Children were randomly allocated , using a computer-generated sequence of numbers , into 1 of 3 groups : caudal 0.25 % levobupivacaine ( Group L ( 0.25 ) ) , caudal 0.20 % levobupivacaine ( Group L ( 0.20 ) ) , or caudal 0.20 % levobupivacaine plus 2 g/kg dexmedetomidine ( Group LD ) .