This clinical study investigates the effects of lidocaine aerosol as an adjunct to low-dose cisatracurium for endotracheal intubation during ERCP (Endoscopic Retrograde Cholangiopancreatography) procedures. The aim is to assess whether lidocaine aerosol can improve the clinical conditions of intubation to a level comparable to the standard dose of cisatracurium, while reducing the amount of muscle relaxant required. The study also seeks to evaluate the impact of this approach on intubation success, extubation time, and recovery time in the operating room, ultimately improving the efficiency of the operating room. Participants will be randomly assigned to either the low-dose cisatracurium group with lidocaine aerosol or the standard-dose cisatracurium group. The primary outcome is the incidence of clinically acceptable intubation conditions, defined by the Cooper's grading system.

Retrospective registration note. Enrollment began on January 17, 2025, was temporarily paused due to investigator training, and is being reactivated at the time of registration. No changes were made to the prespecified primary outcome or analysis plan. This single-center, randomized (1:1), single-blind trial in adult ERCP patients compares low-dose cisatracurium (≈0.05 mg/kg) plus topical lidocaine aerosol versus conventional-dose cisatracurium (≈0.15 mg/kg). Intubation is performed with a video laryngoscope ~3 min after induction. Primary outcome: clinically acceptable intubation conditions (Cooper score ≥6) at the intubation attempt; key secondary outcomes include intubation time, first-pass success, procedure/OR times, extubation time, and safety through 24 h.

Inclusion Criteria:

• Scheduled ERCP under general anesthesia requiring endotracheal intubation.
• Hepatic dysfunction: Child-Pugh class B or C.
• Age 18-70 years.
• ASA physical status I-III.

Exclusion Criteria:

• Severe cardiovascular, cerebrovascular, or respiratory disease judged by investigators to increase risk.
• Predicted difficult airway (e.g., Mallampati IV, mouth opening <3 cm, limited neck extension).
• Suspected gastrointestinal obstruction on preoperative assessment.
• Cervical spine disease with limited neck mobility.
• Child-Pugh class C with hepatic encephalopathy.
• Neuromuscular disease.
• Recurrent laryngeal nerve injury or vocal cord dysfunction.
• Pregnancy or breastfeeding.
• Known allergy/hypersensitivity to any study anesthetic (e.g., cisatracurium, lidocaine, propofol, remifentanil, or sufentanil).
• Refusal to participate in the clinical trial.

Participants are blinded to allocation. Care providers and investigators who prepare drugs and perform intubation are not blinded. Intubation conditions (Cooper score) are rated by the intubating anesthesiologist (unblinded). Objective secondary outcomes (e.g., intubation time, first-pass success, hemodynamic thresholds) are included to mitigate assessment bias.