared to propofol.Conclusion This study showed that in elderly patients under surgical anesthesia,the EEG characteristics induced by clinically relevant doses of remimazolam and propofol were very similar,both showing highly coherent frontal alpha oscillations and slow wave oscillations with lower coherence,and the alpha peak power and peak frequency were also similar to those of propofol,indicating that the two groups had potential common GABAergic mechanisms.However,the absolute,relative power as well as αrelative power of the theta wave of remimazolam are low,suggesting that there are other neural circuit mechanisms of remimazolam.