الفهرس 
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Abstract
Spinal subarachnoid block is one of the most versatile regional anesthesia techniques available today. Regional anesthesia offers several advantages over general anesthesia.
Among the local anesthetics, 0.5% hyperbaric bupivacaine is the most commonly used drug for spinal anesthesia . The most important disadvantage of single injection SAB is the limited duration.
Adjuvants have long been used along with local anesthetics to prolong the duration of anesthesia and Prolongation of pain relief by various adjuvants like opioids (like morphine , fentanyl ), ketamine , clonidine , and neostigmine were investigated by various investigators. However, each drug has its limitations and side effects, and the need for an alternative methods and drugs always exist.
Discovery of benzodiazepine receptors in spinal cord in 1977 triggered the use of intrathecal midazolam for prolongation of spinal anesthesia. In vitro autoradiography has shown that there is a high density of benzodiazepine (GABAA) receptors in Lamina II of the dorsal horn in the human spinal cord, suggesting a possible role in pain modulation .
Magnesium has analgesic properties, primarily related to the regulation of calcium influx into cells and antagonism of N-methyl-D-aspartate (NMDA) receptors in the central nervous system.
The aim of our study is to to decrease the dose of the used Bupivacaine used in spinal anesthesia to decrease the possible complications , on other hand to increase the time to the first analgesic request , so we used adjuvants with intrathecal Bupivacaine in the form of Midazolam & magnesium sulphate. Our Specific aim Is to compare the effect of intrathecal midazolam and magnesium sulphate when added to marcaine during lower limb orthopedic surgeries .
This study was carried out at the anaesthia and ICU. department in El-Minia University Hospital during the period from April 2014 to February 2014 after institutional approval and informed consents obtained from all patients prior to entry in to the study. It involved 60 patients scheduled to undergo lower limb orthopedic surgery using spinal anesthesia, males & females, ASA: class I or II., aged between (18-60)years old, randomized in to three equal Groups . Patients in Group A included 20 patients received 12.5mg of hyperbaric bupivacaine 0.5% (2.5 ml) and 2.5 mg Midazolam (0.5ml) . Patients in Group B included 20 patients received 12.5mg of hyperbaric bupivacaine 0.5% (2.5 ml) and 50 mg of MgSO4 10% (0.5 ml). Patient in group C included 20 patients received 12.5mg of hyperbaric bupivacaine 0.5% (2.5 ml) and normal saline 9% (0.5 ml) . Patients received a volume preload in the form of (500ml) normal saline. Midline-approach spinal anaesthesia was done in the sitting position at L3-4 intervertebral space by one anaesthesiologist in all patients. Hemodynamic measurements (heart rate, mean arterial blood pressure, arterial oxygen saturation), sensory blockade (time to reach VAS=0 , and time for VAS=3 or first rescue analgesia needed), motor blockade (onset, duration and regression using the Bromage score), postoperative pain (visual analogue scale, time to 1st rescue analgesia), and perioperative side effects or complications as (nausea, vomiting , hyptension , sedation ,etc ....).