Efficacy and safety of remimazolam for procedural sedation during ultrasound-guided transversus abdominis plane block and rectus sheath block in patients undergoing abdominal tumor surgery: a single-center randomized controlled trial
Authors: Xiao Yimin , Wei Ran , Chen Lanren , Chen Yunfei , Kong Lingsuo 
Published: December 2022

Abstract
Background
To explore the efficacy and safety of remimazolam for procedural sedation during ultrasound-guided nerve block administration in patients undergoing abdominal tumor surgery, in order to improve and optimize remimazolam use in procedural sedation and clinical anesthesia.

Methods
The enrolled patients were randomly divided into three groups: 50 patients in the remimazolam group (R group), 50 patients in the dexmedetomidine group (D group), and 50 patients in the midazolam group (M group). Before administering an ultrasound-guided nerve block, all patients received sufentanil AND remimazolam or midazolam or dexmedetomidine. Remimazolam 5 mg was administered intravenously in group R, dexmedetomidine 0.6 µg/kg was administered intravenously in group D, and midazolam 0.025 mg/kg was administered intravenously in group M. Sedation was evaluated by the Modified Observer’s Assessment of Alertness and Sedation scale.When the Modified Observer’s Alertness/Sedation (MOAA/S) score was ≤ 2, block operation was started. If the target sedation level was not reached, rescue sedatives of remimazolam 2.5 mg may be intravenously given in group R, dexmedetomidine 0.4 µg/kg be intravenously given in group D, 0.01 mg/kg midazolam may be intravenously given in Group M. Hemodynamic indicators (systolic and diastolic blood pressure, heart rate), pulse oxygen saturation, depth of anesthesia (Narcotrend), MOAA/S,and the incidences of hypoxemia, injection pain, bradycardia and requirement for rescue sedatives were monitored and recorded.

Results
Compared with the control groups (midazolam and dexmedetomidine groups), the Narcotrend index and MOAA/S decreased more in the remimazolam group (P < 0.01). Compared with the control groups, the incidence of hypoxemia and injection pain was slightly higher in the remimazolam group, but the difference was not statistically significant (P > 0.05). Compared with the dexmedetomidine group, the incidence of bradycardia was significantly lower in the remimazolam group.

Conclusion
Remimazolam can be used safely for procedural sedation during ultrasound-guided nerve block administration in patients undergoing abdominal tumor surgery. The sedation effect is better than that with either midazolam or dexmedetomidine, and sedation can be achieved quickly without obvious hemodynamic fluctuations. Remimazolam is associated with better heart rate stability, and slightly higher incidences of hypoxemia and injection pain than are midazolam and dexmedetomidine (no statistically significant difference). The higher incidence of hypoxemia with remimazolam may be related to enhanced sufentanil opioid analgesia, and the mechanism of injection pain with remimazolam must be studied further and clarified.

Trial registration
This study was approved by the Ethics Committee of Anhui Provincial Cancer Hospital (Ethical Review 2021, No. 23) and registered at https://www.chictr.org.cn (ChiCTR2000035388). The pre-registration time of this experiment is 09/08/2020, due to ethical committee of the hospital met irregularly,the ethical approval time is 21/06/2021. The recruitment of patients began after the ethical approval (21/06/2021) and registration update (06/07/2021).The study protocol followed the CONSORT guidelines. The study protocol was performed in the relevant guidelines.