Objective To investigate the effect of anesthesia factor on lung injury in patients undergoing thoracoscopic radical lung cancer surgery and to evaluate efficacy of combination of thoracic paravertebral block(TPVB) with dexmedetomidine mixed with ropivacaine and general anesthesia. Methods One hundred patients of both sexes, aged 18-64 yr, with body mass index of 18-25 kg/m2, of American Society of Anesthesiologists physical statusⅡor Ⅲ, scheduled for elective thoracoscopic radical lung cancer surgery, were divided into 5 groups(n=20 each) using a random number table: general anesthesia group(group G), TPVB with ropivacaine combined with general anesthesia group(group R), intravenously infused dexmedetomidine combined with general anesthesia group(group Div), intravenously infused dexmedetomidine plus TPVB with ropivacaine combined with general anesthesia group(group Div+ R), and TPVB with dexmedetomidine mixed with ropivacaine combined with general anesthesia group(group Dtp+ R). In group R, TPVB was performed under ultrasound guidance, two-point method was selected according to the position of intercostal space at surgical incision, and 0.5% ropivacaine 10 ml was injected into each puncture site.Dexmedetomidine 0.5 μg/kg was intravenously infused over 10 min in group Div.Dexmedetomidine was intravenously infused for TPVB in group Div+ R.TPVB solution contained dexmedetomidine 0.5 μg/kg and ropivacaine in group Dtp+ R.Anesthesia was then induced and maintained by IV infusion of propofol and remifentanil.The intraoperative consumption of propofol and remifentanil and development of adverse reactions such as hypoxemia, hypotension and bradycardia were recorded.Normal lung tissues around the tumor margin were obtained immediately after tumor resection for determination of the expression of hypoxia-inducible factor 1 alpha(HIF-1α), BCL2/adenovirus E1B 19kDa interacting protein 3(BNIP3) and microtubule-associated protein 1 light chain 3 Ⅱ(LC3 Ⅱ)(by Western blot), contents of tumor necrosis factor-alpha(TNF-α) and interleukin-6(IL-6) in lung tissues(by enzyme-linked immunosorbent assay) and cell apoptosis(by TUNEL) and for examination of the pathological changes(with a light microscope) which were scored.Apoptosis index was calculated. Results The amount of propofol consumed was significantly lower in Div+ R and Dtp+ R groups than in the other three groups, and the amount of remifentanil consumed was significantly higher in G and Div groups than in the other three groups(P<0.05). The incidence of hypertension and tachycardia was significantly lower in R and Div groups than in group G(P<0.05). The incidence of hypotension was significantly lower in R, Div and Dtp+ R groups than in group Div+ R(P<0.05). The incidence of bradycardia was significantly higher in Div and Div+ R groups than in group R(P<0.05). Compared with G and R groups, apoptosis index, contents of TNF-α and IL-6 and lung injury scores were significantly decreased, and the expression of HIF-1α, BNIP3 and LC3Ⅱ was up-regulated in Div, Div+ R and Dtp+ R groups(P<0.05). Compared with group Div, the TNF-α content and lung injury scores were significantly decreased, and the expression of HIF-1α and LC3Ⅱ was up-regulated in Div+ R and Dtp+ R groups, and the IL-6 content was significantly decreased in group Dtp+ R(P<0.05). Conclusion Combination of TPVB with dexmedetomidine mixed with ropivacaine and general anesthesia produces better efficacy in reducing lung injury in patients undergoing thoracoscopic radical lung cancer surgery. Key words: Dexmedetomidine; Amides; Nerve block; Anesthesia, general; Lung neoplasms