Impact of Dexmedetomidine on the Post-Operative Cognition Dysfunction(POCD) in Geriatric Patients

Impact of Dexmedetomidine Sedation on the Post-Operative Cognition Dysfunction--a Multiple Center,Randomized, Controlled,Double Blinded Clinical Trial.

Post-Operative Cognition Dysfunction (POCD) is a common complication after surgery, POCD can lead to a reduced ability and seriously affect the quality of life of patients, increase personal and social burden, POCD may also increase mortality.POCD can occur at any age, but the long-term, affect the daily lives of POCD in elderly patients over 60 years of age are more prone. Age is a risk factor for advanced or long-term POCD. POCD determined by preoperative cognitive function and psychological scales postoperative assessment, the main recommendation of the agreed test methods include, Rey auditory verbal test, the connection test, digit span test. In this study, preoperative mini-mental state examination (MMSE) screening, comprehensive neurological function during hospitalization for memory, attention, executive function and exercise capacity test, and telephone follow-up after discharge Scale Revised (TICS-M) test. Few study showed that dexmedetomidine may improve cognitive function in young patients others show that dexmedetomidine did not reduce POCD incidence after 24 hours of surgery. These results conflict and it is necessary to carry out large-scale, multi-center, randomized, controlled clinical study to determine whether dexmedetomidine reduce the POCD incidence or not for elderly patients.

0.5μg/kg Dexmedetomidine as initial loading dose is given for 15 minutes before induction of anesthesia, followed by a maintenance infusion of 0.4μg/kg/h and stopped 30 minutes before the surgery over.

0.5μg/kg Saline as initial loading dose is given for 15 minutes before induction of anesthesia, followed by a maintenance infusion of 0.4μg/kg/h and stopped 30 minutes before the surgery over.

0.5μg/kg Dexmedetomidine as initial loading dose is given for 15 minutes before induction of anesthesia, followed by a maintenance infusion of 0.4μg/kg/min and stopped 30 minutes before the surgery over.

0.5μg/kg saline as initial loading dose is given for 15 minutes before induction of anesthesia, followed by a maintenance infusion of 0.4μg/kg/min and stopped 30 minutes before the surgery over.

The neuropsychological tests performed at the day before the surgery, the 3rd and 7th day after the surgery respectively. A test environment to keep quiet, well-lit, non-interference, all the test items should be completed within 30 min. Normal population (65 to 90 years age-matched 400 non-surgery people) should perform neuropsychological tests in the same time interval, then calculate the score difference(ΔXc), and the standard deviation(SD) of the difference. Calculate the difference(ΔX) between the score obtained before surgery and 3 or 7 days after the surgery (there are both positive and negative, we use the absolute value), with this difference( ΔX) divided by the standard deviation（SD）of the difference of the normal population, that is ΔX / SD and it is the Z score. POCD Diagnosis: if a patient has two or more than two of the absolute value of Z scores ≥1.96, the POCD is exist.

Inclusion Criteria: Written informed consent Selective surgery and general anesthesia patients(abdomen,orthopedics and urology surgery is preferred）； Age 65-90 yrs； Anesthesia Society of American (ASA) Scale II~III； Anticipated surgery time 2-6 hrs； - Exclusion Criteria: Dementia patients（Mini-mental state examination< 20） Factors existed that affect cognition assessment such as language,visual,and auditory dysfunction； Unstable metal status and mental disease； The cognitive function examination in 3-6 months is not anticipated to be completed II-III Atrioventricular block； Heat rate < 50 beats/minutes； Parkinson's Disease； May occur or have occurred the difficult airway or anticipated delayed extubation Sure or suspected abuse of analgesic and sedation drug； Allergic to the trial drug and other anesthesia drug contraindication； -