The purpose of this study is to evaluate the effect of intravenous lidocaine infusion on pain and opioid dosage in patients undergoing single-port thoracoscopic surgery,and to evaluate the effects of perioperative catecholamine levels, extubation time, incidence of nausea and vomiting, patient satisfaction and hospital stay.

The World Congress on Pain identified pain as the "fifth leading indicator of human life" after breathing, pulse, body temperature and blood pressure. Postoperative pain is an acute nociceptive pain caused by surgical trauma and is a complex stress response in the body, especially in 72 hours after surgery. Pain after thoracic surgery is a more severe type of surgery in various types of surgery.

Acute pain at the early stage of operation is not only an external signal of body injury, but also an independent factor inducing stress response and systemic inflammatory response syndrome (SIRS). Pain stimulus can also cause excessive release of catecholamine, damage of vascular endothelial cells and neutrophil aggregation, which can induce cytokine "waterfall" secretion. Stress, pain and inflammation induce and interact with each other, which seriously affects the early recovery of patients after operation. Timely and effective post-operative analgesia can not only alleviate patients'pain, but also avoid a series of stress reactions. It provides favorable conditions for the stability of patients' physiological function and recovery of their body after operation.

Although multimodal analgesia has largely replaced monotherapy with opioids, they are still the most commonly used drugs for postoperative pain. Lidocaine is an amide local anesthetic which when used intravenously demonstrates significant analgesic, anti-hyperalgesic and anti-inflammatory properties .

Intravenous infusion of lidocaine has a good effect on fibromyalgia, chronic neuropathic pain, opioid tolerance and other chronic pain, and can reduce postoperative acute pain. In the 1960s, Barlett et al. first published a study on the use of lidocaine intravenous infusion for postoperative analgesia.Since then, more and more researchers have begun to explore the use of lidocaine in the treatment of postoperative acute pain.In 2007, Kaba et al. selected patients who underwent colectomy as an experimental subject, and intravenously injected lidocaine during the perioperative period. The results showed that the pain of the experimental group was effectively relieved and the use of opioids was reduced. In 2008, Lauwick et al. used laparoscopic cholecystectomy as the experimental subject. The results showed that the dose of opioid analgesia in the lidocaine group was significantly lower than that in the control group, and the postoperative pain was effectively improved. In 2009, Yardeni et al. selected patients undergoing total hysterectomy as experimental subjects and intravenously injected lidocaine during the perioperative period. The results confirmed that the hemodynamics of the experimental group was more stable, the average dosage of anesthetics was reduced, and the pain was significantly improved.However, to date, there is no strong evidence for the effect of perioperative intravenous infusion of lidocaine in single-port thoracoscopic surgery, so we designed this study.

Inclusion Criteria:

• Patients undergoing single-port thoracoscopic with a left double lumen bronchial catheter
• Age ≧ 18 years old, ≦70 years old
• Temperature, white blood cells, and hemoglobin were normal before surgery
• Patient informed consent

Exclusion Criteria:

• Patients with a history of surgery within six months
• Patients with dysfunction of heart, liver, kidney, lung, pancreas or other important organs
• American Society of Anesthesiologists (ASA) physical Status classes ≧ Ⅲ
• Allergic to lidocaine
• Bradycardia (heart rate < 60 beats/min) or atrioventricular block
• Mental disorder
• Patients requiring a right double lumen bronchial catheter