Determination of The 90% Effective Dose of Tegileridine Combined With Propofol for Gastroscopy in Patients of Different Ages: A Biased-Coin Up-and-down Design Study

This single-group, open-label, biased-coin up-and-down sequential dose-finding trial aims to determine the 90% effective dose (ED90) of intravenous tegileridine combined with fixed-dose propofol to eliminate body movement, cough and excessive hemodynamic fluctuations during gastroscopy insertion in adult patients stratified into young (18-64 years) and elderly (≥65 years) subgroups. All subjects receive intravenous tegileridine followed by 1-2 mg/kg propofol for sedation induction. The initial tegileridine dose is 5 μg/kg with a 1 μg/kg dose step. Dose adjustment follows biased-coin algorithm: dose increases by 1 μg/kg if positive response occurs; if negative response, there is an 11% probability to decrease dose by 1 μg/kg. The trial will be terminated when 45 successful cases are accrued in each age subgroup. Primary outcome is ED90 of tegileridine calculated via centered isotonic regression. Secondary outcomes include total propofol consumption, MOAA/S sedation score, blood pressure and heart rate changes, and incidence of perioperative adverse events within 24 hours post-procedure.