Compare the Perioperative Analgesic Effect of Ultrasound Guided Thoracic Paravertebral Block and Ultrasound Guided Serratus Anterior Block in Patients Undergoing Thoracotomy

after patient consenting, induction of anathesia Under sterile conditions, and while the patients will be still on the lateral position with the diseased side up after induction of anesthesia, a linear ultrasound transducer (10-12 MHz) will be placed in a sagittal plane over the mid-clavicular region of the thoracic cage. Then counting down ribs till the seventh rib will be identified in the mid-axillar\]y line. The following muscles will be identified overlying the sixth rib: the latissimus dorsi (superficial and posterior), teres major (superior) and serratus muscle (deep and inferior). The needle (22-G, 50-mm Touhy needle) will be introduced in-plane with respect to the ultrasound probe targeting the plane deep to the serratus anterior muscle . Under continuous ultrasound guidance, 20 ml of 0.25% bupivacaine will be injected then a catheter will be threaded. A continuous infusion of 5 ml/hr of 0.125% bupivacaine will be then started through the catheter.

after concenting patient, induction of anathesia Paravertebral plan block will be performed while the patient is still in lateral position and a linear ultrasound transducer (10-12 MHz) will be used for ultrasound guidance. A sagittal or transverse image can be obtained at the appropriate vertebral level. After image optimization, the Tuohy needle is advanced in plane until the tip rests in the thoracic paravertebral space. Injection of small amounts of fluid (hydrodissection) will aid in needle tip location. Saline or local anesthetic is injected through the Tuohy needle. The endpoint for a successful block is anterior displacement of the pleura. 20 ml of 0.25% bupivacaine will be injected then a catheter will be threaded. A continuous infusion of 5 ml/hr of 0.125% bupivacaine will be then started through the catheter. The catheter is threaded through the Tuohy needle and its position is confirmed by injecting local anesthetic or small air bubbles. Pleural depression should agai