ABSTRACT
Objective To estimate the relationship between the parameters used to estimate the depth of anesthesiaMethods Fifty-two ASA I - II patients undergoing choleeystectomy or exploration of eommon bile duet without jaundice were emdled in the study. Premedieation consisted of midazolam 5 mg and atropine 0.5 mg im.30 min before operation. Anesthesia was induced with fentanyl 4 ug.kg-1 , droperidol 0.08 mg.kg-1 , propofol 2 mg. kg-1 and vecuronium 0.1 mg.kg-1 , and maintained with enflurane and continuous infusion of propofol and intermittent intravenous boluses of vecuronium. The patients were intubated and mechanically ventilated. B1S,HRV and BP were continuously monitored and recorded before induction (T1 ) , 1 min(T2 ) , 3 min(T3 ) after intubation, 1 min before skin incision (T4) , 3 min after skin incision (T5), 1 h after induction (T6), 1 min before extubation (T7) and when the patient was conscious (T8). Blood samples were taken at the same intervals for detenninaton of blood propofol and cortisol level (n = 18) by using radioimmunoasscey and HPL, BIS was maintained at 30 ~ 60 during anesthesia by adjustment of propofol infusion rate. Results There was negative correlation between plasma propofol concentration and BIS/MAP; there was positive correlation between HR and MAP. Plasma cortisol level was positively correlated with BIS, MAP and HR and negatively correlated with plasma propofol concentration. Conclusion The LF and HF can reflect the changes in cardiac sympathetic-vagal tension but cannot reflect the depth of anesthesia. Stress response can be controlled by plasma propofol concentration and estimated by BIS,MAP and HR monitoring.