Lower Thoracic Epidural vs Erector Spinae Block for PNL

before induction of anesthesia,first the investigators identify the correct targeted thoracic level. All epidural block will be performed under all aseptic precautions with a 17-gauge Tuohy needle and 19 G flex-tip catheters. Using the loss of resistance to saline technique, catheter will be inserted 4 cm into the epidural space and a suitable test dose will be administered to exclude intravascular or sub-arachnoid injection. Bupivacaine 0.25% of 7.5-12 ml volume will be given bolus through the epidural catheter then continuous infusion of bupivacaine 0.1% will be infused at a rate of 5 ml/h up to 15ml/h .for breakthrough pain patient controlled analgesia (PCA) using nalbuphine 1 mg bolus , 10 min lockout period . The catheter will be removed under complete aseptic precautions after 48 hrs.

before induction of anasthesia ,highfrequency linear ultrasound probe will be placed in a longitudinal parasagittal orientation 2.5-3 cm lateral to the T9 spinous process. A 21G 10 cm needle will be inserted using an in plane approach. The tip of the needle will be placed into the fascial plane on the deep aspect of the erector spinae muscle.confirmed by visible fluid spread lifting the erector spinae muscle off the bony shadow of the transverse process on ultrasonographic imaging.Then the catheter placement 5cm into the space under the erector spinae muscle and suitable test dose will be administered . Bupivacaine 0.25% of 7.5-12 ml volume will be given bolus through the catheter then continuous infusion of bupivacaine 0.1% will be infused at a rate of 5 ml/h up to 15 ml/h , for breakthrough pain patient controlled analgesia (PCA) using nalbuphine 1mg bolus,10 min lockout period.The catheter will be removed under complete aseptic precautions after 48 hrs.