The Effect Of Dexmedetomidine On Target Controlled Infusion (TCI) With Propofol For Sedation In Patients Undergoing Epidural Anesthesia

Objective To evaluate the influence of dexmedetomidine (Dex) on TCI with propofol for sedation in patients undergoing epidural anesthesia.Methods Sixty ASA I or II patients of women aged 27-55 yr weighted 50～80 kg undergoing elective gynecology surgery with epidural anesthesia who were enrolled in this study. The patients were randomly divided into three groups (n=20each):2 Dex groups received intravenous infusion of Dex at 0.25μg/kg (D1) and 0.50μg/kg (D2) diluted into physiological saline 10ml respectively, the placebo group was infusion with physiological saline 10ml, When epidural anesthesia were onset and valid,the 3 groups received TCI of propofol (the initial target plasma concentration was set at 0.50 ug/ml), Improved OAA/S score and bispectral index(BIS) were used to monitor sedation of patients. MAP, HR, RR, SpO2, Improved OAA/S score were recorded after the patients entered into the operating room clamed for 10 minutes(T0), immediately before or after Dex was administrated(T1,T2),skin incision (T3) at 30 and 60 min after skin incision (T4, T5),at the end of the operation (T6). The target-effect site concentration of was consciously record from the beginning to the end of TCI of propofol, the plasma concentration was up-regulated or down-regulated 0.20 ug/ml every 3 minutes to keep BIS value 65-75. Adverse reactions like anoxic condition, hypotension, bradycardia, agitation were also recorded during operation.Results there were no significant differences in age (F=2.36, P=0.1066), height (F=0.22,P=0.8011),body weight(F=0.00,P=0.9976), duration of operation among the 3groups. RR, SpO2 were fairly stable and maintained within normal range during operation and no significantly differences among the 3 groups. The target effect-site concentration of propofol of D1 groups was lower than that of C group (Q=7.7376, P<0.01), as well as D2 group (Q=5.0332, P<0.01). Hemodynamic of the three groups were basically stable, the patents which needed ephedrine in P, D1and D2 groups happened hypotension in operation were respectively3,2,6. HR was significantly lower at T3 moment and there were 5 patients reduced to 47 bpm in D2 group; the surgeries' satisfaction to anesthesia were similar in the 3 groups, but the patients'satisfaction in P, D1 and D2 groups were respectively 79%,91%,95%.Conclusion Intravenous infusion of 0.25～0.50μg/kg Dex significantly reduced the target-site concentration of propofol administrated by TCI dose-dependently during epidural anesthesia of gynecology patients, Dex can provide safe and available sedation plan.