Effect of Ropivacaine combined with different doses of dexamethasone on thoracic paravertebral nerve block analgesia: a randomized controlled double-blind trial

INTERVENTION: Group R1:Ropivacaine 80 mg (specification: 100 mg/10 ml) and dexamethasone 2.5 mg (specification: 5 mg/1 ml) are added to normal saline to a total volume of 20 ml for thoracic paravertebral nerve block.;Group R2:Ropivacaine 80 mg (specification: 100 mg/10 ml) and dexamethasone 5.0 mg (specification: 5 mg/1 ml) are added to normal saline to a total volume of 20 ml for thoracic paravertebral nerve block.;Group R3:Ropivacaine 80 mg (specification: 100 mg/10 ml) and dexamethasone 10.0 mg (specification: 5 mg/1 ml) are added to normal saline to a total volume of 20 ml for thoracic paravertebral nerve block.;Blank control group:Ropivacaine 80mg (specification: 10ml 100mg) was added to normal saline to a total volume of 20ml, and then a thoracic paravertebral nerve block was performed.; CONDITION: postoperative analgesia PRIMARY OUTCOME: Patient's first remedial analgesia; SECONDARY OUTCOME: Postoperative Pain at Rest Numeric Rating Scale (NRS) Score;Postoperative Pain on Action Numeric Rating Scale (NRS) Score;heart rate;mean arterial pressure;blood glucose;Postoperative chronic pain;adverse reaction;adverse event;important adverse event;serious adverse event;serious adverse reaction; INCLUSION CRITERIA: 1. It meets the indication of unilateral thoracoscopic lobectomy or partial lobectomy 2. Age between 18 and 75 years, inclusive; both males and females are eligible 3. American Society of Anesthesiologists (ASA) Grade I‐III 4. Body mass inde X(BMI) between 18.5 and 28 kg/m², inclusive 5. Patients who voluntarily participate in this experiment and sign the consent form