Influence of  dexmedetomidine and sub-anesthetic dose of  
 ketamine on postoperative delirium in elderly orthopedic 
patients  under total intravenous anesthesia
MA Pan-pan, PIAO Mei-hua,WANG Yan-shu,MA Hai-chun,FENG Chun-sheng
Journal of Jilin University(Medicine Edition) . 2013, (1): 128 -132 .