Erector Spinae Block Vs Ketamine-based Multimodal Analgesia Protocol in Lumber Decompressive Surgery

after induction of anesthesia, patients will receive ketamine bolus of 0.5 mL/kg followed by continuous infusion of 0.12 mL/k/hr until the end of surgical procedure.

after induction of anesthesia, patients will receive ultrasound guided ESPB. A total of 40 mL of 0.25% bupivacaine will be injected bilaterally at the level of transverse process opposing to the mid-point of the planned incision.

wound infiltration at the end of the surgery before the closure of fascia and subcutaneous tissues using a total of 20 ml of 0.25% bupivacaine