The sedation efficacy of different doses remimazolam in elderly patients with regional nerve block anesthesia
Authors: Yang Wan-jun , Geng Zhi-long , Chen Zheng-ze , Cui Chao-yuan , Tian Zi-wei , Guo Xi-lin , Zhang Ya-nan , Wang Lu , Huo Rui , Ma Chen-wei , Gao Yuan-yuan 
Published: March 2024

Background: Remimazolam is a benzodiazepine sedative that is indicated for the induction and maintenance during general anesthesia. Remimazolam also used for sedation in outpatient surgery. Most reports focused on non-elderly patients.Only a few studies have been reported on the use of remimazolam for elderly patients with regional nerve block anesthesia.
Aim: The aim of this study was to evaluate the effect of different doses remimazolam in elderly patients with regional nerve block anesthesia.
Methods: This study was conducted in a university hospital between February 2022 to March 2023. We included 80 patients aged 65 years or older under regional nerve block anesthesia. After determined the effect of anesthesia, patients were administered intravenous different doses of the test drug（4，4.5，5，5.5，6mg），named as R1、R2、R3、R4 and R5 groups respectively. The primary outcome was the lose consciousness time. The secondary outcomes included the maintenance time and the times of required assisted ventilation. We also recorded the exceptional response of patients among the lose consciousness maintenance time，and the values of mean arterial pressure（MAP）, heart rate（HR)，respiratory rate（RR），SpO2 and the Modified Observers Assessment of Alertness/Sedation (MOAA/S) scores were recorded respectively at baseline（T0） , 3 min after after the test drug injection（T1）, 6 min after after the test drug injection（T2）, 9 min after after the test drug injection（T3）, 12 min after after the test drug injection（T4）, 15 min after after the test drug injection（T5），18 min after after the test drug injection（T6），21 min after after the test drug injection（T7）and 24 min after after the test drug injection（T8）.
Results:We incorporated 80 patients according to the inclusion and exclusion criteria，16 patients were in each group.There were no significant differences in sex, age and BMI between the 5 groups. The lose consciousness time was significantly longer in R2 group than in R3、R4 and R5 group (p <0.001).The lose consciousness maintenance time was significantly longer in R5 group than in R3 group (p <0.05).In R1 group，two patients（2/16） were observed the same tendency in chewiness，four patients（4/16）were observed coughs. In R2 group，four patients were observed labored respiration. In R3 group，one patient was observed coughs，four patients were observed limb movements，the total dose of atropine and phenylephrine was 1mg and 80ug respectively，two patients required assisted ventilation 1 time. In R4 group，four patients were observed coughs，two patients were observed labored respiration,two patients were observed hiccups. In R5 group，six patients were observed coughs，six patients were observed labored respiration, the total dose of ephedrine was 20mg , four patients required assisted ventilation 1 time.The MAP was significantly lower in R2 and R5 group than in R1 group in T4(p=0.004)，and significantly lower in R5 group than in R1 group in T5 (p=0.007). The HR was significantly lower in R5 group than in R3 group in T3 (p=0.004)and T4 (p=0.007). The RR was significantly lower in R5 group than in R4 group in T4 (p=0.049)，and significantly higher in R4 group than in R2 group in T5 (p=0.024) and T6 (p=0.020) . The RR was significantly lower in R5 group than in R1、R3 and R4 group in T7 (p=0.001). The RR was significantly higher in R1 group than in R2 and R5 group in T8 (p=0.001).The RR was significantly higher in R4 group than in R2 group in T8 (p=0.001). The SpO2 was significantly lower in R3 group than in R1 group in T3 (p=0.003)，and significantly lower in R3 group than in R1 group and R5 in T4 (p =0.002) 、T5 (p=0.001)、T6（p=0.000）and T7（p=0.000）. The MOAA/S scores was significantly lower in R4 and R5 group than in R1 and R2 group in T1 (p=0.000)，and significantly lower in R5 group than in R1 and R3 group in T2 (p=0.004)，and significantly lower in R5 group than in R1 group in T3 (p=0.036).
Conclusion:We found 5~5.5mg remimazolam is more suitable for elderly patient sedation, and the lose consciousness time was related to remimazolam dosage，but it's not completely positively correlated. We also found the depth of sedation was positively correlated to remimazolam dosage, and the hemodynamic fluctuations occurred approximately 12~15 min after administration of remimazolam for elderly patient sedation.