Explorative age-stratified analysis demonstrated that in stratum I ( n = 112 ) the clonidine group had a significantly lower consumption of fentanyl ( clonidine : 2.1 1.8 g/kg/hr , placebo : 3.2 3.1 g/kg/hr ; p = 0.032 ) and midazolam ( clonidine : 113.0 100.1 g/kg/hr , placebo : 180.2 204.0 g/kg/hr ; p = 0.030 ) .