Association between the apolipoprotein E4 and postoperative cognitive dysfunction in elderly patients undergoing intravenous anesthesia and inhalation anesthesia.

BACKGROUND Intravenous and inhalation anesthesia are commonly used in the clinical setting. Recovery of cognitive function in elderly patients after surgery has received increased attention. In this study, the authors compared recovery of cognitive function in patients after different anesthesia techniques, and investigated which technique is safer. The authors also explored association between apolipoprotein E4 and postoperative cognitive dysfunction in patients undergoing general anesthesia. METHODS A total of 2,000 patients were equally and randomly divided into intravenous and inhalation anesthesia groups. Total intravenous and inhalation anesthesia were used. Within 10 days after surgery, cognitive function was assessed daily using the Mini-Mental State Examination (MMSE). Restriction fragment length polymorphism of apolipoprotein E gene was analyzed. The primary outcome was MMSE score, frequency distribution of apolipoprotein E alleles and genotypes. P < 0.01 was used as statistically significant. RESULTS MMSE score in inhalation preoperative baseline group significantly decreased at day 3 after surgery compared with the preoperational and intravenous anesthesia group. The proportion of patients scoring less than 25 points was significantly greater in the inhalation anesthesia group than in the intravenous anesthesia group at 3 days after surgery. In the inhalation anesthesia group, the decrease in MMSE score was closely related with apolipoprotein E ε4 allele. In the intravenous anesthesia group, the decrease in MMSE score was not correlated with apolipoprotein E ε4 allele. CONCLUSIONS There was a strong association between the apolipoprotein E ε4 and postoperative cognitive dysfunction in elderly patients undergoing inhalation anesthetics.