AnalgesiaAnalgesia, EpiduralAnalgesia, ObstetricalPainAnalgesia, Patient-ControlledPain, PostoperativePain MeasurementAnalgesics, OpioidPain ManagementPain ThresholdChronic PainMorphineBupivacaineAnalgesicsAnesthetics, LocalAcupuncture AnalgesiaFentanylPain, IntractableBack PainLow Back PainLabor PainPain PerceptionAbdominal PainAnesthesia, EpiduralNeck PainMeperidineAcute PainNerve BlockInjections, SpinalSufentanilFacial PainPelvic PainPain, ReferredLabor, ObstetricDouble-Blind MethodAnesthesia, ObstetricalTramadolAnalgesics, Non-NarcoticAmidesShoulder PainAnesthesia, SpinalNociceptive PainHyperalgesiaMusculoskeletal PainNaloxoneLidocaineNeuralgiaPostoperative Nausea and VomitingCesarean SectionKetorolacInterpleural AnalgesiaDrug ToleranceHydromorphoneAnesthesia, GeneralConscious SedationProspective StudiesReceptors, Opioid, muNociceptorsKetamineLabor Stage, FirstAnesthesia, CaudalClonidineFemoral NerveTreatment OutcomeReceptors, OpioidVisceral PainPregnancyAnesthesia and AnalgesiaPirinitramideHypnotics and SedativesButorphanolNarcotic AntagonistsAnesthesia, LocalThoracotomyAlfentanilOpioid PeptidesElectroacupunctureAnesthesia, ConductionNalbuphineKetoprofenAnesthetics, CombinedOxycodonePruritusPlacebo EffectMepivacaineInjections, EpiduralChronic DiseaseSpinal CordPeriaqueductal GrayAnti-Inflammatory Agents, Non-SteroidalDose-Response Relationship, DrugAdjuvants, AnesthesiaPostoperative CareMorphine DerivativesAcetaminophenTime FactorsInjections, Intra-ArticularNitrous OxideBrachial PlexusAmbulatory Surgical Procedures