Abstract PR035

Abstract

Background & Objectives: This study was designed to determine whether dexmedetomidine improves the depressed baroreflex function induced by anesthetics in patients undergoing general anesthesia. Materials & Methods: 72 patients were accepting elective breast lumpectomy undering general anesthesia, and 60 patients completed this study finally. The patients were randomly assigned to one of the two groups (n=30): Dex (treated with dexmedetomidine 0.5 μg/kg for 10 minutes, followed by 0.4μg kg-1 h-1) group and Con group (treated with equal amount of isotonic saline). After the 10-minutes bolus infusion, patients were anaesthetized with propofol 2 mg/kg, sufentanil 0.5 μg/kg and rocuronium 0.6 mg/kg. After loss of consciousness, the laryngeal mask were placed, patients’ lungs were ventilated mechanically. Anesthesia was maintained with propofol and remifentanil. BRS and hemodynamic parameters were measured using Finapres Medical Systems for 5 minutes. Finapres parameters were obtained at the four periods: when patients were calmed down after entering the operating room (T1), after the 10-minutes Dex or saline bolus infusion (T2), 5 min after placing the laryngeal mask (T3), and 5 min after the start of operation (T4). The use of vasoactive medications throughout the process of the study was recorded. Results: At time T3 and T4, BRS decreased in Con group compared with T1 (P<0.05). In Dex group, compared with T1, BRS were significantly higher at T2 (P<0.05), decreased at T3 (P<0.05). Compared with T1, there was no significant difference in BRS at T4 (P>0.05). At time T2, T3 and T4, BRS in Dex group were higher than in Con group (P<0.05). Conclusion: The results indicate that arterial baroreflex function is significantly depressed during anaesthesia in healthy surgical patients. Dexmedetomidine could improve the depressed baroreflex function during anaesthesia.