RESUMO
Objective To investigate the influence of continuous infusion of tramadol on target plasma propofol concentration during maintenance of anesthesia with target-controlled infusion (TCI) system. Methods Fifty ASA Ⅰ - Ⅱ patients (22 male, 28 female) aged between 20-70 yr and weighing 42-85 kg, were randomly divided into two groups of 25 patients each: in group Ⅰ anesthesia was maintained with propofol given by TCI; in group Ⅱ anesthesia was maintained with propofol given by TCI and continuous tramadol infusion (loading dose 3 mg?kg and 0.5 mg?kg ?h for maintenance). The patients were premedicated with intramuscular scopolamine 0.3 mg. Anesthesia was induced with midazoiam 0.035 mg?kg-1, fentanyl 0.1 mg, target plasma propofol concentration 2.5-3.5 ?g?ml-1 and vecuronium 0.1-0. 15mg?kg . After tracheal intubation the patients were mechanically ventilated. During maintenance of anesthesia BIS was maintained at 50 ? 10 by adjustment of target plasma propofol concentration. BIS, MAP, HR, HRV and LF/HF were continuously monitored. The total amount of propofol used during operation, the duration of surgery and time of recovery from anesthesia were recorded. Results There was no significant difference in BIS value between the two groups. Target plasma concentration of propofol was significantly higher at skin incision and extubation in group Ⅰ than that in group Ⅱ (P