الفهرس 
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Abstract
Intrathecal anesthesia has been widely used to provide anesthesia and analgesia which allows a patient to remain awake while avoiding the risks of general anesthesia. Even though the risk of spinal anesthesia is lower than that of general anesthesia. The adverse events caused by Intrathecal anesthesia, such as shivering, are still present during surgical procedures. Shivering is defined as an involuntary, repetitive activity of skeletal muscles, which is one of the common complications involving regional anesthesia, causing discomfort for the patients. The incidence of shivering is up to 55% according to a previously published study. Shivering may lead to increased oxygen consumption and thereby causing hypoxemia, lactic acidosis and negative effects on heart rate, oxygen saturation, and blood pressure. Severe adverse effects may occur if the patient has cardiopulmonary insufficiency. Therefore, the prevention of shivering is rational and could result in better perioperative outcomes. Shivering may occur as a response to hypothermia; however, it may also occur in normothermic patients. Intrathecal anesthesia impairs the thermoregulation system by inhibiting tonic vasoconstriction below the level of anesthesia through sympathetic and somatic neural blockade. Different pharmacological and nonpharmacological techniques have been attempted to prevent shivering, but a gold-standard method has not yet been determined. Non-pharmacological techniques: the combined application of warmed intravenous fluids and forced-air warming has the potential to minimize core temperature loss. Forced-air warming warms the patient from outside inwards, whereas the warmed intravenous fluid may prevent a decrease in body temperature in the setting of redistribution hypothermia. Pharmacological techniques (anti-shivering medication) includes centrally acting analgesics (tramadol), opioid receptor agonists (meperidine, fentanyl), meperidine (the most common intravenous drug which used for treating and preventing shivering; skin warming and meperidine use were the most commonly cited strategies), N-methyl-D-aspartate receptor antagonists (ketamine, magnesium sulfate), alpha 2 -central agonists (dexmedetomidine, clonidine), anti-serotonergic (ondansetron), anti-inflammatory drugs (dexamethasone). Dexmedetomidine has highly specific alpha 2-adrenergic receptor-agonist properties, with strong impacts on the central nervous system without respiratory depression. Dexmedetomidine has a sedative, analgesic, sympatholytic, anesthetic-sparing and hemodynamic-stabilizing properties. The aim of this study is to evaluate the effects of intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine in the prevention of shivering in patients who undergoing surgeries under Intrathecal anesthesia. The study participants were randomized into 2 equal comparable groups: group Bupivacaine-Dexmedetomidine (BD): patients received 5 micrograms of preservative-free dexmedetomidine diluted in 0.5 ml 0.9% normal saline added to 12.5 mg 0.5% heavy bupivacaine intrathecally and group Bupivacaine (B): patients received 0.5 ml 0.9% normal saline added to 12.5mg 0.5% of heavy bupivacaine intrathecally. ❖ The study results showed: 1. There were insignificant differences between both groups as regard to patients’ characteristics (age, BMI, Sex, ASA physical status and duration of surgery). 2. Heart rate decreased significantly in group BD than group B at 20, 25, 30, 45, 60, 75 and 90 minutes but there were insignificant differences between both groups at baseline, 5, 10, 15, 120 minute and at the end. 3. Mean arterial blood pressure decreased significantly in group BD than group B at 10, 15, 20 and 25 minutes but there were insignificant differences between both groups at baseline, 5, 30, 45, 60, 75, 90, 120 minute and at the end. 4. There were insignificant differences at all time measurements between group BD and group B regarding peripheral temperature. 5. There were insignificant differences at all time measurements between both groups regarding core temperature. 6. There were insignificant differences at all time measurements between both groups regarding SpO2. 7. There were insignificant differences between both groups as regard to PONV but there was significant increase as regard to hypotension, bradycardia and sedation in group BD. 8. There was significant difference between both groups as regard to Tsai and Chu score of shivering. There was significant decrease in shivering in group BD in comparison to group B.