Abstract: Objective  To observe the effects of dexmedetomidine on postoperative delirium in severe burns patients. 
Methods  Forty patients with severe burns classified as American Society of Anesthesiologists（ASA） from Ⅱ to  Ⅲ  and scheduled for escharotomy and homograft， were randomly allocated into two groups(n=20): Dex group(Dex group) and normal saline group(NS group). Before ansthesia induction， Dex［1.0 μg/kg bolus and infusion at a rate of 0.5 μg·kg-1·h-1］was administered to the patients of Dex group， while the patients of NS group were given with equivalent normal saline at the same time．Heart rate，mean arterial pressure were observed at before anesthesia induction(T1)， at 10min after induction(T2)， at 1h(T3)， and the levels of interleukin(IL)1β and IL-6 in were determined at T1, T2, T3 and 24 h(T4) after operation finished. S-100 beta protein(S-100 beta protein) of radial glial cells in serum were determined at the preoperative 1 d(T0) and 24 h(T4)， 48 h (T5)， 72 h(T6)  after operation finished. The prevalence of delirium was estimated daily for 72 h via the confusion assessment method for intensive care. 
Results  HR and MAP at T2, T3 were lower in group D than that in group C(P＜0.05). The value of IL-1β and IL-6 were lower in group D than that of group C at T2, T3, T4（P＜0.05）. The value of S-100β were decreased in group D than that of group C at T4, T5, T6（P＜0.05）. Incidence of delirium was lower in group D than this in group C（P＜0.05）.
Conclusion  Dexmedetomidine which was infused iv 1 μg/kg in over 10 min before anaesthesia induction, and then was infused at a rate of 0.5 μg·kg-1·h-1 during operation, can reduce plasma IL-1β 、 IL-6 levels, reduce the level of serum S-100β， and decrease the incidence of postoperative delirium.

Key words: burns, dexmedetomidine, postoperative delirium