Effect of remimazolam on postoperative delirium in elderly patients undergoing laparoscopic radical resection for colorectal cancer: a randomized controlled trial

BACKGROUND: Our study aimed to compare remimazolam, midazolam, and no sedative on postoperative delirium (POD) incidence, cognitive function, inflammation, and recovery in elderly colorectal cancer (CRC) laparoscopic radical resection patients. METHODS: In this single-center, randomized, double-blind trial, 60 patients aged ≥ 60 years were assigned to the Control, Remimazolam, or Midazolam groups (n = 20 each). Anesthesia included remimazolam (6 mg/kg/h for 5 min), midazolam (0.04 mg/kg) before induction, or no sedative. Primary outcome was POD incidence (diagnosed using the Confusion Assessment Method (CAM) algorithm. Secondary outcomes included CAM/Mini-Mental State Examination (MMSE) scores, serum interleukin-6 (IL-6) and S-100 protein (S-100) levels, intraoperative metrics, and recovery times. Data were analyzed using chi-square, ANOVA, and Kruskal-Wallis tests (P < 0.05). RESULTS: Remimazolam significantly reduced POD incidence (5%) compared to the Control (30%) and Midazolam (40%) groups (P = 0.021). At postoperative day 7, compared to the Midazolam group, the Remimazolam group showed both significantly lower CAM scores (12.00 [11.00-13.00] vs. 13.50 [12.00-20.75]) and higher MMSE scores (29.00 [28.00-29.00] vs. 28.00 [21.25-28.00]) (both P = 0.029). Compared to the Control group, the Remimazolam group had numerically lower CAM scores and higher MMSE scores, but these differences were not statistically significant (P = 0.340 for both comparisons). Serum IL-6 levels in the Remimazolam group were consistently and significantly lower than those in the Midazolam group at all measured postoperative time points (Postoperative 1, 3, and 7; all P < 0.05). Compared to the Control group, the Remimazolam group also exhibited significantly lower IL-6 levels on postoperative 1 and postoperative 3 (both P = 0.005), but this difference was no longer significant by postoperative 7 (P = 1.000). Awakening (8.00 [6.00-10.00] min) and extubation times (2.50 [1.25-4.00] min) were significantly shorter with remimazolam (P < 0.001 and P = 0.019, respectively). No significant differences were observed in intraoperative metrics. CONCLUSION: Remimazolam reduced POD incidence and demonstrated faster postoperative recovery in elderly patients undergoing laparoscopic CRC surgery. While remimazolam showed cognitive and anti-inflammatory benefits relative to midazolam, its advantages over the control group were less pronounced. The most consistent clinical advantage was faster postoperative recovery, as evidenced by significantly shorter awakening and extubation times. These findings suggest that remimazolam is a promising alternative, particularly compared with midazolam, warranting further multicenter validation. CLINICAL TRIAL NUMBER: ChiCTR2000034677; Registration Date: 2020/07/14.