Dexmedetomidine Versus Nefopam for management of post spinal anesthesia shivering:A randomized double-blind controlled study

INTERVENTION: dexmedetomidine in a dose of 0.5Ug/Kg intravenous(i.v.) or Nefopam in a dose of 0.15mg/Kg I.v. In the respective groups.each drug was diluted into 5 ml by isotonic saline and given by slow I.v.( one minute) at the onset of shivering.either of the two drugs was given according to the group in the postoperative spinal anesthesia period to patients who develop grade III or IV shivering . When shivering recures additional dose of either of the two drugs according to the group can be given as the same previous dose and recorded. CONDITION: Post spinal anesthesia shivering PRIMARY OUTCOME: Time of stoppage of postspinal anesthesia shivering after treatment with either dexmedetomidine or Nefopam. SECONDARY OUTCOME: Duration of effective postspinal analgesia after treatment with either dexmedetomidine or Nefopam. It is calculated from intrathecal bupivacaine injection to patient first request for rescue analgesic guided by visual analogue scale . Adverse effects are not outcome of the study. INCLUSION CRITERIA: ASA I and II patients scheduled for elective lower abdominal,lower limb , orthopedic and plastic surgeries under spinal anesthesia