DexmedetomidineMedetomidineAdrenergic alpha-2 Receptor AgonistsAdrenergic alpha-AgonistsHypnotics and SedativesImidazolesConscious SedationReceptors, Adrenergic, alpha-2Analgesics, Non-NarcoticAdjuvants, AnesthesiaClonidineAdrenergic alpha-AntagonistsMidazolamShiveringGuanidineIdazoxanDeep SedationAdrenergic alpha-2 Receptor AntagonistsAirway ExtubationDose-Response Relationship, DrugImidazoline ReceptorsHemodynamicsPreanesthetic MedicationTrimethylsilyl CompoundsFentanylConsciousness MonitorsInfusions, IntravenousDioxanesPropofolPsychomotor AgitationAlfentanilDouble-Blind MethodAnalgesicsInjections, SpinalAdjuvants, PharmaceuticSympatholyticsHeart RateAnesthesia Recovery PeriodGuanidinesLocus CoeruleusAnalgesiaAnalgesics, OpioidDeliriumAnesthetics, InhalationRats, Sprague-Dawley