Remimazolam vs Midazolam to Reduce Delirium in Adults ≥65 Undergoing CPB Valve Surgery

"Postoperative delirium is a common and serious complication following cardiac surgery, particularly among older adults who require intensive care. Its incidence is reported to range between 20% and 70% after cardiopulmonary bypass (CPB), and has been associated with prolonged hospitalization, increased medical costs, higher morbidity and mortality, and long-term cognitive decline. Benzodiazepines are frequently used during anesthetic induction in cardiac surgery due to favorable hemodynamic stability, although multiple clinical guidelines have recommended limitation of benzodiazepine exposure because of concerns for delirium. However, robust clinical evidence in cardiac surgery remains limited. Midazolam is currently the most commonly administered benzodiazepine in this setting, though metabolism through hepatic pathways and accumulation of active metabolites may increase the risk of postoperative delirium, especially in older patients and those with organ dysfunction. Remimazolam, a recently approved benzodiazepine, undergoes rapid hydrolysis by plasma esterases and demonstrates predictable pharmacokinetic properties with a markedly shorter context-sensitive half-time compared to midazolam. These pharmacologic features suggest a potentially reduced impact on postoperative delirium risk. Despite this rationale, no randomized controlled trial has evaluated the effect of remimazolam versus midazolam on delirium after CPB-assisted valve surgery. This randomized double-blind controlled trial aims to determine whether remimazolam reduces the incidence of postoperative delirium compared with midazolam in patients aged ≥65 years undergoing valve surgery with CPB. Eligible participants will be randomized in a 1:1 ratio to receive either remimazolam or midazolam for anesthetic induction according to a computer-generated allocation sequence. All other anesthetic management will follow standardized institutional protocols, including depth of anesthesia monitoring. Delirium