Morphine DerivativesMeperidineMorphineAnalgesics, OpioidShiveringMorphine DependenceAdjuvants, AnesthesiaNarcoticsAnalgesia, ObstetricalNaloxoneDrug TolerancePromethazineReceptors, Opioid, muPain MeasurementInjections, SpinalAnalgesia, Patient-ControlledFentanylAnalgesia, EpiduralHydroxyzinePain, PostoperativeDihydroergotamineAnalgesiaAlfentanilPreanesthetic MedicationConscious SedationNarcotic Antagonists