The incidence of awareness during total intravenous anesthesia by TCI of propofol combined with remifentanil

Objective To investigate the incidence of awareness during total intravenous anesthesia by target-controlled infusion(TCI)of propopol combined with remifentanil in non-cardiac surgery and to analyze the possible reasons for its occurrence and related factors,in order to reduce the incidence of intraoperative awareness during total intravenous anesthesia by TCI.Methods One thousand and sixty-one patients who underwent the selected non-cardiac surgery were enrolled,age ranged from 19to 72years,ASA Ⅰ-Ⅲ,without neurophysiological monitoring.The plasma target concentrations of propofol and remifentanil were set according to the Marsh′s model and Minto equation respectively.All patients received propofol and remifentanil at an initial plasma concentration of 3.0-4.0μg/ml and 5-6ng/ml respectively,vecuronium 0.1mg/kg or cisatracurium besilate 0.2 mg/kg was administered and then tracheal intubation was achieved.Anestheisa were maintained by TCI of propofol(plasma target concentration,3.0-3.5μg/ml)and remifentanil(plasma target concentration 5.0-6.0ng/ml),fentanyl 0.1mg was given before skin incision if the surgery lasted more than 2hours estimated,neuromuscular blocking drugs were adminstered intermittently during anesthesia.TCI of propofol was ceased at 15 minutes before surgery was over,while TCI of remifentanil was ceased at skin closure and fentanyl 0.1μg/kg was given.The consumption and transfusing duration of propofol and remifentanil,and the plasma concentrations of propofol during maintain period were recorded.Interviews were conducted twice during 24hand 72hpostoperatively to investigate intraoperative awareness.Results The mean infusion dose of propofol was(973.48± 471.56)mg and the mean infusion time was(138.74±112.85)min.The mean plasma concentrationand infusion rate of propofol was(3.15±0.38)μg/ml and(9.41±3.59)mg·kg-1·h-1.The mean infusion dose of remifentanil was(1 130.29±676.19)μg and the mean infusion time was(140.76± 113.02)min.The mean infusion rate of reminfentanil was(0.15±0.05)μg·kg-1·min-1.Of all the patients,nobody was reported awareness,14(1.3%)reported dreaming during anesthesia. Conclusion The plasma concentration of remifentanil setting at 5.0-6.0ng/ml,combined with the mean plasma concentration of(3.15±0.38)μg/ml or infusion rate of(9.41±3.59)mg·kg-1·h-1of propofol, can maintain adequate depth of anesthesia,significantly reducing the incidence of awareness.