Patients scheduled to undergo thoracic paravertebral block will receive an injection of 20 ml of 0.25% bupivacaine hydrochloride into the paravertebral space between the parietal pleura and the costotransverse ligament using a block needle under ultrasound guidance.

Patients scheduled to undergo an external oblique intercostal block will receive an injection of 30 ml of 0.25% bupivacaine hydrochloride between the external oblique muscle and the intercostal muscle at the level of the 6th rib, using a block needle under ultrasound guidance.

Used for regional anesthesia during nephrectomy procedure (e.g., paravertebral or external oblique intercostal block)

Pain intensity measured using Visual Analog Scale at rest. (Visual Analog Scale ranging from 0 = no pain to 10 = worst pain imaginable; higher scores indicate worse pain).