Ultrasound- Guided Retro Superior Costotransverse Ligament (SCTL) Compartment Block

"For phase 1, healthy human volunteers will be positioned in the lateral position with the side to be scanned in the non-dependent position. An ultrasound scan sequence to describe the retro SCTL space will be performed on both sides.~During phase 2, participants who are scheduled for video-assisted thoracoscopic surgery (VATS) will receive an ultrasound-guided multi-level (T3-4, T5-6 and T7-8) retro SCTL compartment block. After positioning the participants, cleaning and draping the injection site, under sterile aseptic precautions and local anaesthetic infiltration, the block needle is inserted at the corresponding vertebral level (T7-T8) under ultrasound guidance in-plane to the ultrasound beam. Once the needle tip reaches the lateral aspect of the inferior articular process and behind the SCTL ligament, the desired volume (6ml/each level) of LA will be injected. This process will be continued at the remaining two vertebral levels (T5-T6 and T3-T4)."