Muscle Relaxant Effect and Safety of Mivacurium Chloride and Succinylcholine for Bronchoscopy

The goal of this clinical trial is to evaluate whether mivacurium chloride and succinylcholine can provide effective and safe muscle relaxation in adult patients aged 18-60 years undergoing bronchoscopy who require muscle relaxants during anesthesia. The main questions it aims to answer are:

* Is the recovery of spontaneous breathing within 15 minutes after drug discontinuation with mivacurium chloride non-inferior to succinylcholine? * How do mivacurium chloride and succinylcholine compare in terms of intraoperative hemodynamics and post-operative recovery and comfort? Researchers will compare the mivacurium chloride group and the succinylcholine group to observe if mivacurium chloride can provide similar or better recovery effects compared to succinylcholine.

Participants will:

* Receive either mivacurium chloride (0.14 mg/kg induction bolus + 0.5 mg/kg/h maintenance infusion) or succinylcholine (1 mg/kg induction bolus + 5 mg/kg/h maintenance infusion) as a muscle relaxant during bronchoscopy. * Have their vital signs, including blood pressure, oxygen saturation, and heart rate, monitored at multiple time points during the procedure. * Be assessed post-procedure for spontaneous breathing recovery, consciousness recovery, and time to laryngeal mask airway (LMA) removal, as well as overall comfort and satisfaction.