Mid-point Transverse Process to Pleura Block Versus Thoracic Paravertebral Block in Posterolateral Thoracotomy

"the T1-T12 thoracic spinal levels will be sonographically identified using a high frequency linear US probe (HFL\_50, 15\_6MHz). Then the probe will be placed vertically and nearly 3 cm lateral to the spinous process at the thoracic level T4/T5. The paraspinal muscles (erector spinae, trapezius, rhomboid), transverse processes , superior costo-transverse ligament (SCTL) and parietal pleura will be all identified under parasagittal scanning.~In MTP block group, A 22G, 50mm block needle (SONOTAP,Pajunk, -Geisingen,Germany) will be inserted in the cranial to caudal direction via an in-plane approach between the 2 transverse processes and advanced till it reaches the mid-point between the transverse process and pleura. After negative aspiration of blood or air, a total volume of 20 ml of bupivacaine 0.25% ( not exceeding a maximum dose of 2 mg/kg) will be injected superficial to the SCTL."

In the TPV block group , the transverse process and the pleura will be identified and the needle will be inserted in the cranial to caudal direction till it pierces the SCTL and reaches the paravertebral space. After negative aspiration of blood or air a total volume of 20 ml of bupivacaine 0.25% will be injected displacing the pleura downwards