Background: Postoperative delirium is common in older adult patients and associated with a poor prognosis. The use of benzodiazepine was identified as an independent risk factor for delirium, but there is no randomized controlled trial regarding the relationship between remimazolam, a new ultra-short acting benzodiazepine, and postoperative delirium. We designed a randomized controlled trial to evaluate if remimazolam increases the incidence of postoperative delirium compared with propofol in older adult patients undergoing orthopedic surgery with general anesthesia.

Patients and methods: We enrolled 320 patients aged more than 60 with American Society of Anesthesiologists physical status I-III who underwent orthopedic surgery. Patients were randomized to two groups to receive intraoperative remimazolam or propofol, respectively. Our primary outcome was the incidence of delirium within 3 days after surgery. Secondary outcome was emergence quality including the incidence of emergence agitation, extubation time, and length of post-anesthesia care unit (PACU) stay. Adverse events were also recorded.

Results: The incidence of postoperative delirium was 15.6% in the remimazolam group and 12.4% in the propofol group (Risk ratio, 1.26; 95% CI, 0.72 to 2.21; Risk difference, 3.2%; 95% CI, -4.7% to 11.2%; P = 0.42). No significant differences were observed for time of delirium onset, duration of delirium, and delirium subtype between the two groups. Patients in remimazolam group had a lower incidence of hypotension after induction and consumed less vasoactive drugs intraoperatively, but had a longer postoperative extubation time and PACU stay.

Conclusion: General anesthesia with remimazolam was not associated with an increased incidence of postoperative delirium compared with propofol in older adult patients undergoing orthopedic surgery.