This prospective randomized single-blind study evaluated the safety and efficacy of combining dexmedetomidine nasal spray with propofol for ERCP (Endoscopic Retrograde Cholangiopancreatography) sedation in eligible patients aged 18-70 years undergoing elective procedures. The primary objectives were to determine: 1) whether this regimen reduced intraoperative hypoxemia (decreased blood oxygen levels), decreased propofol dosage, and improved postoperative recovery quality; 2) to assess nasal administration safety and identify potential medical issues (e.g., abnormal blood pressure or bradycardia) compared to intravenous injection and control group protocols. Participants were randomly assigned to three groups: ① nasal spray group (preoperative nasal spray of dexmedetomidine + propofol), ② intravenous group (preoperative intravenous injection of dexmedetomidine + propofol), ③ and conventional group (propofol alone).

General Information purpose of research：To evaluate the safety and effectiveness of right mebromide nasal spray combined with propofol in endoscopic retrograde cholangiopancreatography.

Patients with no restriction on gender, aged 18-70 years, with a BMI of 18-30 kg/m², and American Society of Anesthesiologists (ASA) physical status Ⅰ or Ⅱ.

Exclusion criteria: - Patients who explicitly refused to participate in the study; - Patients with difficult airway management (modified Mallampati score of Grade IV); - Patients with anemia or thrombocytopenia (Hb < 90 g/L, PLT < 80×10⁹/L); - Patients with abnormal liver or kidney function; - Patients with a history of nasal surgery/trauma or deviated nasal septum; - Patients with allergies or contraindications to dexmedetomidine, opioids, propofol, rocuronium, or their components; - Patients with a history of abnormal recovery from previous surgery or anesthesia.

Patients were divided into three groups using a random number table method: pre-intranasal spray combined with infusion group (PP group), conventional intravenous combined with infusion group (CP group), and control group (C group).

Anesthetic Method All patients fasted from liquids for 4 hours and solids for 8 hours before surgery. Upon entering the pre-anesthesia preparation room, an upper limb venous access was established, and sodium bicarbonate Ringer's solution was infused at a rate of 300 mL/h. After entering the operating room, the patient assumed a "lateral prone position" and received oxygen via a nasal cannula at a flow rate of 5 L/min until the completion of ERCP and full awakening. All ERCP procedures were performed by experienced endoscopists. Non-invasive blood pressure, heart rate, electrocardiogram, pulse oxygen saturation, and bispectral index (BIS) were monitored. An anesthetic machine, laryngeal mask, endotracheal tube, rescue equipment, and drugs were prepared. Anesthetics were infused through the forearm venous access of the patient. Anesthetic induction methods: - Experimental Group ① (PP group): Thirty minutes before entering the operating room, 50-100 μg of dexmedetomidine injection was administered via intranasal spray in the pre-anesthesia preparation room (Administration method: Hold the dexmedetomidine nasal spray upright. Keep the nozzle away from the mouth, nose, eyes, and other body parts. Place the index and middle fingers on both sides of the top of the spray pump, and the thumb at the bottom of the bottle. Press the spray pump downward with uniform force using the index and middle fingers for 7 times, and at least one complete spray should be observed within these 7 presses. Clean the nostrils before use to ensure the nasal cavity is dry and clean. The patient should be in a sitting position with the head slightly tilted forward, and the product should remain upright during use. Insert the nozzle of the nasal spray into the nostril at an angle consistent with the nasal cavity. Press the spray pump downward fully with uniform force using the index and middle fingers (1 spray). After spraying 1 dose into each nostril, tilt the head slightly backward and inhale gently. After a 30-second interval, spray another dose into each nostril, with a total of 2-4 sprays). Upon entering the operating room, induction was performed with intravenous sufentanil (Yichang Renfu Pharmaceutical Co., Ltd.) at a dose of 0.1 μg/kg and propofol (Jiabo Pharmaceutical, Guangdong, China) at a dose of 1.5-2.0 mg/kg (intravenous injection time > 30 seconds). During induction, the modified Observer's Assessment of Alertness/Sedation (MOAA/s) scale score was evaluated every 30±10 seconds. If the MOAA/s score was still > 1 after 2 minutes, additional sedatives were supplemented (supplementary dose = 1/2 of the initial dose, injection time ≥ 10 seconds). When the patient's MOAA/s score ≤ 1, the endoscopist began to insert the endoscope and continued to infuse sedatives. - Experimental Group ② (CP group): Thirty minutes before induction, normal saline was administered via intranasal spray; 10 minutes before induction, 0.5 μg/kg of dexmedetomidine was administered intravenously. Induction was performed with sufentanil (0.1 μg/kg) and propofol (1.5-2.0 mg/kg), and the remaining procedures were the same as those in the PP group. - Control Group (C group): Induction was performed with sufentanil (0.1 μg/kg) and propofol (1.5-2.0 mg/kg), and the remaining procedures were the same as those in the two experimental groups. At the end of ERCP, the MOAA/s score was evaluated every 3 minutes until the patient was fully awake (MOAA/s score = 5 in three consecutive evaluations). After surgery, the Aldrete score was calculated every 5 minutes, and the patient was transferred from the post-anesthesia care unit (PACU) to the ward when the score reached ≥ 9 in three consecutive evaluations.

