Effects Of Different Methods And Depth Of Anesthesia On Postoperative Cognitive Function In Elderly Patients Undergoing Abdominal Surgery

Objective To observe the effects of different methods and depth of anesthesia on postoperative cognitive function in elderly patients undergoing abdominal surgery.Methods 120 ASA I or III patients, ≥60 years old, scheduled for elective abdominal surgery during general anesthesia, were randomly divided into 2 groups according to methods of anesthesia(n=60 each) firstly: total intravenous anesthesia group(A) and combined intravenous-inhalational anesthesia group(B), and then divided into 3 groups according to depth of anesthesia in each grougs(n=20 each): A1 group(BIS=30-39), A2 group(BIS=40-49) and A3 group(BIS=50-59); B1 group(BIS=30-39), B2 group(BIS=40-49) and B3 group(BIS=50-59). Cognitive function was assessed using Mini-Mental State Examination(MMSE) and Clock Drawing Test(CDT) before operation(T0), 1d after surgery(T1), 3d after surgery(T2) and 5d after surgery(T3). Serum S100β protein was measured before anesthesia(T I), right after surgery(TII), 30min(TIII), at the end of surgery(TIV) and right after leaving PACU(or right after extubation in ICU)(TV).Results 1. Different groups of methods of anesthesia: MMSE scores, CDT scores, serum S100β protein and the incidence of POCD in two groups were not statistically significant(P>0.05). The incidence of POCD was 62.4%(63/101) at T1, 33.7%(34/101) at T2 and 14.9%(15/101) at T3. There were significant changes in the incidence of POCD at different time points in two groups(P<0.05). 2. Different groups of depth of anesthesia: Total intravenous anesthesia(A): MMSE scores, CDT scores, serum S100β protein and the incidence of POCD in three groups were not statistically significant(P>0.05). The incidence of POCD was 66%(35/53) at T1, 32.1%(17/53) at T2 and 11.3% at T3(6/53). There were significant changes in the incidence of POCD at different time points in three groups(P<0.05). Combined intravenous-inhalational anesthesia(B): MMSE scores, CDT scores, serum S100β protein and the incidence of POCD in three groups were not statistically significant(P>0.05). The incidence of POCD was 58.3%(28/48) at T1, 35.4%(17/48) at T2 and 18.8%(9/48) at T3. There were significant changes in the incidence of POCD at different time points in X1 and X3 groups(P<0.05).Conclusion We were unable to detected a significant association between different methods/depth of anesthesia and the presence of POCD after abdominal surgery in elderly patients during general anesthesia, but the cognitive function is more easier to recover to close to the preoperative level under 40≤BIS value<50 after surgery. The peak of POCD in elderly patients occurred at 1d after surgery, and most of them can be recovered to the preoperative level gradually.