RESUMEN
Objective To observe the hemodynamic effects of open-loop target controlled infusion (OLTCI) and closed-loop target controlled infusion (CLTCI) of propofol and fentanyl for general anesthesia induction. Methods Twenty-four female patients with ASA grade I-II who were performed thyroidectomy were randomly allocated into two groups: OLTCI group and CLTCI group(n=12). In OLTCI group, anesthesia induction and maintenance were performed with propofol and fentanyl at the target concentrations of 3 ?g/mL and 3 ng/mL, respectively. In CLTCI group, double CLTCI were performed. Titrations of propofol and fentanyl were guided with bispectral index (BIS) and product of systolic pressure and heart rate (HR). Initiative concentrations of this closed-loop system were 3 ?g/mL and 3 ng/mL, step-up or step-down concentrations were 0.5 ?g/mL and 0.5 ng/mL, and the highest concentrations were 6 ?g/mL and 5 ng/mL, respectively. HR, mean arterial pressure (MAP), HR variability, BIS value and the dosages of propofol and fentanyl in various time of the two groups were recorded. Results One min after intubation and simulative incision stimulation, BIS value of both groups were increased, but the BIS value in CLTCI group was less increased than OLTCI group(P