Frequency and characteristics of patients with bispectral index values of 60 or higher during the induction and maintenance of general anesthesia with remimazolam

Remimazolam Use in Cardiac Anesthesia: A Narrative Review

Remimazolam, a novel ultra-short-acting intravenous benzodiazepine, has garnered recent attention for its use as a general anesthetic. This narrative review aims to summarize and analyze the available literature on the effects of remimazolam use in cardiac surgical patients, including its effects on hemodynamics, safety in patients with baseline myocardial dysfunction, and impact on postoperative management including time to emergence and extubation. Finally, there is discussion regarding potential drawbacks of adopting remimazolam as a routine anesthetic for cardiac surgery.

Case report of atypical re-sedation after general anesthesia using remimazolam

BACKGROUND

Remimazolam, an ultra-short-acting anesthetic with flumazenil as a reversal agent, typically facilitates patient awakening postoperatively. However, our case reveals an unusual occurrence: despite flumazenil initially restoring consciousness, re-sedation due to remimazolam ensued six hours later.

CASE

A 65-year-old woman underwent total intravenous general anesthesia with remimazolam and remifentanil during the 140-min surgery. Despite an initially smooth recovery, she progressively became drowsy upon transfer to the general ward, eventually reaching a stuporous state. Multiple interventions, including opioid reversal (intravenous patient-controlled analgesia discontinuation, and naloxone administration) were attempted. Neurological consultation revealed no issues; however, immediate improvement after flumazenil administration suggested remimazolam's involvement. The patient was discharged without complications.

CONCLUSIONS

This case challenges our understanding of remimazolam's dynamics, emphasizing the necessity for vigilant post-anesthesia monitoring, even in seemingly low-risk cases. It advocates for standardized response protocols to promptly manage unforeseen events and ensure patient safety.

Determination of the effective dose of remimazolam combined with sufentanil for inhibiting body movement during surgical abortion: An up-and-down sequential allocation trial

BACKGROUND

Remimazolam, a recently developed anesthetic characterized by its rapid and ultra-short-acting properties, exhibits pharmacological attributes that make it potentially suitable for painless surgical abortion procedures. The objective of this study was to determine the effective dose of remimazolam when administered in combination with sufentanil, with the intention of inhibiting body movement during surgical abortion. Additionally, a secondary objective was to assess the recovery profile from general anesthesia.

METHODS

The study enrolled a total of 25 healthy women aged 20 to 40, with a body mass index between 18 and 28 kg/m2, in their first trimester of pregnancy (up to 12 weeks), and American Society of Anesthesiologists status I and II. Anesthesia induction was initiated by administering sufentanil at a dose of 0.1 μg/kg. The modified Dixon up-and-down method was employed to determine the induction dose of remimazolam for each patient.

RESULTS

The 50% and 95% effective dose of remimazolam for inhibitory effects of body movement was estimated using centered isotonic regression to be 0.145 mg/kg (95% CI: 0.115, 0.207), and 0.242 mg/kg (95% CI: 0.232, 0.620), respectively. Five out of 25 (20%) experienced hiccups, with 1 patient having persistent hiccups until the end of the surgery. The mean time to first eye-opening was 51.4 ± 20.5 seconds, and the time to obey verbal command was 54.5 ± 20.6 seconds. Upon arrival at the postanesthesia care unit, 95.7% of the patients achieved a Modified Aldrete score ≥ 9.

CONCLUSIONS

The 50% and 95% effective dose of remimazolam for inhibiting body movement during surgical abortion when used in combination with 0.1 μg/kg of sufentanil were 0.145 mg/kg and 0.242 mg/kg, respectively.

Comparison of the bispectral indices of patients receiving remimazolam and propofol for general anesthesia: a randomized crossover trial

BACKGROUND

Remimazolam is a safe and effective new benzodiazepine sedative that has unique advantages in anesthesia induction and maintenance. The differences in the electroencephalogram bispectral index (BIS) during general anesthesia between propofol and remimazolam deserve further exploration.

METHODS

Single-center randomized crossover study. Patients who required multiple hysteroscopic surgery were randomly assigned to use remimazolam (0.27 mg/kg for induction and 1 mg/kg/h for maintenance) first and then propofol (2.0 mg/kg for induction and 6 mg/kg/h for maintenance) during hysteroscopic surgery again 3 months later, or in the opposite order. Both drugs were used at the latest ED95 for unconsciousness. The BIS values (primary endpoint), intraoperative conditions, and incidence of adverse reactions (secondary endpoints) were compared at each time point. BIS values were analyzed with a mixed model of repeated measurements (MMRM).

RESULTS

Seventeen patients completed the study. The lowest BIS value in the remimazolam regimen was significantly higher than that in the propofol regimen (p = 0.001). The MMRM analysis of the BIS values revealed significant differences between the regimens at each time point (p < 0.001). The intraoperative diastolic blood pressure and heart rate changes were smaller, the recovery was faster, and there were fewer adverse reactions and less injection pain, but a greater incidence of intraoperative body movement and hiccups, in the remimazolam regimen.

