Inclusion Criteria:  ASA I, II less than 18months. males and females. scheduled for thoracotomy for closed cardiac surgery.  Exclusion Criteria:  airway abnormalities. heart failure. endocrine disorders. Patients with hypersensitivity to any drug. beta blockers, any analgesics recieved within 24 h before surgery, or any psychotropic drugs. hepatic, renal diseases neuromuscular disease, coagulopathy. a history of hyperthermia. infection at the site of the block.