Influence of sub-anesthetic dose of ketamine and dexmedetomidine 
on early postoperative cognitive function in elderly orthopedic 
patients under total intravenous anesthesia
ZHANG Xiao-dong,PIAO Mei-hua,WANG Yan-shu,FENG Chun-sheng
Journal of Jilin University(Medicine Edition) . 2013, (1): 133 -137 .  DOI: 10.7694/jldxyxb20130130