The study of relationship between postoperative cognitive dysfunction and plasma cortisol levels in aged patients undergoing total hip replacement surgery

Objective To investigate the relationship between postoperative cognitive dysfunction and plasma cortisol levels in aged patients undergoing total hip replacement surgery.Methods Ninety patients aged 65-75 years old,scheduled for total hip replacement surgery under general anesthesia were enrolled in the present study.Cognitive state was tested by mini-mental state examination(MMSE).The patients were divided into two groups,POCD group and non-POCD group.Perioperative plasma levels of cortisol were determined on 2 d preoperative,2 d postoperative and 7 d postoperative.Results Incidence of POCD after 7 d in aged patients undergoing total hip replacement surgery was 37.8%.Compared with day 2 d preoperative,plasma cortisol levels in POCD patients significantly increased on 2 d and 7 d post operation(P0.01 or P0.05).Compared with non-POCD patients,cortisol levels on the 2 d and 7 d postoperative day significantly increased in POCD patients(P0.05).Plasma cortisol levels showed a negative correlation with MMSE scores on postoperative 2 d and 7 d(P0.01).Conclusion Elderly patients have a relatively higher incidence of POCD after hip replacement surgery.POCD may be caused by high plasma cortisol levels in elderly patients following hip replacement surgery under general anesthesia.