Monitoring on depth of anesthesia and determination of true blood Propofol concentration in patients with inhalation of Isoflurane and TCI of Propofol

[Objective] To evaluate the effects of monitoring on the depth of anesthesia in patients with inhalation of Isoflurane and TCI of Propofol by observing the changes of AEP index and determination of the true blood Propofol concentration. [Methods] 20 ASA physical statusⅠ~Ⅱ patients undergoing selective abdominal operations. Anesthesia was induced with Poprofol and Vecuronium. After tracheal intubation, the patients were ventilated with 1.0 MAC Isoflurane in pure oxygen, and after 20 minutes, Propofol was administered with TCI according to the different target plasma concentration from 1.0 μg/mL to 3.0 μg/mL (increased 0.5 μg/mL every time). The changes of mean arterial pressure (MAP), heart rate (HR) and AEP index were recorded simultaneously. Blood samples were taken from radial artery for determination of blood Propofol concentration at the time points of different target plasma concentration of Propofol. [Results] There was no close correlation between both MAP and HR and the target plasma concentration of Propofol. The coefficient of correlation between AAI and the target plasma concentration of propofol was -0.923 (P 0.001). The coefficient of correlation between AAI and the stimulation of endotracheal intubation was -0.728 (P 0.001), however, There was no close correlation between AAI and the stimulation of skin incision and exploration. There was a very high correlation between the target plasma concentration and the measured blood concentration, the coefficient of correlation between both concentrations was r =0.951 (P 0.001). [Conclusion] AEP index is the reliable parameters to monitor the depth of anesthesia with Isoflurane and Propofol, and in response to the stimulation of tracheal intubation too, AEP index can not be used to predict the cardiovascular reaction of skin incision and exploration. The target plasma concentration can be used to indicate the true blood Propofol concentration.