Management of intraoperative adverse events: - For intraoperative hypoxemia or apnea (SpO₂ < 90% for more than 10 seconds): First, increase the oxygen flow rate by 2 L/min; second, lift the mandible, reduce the depth of anesthesia, and insert a nasopharyngeal airway to improve ventilation. - For intraoperative hypotension (systolic blood pressure < 90 mmHg or mean arterial pressure decreased by 20% relative to baseline for more than 2 minutes): Administer 4-12 μg of norepinephrine intravenously. - For bradycardia (heart rate < 50 bpm for more than 1 minute): Administer 0.3-0.5 mg of atropine intravenously.

Observation Indicators :Primary indicators: Intraoperative hypoxemia (SpO₂ < 90% for more than 10 seconds).Secondary indicators: Circulatory fluctuations: Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), and pulse oxygen saturation (SpO₂) were recorded at the following time points: on entry to the operating room (T0), after induction (T1), when the endoscope entered the esophagus (T2), during duodenal papillary intubation (T3), when the endoscope was removed (T4), and at awakening (T5). Incidence of intraoperative adverse events: Including cough during endoscope insertion, nausea, vomiting, postoperative agitation, pain score, respiratory depression, and use of vasopressors during surgery. Induction and maintenance dosages of propofol. Evaluation of awakening speed and quality: Extubation time, and Steward score immediately after awakening and 30 minutes after awakening. Assessment of agitation and sedation levels using the Richmond Agitation-Sedation Scale (RSAS); assessment of pain and analgesic requirements within 24 hours after surgery using the Numerical Rating Scale (NRS).

Statistical Analysis Based on the safety evidence of dexmedetomidine and references to previous clinical trials, the incidence of hypoxemia was approximately 13.3% in the dexmedetomidine group and 26.7% in the control group among subjects undergoing elective general anesthesia induction. With a type Ⅰ error rate (α) of 0.05, a type Ⅱ error rate (β) of 0.1, and an attrition rate of 10%, the total sample size (N) was calculated using PASS software to be 180, with N1 = N2 = N3 = 60. Statistical analysis was performed using SPSS 31 software. Measurement data conforming to a normal distribution were expressed as mean ± standard deviation (x±s), and one-way analysis of variance was used for intergroup comparison. Measurement data not conforming to a normal distribution were expressed as median (M) and interquartile range (IQR), and the nonparametric Mann-Whitney U test was used for intergroup comparison. Count data were expressed as cases (%), and the χ² test or Fisher's exact test was used for intergroup comparison. The rank sum test was used for comparison of ordinal data. A P-value < 0.05 was considered statistically significant.

Inclusion Criteria:

• no restriction on gender,
• aged 18-70 years,
• BMI of 18-30 kg/m²,
• American Society of Anesthesiologists (ASA) physical status Ⅰ or Ⅱ.

Exclusion Criteria:

• Patients who explicitly refused to participate in the study;
• Patients with difficult airway management (modified Mallampati score of Grade IV);
• Patients with anemia or thrombocytopenia (Hb < 90 g/L, PLT < 80×10⁹/L);
• Patients with abnormal liver or kidney function;
• Patients with a history of nasal surgery/trauma or deviated nasal septum;
• Patients with allergies or contraindications to dexmedetomidine, opioids, propofol, rocuronium, or their components;
• Patients with a history of abnormal recovery from previous surgery or anesthesia.

While the anesthesiologists who collected data during ERCP were not blinded, they were excluded from analyzing the follow-up results. The anesthesia was administered by the same experienced anesthesiologist, with post-anesthesia evaluation and follow-up care handled by a different physician. Neither the patients nor the data collectors were aware of the sedation protocol.