CONCLUSION

The trial indicated that remimazolam maintained a higher BIS level than propofol. The correlation between the BIS and the depth of anesthesia induced by remimazolam needs to be further studied.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov: ChiCTR2200064551.

Target-controlled infusion of remimazolam effect-site concentration for total intravenous anesthesia in patients undergoing minimal invasive surgeries

Background

Although pharmacokinetic and pharmacodynamic models of remimazolam have been developed, their clinical application remains limited. This study aimed to administer a target-controlled infusion (TCI) of remimazolam at the effect-site concentration (Ce) in patients undergoing general anesthesia and to investigate the relationship of the remimazolam Ce with sedative effects and with recovery from general anesthesia.

Methods

Fifty patients aged 20-75 years, scheduled for minimally invasive surgery under general anesthesia for less than 2 h, were enrolled. Anesthesia was induced and maintained using Schüttler's model for effect-site TCI of remimazolam. During induction, the remimazolam Ce was increased stepwise, and sedation levels were assessed using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale and bispectral index (BIS). Following attainment of MOAA/S scale 1, continuous infusion of remifentanil was commenced, and rocuronium (0.6 mg/kg) was administered for endotracheal intubation. The target Ce of remimazolam and the remifentanil infusion rate were adjusted to maintain a BIS between 40 and 70 and a heart rate within 20% of the baseline value. Approximately 5 min before surgery completion, the target Ce of remimazolam was reduced by 20-30%, and anesthetic infusion ceased at the end of surgery. Nonlinear mixed-effects modeling was employed to develop pharmacodynamic models for each sedation level as well as emergence from anesthesia.

Results

The remimazolam Ces associated with 50% probability (Ce50) of reaching MOAA/S scale ≤4, 3, 2, and 1 were 0.302, 0.397, 0.483, and 0.654 μg/mL, respectively. The Ce50 values for recovery of responsiveness (ROR) and endotracheal extubation were 0.368 and 0.345 μg/mL, respectively. The prediction probabilities of Ce and BIS for detecting changes in sedation level were 0.797 and 0.756, respectively. The sedation scale significantly correlated with remimazolam Ce (r = -0.793, P < 0.0001) and BIS (r = 0.914, P < 0.0001). Age significantly correlated with Ce at MOAA/S1 and ROR.

Conclusion

Effect-site TCI of remimazolam was successfully performed in patients undergoing general anesthesia. The remimazolam Ce significantly correlated with sedation depth. The Ce50 for MOAA/S scale ≤1 and ROR were determined to be 0.654 and 0.368 μg/mL, respectively.

Remimazolam and Remifentanil Anesthetics for an Adolescent Patient with Stiff-Person Syndrome: A Case Report

Stiff-person syndrome (SPS) is a rare autoimmune disease characterized by fluctuating rigidity and stiffness of the axial muscles. There are no reports on the use of remimazolam in a patient with SPS. A 16-year-old Japanese woman with SPS was scheduled to undergo intrathecal baclofen pump exchange. General anesthesia was induced and maintained using remimazolam, remifentanil, and intermittent rocuronium bromide. No intraoperative mobility or significant autonomic symptoms were observed. Additionally, electroencephalographic signature showed sufficient anesthetic depth. The patient's emergence from general anesthesia was uneventful. In conclusion, remimazolam could be considered an effective anesthetic drug for patients with SPS.

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

(1) Background: The physiological and pharmacological variations between men and women are known to influence drug efficacy. The objective of this study was to determine the 50% and 95% effective doses (ED50 and ED95) of remimazolam required for i-gel supraglottic airway (ISA) insertion under remifentanil infusion without neuromuscular blocking agents (NMBAs) in both males and females. (2) Methods: Patients aged 19-65 years, scheduled for general anesthesia using ISA, were enrolled in this study. Patients were divided into two groups based on their sex. The anesthesia process began with a remifentanil infusion targeting an effect-site concentration of 3.0 ng/mL, accompanied by a remimazolam injection. The initial remimazolam dose was 0.25 mg/kg, and it was adjusted with a step size of 0.05 mg/kg based on the outcome of ISA insertion in the preceding patient. (3) Results: The ED50 of remimazolam (mean ± standard error) was 0.28 ± 0.02 mg/kg in the male group and 0.18 ± 0.02 mg/kg in the female group (p < 0.001). Additionally, ED95, which was calculated using the isotonic regression method, was significantly comparable between the male and female groups (male: 0.35 mg/kg, 95% confidence interval [CI] = 0.34-0.35; female: 0.29 mg/kg, 95% CI = 0.25-0.30). (4) Conclusions: This study showed that both the ED50 and the ED95 of remimazolam for successful ISA insertion was higher for men than that for women. Therefore, while using remimazolam alongside remifentanil infusion without NMBAs for ISA insertion, one should consider the patient's sex for appropriate dosing.