Comparison of Dexmedetomidine and Midazolam for Prevention of Emergence Delirium in Children

In this study, seventy patients scheduled for elective tonsillectomy aged from 24 months to 12 years old Anesthesiologists physical status (ASA) class 1 and 2 will be enrolled. The sample size was calculated based on the former study with a type 1 error estimate of 0.05 at 80% power. The proportion in dexmedetomidine group (group D) was assumed to be 0.4 and the proportion in midazolam group (group M) was 0.1. Considering the drop-out rate of 10%, seventy patients in total were needed.The patients will randomly be allocated into the group D or the group M. The group D will receive dexmedetomidine0.3mcg/kg mixed with 0.9% normal saline, 10mL in total. The group M will receive 0.03mg/kg of midazolam mixed with 0.9% normal saline, 10mL in total. Randomization and drug administration will be done by a single anesthesiologist. Assessment of the patient will be done by another anesthesiologist blinded by the group. Five minutes before the end of the surgery, the study drug will be slowly infused for 5 minutes. In the postanesthesia circuit unit (PACU), presence of emergence delirium will be assessed. The emergence delirium will be assessed by the four-point agitation scale. (1 = calm, 2 = not calm but gould be easily calmed, 3 = not easily calmed, moderately agitated or restless, and 4 = combative, exited or disoriented.) Patients with score 3 and 4 will be diagnosed as emergence delirium and treated with intravenous fentanyl 1mcg/kg. Severity of emergence delirium will be assessed with the pediatric anesthesia emergence delirium scale after 10 mins on arrival of PACU. Pain wil be scored by 5-point scale (0 = no pain, 5 = severe pain ever). Time from discontinuation of anesthetic gas to extubate will be recorded. The data will be compared between the groups by the independent t-test or Mann-Whitney test for the continuous variables. Chi-square test or Fisher's exact test will be used for the categorial variables.