I. Research purpose

1.1 Main Objective: To investigate the efficacy and safety of bupivacaine liposome thoracic paravertebral nerve block for postoperative analgesia after thoracoscopic lobectomy

1.2 Exploratory Objective: To investigate the noninferiority of bupivacaine liposomes in thoracic paravertebral nerve block with standard bupivacaine

Standard monitoring, including electrocardiography (ECG), heart rate (HR), noninvasive blood pressure (NIBP), pulse oxygen saturation (SpO2), end-tidal carbon dioxide (ETCo2), and bispectral index (BIS) was initiated on arrival in the operating room. A neuromuscular monitor (JS-100, Beijing SLGO Medical Technology Co., Ltd., China) was used to confirm neuromuscular block (NMB).

Intravenous anesthesia was induced with 0.04 mg/kg midazolam, 0.3-0.5 μg/kg sufentanil, 1.5-2.5 mg/kg propofol, and 0.6 mg/kg rocuronium. Hemodynamics were supported with vasoactive agents (atropine, norepinephrine, dopamine, esmolol) as needed. After the train of four count (TOFC) ratio reached zero, a double-lumen tube or a single-lumen tube with a bronchial blocker was inserted, with correct positioning confirmed by fiberoptic bronchoscopy. Under real-time ultrasound visualization, a senior anesthesiologist performed thoracic paravertebral blocks at the T4-5, T6-7, and T8-9 levels in patients placed in the lateral decubitus position, injecting 6 mL, 8 mL, and 6 mL of local anesthetic at the respective levels.

Group B : Patients in the intervention group received a mixture of 10 mL of 1.33% liposomal bupivacaine (133 mg) and 10 mL of 0.5% bupivacaine hydrochloride,.

Group A: whereas those in the control group received 20 mL of 0.5% bupivacaine hydrochloride (total dose, 100 mg).

All patients received total intravenous anesthesia during surgery. Propofol was administered at a rate of 2-4 mg/kg/h, and remifentanil was administered at a rate of 0.05-0.3 μg/kg/min to maintain a BIS value range from 40 to 60. Rocuronium will be administered and adjusted to achieve deep NMB (defined as a TOFC=0 and a post-tetanic count =1-2). Standard ventilation parameters included a respiratory rate of 10-12 breaths·min-¹ and a positive end-expiratory pressure (PEEP) of 5cmH₂O. During double-lung ventilation, a tidal volume of 8 mL/kg was used, with ETCo2 maintained between 35-45 mmHg and peak airway pressure kept below 20cmH₂O. During single-lung ventilation, the tidal volume was reduced to 6 mL/kg, with ETCo2 maintained below 60 mmHg and peak airway pressure kept below 30cmH₂O. Intravenous sufentanil (0.15 μg/kg) and ondansetron hydrochloride (8mg) were administered prior to the end of surgery. After surgery, patients were transferred to the post-anesthesia care unit (PACU) for further monitoring. Additionally, 2-4 mg/kg of sugammadex was given to reverse the residual effect of rocuronium.

In the PACU, an intravenous bolus of 0.1 μg/kg sufentanil was administered when the numeric rating scale (NRS; 0, no pain; 1-3, mild pain; 4-6, moderate pain; and 7-10, severe pain) score was ≥4. The drugs used for postoperative patient-controlled intravenous analgesia (PCIA) were sufentanil (2 μg/kg), which were diluted in 0.9% normal saline to a final volume of 100mL. The analgesia pump settings were as follows: background dose, 0 mL/h; self-controlled additional dose, 1 mL/time; and lockout time, 10 min. The patients were sent to the ward upon meeting the following criteria for at least 30 minutes: NRS score <4, an Adrelete score ≥9 and absence of other adverse reactions. The number of PCA attempts and the total drug delivery were automatically recorded by the postoperative analgesia system.

Inclusion Criteria:

• 1) Age ≥18 years old;

  2) Patients undergoing unilateral initial thoracoscopic lobectomy under general anesthesia (TV or robot-assisted);

  3) American Society of Anesthesiologists (ASA) Grade I - III;

  4) Voluntarily participate in the study and sign the informed consent.

Exclusion Criteria:

• 1) Pregnant or lactating women;

  2) Pulmonary wedge-shaped resection;

  3) ≥2 thoracic drainage tubes;

  4) Abnormal liver function: ALT and/or AST>2×ULN, or

TBIL≥1.5×ULN;

5) Renal function impairment (serum creatinine >176μmol/L), or received dialysis treatment within 28 days before surgery;

6) Participate in another research trial involving an investigational drug within 6 months;

7) A history of drug or alcohol abuse;

8) Long-term use of opioids (more than 3 months or more than 5 mg daily morphine equivalent per day for 1 month);

9) History of allergy to local anesthetics or one of the investigational drugs;

10) Uncontrolled mental or neurological symptoms.