Study protocol
pain
All participants undergo an ERCP under sedation using midazolam (approximately 0.05 mg/kg) with pethidine hydrochloride (an initial dose of 35 mg) to maintain the appropriate level of sedation using the Ramsay scale (Ramsay score 4: patient exhibits brisk response to light glabellar tap or loud auditory stimulus; and Ramsay score 5: patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus). The sedation level is evaluated by Ramsay score before the start of sedation, after administration of a sedative, before the insertion of a scope, and at regular intervals after the end of treatment. The sedation level during treatment is evaluated and recorded every 5 min in the same manner as other vital sign evaluations. The NHF is generated by the Airvo™ 2 (Fisher & Paykel Healthcare Ltd., Auckland, New Zealand) with heated humidified air at a flow rate of 40 to 60 L/min.Sedation is performed by an endoscopist using midazolam (approximately 0.05 mg/kg) with pethidine hydrochloride (initial dose of 35 mg) under consultation with an anesthesiologist. Midazolam bolus or pethidine hydrochloride is administered when patients are suspected of experiencing excessive pain or discomfort. When additional intravenous pethidine hydrochloride is administered, the administration unit should be 17.5 mg.Additional doses of midazolam or pethidine hydrochloride are administered at the discretion of the endoscopist, but basically pethidine hydrochloride supersedes midazolam. The depth of sedation is assessed using the Ramsay scale every 5 min, along with the total dose of sedatives and the amount of sedative drug and effective opioid analgesic drug administered and the timing of each amount.The transcutaneous COFor the SpOTo ensure patients’ safety, rescue 50% supplemental O