Abstract: AIM: To explore the optimal dosage of dexmedetomidine for prevention of agitation induced by sevoflurane anesthesia in children. METHODS: One hundred and sixty ASA Ⅰ-Ⅱ pediatric patients, who underwent indirect inguinal hernia or hydrocele were randomly divided into 4 groups: C group (saline group), D0.2 group (dexmedetomidine 0.2 μg/kg), Group D0.4 (dexmedetomidine 0.4 μg/kg); D0.6 group (dexmedetomidine 0.6 μg/kg), 40 cases in each group. The dexmedetomidine was treated with intravenous infusion of the same volume of saline at 10 min before the induction of anesthesia. Observation with induction period and intraoperative hemodynamic situation, postoperative FLACC behavior score, Ramsay sedation scores, extubation time, adverse reactions, such as respiration depression (SpO2<92%), postoperative nausea and vomiting, postoperative agitation were carried out. RESULTS:The intraoperative hemodynamics of D0.4 and D0.6 groups were more stable than the groups of C and D0.2 (P<0.05). The FLACC scores of groups D0.4 and D0.6 were lower than the groups C at the time of T5, T6. The FLACC scores of group D0.6 was lower than the groups C at the time of T7 (P<0.05). The FLACC scores of groups D0.4 and D0.6 were lower than the groups D0.2 at the time of T5, T6 also (P<0.05). The Ramsay sedation score of groups D0.4 and D0.6 were higher than the group C at the time of T5, T6, T7 (P<0.05). The Ramsay sedation score of groups D0.4 and D0.6 were higher than the group D0.2 at the time of T5, T6, and the Ramsay sedation score of group D0.6 was higher than the group D0.2 at the time of T7 also (P<0.05). There was no statistically significant difference in postoperative hypoxic incidence (SpO2<92%) in the four groups (P>0.05). The case of postoperative agitation in the group D0.4 (12 cases), D0.6 (8 cases) lower than the group C (23 cases) and D0.2 (16 cases) (P<0.05). The awakening time of group D0.6 was longer than the group of C (P<0.05). The rate of other adverse reaction were no statistically significant difference in the four groups (P>0.05).CONCLUSION:The usage of 0.4 μg/kg dexmedetomidine for the pediatric inguinal hernia or hydrocele surgery under the anesthesia of sevoflurane has the characteristics of stable hemodynamics during the operation, reducing the incidence of restlessness after sevoflurane anesthesia, not affecting the recovery of children, and not increasing adverse reactions.

Key words: dexmedetomidine, sevoflurane, inguinal hernia, awakening period of agitation, optimal dose