Abstract: Objective To investigate the effects of dexmedetomidine combined with ropivacaine for erector spinae plane block (ESPB) on analgesic efficacy, inflammatory stress and cognitive function in patients undergoing thoracoscopic lung cancer surgery. 
Methods A total of 104 patients who underwent thoracoscopic lung cancer surgery in Pizhou People's Hospital, Jiangsu Province, were selected and divided into research group (n=52) and control group (n=52) by random number table method. The control group received ESPB combined with general anesthesia. On the basis of the control group, the research group was supplemented with dexmedetomidine combined with ropivacaine. The analgesic efficacy, inflammatory response, oxidative stress response, cognitive function and anesthesia-related adverse reactions were compared between the two groups. 
Results The visual analogue scale (VAS) score of both groups decreased gradually after surgery, and there were significant differences in interaction between groups, time points and time points between groups (P＜0.05). After surgery, the serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in both groups first increased and then decreased, and there were significant differences in interactions between groups, time points, and time points between groups (P＜0.05). After surgery, the serum superoxide dismutase (SOD) level of the two groups increased gradually, and there were significant differences in interactions between groups, time points, and time points between groups (P＜0.05). The level of serum malondialdehyde (MDA) in the two groups decreased gradually after surgery, and there were significant differences in interactions between groups, time points, and time points between groups (P＜0.05). After surgery, the scores of mini-mental state examination (MMSE) in both groups gradually decreased, and there were significant differences in interactions between groups, time points, and time points between groups (P＜0.05). There was no difference in the total incidence of anesthesia-related adverse reactions between the two groups (P＞0.05). 
Conclusion Dexmedetomidine combined with ropivacaine for ESPB is effective for analgesia in patients undergoing thoracoscopic lung cancer surgery, which can reduce the inflammatory response and oxidative stress response, and improve cognitive function, with good safety. 

Key words: lung neoplasms, laparoscopy, dexmedetomidine