Retrolaminar Block Versus Subcostal Transversus Abdominis Plane Block in Liver Resection Surgery

patients will be placed in a sitting position. The transducer will be positioned vertically 3 cm lateral to the midline at the level of the 7th thoracic transverse process. The muscles of the back, the transverse process, and the pleura between two transverse processes will be visualized. The needle will be introduced in a cranial-caudal direction toward the lamina using the in-plane method until the tip lay in the lamina 1 mL of normal saline will be injected to confirm the correct needle tip position by visualizing the spread. After negative aspiration, 20 mL of 0.25% isobaric bupivacaine. The procedure will be repeated on the opposite side.

The transducer will be placed obliquely along the subcostal margin near the xiphisternum in the midline of the abdomen. The rectus abdominis muscle and underlying transversus abdominis muscle will be identified. The position of the transversus abdominis muscle will be confirmed by sliding the transducer laterally until the aponeuroses of the external and internal oblique muscle will be visualized. The transversus abdominis muscle will be then identified, being posterior to the internal oblique muscle and will be followed back medially to confirm its position beneath the rectus muscle. the needle will be introduced through the rectus muscle in a superomedial-to-inferolateral direction towards the transversus abdominis muscle using the in-plane method, and 20 mL of 0.25% isobaric bupivacaine will be injected

Before induction of general anesthesia the epidural catheter was inserted under sterile condition with a loss of resistance technique by an 18G needle at a mid-thoracic level (Th 7-10) to cover the dermatomes innervating the incision in the upper abdomen. The epidural infusion consisting of bupivacaine 1 mg/mL, and fentanyl 2 μg/mL was activated on the attending anesthesiologist's decision. Following the hospital protocols, the infusion rate was initiated at 5-10 mL/h, increased to maximum 15 mL/h if necessary, bolus dose of 5 mL was allowed every 30 minutes.