A Comparative Study Between Ultrasound Guided Thoracic Paravertebral Block VS Serrartus Anterior Muscle Block in VATS as Regard Their Effectiveness in Post-operative Analgesia

o Group A: Patients will receive ultrasound guided thoraxic paravertebral block with 0.25% bupivacaine 0.4 ml/kg (max. 40 ml and not exceeding toxic dose of bupivacaine 2.5mg/kg) after induction of anesthesia. A high-frequency linear ultrasound probe will be placed between transverse processes from the T4 level (the level of port introduction) in the paramedian plane while patients is in the lateral decubitus position. The transverse processes, superior costotransverse ligaments, and pleura will be well visualized. The block needle (22 gauge) will be advanced until it crosses the superior costotransverse ligament. The prepared 0.25% bupivacaine will be administered at 0.4 mL/kg (max. 40 mL) in the thoracic paravertebral space. Depression of the pleura will be observed as a result of the spread of local anesthetic.

Group B: Patients will receive ultrasound guided serratus anterior muscle block with 0.25% bupivacaine 0.4 ml/kg (max. 40 ml and not exceeding toxic dose of bupivacaine 2.5mg/kg) after induction of anesthesia. While the patient is in the supine position, a high-frequency linear ultrasound probe will be placed horizontally on the mid-axillary line at the level of 4th or 5th ribs on the side of the block. The serratus anterior, latissimus dorsi, and intercostal muscles will be identified. The block needle (22-gauge) will be advanced below the serratus anterior muscle (SAM) towards the fifth rib (using in-plane technique). The prepared 0.25% bupivacaine will be administered at 0.4 mL/kg (max. 40 mL) between the SAM and the rib. It will be observed that the solution of local anesthesia will spread between the SAM and the rib.