Abstract: Objective To compare the effects of sevoflurane pretreatment and dexmedetomidine (DEX) on postoperative cognitive dysfunction (POCD) in elderly patients with surgery for esophageal carcinoma, and to explore its possible mechanism. Methods A total of 120 patients who underwent esophageal carcinoma were assigned to the following four groups (n=30 for each group): control group, sevoflurane group, DEX group and DEX+sevoflurane group. Before intravenous induction, control group accepted to inhale oxygen, sevoflurane group accepted to pretreat with sevoflurane, DEX group accepted to inhale oxygen and to pretreat with DEX, and DEX+sevoflurane group accepted to pretreat with sevoflurane and DEX. The heart rate (HR) and mean arterial pressure (MAP) before anesthesia administration, after the intubation and extubation were observed in the four groups. The 48 h VAS scores and POCD incidence at 1 d, 3 d and 7 d after operation were compared between the four groups. The S100β and NSE protein concentrations were measured by ELISA before anesthesia administration，after extubation and the 1st, 3rd, and 7th postoperative days. Results There was no interaction between sevoflurane and DEX on HR and MAP during the experiment (P＞0.05). Compared with the control group, the HR decreased in the sevoflurane pretreatment group only after the intubation (P＜0.05), and the HR and MAP decreased in DEX group after the intubation and at the time of extubation (P＜0.05). There was no significant difference in the proportion of patients with satisfactory and analgesia ratio in sevoflurane group 48 h after surgery (P＞0.05). Compared with the control group and sevoflurane group, the proportion of patients with satisfactory and analgesia ratio increased in Dex group and Dex + sevoflurane group, while the proportion of patients with 4-10 scores decreased (P＜0.05). Compared with the control group, the incidence of POCD one day after surgery was decreased in the sevoflurane group, the incidence of POCD 1 d and 7 d after surgery was decreased in the DEX group, and the incidence of POCD 1 d, 3 d and 7 d after surgery was decreased in the DEX+sevoflurane group (P＜0.05). There was no interaction between sevoflurane and DEX on serum S100β protein and NSE protein concentrations during the experiment (P＞0.05). The serum levels of S100β protein and NSE protein decreased after the extubation and 1 d, 3 d after operation in sevoflurane group compared with those of control group (P＜0.05). The serum levels of S100β protein and NSE protein also decreased after the extubation and 1 d, 3 d and 7 d after operation in DEX group (P＜0.05). Conclusion Both sevoflurane and DEX pretreatment can inhibit the increased serum levels of S100β and NSE protein in elderly patients after the surgery for esophageal carcinoma, thereby reducing the incidence of POCD. DEX is more effective, but the combined effect of the two drugs is not ideal.

Key words: esophageal neoplasms, aged, cognitive dysfunction, anesthetics, combined, Dexmedetomidine, S100 calcium binding protein beta subunit, phosphopyruvate hydratase, Sevoflurane