Association Between Postoperative Cognitive Dysfunction And Iron Metabolism In Gerontal Patients After The Operation

Objective: Postoperative cognitive dysfunction(POCD)is a continuously accelerated concept.It is a common central nervous system complications after surgery.It is shown as memory loss,thinking mode disorder,declining of attention,intelligence and learning ability.POCD can lead to the delay of rehabilitation,increase of complications and the hospitalization time.It has been confirmed that the incidence of POCD is closely related with age.There are many factors inducing POCD but the pathogenesis remain unclear.Iron is one of the essential trace elements,involved in the synthesis of various proteins,electron transfer,cell respiration and other important physiological processes of the central nervous system.However,excess iron content can lead to the formation of free radicals and oxidative stress,resulting in damage to nervous system,which is closely related to the occurrence and development of numbers of CNS disorders.This study observed the changes of iron metabolism in gerontal patients after general anesthesia,to explore the relationship between abnormal iron metabolism and the occurrence and development of POCD.Methods: 120 patients(aged 65-85 years)who were treated by operation and received intravenous inhalational anesthesia were included.All patients received mini-mental state examination(MMSE)on preoperative day 1 and postoperative days 1,3,and 7.Peripheral venous blood samples were collected to determine serum ferritin(SF),transferrin(TF),and transferrin saturation(TS)on preoperative day 1 and postoperative days 1,3,and 7.The data were presented as Mean±SD and analyzed with one way ANOVA by SPSS15.0 statistical program,rank sum test for heterogeneity of variance,correlation analysis using Pearson correlation analysis.A level of P<0.05 was supposed to be statistically significant.Results: According to the MMSE results,there were 31 patients with postoperative cognitive dysfunction,and the incidence was 25.8%.Compared with the values on preoperative day 1,the MMSE score,the content of SF,and TS were significantly decreased,and the content of TF was significantly increased in the cognitive impairment group on postoperative days 1 and 3(P<0.05),although there were no significant differences on postoperative day 7(P>0.05).There were no significant differences in MMSE score,the contents of SF and TF,or TS in the non-cognitive impairment group on postoperative days 1,3,and 7(P > 0.05).Compared with the non-cognitive impairment group,the MMSE score,the contents of SF and TS were significantly decreased,and the content of TF was significantly increased in the cognitive impairment group on postoperative days 1 and 3(P<0.05),although there were no significant differences on postoperative 7 d(P>0.05).There was a positive relation between TF,TS and MMSE score in patients with cognitive impairment(P= 0.321,P = 0.0287).Conclusion: Operation and anesthesia can lead to postoperative cognitive dysfunction in some gerontal patients.Abnormal iron metabolism may be involved in the pathogenesis of POCD.