The induction dose of rocuronium is typically decided based on the patient's body weight, but the effect duration of rocuronium is variable. Some studies suggest that body composition analysis data, such as skeletal muscle mass or total body water, may correlate better with the duration time of rocuronium. Therefore, we plan to analyse body composition in patients undergoing total intravenous general anesthesia, give the patients a fixed dose (50mg) of rocuronium, and check the correlation between duration time of rocuronium and body composition analysis data.

Inclusion Criteria:

• Adult patients with ASA class I-II undergoing total intravenous general anesthesia

Exclusion Criteria:

• too overweight (over 111.11kg, which corresponds to less than 0.45mg/kg of induction dose of rocuronium)
• too underweight (under 41.67kg, which corresponds to more than 1.2mg/kg of induction dose of rocuronium)
• pregnancy
• prediagnosed muscle or nerve related disease
• unsuitable for body composition analysis using bioelectrical impedance method
• unsuitable for neuromuscular block monitoring

Adult patients with ASA class I-II undergoing total intravenous general anesthesia