Effect of Pre-injection of Rocuronium on Neuromuscular Blockade Onset Time and Hemodynamics During General Anesthesia Induction

• Rocuronium Bromide (Pretreatment Injection) (Drug): Low-dose rocuronium bromide is injected intravenously in advance before anesthesia induction
• Rocuronium Bromide (Conventional Injection) (Drug): Rocuronium bromide is administered by standard routine intravenous injection during anesthesia induction

Primary outcomes

• Neuromuscular blockade onset time [Within 5 minutes after completion of rocuronium-bromide injection]: The time interval from injection of rocuronium bromide to maximum neuromuscular block effect

Secondary outcomes

• Systolic Blood Pressure (SBP) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]
• Diastolic Blood Pressure (DBP) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]
• Mean Arterial Pressure (MAP) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]
• Heart Rate (HR) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]
• Cardiac Output (CO) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]: Measurement instrument: Non-invasive continuous blood pressure and cardiac output monitoring system (Model T20A). Measurement method: Finger cuff volume pulse wave plethysmography, the device automatically calculates real-time CO value, unit: L/min. Assessment method: Record stable CO value after waveform stabilization for 10 seconds at each time point; compare absolute value and percentage change vs baseline to evaluate the hemodynamic effect of rocuronium.
• Stroke Volume (SV) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]: Measurement instrument: Non-invasive continuous blood pressure and cardiac output monitoring system (Model T20A). Measurement method: Continuous finger pulse wave monitoring, automatic calculation of stroke volume (unit: mL/beat). Assessment method: Record stable SV readings at each time point and analyze dynamic changes compared with baseline.
• Systemic Vascular Resistance (SVR) [Baseline (before rocuronium-bromide injection), 0.5-minute, 1-minute, 2-minute, 3-minute and 5-minute after rocuronium-bromide injection。]: Measurement device: Non-invasive continuous blood pressure and cardiac output monitor (Model T20A). Measurement method: SVR (unit: dyn·s·cm-⁵) is automatically calculated by the monitor using real-time mean arterial pressure, central venous pressure and cardiac output. Assessment: SVR values were recorded once readings stabilized to assess changes in total peripheral vascular resistance after rocuronium administration.
• Injection Pain [Pain assessment is performed within 5 minutes after completion of rocuronium injection.]: Four-point grading scale for evaluating limb withdrawal reaction induced by injection pain: 0 = No limb contraction or twitching; 1. = Only slight wrist movement, no movement of other arm joints; 2. = Entire arm movement/withdrawal involving elbow, shoulder and other joints; 3. = Systemic response with movements across multiple limbs beyond one single limb. Subjects with a score ≥1 are defined as having injection pain.
• Limb Withdrawal Response [Assessment shall be completed within 5 minutes after rocuronium injection.]: Four-point grading scale for evaluating limb withdrawal reaction induced by injection pain: 0 = No limb contraction or twitching; 1. = Only slight wrist movement, no movement of other arm joints; 2. = Entire arm movement/withdrawal involving elbow, shoulder and other joints; 3. = Systemic response with movements across multiple limbs beyond one single limb. Subjects with a score ≥1 are defined as having injection pain.
• Adverse Events [Continuous assessment from the start of anesthesia induction until the end of surgery; the maximum assessment period is the perioperative period of a single operation.]: Record adverse events occurring during perioperative period, including severe bradycardia (heart rate <45 beats per minute), hypotension (mean arterial pressure MAP <65 mmHg), various arrhythmias and allergic reactions. The number and incidence of each type of adverse event will be counted. Assessment method: Vital signs are continuously monitored intraoperatively. Anesthesiologists identify and record all eligible adverse events in real time, with documentation of onset time, duration and corresponding interventions.

Sex: All, ages: 18 Years to 65 Years, accepts healthy volunteers

Inclusion Criteria:

* Aged from 18 to 65 years old
* American Society of Anesthesiologists (ASA) physical status classification Ⅰ, Ⅱ or Ⅲ
* Elective surgery requiring general anesthesia with tracheal intubation
* Able to understand the study and voluntarily sign written informed consent
* Male or female, no gender restriction

Exclusion Criteria:

* Severe hepatic dysfunction (ALT/AST > 3 times the upper limit of normal) or renal dysfunction (creatinine > 2 times the upper limit of normal)
* Central nervous system diseases or severe neuromuscular disorders
* Severe arrhythmia or cardiac dysfunction (NYHA class Ⅲ-Ⅳ, or ejection fraction EF < 30%)
* Known hypersensitivity or allergy to rocuronium, midazolam, propofol or other study-related drugs
* Refusal to participate in this clinical trial
* Pregnant or breastfeeding women
* History of predicted difficult airway requiring awake tracheal intubation
* Contraindications to rapid sequence induction