Preanesthetic MedicationAnxiety, SeparationMidazolamNitrous OxideAdministration, OralDouble-Blind MethodAcepromazineReceptors, Opioid, muTrinidad and TobagoAnalgesics, OpioidReceptors, OpioidReceptors, Opioid, deltaReceptors, Opioid, kappaHypnotics and SedativesAnesthesiaHalothaneAnesthesia, GeneralOpioid PeptidesRespirationMedication ErrorsMedication Adherence