Effects of different depths of sedation on postoperative cognitive function in elderly patients with mild cognitive impairment

Abstract

Objective To evaluate the effects of different depths of sedation on postoperative cognitive function in elderly patients with mild cognitive impairment. Methods A total of 100 patients with mild cognitive impairment before surgery, aged 65-75 yr, weighing 55-75 kg, of American Society of Anesthesiologists physical status Ⅱ or Ⅲ, scheduled for elective gynecological surgery under general anesthesia, were divided into Ⅰ and Ⅱ groups (n=50 each) using a random number table method.Propofol was given by closed-loop target-controlled infusion, and the target plasma concentration was automatically regulated.The bispectral index value was maintained at 40-50 in group Ⅰand at>50-60 in group Ⅱ.Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate the cognitive function at 1 day before operation (T0) and 7 days after operation (T1), and the development of postoperative cognitive dysfunction (POCD) was recorded.Venous blood samples were collected at T0 and T1 for determination of the concentrations of serum interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α) by enzyme-linked immunosorbent assay. Results Compared with the baseline value at T0, MoCA and MMSE scores were significantly decreased at T1, and the serum concentrations of IL-10 and TNF-α were increased in both groups (P<0.05). Compared with group Ⅰ, MoCA and MMSE scores were significantly decreased at T1, and the incidence of POCD was increased, the serum concentration of TNF-α was increased, and the serum concentration of IL-10 was decreased in groupⅡ(P<0.05). Conclusion Maintaining BIS value at 40-50 during operation can decrease the development of POCD in elderly patients with mild cognitive impairment, which may be related to reduced systemic inflammatory responses. Key words: Electroencephalography; Cognition dissorders; Aged