Objective:To investigate the sedative effect of remimazolam on ICU elderly patients undergoing mechanical ventilation and its influence on circulatory system.Methods:Using a prospective research approach, 189 ICU elderly patients undergoing mechanical ventilation in Hebei Petro China Central Hospital from October 2021 to June 2023 were selected. The patients were divided into remimazolam group, dexmedetomidine group and propofol group by random number table method with 63 cases in each group. The patients in remimazolam group, dexmedetomidine group and propofol group were sedated with remimazolam, dexmedetomidine and propofol, respectively. The sedation standard time, sedation standard rate, sedation maintenance time and recovery time after drug withdrawal were compared among the three groups. The heart rate, mean arterial pressure (MAP), respiratory rate and pulse oxygen saturation (SpO 2) before medication (T 0) and medication for 15 min (T 1), 30 min (T 2), 1 h (T 3), 6 h (T 4), 12 h (T 5) were recorded. The incidences of bradycardia, hypotension, respiratory depression, body movement and delirium during sedation were recorded. Results:The sedation standard time and recovery time after drug withdrawal in remimazolam group were significantly shorter than those in dexmedetomidine group and propofol group: (22.27 ± 5.31) min vs. (29.45 ± 6.24) and (30.12 ± 5.87) min, (28.66 ± 7.06) min vs. (32.22 ± 6.85) and (34.34 ± 7.24) min, and there were statistical differences ( P<0.05); there were no statistical difference between dexmedetomidine group and propofol group ( P>0.05). The sedation standard rate in remimazolam group and dexmedetomidine group was significantly higher than that in propofol group: 87.43% (661/756) and 83.60% (632/756) vs. 72.49% (548/756), and there was statistical difference ( P<0.016 7); there was no statistical difference between remimazolam group and dexmedetomidine group ( P>0.016 7). There was no statistical difference in sedation maintenance time among the three groups ( P>0.05). There were no statistical difference in T 0 heart rate, MAP, respiratory rate and SpO 2 among the three groups ( P>0.05). The T 1 to T 5 heart rate and MAP in remimazolam group were significantly higher than those in dexmedetomidine group and propofol group, the T 2 to T 5 heart rate and MAP in dexmedetomidine group were significantly lower than those in propofol group, and there were statistical differences ( P<0.05). The T 2 to T 5 respiratory rate in remimazolam group was significantly lower than that in dexmedetomidine group, the T 1 to T 5 respiratory rate in remimazolam group and dexmedetomidine group was significantly higher than that in propofol group, and there were statistical differences ( P<0.05). The T 2 to T 5 SpO 2 in remimazolam group and dexmedetomidine group was significantly higher than that in propofol group, and there was statistical difference ( P<0.05). The incidence of bradycardia in remimazolam group was significantly lower than that in dexmedetomidine group: 7.94% (5/63) vs. 25.40% (16/63), the incidence of hypotension was significantly lower than that in propofol group: 6.35% (4/63) vs. 23.81% (15/63), and there were statistical differences ( P<0.016 7). The incidence of respiratory depression in remimazolam group and dexmedetomidine group was significantly lower than that in propofol group: 4.76% (3/63) and 1.59% (1/63) vs. 22.22% (14/63), and there was statistical difference ( P<0.016 7). There was statistical difference in incidence of delirium among the three groups ( P<0.05), but there was no statistically significant difference in pairwise comparison ( P>0.016 7). There was no statistical difference in the incidence of body movement among the three groups ( P>0.05). Conclusions:The effect of remimazolam sedation in ICU elderly patients undergoing mechanical ventilation is satisfactory, with little influence on circulation and respiratory system and few adverse reactions.