The Median Effective Concentration (EC50) of Alfentanil Combined with Propofol Closed-Loop Targeted Infusion in Super-Elderly Patients Undergoing Endoscopic Retrograde Cholangiopancreatography (ERCP)

To investigate the median effective concentration (EC50) of alfentanil combined with propofol closed-loop targeted infusion when used for sedation in super-elderly endoscopic retrograde cholangiopancreatography (ERCP) patients. A total of 28 super-elderly patients (>85 years old) undergoing elective ERCP from April to September 2024 were enrolled to receive target-controlled continuous infusion of alfentanil with an initial infusion concentration of 50ng/mL, and the continuous infusion concentration was determined according to the Dixon up and down method, and the incremental/decremental gradient of alfentanil was set at 10ng/mL. The observation was terminated after 8 reflexes. The EC50 of target-controlled infusion of alfentanil combined with propofol in the operation of ERCP in super-aged patients was calculated. HR and MAP were recorded at the time of entering the room at rest (T0), after anesthesia induction (T1), before duodenoscope placement (T2), and within 3 minutes after duodenoscope placement (T3). In this study, the EC50 of alfentanil combined with propofol target-controlled infusion during ERCP in super-elderly patients was determined to be 36.52ng/mL (95% confidence interval [CI]: 32.12-41.71ng/mL). Among the 28 patients, 27 patients (96.43%) had a change in HR less than 20% of baseline during duodenoscopy, and 1 patient (3.57%) had a change in HR more than 20% of baseline during duodenoscopy. Of the 28 patients, 26 (92.86%) had a MAP change of less than 20% of baseline during duodenoscopy, and 2 (7.14%) had a MAP change of more than 20% of baseline. The EC50 of alfentanil combined with propofol by closed-loop target-controlled infusion during ERCP in super-elderly patients is 36.52ng/mL. At this concentration level, the patients can be satisfied with surgical anesthesia and maintain relatively stable hemodynamics.