The aim of this prospective randomized double-blind study was to compare the analgesic efficacy and the side effects of two doses of dexmedetomidine (1 and 2 µg.kg-1) co-administered with bupivacaine with bupivacaine alone for caudal analgesia in children undergoing infra-umbilical surgery.

• Quality assurance plan for data validation and registry: After Data was registered, it was reviewed by a second person who compared it to the Data in patient data collection forms.
• Data check: carried out using Statistical Package for the Social Sciences (SPSS) variable definition protocols. Also data were entered in EXCEL sheets for comparisons to guarantee consistency.
• Source data verification: Paper case report forms and medical records.
• Standard Operating Procedures to address registry operations and analysis activities: Eligible patients were recruited after obtaining consent. Data was collected by qualified personnel rained on the process. Data was entered into Excel sheets and SPSS programs and compared for consistency. Analysis of Data was carried out by a qualified statistician. Adverse events were reported as yes/no variables. Data of patients who had Change in management was omitted from analysis.
• Sample size assessment: Sample size was calculated to detect a 65% reduction in the analgesic requirement during the first 24 h from 75% in the bupivacaine group with α= 0.05 and β=0.80.
• Plan for missing data: Patients with missing Data were omitted from statistical analysis.
• Statistical analysis plan: carried out using International Business Machines (IBM) statistics 19.0 statistical package for windows. Data were compared using analysis of variance for continuous variables, Kruskal-Wallis test for ordinal, and chi square test for categorical ones. Post hoc analyses were carried out as appropriate.

Inclusion criteria:

• Patients with American Society of Anesthesiologists (ASA) - I
• Scheduled for lower abdominal and perineal surgery
• Under general anesthesia

Exclusion criteria:

• history of developmental delay or mental retardation
• known or suspected coagulopathy or recent use of anticoagulant/antiplatelet drugs.
• known allergy to any of the study drugs.
• any signs of infection or congenital abnormalities at the site of the proposed caudal block