Breakthrough PainAdministration, BuccalFentanylPainLabor PainAnalgesics, OpioidPain MeasurementAnalgesia, EpiduralChronic PainPain ManagementDouble-Blind MethodPain ThresholdChronic DiseaseNeoplasmsPain, PostoperativeLow Back PainBack PainPain, IntractableAbdominal PainNeck PainPelvic PainPain PerceptionFacial PainAcute PainPain, ReferredRadionuclide GeneratorsShoulder PainMusculoskeletal PainAnalgesics