الفهرس 
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Abstract
The simplicity of the technique of spinal anaesthesia and its reliability has made it one of the preferred techniques in lower limb surgery. Unexpected early regression of spinal block or prolonged operation can cause intraoperative pain. Increasing the dose of local anaesthetics, addition of opioids to local anaesthetics for spinal anaesthesia would be helpful for prolonging the spinal blockade but may cause hemodynamic instability, nausea, urinary retention, respiratory depression and delayed recovery from motor block.
The aim of this work was to evaluate the effect of addition of dexmedetomidine and dexamethasone to bupivacaine in spinal anaesthesia in lower limb orthopaedic surgery as regard hemodynamic changes and analgesic effect in the postoperative period.
The study was done on sixty patients American Society of Anesthesiologists (ASA) class I or II aged 18 to 60 years old admitted to Al-Hadara University Hospital in Alexandria. After approval of the medical ethical committee, an informed written consent was taken from all patients.
According to the drugs used in spinal anaesthesia, patients were categorized blindly into 3 groups 20 patients each:
group I(control group): Bupivacaine (heavy) 0.5% 3ml (15mg) plus 2ml normal saline 0.9 % intrathecally.
group II(dexamethasone group): Bupivacaine (heavy) 0.5% 3ml (15mg) plus dexamethasone (preservative-free) 2 ml (8 mg) intrathecally.
group III(dexmedetomidine group): Bupivacaine (heavy) 0.5% 3ml (15mg) plus dexmedetomidine 2 ml (10 µg) intrathecally.
Preoperative evaluation was done by complete history taking, physical examination and necessary laboratory investigations.
Before starting the spinal anaesthesia basic monitoring was applied to the patients including electrocardiogram (ECG), noninvasive blood pressure and pulse oxymetry. Baseline reading was measured before starting spinal anaesthesia.
Patients received a volume preload in the form of 10 ml/kg lactated ringers, then they were placed in the sitting position and midline puncture was performed at L4-5 interspace using a 25 gauge Quincke spinal needle. The whole technique was performed by one anesthetist in all patients.
After injection, the patient lied supine with the head resting on a pillow. Oxygen by face mask was given at 3-5 L/min throughout the procedure. When the sensory block level reached T4-8 dermatome, surgery was allowed to start.
The following measurements were recorded through intra and postoperative periods: Hemodynamic measurements (heart rate, mean arterial blood pressure, arterial oxygen saturation).
Sensory blockade (time to reach the highest sensory level, segmental level of highest sensory blockade and time for four-segment regression).
Motor blockade (onset and duration of the motor block using the modified Bromage score).
Efficacy of postoperative analgesia (visual analogue scale, time to 1st complain of pain, 1st rescue analgesia and total dose of opioid used).
Perioperative side