Abstract:

Objective To investigate the incidence of postoperative cognitive d
ysfunction(POCD) using etomidate and to clarify the influence of etomidate in the
  incidence of POCD  and stress response in elderly orthopedic patients underwent  total in
travenous anesthesia. Methods 91 patients(ASA-Ⅲ) aged more than 60 years under
went elective orthopedic surgery were randomly divided into etomidate induction/m
aintainence group (EE, n=31), etomidate induction group (EP, n=30) and propofol
control group (PP, n=30).The patients in each group were administered with an intravenous injection of midazolam

0.03 mg/kg^-1, fentanyl 3-5 μg /kg^-1, cisatracurium 1.5 mg/kg^-1 in turn; the patients in EE group and EP group were adm
inister
ed with  an intravenous injection of etomidate at a dosage of 0.2-0.3 mg/kg^-1
 and the patients in PP group were administered with an intravenous injection of propofol at
 a dosage of 1.5-2.5 mg?kg-1. The patients in EE group were given a continuous
 intravenous infusion of etomidate at 0.6-1.2 mg/kg^-1/h^-1
 while the patients in EP group and PP group were infused with propofol at 4-8 mg/kg^-1/h^-1. The venous
 blood samples were drawn at the time of before anesthesia, after extubation and 24 h after operation,respectively; the level of serum cortisol was detected usi
ng radioimmunoassay (RIA).The mini-mental state examination (MMSE) was applied to evaluate POCD at 1 and 7 d after operation.
Results At 1 and 7 d after operation the incidence of POCD were 26.7% and 13.3% in PP group; 30.0% and 10.0% in EP group; 25.5% and 12.9% in EE group.

The incidence of POCD among the three groups at 1, 7 d after operation had no significant differences (P>0.05). The serum cortisol levels had no significant difference among various groups before operation (P>0.05). Compared with before anesthesia, the levels of serum cortisol after extubation were decreased significantly in all groups (P＜0.05). The level of serum cortisol after extubation was decreased significantly in EE group (P＜0.05), and the levels of serum cortisol at 24 h after operation went back to normal level in three groups. Conclusion Both etomidate and propofol can reduce stress response of elderly orthopedic patients underwent  total introvenous anesthesia in operation, and the effect is significant in EP group; there is no difference between etomidate and propofol in POCD
 in elderly orthopedic patients underwent total introvenous anesthesia.

Key words: etomidate, propofol, elderly, orthopedic surgery, total intravenous anesthesia, postoperative cognitive dysfunction, cortisol;srtess response