Intrathecal Fentanyl and Dexmedetomidine Added to Bupivacaine for Subarachnoid Anaesthesia for Percutaneous Nephrolithotomy

Group fentanyl (F), an injection of bupivacaine 0.5% (3.5 ml) + fentanyl 0.5 ml (25 μg) will be administered intrathecally.

Group dexmedetomidine( D), dexmedetomidine will be first diluted in normal saline to obtain a dose of 5 μg in 0.5 ml. Then, an injection of bupivacaine 0.5% (3.5 ml) + dexmedetomidine 0.5 ml (5 μg) will be administered intrathecally. Drug will be administered over 10 seconds (s) using 5 cc syringes with cephalad orientation of the spinal needle bevel.