Relationship between intracranial excitatory aminoacid levels and postoperative cognitive dysfunction in elderly patients after general anesthesia

Objective To investigate the relationship between the changes in intracranial excitatory amino acid(EAA) levels and the incidence of postoperative cognitive dysfunction (POCD) in eldedy patients after general anesthesia. Methods Forty ASA Ⅰ-Ⅲ patients of both sexes aged 65-79 yr weighing 48-76 kg undergoing elective non-cardiac surgery under general anesthesia were studied.Anesthesia was induced with midazolam,fentanyl,etomidate and succinylcholine and maintained with continuous iv infusion of propofol,remifentanil,isoflurane inhalation and intermittent iv boluses of vecuronium.The right internal jugular vein was cannulated with a catheter which was advanced cephalad until jugular bulb.The jugular bulb venous blood samples were taken before (T0,baseline),at the end of (T1) and at 24,48 and 72h(T2-4) after operation for measurement of plasma concentrations of glutamate (Glu),aspartate (Asp) and glycine (Gly) by RP-HPLC.The cognitive function was evaluated by mini-mental state examination (MMSE) at T0 and T4.Results Eleven of the 40 patients developed POCD (28%).The plasma Gh,Asp and Gly concentrations were significantly increased after operation as compared with the baseline values in POCD patients and were significantly higher than in non-POCD patients.The plasma concentrations of Glu and Asp were negatively correlated with MMSE score(Glu:r=-0.86.P<0.01;Asp:r=-0.99,P<0.01).Conclusion Elderly patients may develop POCD after operation performed under general anesthesia through increase in intracranial EAA levels. Key words: Excitatory amino acids; Aged; Postoperative complications; Cognition disorder; Anesthesia,general