This study compares the effect of nasopharyngeal airway-assisted deep analgosedation (NPA-assisted DAS) versus intubated general anesthesia (GA) on sedation-related adverse events (SRAEs) in older adult patients undergoing ERCP. Patients will be randomized 1:1, stratified by center and hypertension status using permuted blocks of size 2 and 4. The main exclusion criterion is severe cardiopulmonary disease. The primary outcome is a composite of SRAEs including hypoxemia, hypotension, hypertension, laryngospasm, or bronchospasm. Secondary outcomes include escalation of respiratory support, tachycardia, bradycardia, reflux, recovery time, quality of recovery (QoR-15), postoperative nausea and vomiting (PONV), cognitive function, perioperative respiratory failure or ARDS, patient and endoscopist satisfaction, and length of hospital stay. Analyzes will follow a modified intent-to-treat approach. Ethical approval was obtained from the Sir Run Run Shaw Hospital Ethics Committee (2025-0780), the study is registered under NCT07017283.