Spinal anesthesia is the technique of choice in transurethral prostatectomy.However,one of the common complications of spinal anesthesia is shivering which is even exaggerated in patients undergoing transurethral prostatectomy.this high incidence is most probably caused by sympathetic block and use of large amount of irrigation fluid during surgery.There are two methods to reduce shivering.Previous studies showed that intrathecal fentanyl is an appropriate method to reduce shivering.Intrathecal dexamethasone could reduce shivering by regulating immune responses.

Shivering is an involuntary repetitive contractions of skeletal muscles that increases the basal metabolism and is considered to be a defense mechanism for regulating body temperature in adults .

Post spinal shivering may cause discomfort to the patient,and may aggravate wound pain by stretching incisions and increases intracranial and intra ocular pressure.Shivering may increase tissue oxygen demand as much as 500% and is accompanied by increase in minute ventilation and cardiac output to maintain aerobic metabolism.

Tympanic temperature will be recorded preoperatively,after establishment of spinal anesthesia,and every 15 minutes til the end of operation.Core temperature below 36.5 C is considered as hypothermia Shivering intensity will be assessed with a five -point scale validated by Crossly and Maharaj.

Adverse events like hypotension,bradycardia, respiratory depression,nausea and vomiting will be recorded and treated.

Inclusion Criteria:

• ASA(American society of anesthesiologists) physical status grade I-II
• BMI(body mass index) less than 35 kg/m2
• patients undergoing transurethral prostatectomy

Exclusion Criteria:

• patient refusal.
• patients with contraindications to spinal anesthesia e.g coagulopathy,anti coagulant therapy,allergy to local anesthetic,psychological disorders,...
• patient with advanced cardiopulmonary diseases or thyroid diseases.
• patients on corticosteroids therapy or on Alpha2 blocker orAlcohol.
• patients with initial body temperature above 37.5 C or below 36.5 C.